Apologies for the length of the article, but there is much to discuss! In this world of instant bites forgive me for delving deep, but I do hope at least some of you will take the time to read the whole thing. For those who can’t or won’t here is a quick dot point summary:
- Let me make clear that I am not against vegan diets. If you choose to follow that route you can absolutely put together a healthy diet, although you will need to supplement vitamin B12 as this is only present in animal foods. I would also supplement long chain omega-3s as seafood is our major source. Plant sources have only shorter chain omega-3s and although we can elongate these within the body we have a limited capacity to do so.
- The film criticises research showing positive links between animal foods and health as being largely industry funded. Yet this is a documentary produced by James Cameron who, along with his wife, are financially invested in a pea protein company. Executive producer and NBA star, Chris Paul is an investor in the lab-created fake meat company Beyond Meat. Other featured celebrities have similar links. Yet no disclaimers or statements of potential conflicts of interest are declared… something that has to be done in the scientific literature.
- The nutrition science in the film is often wrong or is heavily biased without showing all sides to the story and often cherry picked to support their viewpoint. This commonly happens in documentaries which are then perceived as facts when they are in reality made to persuade you to a certain viewpoint. Drives me nuts!
- Eating more whole plant-foods is clearly a good thing, backed with the bulk of research. What is far less clear is the impact on health of what are very new foods to the human diet like lab-created fake meats and highly processed and refined plant protein powders. What is not revealed in the film is that most if not all of the featured athletes use these powders to heavily supplement their diets and achieve the protein levels needed.
- Most of the published evidence supports a variety of plant-based diets including those that also include fish, other seafood, dairy, eggs and even good quality meats such as game meats, poultry and grass-fed beef. The term plant-rich may be a better way of describing such healthful diets. The documentary does not differentiate between these different diets referring only to plant-based with the inference that it should be 100% plants.
- Anecdotal evidence is not science. Having people tell you how great they felt moving from a regular (aka crappy) American diet to a plant-based diet is hardly surprising - of course they felt better eating more whole foods and less rubbish! This doesn’t mean such a diet is better than a well-balanced whole food diet that includes both plant and animal foods.
- If you read many of the debunking videos, podcasts and commentary online, good points are made as well as equally ridiculous, incorrect science made to the contrary of the film by people who have their own diet tribe to promote. E.g. The carnivore diet where you eat almost no plant foods is crazy talk. The vast majority of nutrition science research shows the important role of eating plants, whether or not you also eat animal foods. Almost all humans throughout history have eaten plants and our paleolithic ancestors ate more than 3 times the amount of fibre recommended in our guidelines today. Don’t get swayed by the extreme diets propositioned by passionately good salespeople of their approach.
- It is ridiculous to suggest that Nate Diaz (who does reportedly sometimes eat fish and eggs so is not really vegan) beat Conor McGregor in a UFC fight due to his vegan diet, while Conor chowed down on steak. Seriously? Read the reports of how that fight came about – Conor was trying to stack on weight to match Nate’s weight class in a very short amount of time. That would certainly impact his energy levels, not to mention the many other factors that decide a fight winner. Neither did they tell you that 6 or so months later Nate LOST the rematch with Conor claiming victory… perhaps they would argue that diet played no role that time! That whole scene was vaguely ridiculous.
- Busting the myth that you need meat to be strong is a plus of the film. Yes, there are indeed some vegan athletes at the top of their game. There are far more who eat animal proteins - but you don't hear about them. But read up on the vegan strongman Patrik Baboumian and you discover he downs several plant protein powder shakes a day as well as handfuls of supplements. While Arnie, well he was eating meat and lots of it at the height of his body building career. This was purely playing the celebrity card not science.
- No discussion was given to the quality of animal foods consumed – they were simply all labelled as bad for health. Newer research does try to tease apart processed meat from fresh meat and any detrimental effects on health are found to be stronger for processed meats. However, there are other major differences including the type of meat itself and how you eat it. Grain fed cattle from intense feedlot farming is a far cry from a pasture fed animal with the room to move and eat its natural diet. A fast food burger with fries is nothing like eating a lean game steak with a big salad and potatoes cooked in their skin. Lumping all animal foods together is grossly unfair.
- If you do only eat plants you need to obtain what are called complementary proteins. Why was this not covered in the film? They state that all plant proteins contain all of the essential amino acids, but they don’t tell you that some are at levels so low as to biologically insignificant. This is nutrition 101. Plant proteins are generally less digestible due to the food matrix of the plant and you need a variety of different plant foods to give you all the amino acids in sufficient quantities. You can overcome this by eating grains with legumes for example. But this is essentially why so many of the featured athletes resort to powders to supplement their diet.
- That said, very few people in the developed world do not get enough protein. Most of us can very easily achieve all the protein we need from eating a combination of plant foods should you choose to do so. However, those with higher protein requirements, such as growing children, the elderly and some athletes, may find it harder to achieve solely through plant foods.
- The environmental arguments for plants versus animals are more complex than made out. It is true that there is a general consensus that collectively we need to reduce our demand for meat and dairy, while increasing our intake of plant foods. However, some areas of land are better suited to animals grazing and cannot be used for planting crops. Monocrops like soy cause huge environmental damage to topsoils and to the natural habitat of animals. What do we do with all those plant farming by-products currently fed to farm animals? Solutions such as regenerative agriculture are not mentioned. There is some evidence these holistic methods of farming can be carbon-neutral or even carbon sinks… surely much better than lab-created processed products? There is much we have to learn in this space.
- There are nutrients we only get from animal foods, namely vitamin B12, and we primarily get long-chain omega-3s from seafood with small amounts in eggs and grass-fed meat. Other nutrients we only get from plants such as vitamin C, polyphenols, fibres of all types, and numerous other phytochemicals. Others you can get from both plants and animals, but minerals like iron are best absorbed from meat and shellfish, while plants are the major sources of others like magnesium. From a nutritional standpoint it is easiest to get a balanced diet that does not need any supplementation by eating both animals and plants… something the vast majority of homo sapiens have done for millennia.
For those up for a longer chat…
Let me make it clear that I am not against vegan diets. We know from nutrition modelling studies that with the right know-how you can put together a 100% plant-based diet that meets most nutritional recommendations. There are some nutrients of concern – chiefly vitamin B12, long chain omega-3 fats, iron and calcium – but with the right foods, fortified foods and/or supplements you can deal with that.
There is also good evidence in the literature about the health benefits of vegetarian and vegan diets. But do these benefits come from eating more plant foods or eating less animal food? Since the comparison group is usually a typical Western diet (pretty much the worse kind of diet!) it’s hardly surprising you see health benefits. Not to mention that people who follow those diets also tend to lead healthier lifestyles (i.e. more active, less smoking, less alcohol and so on).
Is a vegan diet any healthier than a plant-rich diet that also includes good quality animal foods? There is an abundance of evidence for various dietary patterns being associated with better health, most famously the Mediterranean Diet, but also the Nordic diet, the Japanese diet, the DASH diet… all of these diets include animal foods.
Nothing about the movie has changed the general nutrition recommendations that I, along with most dietitians and nutrition scientists, have made for years. That is:
- Eating lots of whole plant foods is good (whether or not you also choose to eat animal foods) – not just good but I’d go so far as to say it’s essential for optimum long-term health.
- Cutting out the crap (forgive my language) is good – or at the very least limit your intake. That means all those modern, ultra-processed ‘foods’ that have only been invented in the last few decades. That means confectionary, ice-cream, junk food, commercial biscuits and cakes, sugary, coloured breakfast cereals, fries, burger buns, deep-pan pizza with even more cheese stuffed into the crust and topped with 4 types of processed meat. But it also means plant-based processed foods too!!
You get the idea. Many of them might well be delicious – they are designed to be by some very clever scientists after all – but we have to resist their pull and temptation as part of our everyday diet.
Note that many of those ultra-processed foods are also plant foods, or at least their ingredients originally came from plants. So, what is absolutely key is that the foundation of any healthy diet is that it is based on whole, minimally processed foods. In other words, the way our ancestors ate long before there were highly technical food companies to mass produce foods specifically created to make them moreish and hard to resist.
"what is absolutely key is that the foundation of any healthy diet is that it is based on whole, minimally processed foods"
This brings to me to a key point. The research behind the benefits of plant foods is for whole, minimally processed plant foods. That means foods such as vegies, fruits, nuts, seeds, wholegrains and legumes.
There is no evidence to suggest a health benefit from eating plant-based protein powders (a highly processed and refined food), plant-based imitation meats made in the lab, or protein bars and balls. These foods may have helped many of the athletes in the film reach their protein intake goals and were probably necessary to do so given their increased requirements, but we simply don’t know what their impact is on health.
As an example, consider the vegan strongman featured in the film Patrik Baboumian. He has discussed his diet and provided a typical day in a video you can watch on You Tube. To spare you the 17 minutes here is a quick summary.
His solid food meals include loads of vegies, falafels, vegan sausages, tofu, potatoes, and he snacks on nuts. He also has whole fruit and fruit juice, mostly it seems in his smoothies of which he has several every day. Into those smoothies goes a lot of protein powder, either soy protein isolate, pea protein or a combination of other extracted and refined plant proteins. Plus, he takes a bunch of supplements. He is clearly worried his diet does not meet his nutrient needs.
That’s the way to do it if you are his size with his muscle mass and need that quantity of protein while following a vegan diet. It would be pretty hard to eat sufficient amounts of lentils or beans after all, so I’m not criticising his approach for his sport. Good on him and all credit given to an incredible athlete.
If the point of the movie is to say it’s possible to be a top-level strength athlete on a vegan diet, then yes, with the help of plant protein powders it certainly is. However, the inference made in the film and in much of the online commentary is that his performance is thanks to his vegan diet. They also forget to mention the amount of supplementation, either in pill or powder form that they have. We simply don’t know how he would perform today had he been following a well put together omnivorous diet including both animal and plant foods. Neither do we know the long-term influence on health of what are effectively highly processed and refined foods. Why should extracted and refined protein be any better for us than extracted and refined carbohydrate or fat?
You could of course argue that many athletes use protein powders and other supplements, whether plant-based or not. That’s true – I’m simply questioning the inference in the film that vegan diets made these athletes better and that it was possible purely with whole foods. Really? And the inference that this is therefore a diet best for us all.
Arnold Schwarzenegger features in the film and is also one of the producers. Arnie claims to be following a mostly vegan diet, so he hasn’t quite given up animal products altogether, however he claims to feel fantastic as a result. If the premise of this is to show you can get big muscles eating plants this is a pretty silly example. Arnie did eat animal foods and reportedly huge quantities of them to get to the size he was at the height of his body building career and when training for his roles in the Terminator movies. To include him in the film as an example is simply playing the celebrity card. It’s not science. How he feels is anecdotal, not science.
"Arnie did eat animal foods and reportedly huge quantities of them to get to the size he was at the height of his body building career and when training for his roles in the Terminator movies. To include him in the film as an example is simply playing the celebrity card. It’s not science."
There are several other athletes featured who genuinely are vegan and are at the top of their game. There are many more athletes at the top of their game who do eat animal foods. If the question is simply to prove that you can be an athlete without meat and dairy, then mission accomplished… of course you can. That doesn’t mean it’s the best way forward for all athletes.
The idea that you need meat to be strong is a myth well worth busting and the film made a good job of doing that. I only object to the sensationalism of the stories… but hey I have enough experience in TV to understand this makes for a good story and compelling viewing. It’s just that to suggest a vegan UFC fighter Nick Diaz beat meat-eating Conor McGregor largely on account of his diet, well surely everyone can see that is vaguely ridiculous. There are clearly many factors at play in a fight and much as I’d love to think diet is at the top of the influence tree, provided key nutrient needs are met, along with kilojoules (or calories in old currency), other factors are going to have an infinitely bigger influence on the outcome.
"The idea that you need meat to be strong is a myth well worth busting and the film made a good job of doing that."
The protein argument
Much has been made in the commentary about the film about the protein claims made, in particular about the comparison of a peanut butter sandwich with a steak. Some people clearly don’t have food analysis software and have stated wrong data. So, let’s be clear. All three of these meals have 22g (rounding to nearest gram) of protein:
- 85g (3oz) raw beef rump steak
- Peanut butter sandwich made with 2 slices wholemeal bread and 60g (just shy of 2.5 tb) peanut butter
- 3 jumbo (extra large) eggs
- 220g cooked lentils (that’s 1.2 cups)
I don’t therefore have any major objection to the comparison made in the film. It was slightly out, but forgivably so. But what wasn’t said is that 85g raw weight of steak is a pretty small steak, whereas 60g of peanut butter on a sandwich is quite a lot… and try eating 1.2 cups of lentils. Your gut microbiota will love it, but you I suspect not so much! A serve of legumes in our Australian dietary guidelines is considered to be 75g.
The second thing to consider in light of the problem we have with overweight and obesity, is the kilojoules each of these food choices bring. To get the same amount of protein the beef (admittedly a leaner cut choice – but that’s what we would recommend) gives you 430kJ (100 Cals); the peanut butter sandwich 2200kJ (525 Cals), the eggs 930kJ (220 Cals) and the lentils 1320kJ (315 Cals). In other words, the meat gives you the same protein for far fewer kilojoules.
The reality of course is that most people would eat a bigger steak than this… but even if you had a 150g steak that’s 760kJ (180 Cals) and 38g protein… so much more protein and still fewer kilojoules than the plant-based food choices.
Before I’m misquoted, this does not mean I am advocating that you have to eat meat. I am not. You can combine your plant foods and get a perfectly adequate protein intake. What I am saying is that you cannot argue against the fact that animal foods are typically higher per serve for protein than plant foods.
Arguments have also been circulating with regard to protein quality. Two factors influence the quality of the protein in a food; the digestibility of that protein and its amino acid composition.
When we eat protein, our digestive system has to break down the protein strands into the constituent amino acids – the building blocks of protein. The protein source as well as other foods eaten alongside influence the digestibility of that protein. In general animal food protein sources are easily digested at 90-99%.
Of the plant proteins soy is one of the most digestible, matching that 90% plus. Other plant proteins don’t fare quite so well with a digestibility of some 70-90%.
Then you have to consider protein quality. There are roughly 20 amino acids humans need, but most of these the liver can make for us. Only 8 are truly essential in that we have to get them from our diet (there are a couple of what are called conditionally essential, but I’ll ignore those for now). In essence then we call high quality protein sources those that deliver the essential amino acids in relatively the same amounts and proportions that humans require.
Read that again because the film made light of this and made it confusing. It is not enough to say a protein contains all the essential amino acids. This is nutrition 101 that every new student learns. Most, but not all, plant protein sources are low in at least one essential amino acid, sometimes more. Plants have a more diverse amino acid profile and the pattern is usually quite different as to that found in animal foods. That’s not really all that surprising when you think about it. We are animals after all and so our protein composition is clearly more different to plants than other animals.
Nevertheless, for most of us this doesn’t really matter. To get your protein from plants, it’s not all that difficult, you simply have to eat a variety of different plant foods to get the complement of amino acids required. You don’t even need them in the same meal, so long as the variety occurs across the course of the day – at least for adults. I really can’t understand why this was not covered in the film. Perhaps to encourage you to buy pea protein powder?!
"To get your protein from plants, it’s not all that difficult, you simply have to eat a variety of different plant foods to get the complement of amino acids required."
There are numerous examples of this in traditional diets from around the world… animal foods can be expensive or hard to get after all, or forbidden in some cultures, and the clever human ancestors we have figured it out without any nutrition science knowledge! Think of corn tortillas and black beans in Mexico, dhal and roti in India, falafels (chickpeas) and flat bread in the Middle East.
What is pretty amazing is that now we can measure these foods in the lab and measure their essential amino acid profiles. We can see that legumes tend to fall short on methionine and tryptophan but are pretty good for isoleucine and lysine… this is the opposite to what we see with grains. So, combine the two together and voila, all the protein you need.
The bottom line is, if you want to follow a vegan diet you need to include a variety of plant food protein sources across the course of the day. Eating legumes and products made from them such as tofu and tempeh and then combine or alternate with wholegrains, nuts and seeds… and you’ll even get a small amount of protein from some vegies. Look for stand out foods that are excellent to boost your protein quality and overall intake such as hemp, chia and quinoa.
For the nerds (all love intended – that includes me) there is something called the protein digestibility-corrected amino acid score (PDCAAS). This basically takes into account both the protein digestibility and the amino acid profile of the protein food. 1.00 is the top value and the two foods that score 1.00 are both animal foods… milk and eggs. Other foods of interest: Beef 0.92, seafood 0.9-1.0, soy 0.91, chickpeas 0.78, other legumes all in the 0.6-0.7 range, dehulled hemp seeds 0.66, oats 0.57 (one of your best grain protein sources), peanuts 0.52 and wholegrain wheat 0.40.
Take home point = if you want to be or are vegan make sure you are eating legumes. They are your best plant protein sources. It’s pretty close to impossible to be paleo and vegan without risking malnourishment, not to mention a very restricted, boring diet!
Segway for a second before I have the paleo and vegan communities on my back. I like many aspects of both of these dietary approaches. I studied true paleolithic diets long before they were popular (and they include both animal and plant foods btw) and believe there is much we can learn… that’s a topic for another chat, but suffice to say that the good part of both approaches is to cut the crap and eat mostly whole minimally processed foods (as I stated above as being key). Hello! There are different ways to eat healthily… and many ways to eat badly.
"There are different ways to eat healthily… and many ways to eat badly."
What about vitamin B12?
Vitamin B12 in its active form is only found in significant quantities in animal foods. This means it almost always comes up in debates about our evolutionary diet. Surely this must be an indicator that humans evolved to eat animal foods.
The film makes the point that B12 is synthesised by bacteria and algae and in the past water, soil and bacterial loads on vegetables and other plant foods would have supplied sufficient B12 (there are tiny amounts on mushrooms for example contaminated with compost). They argue that today due to our hygiene practices, chemical treatment of water supplies to make them safe and minimal if any contact with soil, we no longer obtain B12 via these means.
Some commentators have criticised this line of thinking, saying there is no evidence that this was the case. But really to me it’s a rather silly point to argue over. It is feasible that these were indeed sources of B12, but we have no idea whether requirements were met via these routes and the likelihood is that they weren’t. Regardless, it’s all a moot point since you can’t get your B12 that way anymore.
One of the silliest arguments put forward in the film is the fact that animals like gorillas and oxen are strong and muscular and they follow a plant-based diet.
We may share a good proportion of our DNA with gorillas, but both these animals are widely different to humans. For starters they spend most of their day eating simply to get enough plant food to provide the energy they need. Plus, we are even more similar to chimps and they are omnivores!
Gorillas are also not vegans. They eat lots of plants for sure, but they also get B12 and protein, along with other nutrients, from eating insects, termites, beetles, ants and moths. They also eat their own poo. Since bacteria in the colon synthesise B12, this practice helps to give them the B12 they need.
"Gorillas are not vegans. They eat lots of plants for sure, but they also eat insects, termites, beetles, ants, moths... and their own poo!"
What about oxen? Well ruminant animals have a totally different gut and digestive system to us. They have a specialised stomach with four compartments that is designed to work in concert with bacteria to help them to break down tough fibrous plants and obtain the nutrients they need. Their gut bacteria produce the B12 they need – when we eat the liver, muscle flesh or milk of the animal the B12 is passed on to us.
We too have gut bacteria and fermentation that goes on, but the vast majority of this happens in our colon. B12 has a very specialised system for absorption and this happens at the end of the small intestine. Any B12 produced in the colon is too late in our digestive system and it is excreted in poo. Unless you want to behave like a gorilla that isn’t much good to us!
We have to get our B12 from food or supplements. We only need very small amounts and our bodies are very good at recycling and hanging on to the stores we have. If you make the change to a vegan diet it would most likely take at least a couple of years for you to become deficient, but you really don’t want that to happen.
Vitamin B12 is essential for making DNA, new cells, for metabolising fats and protein, and for the nervous system. Deficiency can lead to a host of symptoms including impairment of brain function, anaemia, fatigue, sore tongue, loss of appetite, constipation and nerve damage.
If you are following a 100% plant-based diet then either include foods that are fortified with B12 – many soy milks for example – or take a supplement.
Note however, that it is not just vegans who are at risk of B12 deficiency. Most cases are not due to dietary inadequacy but gut problems leading to poor absorption. If you have had a gastric bypass, gut resection, or you have stomach problems like gastric atrophy (common in the over 50s – as we get older we may produce less intrinsic factor, the chemical required to absorb B12) or gastric ulcers, you might want to have your doctor check for B12 deficiency. You may need B12 injections to bypass the gut completely in some instances.
"If you are following a 100% plant-based diet then either include foods that are fortified with B12 – many soy milks for example – or take a supplement."
The other argument I found really daft in the film was that since many cattle are supplemented with B12, we are all really getting this vitamin via supplements. Further they went on to recommend that everyone take a supplement! Cattle in feedlots fed diets far removed from their natural pasture style diet are given supplements of all sorts of nutrients. That is reflective of the intensive means of producing meat and we can all agree there are problems with that.
What about the environmental aspects of our diet choices?
This is an area I am hugely interested in and you’ll find me writing and speaking more on the topic as I learn from agriculturists and scientists researching and working in the field.
Here’s what I know to refute some of the arguments made in this film.
- Some areas of land are better suited to animal farming and may be completely unsuitable to plant crops.
- Vast areas of land farmed for the production of monocrops such as soy, corn or wheat are hugely problematic for the environment. Loss of topsoil, loss of natural habitats to create farming land destroys eco-systems and animals, the use of pesticides and fertilisers, the requirement for water… and so on. In short, plant agriculture on the scale required to feed a growing world population is not without problems.
- There is no doubt massive feedlots producing grain-fattened meat are not good for our health or our planet’s health. But there are other solutions. Regenerative agriculture is something we will hear more about and is already active in Australia. Progressive farms utilising these methods have actually shown they can be carbon sinks.
- Here in Australia most of our cattle are grass fed on pasture for most of their lives, bar when there is drought making that impossible. Some are fattened up on grain to produce marbled fattier meats – favoured by the Japanese and some chefs, not by me! But our farming systems are very different to the US where most of the negative meat and health studies have come from.
- Animal farming actually turns much of the by-products from plant farming into more nutrient-dense food for us. What would happen to all these farm animals were we all to turn to only eating plants?
You cannot argue with those who choose to be vegan because they don’t want to kill or exploit animals for food. That is a moral, ethical decision we must all make. However, it is also valid to raise the fact that many animals also die in the process of farming plants. Most people are concerned about animal welfare and most certainly we have to try to ensure farming at all levels is as humane as possible. Improvements can almost certainly be made, but doesn’t this then come down to us improving both plant and animal farming across the board?
This is another biased documentary that does not tell the whole story and is often misleading or just plain silly (I didn’t even touch on the erectile function ‘experiment’ – please this was not science!). If it encourages you to eat more whole plant foods then terrific - very few people in the developed world are eating enough. Were we all to shift to more whole plants and concentrate on removing the junk foods from our diets, we would see significant changes in health. Make that your take home message. Whole foods are the way to go and include plentiful plants whether or not you also choose to eat animal foods.
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