To read my general thoughts on the film, go to Part One. Evidence relating to claims about athletic performance was deconstructed in Part Two.

Claim #12: Animal Protein & Inflammation

It is well established in scientific studies that chronic, low-level inflammation has been linked to a multitude of non-communicable diseases, including cancer, type 2 diabetes and cardiovascular disease (CVD).

Claim #12a: Heme Iron

The film claims that 1mg/d of heme iron (found in meat, particularly red meat) increases risk of CVD by 27% [1]. However, an important detail they left out is that this is referring to relative risk, rather than absolute risk – a recurring theme in risk stats used in the film.

Relative Vs Acute Risk

Let’s say your current risk of developing CVD was 30%.

An increase of 27% in absolute risk would mean your overall risk of getting CVD is 27% higher – i.e. your total risk is now 57% (30+27).

An increase of 27% in relative risk means your risk of developing CVD is 27% higher compared to your risk without – i.e. total risk is 38% (30×1.27).

Even at that though, this is a misrepresentation of the large body of evidence surrounding the topic. Heme iron is an essential molecule for several fundamental functions of the body. However, if large quantities of free heme iron are released within the body, this can lead to toxicity and inflammation [2]. Levels of iron in the blood are therefore tightly regulated by the body itself. However, both deficiency (which typically results from insufficient dietary intake of iron), or overload (caused only by inherited disorders of iron metabolism or certain chronic health conditions) can interfere with this system, resulting in excessive free iron in the blood and ultimately, inflammation [3][4]. It is possible to get iron from plant sources, but the easiest source is red meat, because it’s significantly more easily absorbed. Females, in particular, are susceptible to anaemia due to menstruation, so it’s recommended to aim for 1 portion of red meat a week. So, cutting out red meat completely, based on the idea that the heme iron it contains will cause inflammation, could actually cause inflammation (along with fatigue, lack of concentration etc that come alongside anaemia). Going back to the study used in the documentary, having one 3-4oz steak a week (containing ~2.4mg of heme iron) would therefore still not be close to breaching the 1mg/d (or 7mg/wk) “limit” of the study.

They then discuss another finding of the Hass avocado study used in the first burrito experiment; that “one hamburger increases inflammation by 70%” [5]. Let’s be clear – the study concluded that levels of a single inflammatory biomarker (IL-6) increased by 70% (not total inflammation) after eating a burger, and that this increase was attributed to the high saturated fat content, which we know should be limited in the diet. But the whole idea of this study was to see how adding avocado impacted this (i.e. both groups in the study were still eating meat). The good news is, if you like avocado on your burger, go live your best life – the study found that adding avocado to a burger attenuates the increase in IL-6. I’m an avocado fiend so this is all music to my ears. Again, using a fatty burger to discuss if meat is harmful is not particularly useful, and again, the main take away from this study is how the overall composition of our diet is what matters.

Claim #12b: HCAs, TMAO, Nitrosamines

Then they turn to inflammatory compounds released from animal protein sources that “corrode the cardiovascular system” :

HCAs: associated with well-done meat

TMAO: associated mainly with seafood and interactions with gut bacteria

Nitrosamines: added to processed meats

While all three compounds have associations with inflammation, cardiovascular disease and cancer, it’s important we delve into the circumstances around when this is the case, and, for starters, the evidence is not cut and dry. For example, not all studies on TMAO show an association between what we eat and TMAO levels in our blood; and not all studies saw an association between TMAO and CVD at all [6][7]. Plus, the evidence is rather contradictory considering that TMAO is mostly associated with seafood, which has repeatedly shown to benefit health, particularly heart health. This is a key point because when looking at science we need to look at overall outcomes. If eating TMAO in seafood is so bad for heart health, then why is a diet rich in seafood protective? Some hypothesize that elevated TMAO in humans could be a marker, rather than a mediator, of disease [9].

HCAs, on the other hand, are not so much an issue with meat itself, but with over-cooking it (e.g. BBQ’d meat) [9]. An issue for sure; however, acrylamide (a compound formed when starchy foods are over-cooked at high temperatures) has also been linked to cancer. So, it’s not a meat issue, rather than a “don’t burn your food” issue.

Finally, though nitrosamines have been linked to increased risk of cancer, it’s difficult to tell if it’s these compounds themselves, the saturated fat, or the salt content of processed meats that are the problem [10]. Regardless, I don’t think there’s anyone arguing that processed meat is healthy or should be consumed in anything other than small amounts.

Claim #12c: Antioxidants

The documentary then turns attention to the antioxidant content of plant foods, which are generally much more abundant than in animal foods. Again, true. But an omnivorous diet includes plant foods does it not? Anyway, I’m definitely not going to argue that plants are a fantastic source of antioxidants. Moving on…

Claim #13: Animal Protein & CVD

“In all of Western civilization, there is nothing more common than coronary heart disease, and that is because of the foods that most people eat every day“.

That’s a quote from Dr Caldwell Esselstyn in the film – and it’s true. Westernized diets are, let me find the word… extremely crappy. And it’s showing in our health outcomes, such as the fact 1 in 3 of us will develop heart disease. While there are many contributing factors, including age, race, gender, genetics & socio-economic status – poor diet and lack of physical exercise take the lead by far. A huge proportion of CVD could be prevented by better lifestyle.

But the evidence on what diet, specifically, isn’t as clear cut as the film would have us believe. The data strongly supports a varied diet, rich in fruits and veg, starchy wholegrains, fibre and healthy fats. That much is clear. But because of the nature of the documentary, I always have to bring it back to the question – does the inclusion of animal products in and of itself inherently cause/have an association with heart disease?

Claim #13a: Guilty By Association

The film tries to create doubt around any study that is in any way funded by the animal agriculture industry that says there is no link between CVD and animal products (studies cited in the film include: [11][12][13][14] – note these are all huge studies and meta-analyses, which are considered the highest quality of evidence – but sure, let’s throw them out). As I have already discussed, while funding certainly has the potential for some bias, it’s a lazy criticism. When there is doubt over the credibility of a study, what do we do? We look at the totality of the evidence – does it fit? If yes, it makes it very hard to argue the paper is invalid because of who sourced the money.

The film then becomes a bit of a conspiracy documentary. Just before discussing how meat and dairy are “causing heart disease”, Wilks spends a significant period of time talking about cigarettes. Most of us know the story – by the time smoking was shown to be harmful it was a multi-million-pound business, so the risks were quietly brushed under the rug for some time. If you construed this slick juxtaposition to mean that eating meat is as harmful as smoking – you’re exactly where Wilks intended you to be and you’re not alone.

Essentially, Wilks claims that the animal agriculture industry is “using the same playbook” as cigarette companies in the 60s. There is NO evidence (industry-funded or not) that backs this claim. Wilks has since argued that this isn’t what they were trying to insinuate, but then why include it at all?? There is no doubt that this was a deliberate move to create doubt around the credibility of research. Regardless, I would also argue that if anyone is using the same playbook, it’s the fast-food companies; not the agricultural food industry in general.

Claim #13b: Healthy User Bias

The film claims that plant-based diets are associated with a reduced risk of heart disease. I would say that this is generally true. But, as we have already discussed in Part One, association is not causation. Let’s unpack this a little more.

Up to this point, veganism was relatively rare. No fast-food chains were offering vegan burgers, restaurants didn’t have entire vegan menus, and there certainly wasn’t the plethora of vegan products in the supermarkets that there is today. By default, the bulk of their diet would have been whole foods (fruits, vegetables, legumes, nuts, seeds…), prepared and cooked from scratch. Not only this, but most vegans/vegetarians are invested in maintaining their physical health. As mentioned in Part One, epidemiology studies (such as the one mentioned in this part of the film [15]) must be interpreted with caution. So while the study may show that those who were vegan had fewer heart attacks, it is impossible to conclude that it is veganism itself that is behind this trend, and not the fact that vegans were more likely to engage in health-seeking behaviour (i.e. drink less alcohol, smoke less, be more physically active). This is a well-known concept known as healthy-user bias. They are also more likely to be of a lower BMI and have lower body fat (which are established drivers of inflammation).

This study, like many, also used food-frequency questionnaires to collect data regarding dietary intake. Again the limitations of dietary recall have already been highlighted, but importantly in this particular study, they did not differentiate between the type of meat being consumed (was it organic chicken breast, or was it deep-fried hamburgers?). This greatly impacts the interpretation of the data.

However, there have been studies showing that once BMI was corrected for, there was no statistically significant association between meat consumption and inflammation, but the association between higher body fat and inflammation remained [16]. Other studies have researched the difference between “health-seeking vegans” vs “health-seeking non-vegans” (11,000 participants) over a 17-year follow up period; concluding no difference in mortality rates [17].

As for dairy, there is a whole host of evidence that dairy does not have the effect on cardiovascular health that would be expected given its saturated fat profile; with many studies suggesting a protective effect [18][19][20][21][22][23].

I’m interested to see where things go in the future now that vegan junk food is more available and cooking from scratch may not be the necessity it once was for vegans. A study comparing dairy cheese with vegan cheese found that the inflammatory marker CRP was significantly lower in response to the dairy cheese compared to the vegan alternative [24]. Additionally, studies have shown that when controlling for intake of calories, protein, carbohydrates and fat that weight loss occurs at the same rate (alongside a reduction in inflammation), whether or not the protein is sourced from plants or animals [25].

So, once again, weight loss and general health come down to the overall quality of your diet. While eating more plant foods will always be beneficial for health, it’s important to highlight (and I know I’m sounding like a broken record – but I hope you’re getting it), that the effect is not simply down to inclusion or exclusion of animal foods. Likewise, vegan junk food isn’t going to give you the benefits, just because it’s vegan. Healthy plant-based diets need to be based on whole foods.

As for the claim that the only diet to reduce risk of heart disease is a plant-based one – looks like tens of thousands of studies showing the benefits of the Meditteranean diet (which includes a moderate intake of lean meats and dairy) got lost, along with those showing the protective effect of oily fish.

Claim #14: Animal Protein & Cancer

I’d be repeating myself here if I went into the claims made here. Basically, lots of relative risk as opposed to absolute risk being quoted and similar confounding between veganism vs health-seeking behaviours and lower body fat. However, this is generally a highly talked-about concept in recent years, so I wanted to address it.

Over the past few years have been a lot of big headlines that red meat is as bad as smoking for cancer risk. This is sensationalist language that twists the evidence. There is a difference between “level of risk” and “strength of evidence”, and that’s something the media often failed to realise.

Carcinogens: Level of Risk Vs Strength of Evidence

The World Health Organisation classified processed meat (sausages, bacon, ham, some burgers) as group 1 carcinogens – the same category as tobacco, alcohol, arsenic and asbestos (hence the headlines). But these groups are classified according to strength of evidence, not the level of risk.

It is estimated that smoking causes 86% of lung cancers and 19% of all cancers. If no one smoked, there would be an estimated 64,500 fewer cases of cancer, just in the UK alone. By stark contrast, it is estimated that processed meat caused 21% of bowel cancers. If all processed meat was eliminated from the diet, there would be an estimated 8,800 fewer cases of cancer per year.

So there is a causal link, and not one to be ignored, which is why since this report recommendations are to avoid consumption of processed meat. But it’s not “as harmful as smoking“, and a sausage or two once a week is not going to do you harm.

With red meat, the evidence is less strong; with classification as a group 2a carcinogen. WHO highlight that evidence is too limited to draw conclusions, because most of the evidence is from epidemiological studies, making it too difficult to rule out confounding or bias (as discussed above) [26] (also see American Cancer Society position statement here).

The film does include a snippet where a dietitian appeared on CNN, who was also a member of the National Cattleman’s Beef Association. She claims that there is no casual link between processed meat and any type of cancer, and wouldn’t advise reducing meat consumption at all. I agree no causal link has been found, but I do find it jarring that she doesn’t recommend any reduction whatsoever; I can only assume they found one of the small percentage of dietitians who would say that. I know for a fact that what she said does not align with health recommendations or general dietary advice among dietitians or other health professionals. We’ve known for years that a high intake of processed meats is sub-optimal for health, long before the WHO report surfaced. While I don’t agree meat is inherently bad for us, that doesn’t mean I think any meat of any quality and in any quantity is fine, and I do agree that processed meat should be kept to a minimum.

Finally, a 2019 large scale review, pooling results from other meta-analyses and systematic reviews (each including tens to hundreds of individual studies) concluded that 71% showed no statistically significant associations between dairy and cancer, 13% showed a protective effect and 16% showed an increased risk [27]. Where there is an associated increased risk, whether this relates to the fat content of the milk is down to debate, and again could risk confounding (e.g. those who drink fuller fat milk may be more likely to overall live a less healthy lifestyle). James Wilks has spoken about this study – he is somehow convinced that the study shows dairy causes cancer.

Other studies and meta-analyses have similar findings [28][29].

Claim #15: Archeology & Ancestry Evidence – Are Humans Designed to Eat Meat?

I hate this argument for the same reasons I hate the Paleo diet argument: (i) We will never truly know what our ancestors ate, (ii) It likely largely depended on location (they ate whatever was available), (iii) It’s irrelevant in today’s societal and food environment. To argue that meat didn’t feature in the diet of our ancestors is a stretch – there is plenty of evidence to suggest it did, and has done for millions of years (e.g. knife marks on animal bones and the change in human anatomy [30]).

The film consistently makes arguments of how we differ from carnivorous animals – therefore cannot be meant to eat meat. Let’s remember that no one is claiming we are carnivores – we’re omnivores; and if you are highlighting the differences between us and carnivores, let’s also highlight the differences between us and herbivores. The main arguments focus on differences between carnivorous teeth and gut length and our own. True – we lack the razor-like teeth seen in, let’s say, a lion, and possess a much longer intestinal tract. However, nor do we have the jaw strength or sharp canines of a gorilla. And when it comes to our intestines, this time we’re on the short side. So, pretty much bang in the middle (okay maybe leaning towards the herbivore side). But still – omnivorous, not carnivorous.

There is often the assumption that meat requires more chewing than plants – but the opposite is true. Herbivorous animals almost all have increased chewing muscles and bite force. Not to mention greater digestive capabilities, allowing them to extract and digest plant compounds, such as amino acids, that humans can’t. Likewise, cows have four stomachs and chew the cud, so do we really want to argue we are comparable? Anyway, studies suggest that meat in the diet would reduce the chewing and masticatory force needed, particularly if meat was sliced and/or cooked. Its, therefore, thought that our smaller teeth and weak chewing capabilities are adaptations to the introduction of meat in the diet, rather than evidence of the opposite, particularly as these adaptations occurred alongside the increase in body and brain size, which would have increased energy demands. Thus, having reduced eating and digestive abilities would be counter-productive in meeting these higher demands, unless a somewhat better energy source was available (i.e. meat) [31].

And don’t try me with the whole “if we were meant to eat meat, we would be able to tackle, kill and eat prey raw”. The use of tools is one feature that sets humans apart from many (not all) other animals. But aside from that, unless you never eat food that has to be cooked or processed in any way, your point is highly irrelevant (e.g. dried or fresh rice, potatoes and kidney beans are just three quick examples of raw plant foods that require cooking to be edible from a textural or food safety point of view, and that’s not even getting into if you eat otherwise processed vegan foods – pasta, veggie burgers….).

Regardless though, I’m not sure of what paleolithic type studies have to add to today’s nutritional science, other than interest. I am more interested in health outcomes associated with different dietary patterns today.

And since the film uses gorillas as an example (fair enough, they’re muscular AF and eat mostly plants), let us remember they also eat 18kg of food a day.

Claim #16: Environment

I say this often, but for me this is the most compelling reason to re-assess the way we eat. From a physical health perspective, yes – I believe we need to reduce our over-reliance on animal foods and eat a few more plants. But I do not believe the science shows that it is inherently harmful in the context of a healthy diet and lifestyle.

However, with everything going on globally with climate change; namely, the tragic bush fires currently raging in Australia, thinking about how we live and the impact on the planet is essential. Similar to my beliefs about health, I do not believe that eating some animal products is bad for the environment. But what I do believe is that intensive farming & deforestation to make room for animal crops is poor for animal welfare and for our planet. I’m certainly no expert in climate change, so this isn’t something I’m going to delve into at this time.

Final Thoughts

Man – this took me down a black hole I thought I’d never get out of. I know there was a huge amount of information in these posts, but I really wanted to dig deep to give you the best information possible around this very topical issue.

The film tackles some of the myths surrounding food and fitness – namely, that you need meat to be strong, athletic or indeed “manly”, and it tackles these very well. There is no doubt there is mass confusion when it comes to nutrition, and while Game Changers tries to point the finger at the meat industry, I would argue that newspapers, mass media, Instagram influencers, and Netflix filmmakers are more to blame. The way the scientific literature is misconstrued and misinterpreted, twisted and shaped to fit a certain narrative – it’s a problem; a significant one. But has this film taken a high ground? Has it gone against the grain and actually presented trustworthy evidence, without clever wording or slick manipulation? Sadly, I can’t comfortably say it has.

‘Nutritionism’ is the paradigm that dominates much of nutrition-related thinking, an ideology that until recently was relatively unchallenged. It undermines the broader picture, the contextualized relationship between food and the body. It bases the value of food solely on its’ nutritional composition. In reality, this is useless thinking – and scientists are finally seeing that. We need to stop focusing on individual foods and nutrients and look at overall patterns of dietary quality. This new way of thinking, aligned with scientific evidence, shows that there is not any specific diet we should follow for optimal health, but a range of plant-heavy eating patterns.

My biggest problem with the documentary is just that; this picture it paints of good vs bad, light vs dark, an ‘all or nothing’ message. It portrays all plant food as “good” (insert clips of athletes gorging on vegan “chicken wings” and “mac and cheese”, insisting that these are the foods behind their success) and all animal products as “bad”, despite the overwhelming body of evidence that contests against that claim. Wilks himself reported that many of the experts featured are not themselves vegan, or even vegetarian. Promoting a diet that gets people to eat more plants is great, but not by having people believe meat is killing them. It’s a false dichotomy. It’s immoral and utterly misleading.

The athletes showcased are absolutely incredible. They’re inspiring in every sense of the word, and the fact they are promoting a healthy diet that was previously looked down on in the sports & fitness world is amazing. But they are not incredible because they left meat behind. They’re incredible because they eat one of the multiple healthy diets out there, are supported by teams of nutritionists and chefs, physios and coaches, and because they are absolutely dedicated to their sport, giving it their all – day in, day out. So don’t expect to be able to run a marathon in a day, or go for an hour-long battle ropes session (*cough cough*) just because you forfeited meat. And don’t buy into the idea that vegan anything is healthy – vegan junk food is still junk food.

I think Dr David Katz says it quite perfectly in the film: “Despite the appearance in our media of confusion, there is massive global consensus about the fundamentals of a health-promoting diet […]: a plant food predominant diet“.

Does that mean I can get behind Wilks claims that meat or animal products are hindering health or performance? Not at all. Plant-based diets, whether omnivorous, vegetarian or 100% vegan are the way forward, but there is no one approach fits all. The key is finding which works for you: your body, your needs, your lifestyle, your preferences. If this film made you want to improve your diet, my advice would be to fix it up without giving up animal products completely, at least at first; that is, include plenty of fibre, fruit & veg, healthy fats, lean protein and whole grains. Minimise processed foods and sugar. Cook from scratch as much as possible. After a while of this, and if you still want to give veganism a try, go for it. See the effects for yourself. While some may notice further improvements after cutting animal products completely, many others won’t. Find what works for you.

But as interesting as the film was, keep in mind that it’s exactly that – a film, entertainment. Sweeping, fearmongering statements, made by a few individuals, are not evidence. While they made plenty of claims that were sort of what the research says, they also focused on anecdotal evidence & epidemiology studies, which have their own limitations, and tried to discredit any opposing papers by using the “conflict of interest” card, without stating their own. While films like this can be a starting point, we shouldn’t be making decisions about health solely based on a movie.

While I want to stress here that every diet should be properly planned, the reason why this is particularly important for vegans is that it is against the norm. It takes unlearning and relearning – it’s not what most of us grew up knowing. To create the idea that making the switch is simple and takes no work to avoid deficiencies is irresponsible. Please, if you are considering veganism – take your time & educate yourself properly using verified resources based on good quality clinical data.