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2020 Must-Read!

The Game, Unchanged

by Dr. Mel Davis, PhD [@regressive_underload on Instagram] | Jan 03, 2020

A comprehensive critique of the Game Changers documentary


I am not the first to write a critique of the documentary The Game Changers, but I chose to write mine before reading others so as not to be influenced. When I finally read the other blogs out there in their entirety, I found that many of the things that troubled me the most also troubled others. Some eloquently written in blogs by Layne Norton and Menno Henselmans, have some overlap with this analysis, but I have added additional points. In my opinion, the more voices for science and unbiased truth, the better.

I will dive very deeply into both the main and minor claims and implications made by GC and go over the actual consensus (or lack thereof) as supported by more than 200 references. I will discuss what the creators of GC got right, what they got almost right, what we just don’t know yet, and what they got dead wrong.  I will walk through the film minute by minute so that you can follow along while watching if you would like.

Hopefully at the end of the day all of this helps those swayed by the clever propaganda utilized in this film to better understand how to critically analyze claims and come to the (usually less sexy and more moderate) truths for themselves.  

I will summarize each section throughout this article, but first, here is the overarching “TLDR” summary for those not ready to walk through all 60 pages of the gritty details with me. Or, please check out the short version here

SYNOPSIS:  While there is an enormous scientific consensus that eating a plant predominant diet has a multitude of potential health benefits, those benefits appear to result mainly from adding whole plant food rather than from eliminating animal products. There is evidence in support of reducing red meat consumption and some very strong evidence for minimizing or eliminating processed meat consumption. 


The overall data suggest that a health and fitness promoting diet need not be vegan, unless you want it to be. There are some supplements that vegans might need for optimal health and fitness and some caveats and care that omnivores must take for optimal nutrition. 

Health comes down to maintaining a healthy weight, exercising, and eating a diet rich in fruits, vegetables, enough protein, healthy fat sources, and unprocessed whole foods. Athletic achievement comes down to rational diet choices (omnivore or vegan), relentless hard work, and good genetics. This is what the data support.

The disappointing part about this film is that it had the opportunity to explain how veganism can be a viable diet choice for high achieving athletes if they make good nutritional choices. They could have outlined the basic principles of a healthy diet rather than leading people to believe that peanut butter cheesecake, mac-n-cheese, and other processed foods are rendered totally healthy so long as they are vegan. 



















This article will touch on but not tackle arguments regarding the effects of dairy and meat consumption on the environment or ethical considerations. I think that both of these considerations are relevant to food choice, but what I want to do here is address the nutrition-science aspects of veganism discussed in The Game Changers.

Before we delve into that, I think that the interests of the creators of the documentary warrant a small amount of attention. I will not argue that having a vested business interest in people going vegan (as does virtually every contributor to Game Changers) means that they must be biased. What I will say is that, given the lack of impartiality in Game Changers, along with the fact that the film bashes some literature funded by the dairy industry for being biased, the multiple associations with vegan businesses is more suspect.  (I myself have a vested interest in “vegan business” – I wrote and earn profit from the RP Vegan templates, but as a scientist I would never say veganism is a better or worse choice for health or fitness, just a choice like others that can be done well or poorly). This will end my comments on this topic. Pop over to Layne Norton’s blog (linked above) for a list of affiliations between Game Changers contributors and businesses selling vegan products.

I will go through the film’s claims chronologically with minute references. In some cases the documentary brings up a point and follows it up much later, in which case I will write my critique at first mention, but note all related minute marks.

 

[0:00-5:00] JAMES WILKES LIFE

The film starts with some stories about the narrator’s life and brief UFC career a decade ago and a summarized philosophy from from Bruce Lee:

  • Research your own experience
  • Absorb what is useful
  • Reject what is useless
  • Add what is specifically your own

I love Bruce Lee as much as the next gal, but his set of recommendations should not be extended to science and nutrition. I would adjust these recommendations for nutrition to the following:

  • Research quality scientific literature
  • Absorb the full consensus of the literature (do not cherry pick* articles)
  • Reject anecdote as evidence and do not assume correlations mean causation**
  • Adjust choices based on data and trade offs you are willing to make for personal preference

Cherry Picking Explained 

 
What does it mean to “cherry pick” articles? This is a term used to describe people taking one or two single studies that support their claim and ignoring a whole other body of research that refutes it. An example would be taking the one pair of blue cherries off of this tree and proclaiming that the tree is a blue cherry tree and only produces blue cherries, when there is actually more evidence that it is a red cherry tree or at least a red and blue cherry tree. (Image used with creative commons license from skepticalscience.com).


**Correlation does not necessarily indicate a causal relationship example

Imagine you did a study of male workers at several different companies and found a positive correlation between good job performance and baldness (bald men tended to perform better at their jobs). What you cannot do here is assume that being bald caused you to perform better. There are alternative possible conclusions and more research would be needed to determine what variable was likely responsible for better performance. One example might be that older men had been working at their jobs longer, had more experience, and therefor performed better and it just so happens that older men are more likely to be bald. Another explanation might be that working long hours results in better performances but also results in high stress, which increases hair loss. There might be more possible explanations (a gene for baldness that co-inherits with a gene for good work ethic and so on). The point here is that seeing the initial correlation (two things that happen to occur at the same time often) does not allow you to conclude what caused what and more research is needed to determine likely relationships. 

 

[~6:00] GLADIATORS

After talking about peer-reviewed research, Wilkes references an article on the gladiator diet which is ironically not peer-reviewed and which he mistakenly refers to as a study. This article is written by a journalist after speaking with archeologists. The archeologist interviewed states not that gladiators were vegans, but that they ate very little animal protein and a lot of barley and legumes. The latter was consumed in excess in order to keep a hefty fat layer to protect them from dangerous injuries in the arena. 

Here is a direct quote from the article:

Consuming a lot of simple carbohydrates, such as barley, and legumes, like beans, was designed for survival in the arena. Packing in the carbs also packed on the pounds. "Gladiators needed subcutaneous fat," Grossschmidt explains. "A fat cushion protects you from cut wounds and shields nerves and blood vessels in a fight." Not only would a lean gladiator have been dead meat, he would have made for a bad show. Surface wounds "look more spectacular," says Grossschmidt.

So gladiators ate a lot of carbs and stayed a little tubby and probably did not eat much meat. That is a long way from saying they were vegetarian and had the physique and health parameters we are presumably looking for in the modern era. 

The next reference is a peer-reviewed study looking at the isotope strontium in the bones of gladiators found in a grave in Turkey (Lösch, Moghaddam, Grossschmidt, Risser, & Kanz, 2014). Higher strontium levels are found in bones of herbivores and also (though this important point is not mentioned) in the bones of those who consume seafood (Burton & Price, 1999; Schoeninger & Peebles, 1981; Schroeder, Tipton, & Nason, 1972). Burning strontium produces a bright red flame, which was used in the documentary to make the results of this study flashy and tangible. Here is where you have to listen carefully. The scientist says there are “higher strontium levels in vegetarians and lower levels in carnivores”, but what about omnivores?  To find out I looked up bone - associations. 

A graphic below that I created based on data from early studies that helped establish dietary intake effects on bone levels of strontium shows which levels of strontium indicate which likely diet.

Created based on data from (Lambert, Simpson, Szpunar, & Buikstra, 1984) and example bone analysis of a population who consumed mollusks regularly (Schoeninger & Peebles, 1981).

I then went back to the article referenced in the film and plotted the raw data given for strontium levels in the bones of gladiators myself (the total n-size, or number of individual skeletons used in the analysis for strontium was 35 rather than the full 68 GC mentions were found at the grave or the 5000 bones said to be analyzed). I plotted these numbers in a simple excel graph (x-axis is randomly assigned subject number, y-axis is strontium parts per million found in the bone). I then overlaid a green box for values that fell in the likely herbivore or heavy seafood consumption range, a brown box for likely omnivore range, and red for the likely carnivore range (as expected no values fell in the carnivore zone because a fully carnivorous diet is rare for humans). Most fell in the omnivore range according to this assessment, though with a decent proportion in the high strontium likely-vegetarian or seafood-consuming range. Since we can conclude that these gladiators were either mainly vegetarian or ate a lot of fish, I looked up some historical information on ancient Roman diet and found that fish was commonly consumed by Romans and further, a Google map search reminded me that Ephesus (where the graves were discovered) is pretty close to the ocean, making access to seafood likely cheap and easy (Antonia-Leda Matalas, Antonis Zampelas, 2001).

On top of all of this, the study itself lists some of the caveats for isotope analysis (Lösch et al., 2014) and another study warns that “Variations in the strontium levels of bone thus more likely reflect differential consumption of plants rather than trophic position [carnivore versus herbivore]” (Burton & Price, 2006). In other words, isotope analysis of bones might not even be a very precise way to assess details of the organism’s diet.

SUMMARY:  Gladiators almost definitely ate a lot of grains but may or may not have eaten meat and or seafood products. Their general body composition was a little on fatter side to protect them from superficial injury during battle. They fought violently for their lives and usually died young (occupational hazard). All in all even if we knew for sure the details of their actual diets, they probably are not a nutritional ideal to aspire to unless the goal is to be overweight, forced to fight wild animals, and die young (albeit gloriously).

 

[~6:55] SNARKY SIDE COMMENT

It is good to remember that “the most advanced training and medical care in the Roman Empire” is thousands of years old as would be Roman nutritional advice. 


[~8:00]
ANECDOTES

Here we begin the anecdotal evidence references.  This is one of the main problems with Game Changers –– the reliance on anecdote and subjective experience. In science this is not at all convincing data. The choices or opinions of any individual athlete who succeeded while being vegan or “felt stronger” once they went vegan is not evidence that veganism confers any real advantage.  The fact that Nate Diaz beat Conor McGregor (as satisfying as that was for some of us) is not evidence that veganism makes a better athlete. In this case it was more directly evidence that Conor needed to work on ground defense against a really good black belt.  

Mind you Conor won in the rematch and not long after Nate Diaz was rather spectacularly beaten by a meat-eating Masvidal. This is also not evidence that omnivores are better athletes. These are anecdotes and you can see the problem with them – single instances of correlation do not mean anything about the relationship of animal consumption and performance, especially not when there are examples of positive (winning and being vegan) and negative correlation (losing and being vegan). 

If it rains on a day that you wear a red shirt, do you shout that red shirts make it rain? No –– because an anecdotal correlation does not mean anything about a real relationship between shirt color and weather. Of course, diet is a little more intertwined with athletic performance than clothes and rain in this silly example, but it illustrates the point –– a single story or individual correlation or experience does not make for reliable data. 

There is a roughly agreed upon hierarchy of evidence strength in science and although the details are sometimes debated, it usually looks something like this (CRD, 2009; Greenhalgh, 1997; Manchikanti et al., 2014) (listed from strongest evidence to weakest):

  1. Systematic reviews and meta-analyses 
  2. Experiments and randomized controlled studies 
  3. Cohort and survey studies
  4. Case reports, anecdote, and expert opinion

I will list below some explanations for those of you unfamiliar with these classifications. Ill start with the simplest and least powerful and move up to the most complex and most powerful. To make it easier to understand I will describe each example within the context of an imaginary scientific question: “Does eating a newly discovered Amazonian plant help with weight loss?”

INCONCLUSIVE / WEAKEST EVIDENCE TYPES:

Expert opinion: Based on related information, an expert makes their best guess. For example, an expert in Amazonian plants says this newly discovered plant looks and grows like a known plant that has a molecule already extracted to make weight loss enhancing drugs. This expert thinks it is likely that that molecule or a related one with similar effects might exist in this newly discovered plant. (This is not evidence, but opinion that directs what studies need to be done to collect actual evidence).

Anecdote: Some people visiting the Amazon made tea with the plant’s leaves and lost weight. It is difficult to say that the weight loss resulted from the tea and not from hiking in the Amazon or eating less calores while traveling. (Again, this is not evidence, but directs interest in potential studies).

Case report: Scientists observe a person or two consuming the plant, measure weight changes, and see decreases in weight. It is hard to say whether the person made other changes to diet and exercise that might have caused the weight loss and be unrelated to the plant. (This is not strong evidence, but observation that directs what studies need to be done to draw stronger conclusions).

MORE CONVINCING EVIDENCE TYPE:

Cohort/Survey Studies: These are observational and not experimental –– they do not have controlled variables (though many such studies will attempt to account for additional variables in analysis). People are asked to report what they eat / do / etc. and associations are drawn from these data. So in our example this would mean that scientists surveyed a large number of people and asked if they ate the new Amazon plant, when they started eating it, how much they ate daily, and to report their weight across some period of time. Then they might see that people who consumed a lot of the new plant lost weight more than those who did not. This is a correlation. (It is not causation though because, for example, maybe the plant is sold in health food stores meaning people who are exposed to it were more likely to already care about health and fitness. Perhaps the study was done in spring when fitness oriented people are preparing for bathing suit weather in the summer and had started diets. These are examples of confounds that have to be considered or controlled for before scientists could say that data support the idea that the plant enhances weight loss directly. Good cohort studies assess these types of confounds and attempt to account for them, but not all potential confounds are obvious.

EVEN MORE CONVINCING EVIDENCE TYPE:

Experiments and randomized, controlled studies:

These types of studies include actual experiments. They have variables and controls. Subjects are randomly included in the different test or control groups to prevent bias. An example might be scientists assigning 15 people to each of two groups. Both groups are assigned the same diet and exercise regimen. 

One group is given a daily tea made with mint and the Amazon plant, the other group is given a daily tea made with just mint (so that neither group knows if they are getting the plant and will not have a biased response). Both groups then have their weight assessed weekly by scientists. The scientist assessing weight cannot see which subjects are in which group so that the analysis cannot be biased. When the analysis is finished the scientists compare weight loss in each group. Then the scientists assess the statistical likelihood that more weight was lost by chance in the plant group. If the Amazon-plant-tea group was statistically more likely to lose weight or lose more weight compared to the mint-only-tea group, this is good evidence that the plant does have an effect on weight loss. To be really convinced though, we like to see lots of the same study done slightly different ways (this is called replicating results), which is where the strongest evidence classification comes in:

THE MOST CONVINCING EVIDENCE TYPE:

Systematic reviews, meta-analyses, and umbrella reviews:

These types of scientific papers analyze a bunch of experimental and or cohort data (sometimes from hundreds of studies) and use all of the results to draw a conclusion. When you find a few recent systematic reviews on a topic all in agreement about a relationship between a variable and an outcome, in this example between our imaginary Amazon plant and enhanced weight loss you can start to feel confident about conclusions. It is still important to look at caveats and side effects and so on, but this kind of data can allow you to confidently assume a relationship. Umbrella reviews analyze the conclusions of multiple systematic reviews and meta-analyses and are especially reliable.

Anecdote is not used in science as evidence independent of other data, but can be used to initiate lines of inquiry using more reliable methods. For example, if this new plant were discovered in the Amazon forest and a few people who had consumed it reported losing weight, these anecdotal stories might spur some cohort studies (more thorough, powerful assessments of reported effects) which would be a little more convincing. Still this type of evidence is prone to some errors and biases. Next we would want to set up a randomized controlled study looking at weight change in subjects whose diets were otherwise the same and who were unaware of whether they were consuming plant or placebo with someone analyzing the data who is also “blind” to which subject is in which group (this is called double-blind and significantly reduces chances of bias). After several of each of these last two studies were published, a systematic review and meta-analysis of all of those cohort and experimental studies that concluded that the Amazon plant had weight loss enhancing effects would be pretty solid evidence on which to base the claims. For further assurance that the effect was real and reliable we would also probably want to see a mechanistic explanation (how does the plant facilitate more weight loss?) and a dose response relationship (perhaps that more plant leads to more weight loss). 

No scientist would be convinced of the effect of the plant based merely on a few people’s opinions or reports, just as we should not be convinced that veganism makes you a better athlete based on some examples of good vegan athletes.


[~9:00] MORE ANECDOTE

Scott Jurek is a phenomenal ultra-endurance athlete. He is also a vegan. You can only conclude that you can be both vegan and a great ultra-runner, not that you must be vegan to be a great ultra-runner. There are loads of omnivorous ultra-runners who also perform exceptionally. All of their success is likely tied to genetics, an amazing work ethic and pain tolerance, a lot of years of training, good sleep and good nutrition (irrespective of protein source).


[~10:00] WILKES’ SURPRISE THAT PROTEIN IS NOT A PRIMARY ENERGY SOURCE

Wilkes explains that he is “confused about how Scott’s meat free diet could possibly give him enough energy”. This statement reveals some fundamental lapses in nutrition knowledge on Wilkes’ part. Not that I am knocking him for that, when you don’t know things, you seek to learn them and he was clearly on that mission. Those with a basic background in nutrition will be aware that the energy for endurance (and most athletic endeavors for that matter) comes primarily from carbs. (Ironically, one exception is in ultra-long runs when fats begin to be a viable energy source, but that is a long story not necessary here. For more info on endurance fueling [shameless plug] see our recent ebook on endurance nutrition). (Hint: we recommend loads of carbs and some fats, not meat, to fuel endurance efforts whether you are vegan or not).

So whether your protein comes from meat or plants is really irrelevant to your energy intake and energy needs. Energy for endurance is all about how many calories you are consuming and how steady you can keep available glucose levels in your blood to keep you moving for hours and hours. It is secondarily about recovery (for multiple day events like the one Scott is gearing up for in this part of the film), which is also more reliant on carbs than any other macronutrient. A side point here is that endurance sport is one of the only sports in which muscle can be a liability if the runner is carrying more than needed. Thus endurance running is a sport for which muscle loss can be less devastating to some extent and therefor a sport for which protein consumption totals and quality is a bit less critical a concern. (More on protein and sport to come later).


[~11:00] (NOT) POUNDING FATTY MEAT THE NIGHT BEFORE A GAME

Dr. James Loomis is spot on. Meals the night before a big game that requires repeated athletic efforts should be carbohydrate heavy in order to keep glycogen (carbohydrate stores in the muscles) high and prepare the athlete to perform. The daily needed amount of protein however still stands for athletes to maintain their muscle. Eating protein beyond the needed range does take away from calories that would be better spent on carbs or fats, but this is all irrespective of protein type. This argument better supports the conclusion that keto diets are not optimal for sport performance (which they are not––though they do have other uses and benefits for non-athletes––but that is another article entirely). 


[~11:30] LIEBIG, HISTORY

Ironically, the assertions of the 1800’s chemist, Liebig, about the need for meat consumption in athletics were based on anecdote and theoretical calculations (he never carried out a physiological experiment). Some might say this is similar to the reliance on anecdote by the writers of The Game Changers documentary. At any rate Liebig’s ideas were questioned and abandoned by science over 100 years ago (Guggenheim & Wolinsky, 1981). I think the advice we can garner from this little bit of history is to not buy into diet fads based on anecdote and speculation


[~12:00 – 14:30]

More anecdote that can be disregarded, aside from to say that a vegan diet can support elite athletic performance. 


[~14:30] MEAT MISCONCEPTIONS

There is a misconception among many that animal protein is needed for sport performance––it is not at all mandatory. It might take a little more care to get all needed amino acids in the needed ratios from plants, but it is completely possible. There is no reason a vegan athlete cannot eat enough protein to gain and maintain needed muscle for performance. You just cannot extend this to say that getting your protein from animals is detrimental to performance or somehow prevents best performance. 


[~15:30] LENTILS OR PEANUT BUTTER SANDWICH VS BEEF OR EGGS

Even if these items have equivalent total protein, amino acid ratios, digestion and absorption differ. If you had the lentils and the equivalent amount of protein from beef or eggs, you would be short on the essential amino acids methionine and cysteine and you would probably absorb about 20% less protein from the lentils than from the beef or eggs (Kniskern & Johnston, 2011; Marsh, Zeuschner, & Saunders, 2012; Rogerson, 2017; Young & Pellett, 1994)

Wheat bread and peanut butter is a bit better on the amino acid profile as wheat has the methionine and cysteine that peanut butter is low in and peanut butter has the lysine the bread is low in. The digestion and absorption would still be less complete compared to the animal protein, requiring you to eat a bit more to match total absorbed protein. 

Dairy protein supplements do seem to promote better muscle protein synthesis compared to plant based ones (Hartman JW, Tang JE, Wilkinson SB, Tarnopolsky MA, Lawrence RL, Fullerton AV, 2007; S. M. Phillips, 2014; Tang, Moore, Kujbida, Tarnopolsky, & Phillips, 2009; Volek et al., 2013; Wilkinson et al., 2007), though less research has been done on plant protein supplements and muscle protein synthesis compared to dairy based supplements (van Vliet, Burd, & van Loon, 2015). Increasing the amount of plant protein and paying attention to amino acid profiles of plant proteins might ameliorate differences though (Langer & Carlsohn, 2014).

As Wilkes says, as long as you get enough of all of the needed essential amino acids, the source is probably irrelevant.  He is just leaving out the amino acid ratio issues and the absorption differences that require increases in total consumption and attention to amino acid profiles if you want to get what you need as a vegan.

SUMMARY:  It is possible to get all of the essential amino acids from plant or animal protein and your body probably does not care about the source as long as the ratios are good and there are sufficient amounts absorbed. Achieving this just takes a little more care and consideration on a vegan diet.

 

[~17:00] STRONG ANECDOTAL EXAMPLES, WEAK EVIDENCE

I love Kendrick Farris and Patrik Baboumian, but this is just more anecdote. There are weightlifters and strongmen on the same level who are omnivores. Neither group can blame their accomplishments on whether their protein comes form plants or animals.

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[~21:30] ANECDOTE: VEGAN BOXER LOSES TO KLITSCHKO

Another anecdote, but one worth diving into as I think they were reaching with this one. The vegan boxer “went the distance” (combat sports lingo for ‘he lost, but not embarrassingly’) against Wladimir Klitschko who did eat meat (as evidenced by an interview where he gives the following diet advice: “switch from meat to fish every once in a while”).  So the conclusion from this anecdote is you can be vegan and be an athlete. An even weaker conclusion than the previous anecdotes provide.

Next, the documentary dives into endothelial function, which I will cover in depth, but first an important tangent into the actual data on muscle mass, athletic performance, and protein sources. I have critiqued the claims and implied claims made directly by The Game Changers, but I think a discussion of what the bulk of the literature actually says about protein sources and sport nutrition is worthwhile. 

One of the major takeaways that the film’s creators are clearly going for is that a vegan diet will improve athletic performance compared to a non-vegan diet. Both vegans and omnivores can consume fruits, vegetables, whole grains, legumes, fiber, and healthy fat sources. The primary difference between vegan and non-vegan diets is protein sources and to a smaller extent fat sources as omnivores will get at least some animal fat even with lean meat consumption. So let’s examine the data on protein source and fat source effects on muscle mass and athletic performance outcomes.  

PROTEIN

Since it does not provide the most efficient energy source, the main effect of protein within the context of athletics is on lean mass gains and retention (and at a very basic level physiological function as most body processes are dependent on enzymes that are made of protein) (Jeukendrup & Gleeson, 2018)

Here are the differences between animal and plant protein, summarized:

Animal protein contains more branch chained amino acids (important amino acids for muscle protein synthesis) and more favorable amino acid ratios. Animal based protein might therefor better support muscle maintenance and growth (van Vliet et al., 2015). Plant proteins are packaged in more difficult to digest cellulose and plants contain more antinutritional factors like glucosinolates, trypsin inhibitors, hemagglutinins, tannins, phytates, and gossypol that affect the digestibility of protein (Bye, Cowieson, Cowieson, Selle, & Falconer, 2013; Friedman & Brandon, 2001; Gilani, G. Sarwar; Cockell, Kevin A.; Sepehr, 2005; Jansman, Enting, Verstegen, & Huisman, 1994). (Before anyone gets upset at the attack on plants here – plants also contain more micronutrients and have a host of health benefits, and we will get to that, but this section is just about the accessibility and quality of protein). All of this being said, increasing the amount of plant protein consumed, and paying attention to amino acid profiles can likely make up for these differences, as mentioned.

Athletic performance generally involves the need for power (largely influenced by strength and dependent on cross sectional area of muscle) and or endurance. As such we will divide the discussion into effects of protein source on muscle mass and effects of protein source on endurance performance: 

MUSCLE MASS

As discussed briefly already, there have been a host of studies supporting animal protein as a better amino acid source for muscle mass gains (Campbell et al., 1999; Yang Du, Oh, & No, 2019; Mobley et al., 2017; Rondanelli et al., 2016; Volek et al., 2013; Wiebe, Bruce, & McDonald, 1984; Wilkinson et al., 2007). There have also been recent studies claiming that plant protein and animal protein can equivalently support muscle growth (Maltais, Ladouceur, & Dionne, 2016; McEvoy, Temple, & Woodside, 2012; Nebl et al., 2019). A 2019 study from Ciuris et al showed lower average muscle mass in vegetarian endurance runners compared to omnivores, but thankfully rather than concluding a vegan diet cannot support muscle mass, the authors delved deeper. They found that protein consumption was lower in the vegetarians studied and concluded that this along with lower absorption rates might account for their having less muscle. (Ciuris, Lynch, Wharton, & Johnston, 2019). When looking at all of the data, it seems likely that any the differences in muscle mass would be reduced or eliminated if the vegetarian athletes increased the amount of plant-based protein they consumed. 

It is worth noting that there is a lack of data to support that vegan athletes have or gain more lean body mass on average. The fact that the literature either suggests that animal protein is superior to plant protein or that they are equivalent for muscle mass gains probably means that, under the right circumstances, they can be equivalent. 

To summarize, I think that the differences in the literature on this topic are likely primarily the result of the following points:

  1. We might sometimes see no difference in muscle mass between vegans and omnivores due to the subjects studied. Those new to weight training are likely to have muscle growth results under a much wider range of conditions irrespective of diet (Pasiakos, McLellan, & Lieberman, 2014). In other words, when you are testing newbs for muscle growth, variables that might normally limit growth in trained individuals will not have as significant an effect. Simply put – newbs are gonna grow almost no matter what they do so the size of that growth might be so big that the effects of diet changes will be masked. 
  2. It might look like meat eaters have an advantage due to a failure to control for total protein consumption and absorption. Many studies, in attempt to control variables, assign equal amounts of protein to the plant and animal protein groups. This does not account for the better digestion and absorption and amino acid ratios found in animal protein. In other words, when fed equivalent grams of protein, the animal protein group will actually have more bioavailable amino acids. In order to truly match usable protein between groups, approximately 20% more plant protein would need to be consumed by the plant group. (Kniskern & Johnston, 2011; Schaafsma, 2000)

SUMMARY:  There is no evidence that plant protein is better for muscle mass retention or gain. There is evidence that animal protein is superior in this regard, but a growing body of recent research suggests that under the same conditions (including adequate consumption to make up for lower absorption and attention to amino acid ratios) the source of protein is likely irrelevant for muscle protein synthesis.



ENDURANCE

As mentioned, protein is not a primary energy source and is certainly not an efficient energy source for endurance performance. Carbohydrates (and in the case of ultra-endurance also fats) provide the energy needed for extended output. An interesting aspect of pure endurance sport is that it is one of the few examples of a sport for which more muscle and more strength is not always beneficial. So it is true that endurance athletes often benefit from eating slightly less than otherwise recommended protein amounts in order to make calorie room for more carbohydrates to support performance, even at the cost of some muscle loss (Jeukendrup, 2011)

When energy totals and carbohydrate amounts are controlled for, we generally see no differences in performance between non-vegetarians and vegans and vegetarians (Baguet et al., 2011; Craddock, Probst, & Peoples, 2016; Nebl et al., 2019; D. C. Nieman, 1988; David C Nieman, 1999; “Nutrition and Athletic Performance,” 2016; Raben et al., 1992)

Though a couple studies have shown either better performance in omnivores or better performance in vegetarians, this might be due to the type of endurance bout tested and or a lack of controls for energy and carbohydrate intake (Khanna, Lal, Kommi, & Chakraborty, 2014; Lynch, Wharton, & Johnston, 2016).

To summarize, although the consensus is pretty solid that protein source does not impact athletic performance and that carbohydrate intake and health are better determinants. I think that the minor differences in the literature are likely a result of the following points:

  1. Comparing vegetarian, vegan, and omnivorous endurance output without controlling for differences in total energy and carbohydrate intake. Many vegetarians default eat more carbohydrates since their protein sources often contain carbs, but controlling for carb and total energy amounts will likely eliminate differences. 
  2. Different endurance performances might favor more or less muscle mass. If the sport requires more muscle mass and power (like track cycling) then someone with more muscle mass will probably perform better and these sports might favor athletes with more muscle mass. In contrast distance running is benefitted by lower body weight, so a less muscled athlete might perform better.)

SUMMARY:  Total carbohydrate and total energy intake is the main determinant of endurance performances in healthy athletes. The literature suggests no consistent difference between omnivores and vegetarians or vegans in endurance performance capacity.

FATS

The other main difference between an omnivorous diet and vegan diet is that animal fats will be consumed to some extent by omnivores. Animal fats generally differ in some ways from many plant fats. Fat type is more relevant in health, but we will walk through the ways that fat in general matters for athletic performance.

Timing of fat intake can play an indirect role in performance in that dietary fat will slow digestion of other macronutrients such as carbohydrates that might be needed for performance. Further, fat intake prior to training can impact endothelial function and therefor blood delivery to working tissues. This effect is not plant versus animal source dependent however (much more on this soon). 

In terms of muscle gain and athletic performance, fat source does not appear to have a direct impact insofar as enough is consumed. There is a general consensus agreed upon by the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine among others. They agree that the main importance of dietary fat intake for athletes is that it be sufficient to provide the essential fatty acids, allow absorption of fat-soluble vitamins, and support hormonal and cellular health. Getting enough essential fatty acids (found primarily in fish, but available as supplements) and consuming primarily unsaturated fats is also recommended. Limiting saturated fat intake to 10% of total fat intake and avoiding trans-fats is also broadly agreed upon, though this recommendation is for health and not gains or performance per se (“2015-2020 Dietary Guidelines | health.gov,” 2015; “Nutrition and athletic performance,” 2009; “Nutrition and Athletic Performance,” 2016; Bytomski, 2017; Potgieter S, 2013).

It is worth considering that health is a prerequisite for long-term athletic performance across life and there is quite a lot of data supporting differential effects of different fat types on health. Getting a larger proportion of fats from plant sources is probably a good idea to help limit saturated fat intake. Likewise avoiding processed foods (vegan or not) is wise to limit trans-fat intake.


[~23:00] BURRITO EXPERIMENT

There are a number of problems here. First the macronutrients and fat types in the burritos do not appear to be controlled, the subjects are not blind, but most importantly, no explanation for why cloudy blood is bad or should be avoided is ever provided. The truth is that a very fatty vegan meal would produce the same result, as would any fatty meal at any time. If they had compared a fat free animal burrito to a fatty vegan burrito, the opposite effect would have been seen (cloudy post-vegan meal blood) Blood lipemia (that results in the cloudiness) comes from the amount of fat in your blood and may be impacted by type of fat, but not animal versus plant fat source (Sciarrillo, Koemel, Tomko, Bode, & Emerson, 2019). So this little exercise showed and proved nothing, but admittedly served as a sexy, striking distraction. 

The seed of truth in this exercise is that plants tend to have higher ratios of “healthy fat” (monounsaturated and polyunsaturated fat) to unhealthy fat than many animal sources. Similar to the protein issue, however, a careful diet can result in healthy intake whether you are vegan or omnivorous and likewise, terrible choices that do affect cardiovascular health can be made under either diet constraint.


[~25:30]

“Dr. Vogel’s experiment was backed up by numerous studies measuring how a single animal based meal can impair blood flow”.

First of all that was not an experiment, it was a poorly executed collection of anecdotal information under uncontrolled, biased conditions. Second, only one of the 22 studies referenced in this section compare vegan to animal food ingestion, so saying this concept was “backed by numerous studies” is outright incorrect. In this single study that did compare animal to plant based meals, the meat meal had 53g of fat compared to 3g of fat in the non-meat meal, adding an important variable that actually accounts for the differences in endothelial function observed (Bae et al., 2001). As such it is titled: Postprandial hypertriglyceridemia impairs endothelial function by enhanced oxidant stress, demonstrating that that the comparison the authors were actually shooting for was fatty versus low-fat meals and the conclusions the authors made were about the effects of fat, not animal products. Granted they should have perhaps controlled for that variable as well, but luckily tons of other literature has taken care of that and we do not have to rely on this one study. The groups whose endothelial function were compared in the study ate one of the following meals:

HIGH FAT (53.4 g fat)

803 kcal from: Korean barbecue, egg, milk, oil, mayonnaise, rice and vegetables 

LOW FAT (3 g fat)

802 kcal from: rice, vegetable soup, vegetable, orange juice, apple, kimchi

As expected based on what we know about a high fat meal, the high fat meal (that happens to contain meat) reduced endothelial function. 

The next study shown, titled, Impaired flow-mediated vasoactivity during post-prandial phase in young healthy men (Marchesi et al., 2000) compares vasodilation after fasting compared to after a high fat meal. So even less relevant to the points the documentary creators are trying to make. 

So far all we know is that after you eat a fatty meal, those fats are digested and components are transported in your blood (just like any other macronutrient) and that this reduces endothelial function following that meal. Whether or not this temporary reduction in function is negative has yet to be determined. What this does point to is that eating a fatty meal in the hours before training is probably not great for athletic performance. 

The next study about avocados actually suggests that consuming avocado alongside meat eliminated the inflammatory effects of the hamburger meal. This particular study would support the conclusion that adding avocado to a meat meal is equally effective to not eating the meat (assuming anyone is still onboard with meat being the effective variable). It is also notable that this is a pilot study and has not been peer reviewed by experts in the field (Z. Li et al., 2013). At any rate, a subsequent meta-analysis and systematic review of the avocado research found that signs point to no net impact of avocado on its own in this regard, so we can probably disregard the pilot study altogether as support for any conclusion. (Mahmassani, Avendano, Raman, & Johnson, 2018)

Recent studies comparing effects of various fats saw equivalent lipemic responses (the blood cloudiness shown in the documentary that temporarily reduces endothelial function) across fats, plant and animal based alike (Sciarrillo et al., 2019). Another study directly compared the inflammatory effects (thought to lead to endothelial dysfunction in the longer term) of a high fat vegan meal to a high fat non-vegan meal. This study concluded that responses after a high-fat meal were the same whether the main fat source was cheese or palm oil. When variables are controlled, it appears that animal based foods have no particular, special effect on endothelial function (Demmer et al., 2016)

Another study showed that two different types of plant-based fat had differing effects on endothelial function – shea butter based fat did not impair function, whereas sunflower oil did (Berry et al., 2008). So some mixed results here, but none pointing to the conclusion that animal fats have any larger or differing effect on lipemia or endothelial function compared to plant based fats. 

A 2019 Nutrition Review concludes that at this time there are too few studies to make any conclusions regarding the modulation of endothelial function by dietary monounsaturated and polyunsaturated fatty acids, but there is some mounting evidence that saturated fatty acids impair function. They also note that distinguishing between acute effects of blood triglycerides from eating a fatty meal need to be distinguished from long term detrimental effects on endothelial function (Youjia Du, Taylor, & Zahradka, 2019). In short, there is not even a conclusion that different classes of fats (irrespective of source) have any differential effects, much less that those types of fats from animal or plant sources would act differently. Further, there is a question as to whether the acute effects of a fatty meal on the endothelium are related to any long-term detrimental issues.

There are 19 other studies referenced in the lower left corner of the screen while the video of a blood vessel model flows in the background at around 26 minutes. The following are those studies and their conclusions:

Circulation. 100(10:1050-5 | Purple grape juice improves endothelial function in patients with coronary artery disease

Ann Agric Environ Med. 16(2):305-8Regular drinking of chokeberry juice has a beneficial effect on endothelial function and lipid metabolism in men with mild hypercholesterolemia

Am J Clin Nutr. 98(5):1179-91Blueberry intake acutely improves vascular function in healthy men in a time- and intake-dependent manner

Am J Clin Nutr. 88(6):1685-96Daily consumption of cocoa for 2 weeks is not sufficient to reduce blood pressure or improve insulin resistance in human subjects with essential hypertension

Am J Cardiol. 93(11):1384-8 Acute black tea consumption improves coronary vessel function

Free Radic Biol Med. 72:232-7Consumption of blackcurrant juice drink can improve vascular health in people who do not eat fruits and vegetables regularly

Free Radic Biol Med. 52(1):95-102Apples and spinach improve endothelial function in healthy men and women

Clin Sci. 102(2): 195-201These results suggest that one mechanism by which black tea may reduce cardiovascular risk is via improved vasodilator function of conduit arteries

Circulation. 104(2):151-6 | Short- and long-term black tea consumption reverses endothelial vasomotor dysfunction in patients with coronary artery disease

Br J Nutr. 99(4):863-8 | Black tea is as effective as green tea at improving endothelial function

JAMA. 298(1):49-60 | Small amounts of dark chocolate intake can reduce blood pressure and improve vasodilation

Int J Food Sci Nutr. 64(8):988-92 | Results suggest that daily intake of boysenberry juice might reduce cardiovascular risk

Hypertension. 46(2): 398-405 | Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. 

Heart. 92(1):119-20 | Dark chocolate improves endothelial function

Heart. 90(12):1485-6 | Green tea improves endothelial function in healthy smokers

Nutrients. 7(6):4107-23 | Blueberry consumption improves endothelial function in adults with metabolic syndrome

Phytother Res. 28(10): 1492-8 | Consumption of black raspberry significantly improved vascular endothelial function in patients with metabolic syndrome.

J Am Coll Nutr. 23(3): 197-204 | Daily consumption of grape and pomegranate juice may improve endothelial function in adolescents with pediatric metabolic syndrome

J Am Coll Cardiol. 46(7): 1276-83 | Endothelium-dependent vasodilation is acutely increased in smokers following ingestion of a cocoa drink

SUMMARY:  So it is as Wilkes says, there is a large body of research saying that plants can have a positive impact on endothelial function, but all these 19 papers do is support the healthy effects of a variety of fruits, cocoa, and tea on endothelial and related function. Just keep in mind – you can eat blueberries, drink green tea and eat chicken (if you want to). This literature does not support any benefits of eating meat or refraining from eating meat. High fat meals acutely impair endothelial function (but what that means in the long term is still unclear). Also, consuming certain plants seems to improve endothelial function. (No need to go vegan to reap the benefits, but also no suggestion that you cannot go vegan).


[~26:00] BEETROOT JUICE

Drinking beet juice before training allows longer cycling and heavier bench press, but is this evidence that a vegan diet is superior? 

Here are are several studies showing no change in performance with beetroot juice consumption in elite cyclists, able-bodied hand cyclists, paracyclists, kayakers, or sprinters. (Buck et al., 2015; Cermak et al., 2012; Flueck et al., 2019; Muggeridge et al., 2013) And another suggesting there are sex based differences in response to beetroot juice (more specifically the purported important ingredient in beetroot, dietary nitrate) (Wickham & Spriet, 2019). Finally here is a recent systematic review and meta-analysis of the dietary nitrate data concluding that dietary nitrate supplementation may improve endurance outcomes but not timed trial performances and calling for more research (McMahon, Leveritt, & Pavey, 2017). 

Something especially important to note is that none of the subjects in any of the beetroot juice or nitrate studies cited by myself or by Game Changers were listed as vegetarian or vegan. So it is feasible that even if beetroot juice has some incredible performance enhancing effects under some specific circumstances, we don’t know if that effect would be the same in vegan participants since that study has not (to our knowledge) been done.  

GC also implies that the cited paper supports increased bench press weight with beetroot juice consumption. The paper they cite does not actually study bench press at all, but it does reference a primary source that does (Mosher, Andy Sparks, Williams, Bentley, & Naughton, 2016)

The bench press beetroot study is a double blind, controlled, randomized cross-over study which does indeed show significant increases in repetitions to failure and total weight lifted for the beetroot juice group compared to placebo. The authors conclude that “nitrate supplementation has the potential to improve resistance training performance and work output compared with a placebo”, but not surprisingly they do not conclude that powerlifters should go vegan. Veganism is not a part of this study.

Hopefully you are seeing the bait and switch trend here. “Here is real data that involves a food” (we won’t mention that subjects were not vegan and veganism is not tested here at all)…. “You should be vegan for these benefits”.

You can drink beet juice without being vegan. No really, you can. Give it a try.

SUMMARY:  Dietary nitrate (contained in beetroot juice) might be a worthwhile supplement for athletes, but the details, dosages, and effects are still being worked out. No studies of relative effects of beetroot juice or dietary nitrate on vegans versus omnivores have been done, but it is prudent to assume that other differences in diet would not prevent or enhance effects.

 

[~27:00] DOTSIE THE OLYMPIAN 

I am troubled by Dotsie’s partial range of motion leg press, but that is a topic for another day – she is clearly an incredible athlete and this training practice has not hindered her from achieving truly incredible athletic performances. This is often the case. The greatest athletes in the world can get away with some minor sub-optimal practices and still succeed due to amazing genetics and years of hard work. Their success does not mean their habits are a model for best practice. I read about a woman who drank alcohol the night before a marathon and still placed top in her age group. I would not recommend everyone start drinking the night before an endurance race based on this anecdote though. Science can dictate best practice and often there is a range of best practice or at least some basic principles, within which, for example, a variety of diets can fit. 


[~28:00] PROTEIN PACKAGES / INFLAMMATION

Neu5gc

Neu5gc (aka N-Glycolylneuraminic acid) is mentioned here and also built into the infographic at around 35 minutes. This molecule is indeed found only in meat. There are correlations between colorectal cancer and processed meat and overconsumption of red meat, both of which contain Neu5gc. It is in part because of this that Neu5gc has been implicated as a molecule that might be involved in cancer. (If you remember from earlier, finding a mechanistic explanation for how a food might cause an effect strengthens the argument that a cause-effect relationship exists). 

The film cites just one paper, but refers to several articles discussed within that paper. One of those explains that humans have an antibody to neu5gc thanks to infant ingestion, even though our bodies do not produce neu5gc themselves. Interesting, but does not really suggest neu5gc to be problematic and so not really relevant to the question or debate at hand (Taylor et al., 2010)

There have also been some animal studies supporting Neu5gc as inflammation producing and potentially linked to tumor development via that inflammation, but the authors acknowledge that the mouse model used and experimental procedures do not mimic human patterns of consumption or antibody production well (Samraj et al., 2015).

A 2018 review lists the various candidate molecules to explain the correlation between high red meat and processed meat consumption and concludes that more research is needed to elucidate the molecules involved in this correlation (Cascella et al., 2018)

More research is needed, but there is a correlation between processed and red meat consumption and colorectal cancer. Though some think this correlation can be eliminated with moderate consumption of these products (De Smet & Vossen, 2016). The molecules listed in this part of the documentary are candidates in the search to explain a confirmed correlation in order to support causation. 

Since what we know for sure is that consumption of processed meat products and overconsumption of red meat are correlated with increased cancer risk, we can cut down or eliminate these from our diet for now and not worry about which of their molecules might be responsible. I can get behind this recommendation, but not the take away that cancer causing molecules are in all animal products and that these must be eliminated from the diet for cancer prevention. 

dAGEs

Another scary sounding set of molecules accused of evil are dietary advanced glycation end products (dAGEs). First, the cited paper lists AGE content of foods and although fatty meats do tend to have the highest numbers, an in depth look reveals that broccoli, pasta, and hummus all contain more than milk –– in other words there is no correlation between animal products in general and increased AGEs. Further, the study concludes the following: “The current dAGE database demonstrates that a significantly reduced intake of dAGEs can be achieved by increasing the consumption of fish, legumes, low-fat milk products, vegetables, fruits, and whole grains and by reducing intake of solid fats, fatty meats, full-fat dairy products, and highly processed foods.” (Uribarri et al., 2010)

In short, the scientists who wrote the paper did not by any means conclude that veganism was the solution. In fact they recommended the consumption of some animal products in order to reduce risks. A further look at the literature suggests that vegetarians actually tend to have higher AGE levels than omnivores (Šebeková et al., 2001), but before we conclude that the omnivorous people are healthier, the literature is unclear as to whether AGEs are all good or all bad or whether different types have differing effects as described in a systematic review by Kellow and Savige (Kellow & Savige, 2013).

Endotoxins

These are also known as lipoglycans or lipopolysaccharides. They do not come from animal protein, they are produced in certain types of bacteria, some of which live in your gut (Brade, 1999; Raetz & Whitfield, 2002). An excess of endotoxins is referred to as endotoxemia and it has been shown that the consumption of fish, fresh vegetables, fruits (in particular berries) may reduce systemic endotoxemia (Ahola et al., 2017).  

The angle they are getting at here in the film is that dietary factors may alter the bacterial composition of your gut and potentially lead to increases in endotoxins by disrupting the health of your microbiome. Interestingly, this study suggested meat consumption might maintain more balanced gut bacterial populations and reduce inflammatory gut responses (Zhu et al., 2015). I would not put too much stock in either conclusion though as the microbiome is an extremely complex system with massive individual differences that we are just beginning to understand.

Other studies have suggested that endotoxemia is associated with high serum triglyceride concentrations, in other words that eating a high fat diet and maintaining high levels of fat in your blood might increase endotoxin circulation irrespective of fat source (Lassenius et al., 2011; Moreira, Texeira, Ferreira, Do Carmo Gouveia Peluzio, & De Cássia Gonçalves Alfenas, 2012; Pendyala, Walker, & Holt, 2012; S. Bibbo, G. Ianiro, V. Giorgio, F. Scaldaferri & A. Gasbarrini, 2016). 

Two 2019 reviews on the topic however, suggest that all things considered, even the more strongly supported idea that endotoxemia is related to high fat diets, falls into question when all of the literature is assessed. Both sets of authors conclude that large individual differences exist and that a great deal more research is needed to understand the relationship between any diet items and endotoxemia and the gut microbiome (Danneskiold-Samsøe et al., 2019; Fuke, Nagata, Suganuma, & Ota, 2019)

Heme Iron

The film also warns that meat contains heme iron, which it does, but the warning part was at first a bit confusing to me. Iron is a mineral needed by the human body and its heme form (found primarily in meat) is better absorbed than non-heme iron (Buzała, Słomka, & Janicki, 2016). Chronically inadequate iron absorption results in iron-deficiency anemia (a decrease in the number of healthy red blood cells). This means that the blood’s ability to deliver oxygen to working tissue is decreased. The presence of heme iron in meat is actually an advantage for omnivores, particularly athlete omnivores. 

The meta-analysis study cited in GC helped me understand my earlier confusion. The study does conclude that heme iron intake is associated with coronary heart disease (Yang et al., 2014). A 2019 review further helped me reconcile the idea that iron could be both needed and its best-absorbed form dangerous. The review concluded that all trace-mineral (some of which have non-meat dietary sources) intake likely has a bell shaped curve of effect wherein too little or too much will have health consequences (Mohammadifard et al., 2019).  A scientific advisory committee on nutrition from the UK recommended varying dietary iron sources and limiting red and processed meats (nothing new in that last clause) (Geissler & Singh, 2011). A 2016 review assesses literature suggesting that chronic iron deficiency increases the risk of certain cancers as well as the literature suggesting that an excess of iron increases the risk of other cancers (Davoodi, Jamshidi-Naeini, Esmaeili, Sohrabvandi, & Mortazavian, 2016). As echoed in many studies, the authors recommend people: “avoid [the] adverse consequences of either iron deficiency or oversufficiency” by consuming the recommended amount from “plant-based sources and white meats”,  “avoiding processed meats”…“and limiting the intake of red meat to 500 g/wk.”

Vegetarians and vegans are also more likely to be iron deficient due to a lack of heme iron sources in their diet – though this can be avoided with careful nutrition and supplementation.  Just as an excess of heme iron can be avoided on an omnivorous diet with varied iron sources. 

Below is a qualitative hypothetical graph of a curve that could explain what at first seem to be disparate data. This is not a graph of real data, just an example of how results from different studies could suggest benefits and dangers for the intake of one food type, vitamin, or mineral depending on the amount consumed in the study. It is essential to look at a body of research before drawing conclusions – we cannot ignore a large body of legitimate results because it does not fit the point we are trying to make in say, a Netflix documentary for example.  

There is likely some ideal amount iron or heme iron to be consumed for best health. Too little appears to have consequences and too much appears to also have consequences.  This seems to be what the literature supports. 

The recommended daily allowance for iron intake is 8-18mg per day (with more recommended for premenopausal women and less for men and postmenopausal women) (NIH, 2019). Taking the mean, 13mg per day would require about 144oz of fish, 25oz of chicken, or 18 oz. of beef. As you can see from these numbers, higher red meat consumption might actually contribute to hitting that area to the right of ideal on the bell curve of iron consumption due to its higher heme iron content. In contrast, diets like the Mediterranean diet that have fish as primary heme iron sources might fall closer to the best-recommended amounts of heme iron for good health.

What GC may have done (on purpose or due to inadequate literature review) is hide half of the hypothesized bell curve so that they were only looking at the “too much heme iron is bad” side of the curve:

A recent and interesting study attempts to parse the meat versus iron variable using adjusted Cox regression models. These authors conclude that “Increased ferritin concentrations may be a marker of an overall unfavorable risk factor profile rather than a mediator of greater CVD [cardiovascular disease] risk due to meat consumption” (Quintana Pacheco et al., 2018). This means that meat per se may not be a contributing variable independent of over consumption of iron or heme iron as related to other individual risk factors—we already know that people who overconsume red meat have health issues and high heme iron intake might be a side effect of red meat consumption rather than a causative variable. Further, this study titled Dietary Intakes of Zinc and Heme Iron from Red Meat, but Not from Other Sources, Are Associated with Greater Risk of Metabolic Syndrome and Cardiovascular Disease concludes that the heme iron association with cardiovascular problems is eliminated when the heme iron source is white meat (de Oliveira Otto et al., 2012)

SUMMARY:  Heme iron is a valuable, well-absorbed version of a mineral essential for bodily function found only in meat, but over-consumption of this and other trace minerals may have health risks. Being moderate with red meat consumption is wise. Vegans run the risk of under-consuming iron, which can lead to anemia and has been associated with cardiovascular dysfunction and the risk of developing certain cancers, but this can be mediated with careful nutrition and supplementation. Meat eaters run the risk of excessive iron or heme iron consumption which is associated with cardiovascular risk and the risk of developing other types of cancer, but this can be mediated by minimizing red and processed meat consumption and varying iron sources.








 

[~28:30] MICROBIOME / TMAO

Microbiome

Eating meat changes the microbiome. Everything we eat changes the microbiome. This area of study is a new frontier and conclusions too far beyond “eat more fiber and lots of fruits and veggies” based on gut research are probably not yet possible as discussed in the last section. To give you a further idea, here is the conclusion from the most recent available systematic review:

Diet and nutrition have profound effects on the gut microbiome composition. This, in turn, affects a wide array of metabolic, hormonal, and neurological processes that influence our health and disease. Currently, there is no consensus in the scientific community on what defines a “healthy” gut microbiome. Future research must consider individual responses to diet and the role of diet in the response of the gut microbiome to interventions (Frame, Costa, & Jackson, 2019).

TMAO

GC repeatedly brings up TMAO (trimethylamine-N-oxide), suggesting that it is a dangerous byproduct of meat consumption that interacts with the gut microbiome in a negative way. This very recent study on this exact topic concludes that the “consumption of fish yield[s] substantially greater increases in circulating TMAO than eggs or beef” and further that their data indicate that “TMAO production is a function of individual differences in the gut microbiome.” In other words, fish (the consumption of which has been show to be cardiovascularly protective), but not other animal products, resulted in increased TMAO, but this response was modified by individual microbiome differences (Cho et al., 2017). Another study compares vegans, vegetarians, and omnivores and finds that high vegetable and predominantly healthy fat consumption rather than the presence or absence of meat was what mediated lower TMAO levels and microbiome health (De Filippis et al., 2015).  In short, whether or not eating meat or any other food will increase TMAO for you will depend on your own individual microbiome.

Another review and meta-analysis also concludes that large individual differences exist and that “the results on the link between TMAO and CVD remain limited and inconsistent” (Qi et al., 2018). Many research papers and reviews conclude that TMAO might just be a marker of disrupted homeostasis and that we cannot currently make any dietary recommendations based on TMAO (Brial, Le Lay, Dumas, & Gauguier, 2018; Cho & Caudill, 2017; Nowiński & Ufnal, 2018; Subramaniam & Fletcher, 2018; Velasquez, Ramezani, Manal, & Raj, 2016)

I could go on here, but someone else has very recently written an extremely in depth and well referenced analysis that will have you thoroughly convinced that much more research is needed before we outline any causal relationships between TMAO and negative outcomes.

SUMMARY:  We do not know enough about TMAO to make any dietary recommendations. We do not know enough about the microbiome to conclude anything about TMAO with relation to it. Both the microbiome and TMAO measures in response to foods vary person to person.





 

[~29:00] HAMBURGER AVOCADO PILOT STUDY

Wilkes says “The study that showed that a single hamburger impairs blood flow also showed that it can increase measures of inflammation by 70%”

Again, this is a small pilot study, but its results do not actually support reducing meat intake, so it is funny that GC refers to it multiple times.

To refresh your memory, in this study, subjects ate either a hamburger or a hamburger with avocado. Everyone got a hamburger. One of the things they looked at was IL-6 (an interleukin that has been associated with inflammation and implicated in increased risk of cardiovascular disease) (Lobbes et al., 2006; Tzoulaki et al., 2005). They use the measure of IL-6 as a proxy of potential inflammatory effect. Here is the fun part though – their results show an increase in IL-6 after hamburger consumption, but no increase in IL-6 after hamburger consumption with avocado. So add avocado to your beef is the logical conclusion. I think the literature overall supports decreased red meat consumption and that adding avocado will not eliminate the risks of heavy red meat intake, but you would not think so if you relied only on this paper – you would just throw some avo on your beef and call it good (Mahmassani et al., 2018).

Here is a direct quote form the paper GC keeps citing and the graph showing the changes in IL-6 under both the hamburger and the hamburger+avocado conditions. 

“Postprandial plasma IL-6 levels increased by ∼70% at 4 hours with burger only but this increase was attenuated when avocado was ingested with the burger despite the added fat and calories from the avocado” (Z. Li et al., 2013).

As mentioned earlier, a subsequent meta-analysis and systematic review of the avocado research found no net impact of avocado eaten alongside a fatty meal, so the results of this pilot study are probably anomalous. (Mahmassani et al., 2018).


[~29:00] ICEBERG LETTUCE & PLANT ANTIOXIDANTS AND VITAMINS

Agreed, the literature absolutely supports the health benefits of plentiful plant consumption. This does not obligate a lack of meat to enjoy the benefits of plants. 

All of the antioxidants, phytochemicals, vitamins etc. from plants can be consumed by eating a healthy fruit and vegetable intake with or without meat as a protein source. 

Even if iceberg lettuce has more antioxidants than salmon, but why not have salmon on your salad and get the best of all worlds: high quality, well absorbed protein, omega-3 fatty acids and plant antioxidants? 

Here is the funny part. I looked up the data from the study they site (using smaller than usual font size in the lower left corner) and they listed the antioxidant values below in millimoles per 100g of food. The study assessed antioxidants in several versions of each type of food, so I will list the range of values for each.

Iceberg Lettuce 0.02 – 0.17mmol antioxidants /100g mean: 0.10mmol
Salmon (pink or sockeye) 0.03 – 0.13mmol antioxidants /100g mean: 0.08mmol
Eggs (whole) 0.02 – 0.06 mmol antioxidants/100g mean: 0.04mmol


So they are correct, iceberg lettuce does have more, but not by as much as they imply. (Also, they did not choose to compare tuna, which had a mean of 0.12 mmol/100g, more than iceberg lettuce. In any case, plants do tend to have more antioxidants and I am not disputing that)
(Carlsen et al., 2010).

Oddly there are no units in the numbers listed under the foods in the documentary. Assuming the units are in mmol/grams of food still, to get these larger numbers with a more impressive difference than “0.02-0.06mmol more”, they multiplied the amounts by 100. Here is the tricky part, they cherry picked the highest value listed for iceberg lettuce antioxidant content but used the mean values for salmon and egg content. They must have decided this looked better than 10:8:4 that results from using the mean values of all the foods to multiply by, but is not a very honest or complete comparison. Again, I am not arguing that most plants do not have more antioxidants than most animal products. Just highlighted some of the deceptive techniques used.

SUMMARY:  On average, plants do have more antioxidants than animal products but you can eat both and still get the benefits of plants. The makers of GC also did a bit of slimy presentation here, skewing the data for a stronger impact (and diminishing their reputation for fair presentation of data even further).


 

[~29:20] 29% DECREASE IN INFLAMMATION

Finally GC references an article that actually looks at vegan subjects. Indeed this lifestyle intervention study saw a reduction in markers of inflammation in response to a vegan lifestyle intervention, but even the authors of this study concede that “It is likely that the vegetable and high fiber content of a vegan diet reduces CRP [C-reactive protein, the measure of inflammation used] in the presences of obesity” (Sutliffe, Wilson, de Heer, Foster, & Carnot, 2015). Meaning, you could likely add all those great veggies and increase fiber without eliminating meat and get the same effect. In fact, this has been done and here are the conclusions of one such study:

The health benefits of vegetarian diets are not unique. Prudent plant-based dietary patterns that also allow small intakes of red meat, fish and dairy products have demonstrated significant improvements in health status as well. At this time an optimal dietary intake for health status is unknown. Plant-based diets contain a host of food and nutrients known to have independent health benefits. While vegetarian diets have not shown any adverse effects on health, restrictive and monotonous vegetarian diets may result in nutrient deficiencies with deleterious effects on health. For this reason, appropriate advice is important to ensure a vegetarian diet is nutritionally adequate especially for vulnerable groups.” (McEvoy et al., 2012)

SUMMARY:  Vegan and vegetarian interventions consistently have health benefits and I am not here to say they are a bad idea for health or not a viable option for athletes; they can absolutely be both of these things. The thing is, adding fruits, vegetables, fiber, and consuming primarily whole foods as an omnivore has the same benefits. Likewise, eating a junky vegan diet is probably as bad as an unhealthy omnivorous diet.







[~30:00] MORE DOTSIE ANECDOTE


[~31:00] NFL, INJURY & RECOVERY

There is evidence that vegans and vegetarians on average have lower bone mineral density and high rates of fracture injury (Iguacel, Miguel-Berges, Gómez-Bruton, Moreno, & Julián, 2019; Veronese & Reginster, 2019). If I were to conclude that veganism results in poor bone health however, I would be as guilty as GC is when they imply that meat consumption results in heart disease and cancer. A careful vegan diet can support bone health. These results are likely due to the fact that many people on vegan diets are not educated about their nutritional needs and supplementing and planning accordingly. 

As mentioned earlier, an excess of carbs is more important for recovery from training than other macronutrients and switching to a vegan diet might default increase carb intake, but it is not the only way to do so. Further we should not be conflating recovery from injury with recovery from training. Some swelling and soreness in the latter may be a part of adaptation (getting better) –not all inflammation is bad! 

Switching to a diet with more plants and less red meat and processed foods probably results in improvement, but we cannot conclude (and research suggests we should not conclude) that the lack of meat is the responsible variable or that recovery from injury will be better facilitated on a vegan diet when other variables are held equivalent.


[~32:00] ROPE TEST

This assessment does not take into account how well recovered Wilkes was after all the time off from injury, the fact that he was likely eating more carbs by default on his vegan diet, or the fact that having a camera on you and trying to prove a point is very motivating. In any case, so many variables affect how you perform on an endurance test, that attributing it to not eating meat makes no sense at all. 

[~34:00] DR. ORNISH

Dr. Ornish is the author of a 1990 paper in which subjects converted to a low-fat vegetarian diet, stopped smoking, participated in stress management training, and added moderate exercise to their weekly regimen. Not surprisingly these subjects had positive cardiovascular outcomes (but Ornish did not control for which of these variables contributed to changes). (Ornish et al., 1990).

Some statements follow about how animal product consumption results in plaque formation in the vasculature and therefor in cardiovascular risk. A large body of data suggest that this broad statement is false (Dieter & Tuttle, 2017; Haring et al., 2014; Mohammadi, Jayedi, Ghaedi, Golbidi, & Shab-bidar, 2018; Mozaffarian, 2016; Petersen et al., 2017; Richter, Skulas-Ray, Champagne, & Kris-Etherton, 2015; Würtz et al., 2016).

Repeat molecules: Refer back to earlier discussion of TMAO, Neu5gc, HCAs, heme iron, endotoxins and DAG’s. This part of the documentary diverges pretty heavily from the actual consensus of the literature. 


[~35:30] HEME IRON STUDY
(Yang et al., 2014)

“1mg per day associated with 27% increase in risk of CHD [coronary heart disease]” flashes on the screen. The study in fact sees a 27% increase in risk with an increase of 1mg across a host of studies using different intake ranges or serum levels (measured from body fluids rather than intake). These are two different things and the incorrect statement on the part of GC might be a result of intentional deception or just a misunderstanding of the data.

The review also excluded studies from Japan where no correlation or risk increase was seen (this might be because the main source of heme iron in Japan is fish). So what it boils down to is again, too much heme iron, particularly too much from red meat seems to be associated with cardiovascular risk (the authors themselves acknowledge that other components of red meat like saturated fat and cholesterol might have confounded the results)(Yang et al., 2014)

Again, though this study did have some convincing statistics, a larger body of literature says that the effects associated with heme iron seem to fall away when we look at non-red meat and non-processed meat consumption. Relationships between iron intake and cardiovascular risk are inconsistent, and the full body of literature does not support a strong or understood association despite what the documentary suggests (Bronzato & Durante, 2017; Etemadi et al., 2017; Geissler & Singh, 2011)

For cardiovascular risk prevention, the 2019 American Heart Association dietary recommendations are as follows: “A diet high in fruits, vegetables, and whole grains is best. Fish, legumes, and poultry are the preferred sources of protein. Minimizing the consumption of trans fats, added sugars (including sugar-sweetened beverages), red meats, sodium, and saturated fats is also important” (Arnett et al., 2019).

The next study to show up on the screen has the sexy title Dietary protein and risk of ischemic heart disease in middle-aged men (Preis, Stampfer, Spiegelman, Willett, & Rimm, 2010). Looking closer, this is a single cohort study with dietary intake measured by a questionnaire administered every few years. The authors acknowledge that this is not the ideal means of assessing intake, as it is prone to error. The initial conclusion from the data is that there was no observed association between dietary protein and risk of total ischemic heart disease. The correlation they did observe surfaced when they restricted the assessment to what they deemed “healthy men” (those free of hypertension, hypercholesterolemia, and diabetes). For the statisticians among us, the RR of IHD was 1.21 (95% CI: 1.01, 1.44; P for trend = 0.02) for total protein, and 0.93 (95% CI: 0.72, 1.19; P for trend = 0.65) for vegetable protein –– small but compelling difference in outcomes. If I read only this result, I would be intrigued, but not convinced. Cohort studies have notorious limitations and dietary recommendations should never be based on single cohort study associations due to the multiple variables at play – as warned by biostatisticians, doctors of epidemiology, and obesity researchers (Cofield, Corona, & Allison, 2010).

The issue is there are studies that are equally compelling and come to the opposite or at least a much more neutral conclusion. You can cherry pick cohort and observational studies in nutrition to support any side of this argument. The job of a scientist is to consider the bulk of evidence and make the more reasonable conclusion based on all of it. As an example to contrast the above article is a study titled Arterial compliance, blood pressure, plasma leptin, and plasma lipids in women are improved with weight reduction equally with a meat-based diet and a plant-based diet (Yamashita, Sasahara, Pomeroy, Collier, & Nestel, 1998). This study found no difference in cardiovascular risk factors in a group losing weight on a plant based or lean meat based diet. Weight loss was however correlated with reduced risk. Other studies in various subjects suggest that protein source is not a relevant factor for cardiovascular risk in and of itself (Hecker, 2001; Richter et al., 2015; Salter, 2013; Sucher et al., 2017). Though, as mentioned repeatedly, limiting red meat, eliminating processed meat, and varying protein sources might be beneficial.

SUMMARY:  The bulk of the literature suggests that cardiovascular risk is not associated with plant versus animal protein source.

 

[~36:30] HCAs AND PAHs

Heterocyclic Amines (HCA) / Polycyclic Aromatic Hydrocarbons (PAH)

Both of these compounds will be referenced in Game Changers though only heterocyclic amines are brought up at this point in the documentary. Since they are related I will discuss both here. HCAs and PAHs are produced when foods (particularly meat) are cooked at high temperatures, over an open flame, or smoked. Although these compounds are thought to be potentially mutagenic (cancer causing), no causal link has been established and altering cooking practices can minimize the compounds produced (Alaejos & Afonso, 2011). Olive oil, lemon juice, garlic, and alcohol marinades have even been shown to cut heterocyclic amines in cooked chicken and beef by as much as 90% (Melo, Viegas, Petisca, Pinho, & Ferreira, 2008).

A reference flashes on the screen and the narrator proceeds to explain that all animal products increase cardiovascular disease risk. The reference is not the primary source for data on the supposedly responsible molecules and byproducts listed in the infographic in the background, but some studies and fact sheets are referenced within that reference. 

The first of which is regarding polycyclic aromatic hydrocarbons (PAH’s). It is from the National Cancer Institute and is titled “Chemicals in Meat Cooked at High Temperatures and Cancer Risk”. It outlines the means of cooking and variables (including individual genetic differences in people consuming the meat) affect the production and reaction to these compounds. They do not recommend cessation of meat consumption, but rather that you limit consumption of meat cooked over open flames, flip meat often when you do cook over an open flame, and removed charred portions of meat. In fact the report concludes that there is no established definitive link between HCA or PAH exposure from cooked meats and cancer in humans (NCI, 2016).

Interestingly most exposure to these compounds is probably fairly low, not all PAHs are carcinogenic, and PAHs also come from cereals and vegetables, particularly grilled vegetables (Alomirah et al., 2011; D. H. Phillips, 1999).


[~37:00] in THE ORNISH STUDIES 

The paper used to support the idea that “the only diet that has ever been shown to actually reverse heart disease is a plant based one” is the paper we discussed earlier in which subjects converted to a low-fat vegetarian (not vegan) diet, but in addition stopping smoking, participated in stress management training, and added moderate exercise to their weekly regimen. Again, there was no control for whether reducing fat, quitting smoking, managing stress, and or exercising were the important variables. With all of these changes it is impossible to conclude which had effects and how large those effects were. These participants did not eliminate all animal protein, so even if diet were isolated we would be hard pressed to conclude anything about veganism. We would not even be able to conclude much about vegetarianism given the low-fat alteration as a variable in addition to eliminating meat (Ornish et al., 1990).


[~38:00] (revisited at ~68-74:00) FIREFIGHTERS’ DIET CHANGE

There are several issues here. The healthiness of (or lack thereof) of participants’ diets prior to going vegan  was not assessed. There is nothing here to suggest that switching to a healthy, low-fat, high fiber, veggie and fruit-centric diet with lean animal protein would not have had the same effect. Real data suggest that it would have. 

The two point number comparisons here (cholesterol before and after) are also irrelevant without an assessment of normal deviation and variability. I do suspect that the health of these participants was improved even though the data cannot directly support this. Pinning that on veganism is however a totally unwarranted conclusion. It is more likely that the firemen have included much more whole foods and fruits and vegetables into their diets for the first time, resulting in changes the literature would predict.

Also, the two cholesterol changes highlighted that were around 100 points were clearly outliers since they mention that the average change was 19 points. You don’t get an average of 19 with two incidences of ~100 unless all of the other changes were much smaller (or the n-size was huge, which it did not appear to be). 


[~40:00] COACH LOU

 Anyone who has read this far knows that anecdote is not strong evidence. I can find you some healthy, jacked 60 year olds who eat meat, some healthy jacked 60 year olds that adhere to a fasting regimen, and so on. Some are hitting healthy nutrition by accident, some just have excellent genetics and would excel in many conditions, some a combination of both. Also, many people accidentally increase plant intake and general healthy eating practices when they go vegan and attribute changes to a lack of meat rather than an increase in healthy items.   


[~40.30] A LITTLE MORE SNARK

(Also, his push-ups are not full range of motion, so how can we trust him?)


[~42:00] THE GOVERNATOR 

The truth is that it is very likely that a switch from an ill-informed omnivorous diet to a well planned vegetarian diet will result in lowered cholesterol, but to attribute this to a lack of meat is equivalent to attributing learning at school to riding a school bus. It’s not the school bus ride that provides knowledge, but it is one way to get to school where you can learn. Veganism might be the school bus here, but it is not the teacher. A low-fat omnivorous diet where most fats come from healthy plant sources is another way to get to school so to speak. The result, lower cholesterol is attributed to veganism in this documentary when the data actually suggest that veganism was just a way to default decrease unhealthy fat consumption and increase plant intake, which could be done as effectively on an omnivorous diet (Mensink, Zock, Kester, & Katan, 2003).

Current consensus in the literature implicates carbohydrate and dietary fat ratios as nutritional factors that can influence cholesterol levels (Gjuladin-Hellon, Davies, Penson, & Amiri Baghbadorani, 2019; L, M, A, H, & A, 2019). Lowering cholesterol is actually probably much more complex an issue than changing one aspect of diet though. The current CDC recommends limiting foods high in saturated fats and eating foods naturally high in fiber, not consuming tobacco products, and exercising regularly as the best way to impact bodily cholesterol levels (CDC, 2019). These recommendations can easily by followed on a vegan, vegetarian, or omnivorous diet.


[~43:00]
MORE DR. ORNISH

At this point I can refer you back to the hosts of papers cited earlier showing that animal protein itself does not appear to be associated with cancer or cardiovascular risks and that some animal based foods are associated with improved health parameters and decreased cancer risk. Even so, read on and I will cite additional papers that make this single study (Levine et al., 2014) Ornish is referencing seem irrelevant or anomalous. 

As a quick side note, the paper Dr. Ornish cites also states that in respondents over 65, high protein intake is associated with reduced cancer and overall mortality. The most recent anecdotal examples (Coach Lou and Arnie) are older males, who this study concludes have reduced cancer risk with more protein consumption (Levine et al., 2014).

Various Cancers and Type II Diabetes are listed on the screen as associated with meat consumption. Let’s walk through each of these.

Prostate Cancer: According to the World Cancer Research Fund, the strongest association with risk of prostate cancer is adult body fatness (AICR & WCRF, 2018)Recent reviews and an umbrella review conclude that individual dietary factors are not conclusively predictive of prostate cancer risk, but that eating a diet with lots of whole foods and n-3 polyunsaturated fatty acids (whose primary source is fish), and limiting alcohol intake are best choices (Ismail, 2019; Markozannes et al., 2016; Peisch, Van Blarigan, Chan, Stampfer, & Kenfield, 2017).

Breast Cancer According to the World Cancer Research Fund, the strongest association with risk of breast cancer is alcohol consumption, adult weight gain, and adult body fatness, while physical activity and lactation are associated with decreased risk (AICR & WCRF, 2018)Some data actually link low-fat dairy with decreased breast cancer risk, but others see no association (Godos et al., 2019; Moorman & Terry, 2004; Rock & Demark-Wahnefried, 2002; Zang, Shen, Du, Chen, & Zou, 2015)

Colorectal Cancer:  Many studies have determined that fish and poultry consumption are not associated with risk of colorectal cancer or are associated with decreased risk (Carr, Walter, Brenner, & Hoffmeister, 2016; Chao et al., 2005; English et al., 2004; Ganesh, Talole, & Dikshit, 2009; Marques-Vidal, Ravasco, & Camilo, 2006; Teresa Norat et al., 2005; Teresa Norat & Riboli, 2009). According to the World Cancer Research Fund, the strongest associations with risk of colorectal cancer include salted fish consumption, alcoholic drink consumption, and adult body fatness (AICR & WCRF, 2018). Smoked foods of any kind and meats cooked under high heat also seem to be risk factors (Alomirah et al., 2011; Marques-Vidal et al., 2006; Uribarri et al., 2010). Eating lots of fruits, vegetables, and fiber appear to be associated with reduced risk (Garcia-Larsen et al., 2019). These three systematic review and meta-analyses also show that milk products are associated with a reduction in colorectal cancer risk (Aune et al., 2012; Barrubés, Babio, Becerra-Tomás, Rosique-Esteban, & Salas-Salvadó, 2019; Vieira et al., 2017)

Type II diabetes: A Mediterranean diet (which includes fish) and increased exercise have been shown to reduce type II diabetes risk (Balk et al., 2015; Esposito et al., 2015; Jannasch, Kröger, & Schulze, 2017; Schwingshackl, Missbach, König, & Hoffmann, 2015)























Another follow up review concludes that previous correlations between meat consumption and cancer fall away when animal fat is controlled for. In other words, lean meats do not have this link and in fact might have anti-carcinogenic properties (Potter, Brown, Williams, Byles, & Collins, 2016). So, along with the already noted problems with inferring causality from cohort studies, comes the problem of disentangling food types in order to avoid misleading correlations. 

The Center for Integrated Medicine at UCSF writes a succinct summary of the meat and cancer risk debate based on the last decade of research and is worth a read. 

I will quote their conclusions here: 

Because there are levels of methodology within each of these categories, there are also heuristics for accepting results based on a variety of data. The world cancer research fund outlined these in its 2018 continuously updated report:

In order to be considered convincing, evidence must: 

  • Come from more than one study type
  • Be replicated if from cohort studies
  • Must not have differing results depending on study type or population studied
  • High quality methodology excludes possibility that observations result from random or systematic error or confounding variables
  • There exists a plausible biological gradient for a dose-response relationship
  • Strong and plausible experimental evidence from human or animal studies

The over-arching claim to avoid all meat and animal products is not warranted. You do not need to be vegan to lower your risk for cancer but you do need to consume a lot of plant foods. After reviewing recent research the risk versus benefit of animal foods varies quite a bit depending on the type of animal protein and the way it is prepared.  Overall the cooking method (e.g., high temperature cooking) and processing of meat (e.g., smoking and curing) provide the strongest concern for cancer risk whereas certain animal proteins, especially fish, may actually be protective.

The American Institute for Cancer Research’s recommendations for cancer prevention outline a plant-based diet that can include fish, poultry, limited amounts of red meat and moderate amounts of dairy. They make the following broad recommendations:

  • Limit consumption of energy-dense foods (like fast foods) and avoid sugary drinks. (This recommendation aims to help us stay at a healthy weight.)
  • Eat mostly foods of plant origin, like vegetables, fruits, whole grains and legumes. 
  • Limit how much red meat you eat and avoid processed meat. (Eat less than 18 ounces (cooked) of beef, pork or lamb per week; avoid smoked, cured or salted meats).
  • Limit alcoholic drinks. If you drink, limit to no more than two drinks a day for men and one drink a day for women.
  • Limit consumption of salt.

These five Recommendations add up to a diet than can contain some, little or no animal products. AICR’s review of the evidence does not show an additional benefit from following a completely vegan diet and states that poultry and fish are not linked to increased risk for any specific cancers (AICR, 2020).

World Cancer Research Foundation has similar recommendations based on the literature:

  • Maintain a healthy weight
  • Exercise
  • Limit alcohol
  • Consume 30g fiber per day
  • Consume 400g of non-starchy fruits and vegetables daily
  • Limit consumption of processed foods 
  • Specifically limit consumption of processed meat
  • Limit red meat consumption to 12-18oz per week
  • Limit sugar sweetened drinks
  • Meet nutritional needs via foods rather than supplements when possible
  • Breastfeed if you can












(AICR & WCRF, 2018)

They also provide an easy to read, color coded summary of recent literature and cancer associations which was sadly too large and complex for easy reading on a website, so please see the report referenced above to take a look. It makes very clear that what by far seem to be most predictive of cancer are adult body composition and alcohol intake. In fact dairy has fairly strong evidence to support its being cancer protective.  Not quite the picture painted by Game Changers. 

SUMMARY:  The largest cancer research institutions in the world overwhelmingly agree on what reduces cancer risk and none of them recommends for or against veganism.








[~43.30] AMINO ACIDS FROM ANIMALS TEND TO "MAKE OUR CELLS REV UP AND MULTIPLY FASTER"

There is no difference between any individual amino acid from a plant versus animal souce (you would think GC would avoid trying to convince us otherwise). Here are the molecular structures of the essential amino acids (that we need for bodily functions). Their structure does not differ depending on protein source:

(Joseph, 2019)

The amino acid ratios in protein sources do differ, but again, the ratios naturally present in animal protein better support muscle maintenance and muscle gain. In this sense, there is some truth to this odd statement about revving up cells –– the ratios in animal protein are good for cell growth, including muscle cells or tumor cells if those happen to exist. It does not mean animal proteins initiate tumors. All things that support general cell health support cancer cells as well. A cell is a cell. We need to worry about what initiates cancerous cells in the first place. This fallacious way of arguing that something supports tumor growth is similar to mis-conclusions in The China Study. Anything that supports cell proliferation supports tumor growth since tumors are made from cells, but you definitely do not want to blanket stop cell proliferation in your body.


[~43.30] A 22 YEAR OLD STUDY THAT HAS BEEN DISPROVED

GC cites a single cohort study from 1998 (Singh & Fraser, 1998) regarding colorectal cancer, but many subsequent studies have since determined that fish and poultry consumption are not associated with risk of colorectal cancer or are associated with decreased risk (Carr et al., 2016; Chao et al., 2005; English et al., 2004; Ganesh et al., 2009; Marques-Vidal et al., 2006; Teresa Norat et al., 2005; Teresa Norat & Riboli, 2009).


[~44:00] WHAT HUMANS HAVE EVOLVED TO EAT

A young geneticist tells us that humans do not have any genetic, anatomical, or physiological adaptations to meat consumption. Meanwhile evidence suggests that meat consumption early on allowed geographical expansion of our ancestors and is widely accepted to have resulted in adaptations such as increasing brain size and altered gut structure (Mann, 2018) so it would be a surprise if we did not have any adaptations to meat eating given its huge role in our evolution. Granted this is not in itself evidence of adaptations for meat eating, but rather adaptations resulting from a secondary effect of meat eating. At any rate, that is just to say that our ancestors consumed meat and its consumption did us all a solid. There is also evidence for meat adaptive genes, anatomy, and physiology, but Ill let a peer-reviewed paper on genetic diet adaptations in humans convince you (Luca, Perry, & Di Rienzo, 2010).

The geneticist in GC goes on to explain that humans have many adaptations to plant consumption. I don’t think anyone (ok maybe carnivore and snake-diet fans) is advocating not eating plants. In fact as we have seen throughout this assessment, eating more plants seems to be extremely healthy and might be the main variable creating correlations with health and veganism (rather than the lack of meat).  

The contrast between a human digestive tract and a lion digestive tract is another misleading comparison. It shows that lions cannot digest plant matter and that humans can, but does not in any way suggest that humans cannot or should not consume animal products. It probably suggests that we shouldn’t only consume animal products (sorry snake diet enthusiasts). 

Two more references appear on the screen. One concludes that lions have short digestive tracts. No further conclusion (Smith, De Waal, & Kok, 2006). This is not a study meant to confer any information about human biology. The second reference is a book on mammals that I did not purchase in order to read, but that presumably describes lion digestive tracts. I conclude that lions have short digestive tracts that are unlikely to be able to process plant matter. Lions should not go vegan. 

The geneticist argues that the fact that we need vitamin C, but do not produce it and must get it from plants indicates “just how reliant on plants we actually are”. How this translates to “do not eat meat” is unclear. We can survive without meat, but we can also survive without carbs. We are reliant on neither, but a lack of reliance is not a mandate to avoid. Survival and optimal health are two very different things.  

B12

They attempt to address this B12 issue by arguing that B12 is available in soil, and used to be available in water as a product of bacterial metabolism. Let’s walk through this. Soil and water contaminated with bacteria can provide B12. We purposefully kill bacteria in water and soil for good reason: disease prevention. Even if we once got all the B12 we needed from eating dirt with our veggies, we can’t now, but we still need it.

All of that being said, even if we could get B21 from eating dirt, it does not mean we have to or even should. So if you are vegan I would recommend a supplement. If you are an omnivore I would recommend not worrying about it.  

Glucose consumption by the brain

The next dude makes a solid point regarding the brain’s insatiable thirst for glucose and how this might relate to our color vision. This is interesting stuff, but still nothing to support avoiding meat. Let’s also not forget that humans evolved eating cooked foods from a very early point, which would alter the need for the flesh-tearing teeth of traditional carnivores and might explain why we don’t have razor sharp dentition (Carmody et al., 2016)

A vegan diet is not suitable for lions. Humans can eat plants. (A side note, why do we care what our ancestors ate? Did they live longer, healthier lives than us? (Hint: resounding no). The truth is our ancestors ate whatever they could get their hands on and lived short and likely brutal lives. I would rather use the current, modern scientific literature to support my healthy eating habits.) 






 

[~52:00] ERECTIONS 

Their study: First, obviously lacking power, an n of three is not statistically relevant (n size is the number of subjects you study, with more subjects allowing for stronger conclusions). The lack of power here is less of an issue for me though, there are much bigger problems. A small n size can be a good preliminary study to direct further research, but if you are going to have a small n size you gotta at least have a good study design. 

For this preliminary data to be even vaguely meaningful, the subjects should not have been told what they were eating, the person analyzing the data should not know what meal the subjects had eaten when assessing data, and most importantly some of the subjects should have had meat the first day, vegan protein the second day and some visa versa. As done, all three subjects got meat the first day and vegan protein the second day. You could just conclude that all subjects were more relaxed with their night time penis-accessory by the second night, allowing better blood flow, better sleep, and larger, longer erections that had nothing to do with their meals.

Some of the staples of a healthy diet such as fruit, vegetables, nuts, whole grains, and fish along with maintaining a lean body composition and exercising regularly support this kind of positive outcome: decreased incidence of erectile dysfunction (Esposito, Giugliano, Maiorino, & Giugliano, 2010; Giugliano, Giugliano, & Esposito, 2006). 


[~57:00] TESTOSTERONE

FIRST PAPER PRESENTED ON SCREEN

Here we begin to delve into the testosterone arguments, but they lead this section flashing the Oxford Vegetarian Study, which did not assess testosterone. This study looked at long-term health in a group of vegetarians and non-vegetarians, concluding that vegetarians were healthier. Again, the issue is that this is single study done 20 years ago that does not (as most cohort or questionnaire studies usually cannot) control for all relevant variables (Appleby, Thorogood, Mann, & Key, 1999). For example, vegans in 1999 may have been a group of people much more likely to exercise and eat plenty of fiber and vegetables than their omnivorous counterparts at that time and this rather than a lack of meat might explain the results, which according to current research seems to be the case. Twenty years later a systematic review and dose-response meta-analysis has compared the relative risk factors according to articles over the last several decades of available research and concluded that: there are optimal intakes for whole grains, vegetables, fruits, nuts, legumes, dairy, and fish, and that we should limit red and processed meat, eggs and sugar sweetened beverages in order to lower the risk of coronary heart disease, stroke, and heart failure (Bechthold et al., 2019). This current conclusion based on hundreds of research papers across decades seems much more moderate than that taken from the single 1999 study.

SECOND PAPER ON SCREEN

This 1990 study actually does look at (free) testosterone, along with sex hormone-binding globulin, and estradiol (Key et al., 1990).  The study only finds a difference in sex hormone-binding globulin, which was higher in vegans – as it is in women compared to men. Sex hormone-binding globulin “grabs” testosterone and sequesters it (preventing it from acting). This would be a negative for most male athletes if not for the fact that no differences in free testosterone were found. In other words, testosterone production was likely increased in vegans to make up for more sequestering, resulting in no difference in free testosterone. Another study showed the same results for vegans compared to vegetarians and meat-eaters, (Key et al, 1990; Pusateri etal, 1990). More recent controlled studies also show no change in hormones (or lean body mass which is one of the downstream concerns) when animal protein was replaced with soy protein in a group of males (Kalman, Feldman, Martinez, Krieger, & Tallon, 2007). This is all to say that veganism confers no benefit for testosterone, but probably does not negatively impact it either.

THIRD PAPER ON SCREEN:

This study also found no differences in free testosterone, but did see lower serum insulin-like growth factor in vegans compared to meat-eaters and vegetarians (Allen, Appleby, Davey, & Key, 2000). Insulin like growth factor is a factor that is essential for human growth and survival but that in excess has been implicated in the progression of some cancer (Brahmkhatri, Prasanna, & Atreya, 2015). Other data suggests that vegetable consumption reduces IGF, suggesting again that adding vegetables is the important variable (Diener & Rohrmann, 2016).

IGF-1 is present in milk. A correlation between IGF-1 blood levels and prostate cancer has been shown, but the IGF-1 found in dairy milk has also been shown to have no biological effect on humans, likely due to low concentrations compared to endogenous IGF-1 (since bovine and human IGF-1 are the same) (Collier & Bauman, 2014; FDA, 2019)

On the other hand high IGF-1 levels have also been associated with a lower risk of colorectal cancer (Ma et al., 2001) and a recent meta-analysis links dairy intake with a reduced risk of breast cancer (Zang et al., 2015). When aspects of milk are parsed, it seems that different aspects of dairy products might have both cancer protective and cancer risk increasing components (Um, Prizment, Hong, Lazovich, & Bostick, 2019). A host of reviews and meta-analyses found no consistent association between milk consumption and health issues or mortality. (Drouin-Chartier et al., 2016; Guo et al., 2017; Larsson, Crippa, Orsini, Wolk, & Michaëlsson, 2015; Marangoni et al., 2019; Pala et al., 2019; Thorning et al., 2016). Finally, this 2018 article discusses how some earlier primary research may have mistakenly associated dairy and health issues by failing to parse confounding variables (Johansson, Nilsson, Esberg, Jansson, & Winkvist, 2018).

In fact, it appears that soy raises IGF-1 more than milk consumption. Soy does not contain IGF-1 but it does stimulate endogenous production. Endogenous production appears to be altered by food intake, particularly protein irrespective of plant or animal source and low IGF-1 is associated with frailty due to nutrition problems in elderly populations (Maggio et al., 2013; McLaughlin et al., 2011; T. Norat et al., 2007)

The relationship between diet and sex hormones might be even less simple. A 2008 review summarized research on the effect of various diets sex hormones and related compounds. Calorie reduction leading to weight loss was shown to increases sex hormone-binding globulin levels regardless of diet composition, particularly in women. So reduced calories and weight loss had the same effect of as a vegan diet. They also found, based on cross-sectional studies, that dietary composition is not usually associated with sex hormone-binding globulin if weight is controlled for. Finally, they conclude that “no clear conclusion can be reached regarding the effect of various eating habits or dietary composition on circulating androgens. The evidence indicates that dietary effects on circulating sex hormone-binding globulin, and possibly androgens, can be expected if body weight or fatness and/or insulin homeostasis are modulated” (Morisset, Blouin, & Tchernof, 2008)

SUMMARY:  Veganism does not appear to alter free testosterone. Further, it seems that diet itself might not affect sex hormones in a meaningful way at all, but that weight and body fat percentages may have an impact. High IGF levels have been implicated in some cancer progression and in reduced risk of other cancers. IGF is present in milk, but is also endogenously increased by soy intake.  More research is needed to make dietary impacts on IGF clear and to elucidate whether alterations are causally related to positive or negative outcomes.







 

[~57:30] SOY INTAKE AND TESTOSTERONE

Although there do not appear to be free testosterone changes with soy consumption (Terrier & Isidori, 2016), there are minor concerns that are still being studied such as some evidence that suggests that phytoestrogens may alter reproductive hormones, spermatogenesis, sperm capacitation and fertility. (Christopher R. Cederroth, Auger, Zimmermann, Eustache, & Nef, 2010; Christopher Robin Cederroth, Zimmermann, & Nef, 2012; Patisaul & Jefferson, 2010; Retana-Márquez et al., 2011)

The bulk of the literature suggests that soy consumption has many health and possibly cognitive benefits and it seems likely that moderate consumption is a net positive. This systematic review of human trials, prospective human trials, observational human studies, animal models, in vitro studies, and laboratory analyses of soy components concluded the following benefits and risks (D’Adamo & Sahin, 2014):

Health benefits associated with soy consumption:

  • Relief of menopausal symptoms 
  • Decreased risk of heart disease,
  • Decreased risk of breast cancer 
  • Decreased risk of prostate cancer 

Health risks associated with soy consumption:

  • Increased risk of breast cancer 
  • Increased risk of male hormonal and fertility problems (though evidence is conflicting)
  • Increased risk of hypothyroidism (though data is inconsistent)
  • Antinutrient content
  • Possibly harmful processing by-products

RP Tools For Vegans

Vegan Diet Templates 
A modified version of our top-selling diet templates to fit the needs of vegan athletes and fitness enthusiasts.

RP Vegan 
50 RP diet-friendly and delicious protein recipes for a plant-based diet!

The RP Diet For Endurance 
This 50 page read has everything you need to know about fueling, hydrating and managing electrolytes for ultimate performance.

 

[~57:45] ANIMAL ESTROGENS

The paper they reference states that the current evidence on animal estrogens in food is inconclusive and requires further research, not sure why they used it to support their statement (Daxenberger, Ibarreta, & Meyer, 2001). In general the amounts of hormones in animal products are extremely low and many are not bioavailable when consumed orally and the literature suggests phytoestrogens (found in soy) to be of more potential concern (though this line of research still needs fleshing out) (Prakash Rath Ph scholar et al., 2018).

The study GC highlights showing changes in testosterone with dairy intake (Maruyama, Oshima, & Ohyama, 2010) was followed up by studies that suggested these results were confounded by fat content and that low fat dairy does not have the same effect (and that low fat dairy consumption might even increase sperm count) (M. C. Afeiche et al., 2014; M. Afeiche et al., 2013; Eslamian et al., 2015; Haimov-Kochman, Shore, & Laufer, 2016; Salas-Huetos, Bulló, & Salas-Salvadó, 2017). A comprehensive literature search of nearly 100 articles published over the last 10 years suggests that “high intake of fats, especially saturated ones, and trans-fatty acids is negatively related to sperm count and concentration” polyunsaturated n-3 fatty acids (for which fish is a primary source) had a positive effect on total sperm count, sperm concentration and favorable sperm morphology (Suliga & Głuszek, 2019). So it seems as though fat content may have confounded the earlier study GC cites.

In terms of estrogen, about 1000x typical milk estrogen content is needed to produce a change in bodily estrogen amounts. The reason for this is that the liver effectively metabolizes hormones like estrogen when they are consumed orally until massive amounts surpass the liver’s capacity to metabolize (Pond & Tozer, 1984). This explains why “enhanced” body builders inject rather than orally consume anabolics.  If you are injecting cows milk intravenously, you might have some bigger concerns, but I wouldn’t recommend that practice for multiple reasons. 

SUMMARY:  Soy consumption appears to have benefits and risks (similar to many food products). There is no evidence that erections are related to plant versus animal protein consumption. With respect to hormones and animal products, it appears that the dairy research is confounded by fat content effects and that when animal products low in fat are consumed, the risks formerly associated with those products fall away.

 

[~58.00] CORTISOL AND ANIMAL PRODUCTS

GC cites a study that outright states that the diets given to subjects were “not meant to replicate compositions of diets normally consumed”  –– in other words the diets in the study were not something anyone would eat in real life. (Anderson et al., 1987).

At any rate, the data from this 30-year old study do look to be in line with current research conclusions. The conclusions just don’t have any relevance to dietary recommendations for health or fitness.

Remember sex hormone binding globulin from the milk intake studies? (If sex hormone binding globulin is increased and starts grabbing more free testosterone, testosterone production is also increased resulting in no net change in free testosterone) Cortisol has a similar issue. Higher protein diets also increase corticosteroid binding protein, necessitating an increase in cortisol to maintain homeostasis.  Below are the figures from study cited in GC. Nowhere in the study do they conclude that the high-carbohydrate diet is better for health. In fact, the high carbohydrate group in this study was fed candy, which it would be difficult to argue is an optimal health choice.

Below are the figures from this study showing the decrease in binding proteins and concomitant increase in testosterone or cortisol:

More recent research delving deeper into the relationship of meal content and hormonal responses highlight the complexity of this issue and demonstrate that “protein increases stress hormones” is neither correct nor complex enough a hypothesis to even propose.

A 2002 study showed cortisol increases when stress was coupled with a glucose, but not fat or protein meal (Gonzalez-Bono, Rohleder, Hellhammer, Salvador, & Kirschbaum, 2002). Lovallo et al. showed a meal coupled with a physical (but not a mental) stressor increased salivary cortisol, but that there were sex differences in cortisol responses (Lovallo, Farag, Vincent, Thomas, & Wilson, 2006). Still another study shows no macronutrient content related alterations in cortisol levels (Lemmens, Born, Martens, Martens, & Westerterp-Plantenga, 2011). In 2010, some of the same authors of the latter study looked at the effects of single macronutrient intake (rather than mixed meals with varying proportions of macros) on cortisol levels and found that carbohydrates increased levels compared to fat or protein (Martens, Rutters, Lemmens, Born, & Westerterp-Plantenga, 2010).

Chronic stress is associated with increased cortisol levels, which indeed seems to be associated with fat accumulation (Björntorp, 2001; Björntorp & Rosmond, 2000; Torres & Nowson, 2007). When stressed, people tend to eat more carbohydrates and the actual concern in the literature is that over-consumption of carbohydrates increases HPA-axis (hypothalamic pituitary axis) activity (and therefor cortisol) in a positive-feedback loop. The bulk of the evidence suggests that carbohydrates increase cortisol and that protein may lower it or be neutral and some studies suggest that this response differs depending on other health parameters (Vicennati V, Ceroni L, Gagliardi L, Gambineri A, 2002).

SUMMARY:  Relationships between meal content and stress hormones are complex, but carbohydrates seem to be more related to cortisol changes than protein.








[~58:30] PEOPLE THINK “YOU CAN’T GO SHREDDED” AS A VEGAN BECAUSE OF CARBS”

No one at RP is going to tell you that getting lean requires eliminating carbs, but that has nothing to do with protein source. Wilkes says he knew that processed carbs and sugar could lead to weight gain. Anything can lead to weight gain if eaten in excess. Processed carbs and sugar can be poor nutritional sources if you are inactive, but can be a part of excellent fuel plans for glycogen replenishment in athletes, vegan and omnivore alike in moderation. This is essentially more anecdote – you can be vegan and be a body builder. 


[~59:00] UNPROCESSED CARBS

Statement: unprocessed carbs are associated with decreased body fat. Nothing in the omnivore diet says not to eat healthy carbs. They are setting up a false dichotomy. 


[~59:30] KETO DIET STUDY

This study just shows better muscle growth when carbs are consumed. We are on the same page here. The subjects in the study are not vegan, they are just trained men eating carbs or a ketogenic diet (minimal carbs), so this segment is pretty irrelevant (Vargas et al., 2018). I don’t think most current, successful body builders follow a low carb diet either (except perhaps deep in contest prep when calorie constraints require fats and carbs to be brought to minimums, a fact that is not altered by where they are getting their protein).


[~61:00] FOOTBALL PLAYERS EATING VEGAN DINNER SPREAD

You would be hard pressed to convince any nutrition scientist that truffle mac-n-cheese, impossible burgers (with more fat and higher saturated fat than most lean hamburger patties), ceaser dressing, and peanut butter cheesecake (plant based or not) are optimally healthy. These foods are delicious, sure, but not very different in terms of health and fitness promotion from animal based versions of the same processed, fatty foods. She throws a smoked sauce on the Brussels sprouts too –– if we call back to the discussion of potentially carcinogenic polycyclic aromatic hydrocarbons (PAHs) you might remember that smoked foods were of more concern for these potentially carcinogenic compounds than any other food. 


[~63:00] THE CIGARETTE COMPARISON

The relationship between smoking and lung cancer fulfills criteria for inferring causality. In other words, the data are strong enough that it is a safe assumption that smoking causes lung cancer. Let’s take a look:

  • Smoking increases the risk of lung cancer by ~2000%
  • This effect is seen in all studies and in all populations 
  • Non-smokers almost never get lung cancer
  • There is a dose-response relationship between smoking and cancer (more smoke means more likelihood of cancer)
  • There is biological plausibility / a mechanism (cigarette smoke contains known carcinogens)

Data for the effect of animal protein on any parameter of health comes nowhere near this.  Cancer risk is increased or decreased depending on the cancer, the food, the population, and the study. Vegetarians still get cancer. There does not appear to be any linear dose-response relationship between animal protein (or any food item for that matter) and any parameter of health outcome, except perhaps in the case of processed meats and smoked foods. 

Taking the misleading cigarette ads of yesteryears and drawing a parallel with meat consumption makes no sense. The parallel might be to an unmitigated proposal that there could be no ill effects of a meat-based diet no matter what you ate. Perhaps some meat advertisements are guilty of this, but irresponsible advertising (most athletes would indeed be best served to avoid fast food meals – real meat or impossible burger based) cannot discredit an entire food group. The scene with the football players eating the tasty vegan dinner at ~61 minutes is as guilty as Burger King parading basketball players around with their burgers though. Suggesting that these types of processed, high fat foods are the best choices to support athletic performance is shady whether the protein came from animals or plants.


[~64:00] NUTRITION IN THE NEWS

Newspapers from the 90’s about meat and cancer flash across the screen. We will ignore those as (hopefully) not one of us thinks the News is an accurate source for scientific information and I think I’ve beaten the meat-cancer-horse to death and then some in this article. 

They are still working on setting up the comparison of cigarette companies and the meat industry. Might Burger King and KFC showing you athletes eating their products be misleading you when we know that fatty processed foods are not healthy or fitness enhancing? Of course! Does this mean that all animal products of all types are bad for you? Absolutely not. In fact Burger King has recently been hitting the advertisement of its impossible meatless burger pretty hard lately. Shall we liken “big vegan” to cigarette companies as well? Ads here are also trying to convince us that a fast food burger is a healthy option when it absolutely is not. 

They then add some actual scientific articles to the mix, the first of which was an observational study showing higher fracture rates with more milk consumption, that warns that “Given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended” (Michaëlsson et al., 2014). The Game Changers writers chose not to heed this warning or to recognize a larger body of data finding the opposite correlations. In fact some of the same authors of this paper, wrote a subsequent review which concluded: “Our review of the totality of available scientific evidence supports that intake of milk and dairy products contributes to meeting nutrient recommendations and may protect against the most prevalent, chronic non-communicable diseases, whereas very few adverse effects have been reported” (Thorning et al., 2016).

This 2019 meta-analysis (so more than just one observational study) found that “compared with omnivores, vegetarians and vegans had lower BMD [bone mineral density] at the femoral neck and lumbar spine and vegans also had higher fracture rates (Iguacel et al., 2019). Another recent review also concludes that a vegan diet leads to lower bone mineral density and recommends supplementation for vegans to maintain bone health and prevent fractures (Veronese & Reginster, 2019). A 2019 consensus statement published by Osteoporosis International describes the positive associations between dairy consumption and bone and muscle health (Geiker et al., 2019).

The next study looks at levels of egg consumption and cardiovascular disease and diabetes in an observational study, but fails to control for any other variables (Y. Li, Zhou, Zhou, & Li, 2013). A review the following year cites this review and criticizes its conclusions after assessing the available literature. The authors state: “Differences in study design, T2DM (type II diabetes mellitus) status, exposure measurement, subject age, control for confounders and follow-up time present significant challenges for conducting a meta-analysis. Conflicting results, coupled with small sample sizes, prevent broad interpretation. Given the study limitations, these findings need to be further investigated.” (Tran, Barraj, Heilman, & Scrafford, 2014).

When a 2017 review looked at controlled trials (which as we have discussed are much stronger than observational studies), authors concluded that “consumption of 6 to 12 eggs per week, in the context of a diet that is consistent with guidelines on cardiovascular health promotion, has no adverse effect on major CVD [cardiovascular disease] risk factors in individuals at risk for developing diabetes or with type II diabetes” but acknowledge that “heterogeneities in study design, population included and interventions prevent firm conclusions from being drawn” (Richard et al., 2017).

Finally a 2019 umbrella review (a review that reviews other comprehensive reviews and sums their conclusions) concluded that there is “no association between egg consumption and a number of health outcomes, including cancer, cardiovascular and metabolic disorders. In contrast, evidence of possible beneficial effects toward stroke risk has been found”  (Marventano et al., 2019).

So a 2019 review reviewing all of the high level reviews of the egg literature found no evidence of association with risk. Ill take their conclusion over a single study looking at observational relationships in a niche population when it comes to making decisions for my nutrition. 

The next study shown on the screen has data that show a decrease in mortality rate associated with white meat intake along with a modest increase in mortality with higher red and processed meat intake (the latter part we already knew, but the former part is actually in contrast to the recommendations made by Game Changers) (Sinha, Cross, Graubard, Leitzmann, & Schatzkin, 2009). This study suggests that eating white meat can keep you alive longer, not sure why it would be cited in this documentary. Maybe the creators of Game Changers only read the abstract…


[~65:00] BIAS

The next series attempts to discredit research funded by the meat and dairy industries as biased. An odd turn to take given that the entire production team and most of the contributors to the documentary stand to make money off of vegan nutrition products and companies. Further, two things. One: funding does not mean inherent bias. Studies must still be peer reviewed by the scientific competition (those who most benefit from preventing other studies from being published and who are not being funded by anyone to review the papers). Two: there is a massive amount of literature on these topics and only a very small percentage of it is funded by the food industry. 


[~66:00] PLANT PREDOMINANT VS VEGAN

What comes up as the healthiest diet again and again? “A plant-food-predominant diet”. Yeah, agreed, but a plant-food-predominant diet does not preclude animal product consumption. That’s the problem. You cannot take the overwhelming evidence that eating lots of plants is good for you and construe to mean you must eat only plants to be healthy. Another recent analysis of the current state of the data on nutrition for disease prevention listed echoes this with what I think are very clear recommendations:

Food based prevention of chronic disease risk should prioritize fruits, vegetables, whole grains and fish and lower consumption of red and processed meats and sugar sweetened drinks…Higher consumption of nuts, legumes, vegetable oils, fermented dairy products, and coffee are further likely to confer benefit. (Schulze, Martínez-González, Fung, Lichtenstein, & Forouhi, 2018)


[~67:00] CONSERVATION + ENVIRONMENT

I won’t delve too deeply into this part of the argument as I think it becomes less than scientific to do so. I do think there is something wrong with drawing parallels between meat consumption and anti-conservation. Conservation involves the preservation of wildlife, ecosystems, and species. Meat consumption is not necessarily in opposition to this and in some cases it may even support conservation. The efforts of hunters have contributed massively to wildlife conservation despite the taking of animal lives. In fact the culling of populations can sometimes improve the well being of the remaining animals and contribute to a more sustainable ecosystem. Obviously meat farming is a different thing entirely and probably has some very real environmental impacts. While the environmental issues are more compelling in that they are better supported by data, I would encourage you to consider the host of other things we do as humans that impact the environment hugely, including but not limited to: 

  • Breathing
  • Having children (who also breath)
  • Driving cars
  • Flying in airplanes
  • Purchasing products flown in airplanes to our region
  • Purchasing products made in factories
  • Building homes, shopping centers, highways and parks on previously wild land

There is no way to live on earth as a human and not impact the environment. I think we each need to choose the ways that we can contribute to decreasing that impact, whether that be to bike to work, grow our own vegetables and hunt our own meat, go vegan, never fly again, contribute money to conservation and environmental causes, or not have kids. We cannot make value judgments on how others do or do not contribute to helping the environment given the extraordinarily complex variables involved and the utter impossibility of living as a human without contributing to some negative environmental outcomes. 

I understand ethical arguments against eating meat and think that any one who has an opposition to harming animals should absolutely adhere to a vegan diet and refrain from the use of animal products in order to be the least dissonant to their personal beliefs. That being said, poaching and choosing to consume meat are not at all, in my opinion, even close to ethically comparable. 

Ill also throw in that asking what a gorilla eats is as relevant as asking what a lion eats. We are different species and what works well for any of them has no bearing on human nutrition optimalities.


[~68:00] FIREFIGHTERS

(See ~38 minutes earlier for analysis of the conclusion of the firefighter diet test)


ENDING MINUTES AND ENDING THOUGHTS:

The documentary concludes with a crescendo of glorious anecdote. A disappointing way to end after bringing up what I find the most compelling argument for veganism (outside of animal rights if that is something you personally feel strongly about)—environmental issues. Though given the inattention to the big picture and cherry picking of the literature for the nutritional portion of this film, I am skeptical that the opinions and research conclusions are the whole story for this either. That is for another article though…

Suffice to say veganism can be a very healthy and effective option for athletes, fitness enthusiasts, and health conscious people, but the path to best nutrition is not a one-lane road. There are many options and means to apply the basic principles and these are supported again and again in the literature and are simply this: eat lots of plants and other whole foods, limit red meat and minimize processed foods. 

If you made it this far, thank you for reading! I hope this has helped dispel some of the overwhelm and confusion and made eating choices less stressful for some of you! 


Dr. Mel Davis, PhD
@regressive_underload


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