How does a Vegan Diet affect your health and intelligence?

There’s a lot more digging to be done before we know for certain if Veganism can be healthier than any other diet – especially when it comes to long-term health effects. The vegan diet is low in – or, in some cases, entirely devoid of – several important brain nutrients. Could these shortcomings be affecting vegans’ abilities to think? How healthy is Veganism? Is the diet good for you, or is it potentially dangerous to your health?

By Zaria Gorvett for The International Chronicles

It was the late 1880s in the city of Rajkot, India. The meeting was to take place on the banks of the local river – and discretion was essential. Mahatma Gandhi, who was just a teenager at the time, hadn’t told his parents where he was going; if they had found out, they would have been shocked to death.

As it happens, Gandhi was having a picnic. And on this occasion, India’s future national hero – and one of the most famous vegetarians in history – wasn’t planning to dine on cucumber sandwiches. No, for the first time in his life, he was going to eat meat.

As he later wrote in his biography, Gandhi was raised as a strict Vaishnava Hindu, so he had never even seen meat before this fateful day. But his picnic companion was a shady character with an unusual obsession – the idea that meat held the key to being physically and mentally strong.

In the end, Gandhi braved the meat. It was as tough as leather.

More stories on The Vegan Factor from BBC Good Food

The idea that avoiding meat is bad for our brains makes some intuitive sense; anthropologists have been arguing about what our ancestors ate for decades, but many scientists think that there was a lot of bone-crunching and brain-slurping on the road to evolving these remarkable 1.4kg (3lb) organs. Some have even gone so far as to say that meat made us human.

One reason is that intelligence is expensive – the brain devours about 20% of our daily calories, though it accounts for just 2% of our body weight – and what better way to find the enormous array of fats, amino acids, vitamins and minerals these fastidious organs require, than by feasting on animals which have already painstakingly collected or made them.

Mahatma Gandhi, India’s pioneering independence leader, even toyed with eating meat despite his vegetarian beliefs (Credit: Getty Images)

But though it’s hard to imagine our ancestors choosing turnips over tuna, today it’s a different story. According to the latest statistics, there are around 375 million vegetarians on the planet. In the West, veganism has ditched the hippie stigma to become one of the fastest-growing millennial trends; in the United States, it grew by 600% between 2014 and 2017. Meanwhile in India, meat-free diets have been mainstream since the 6th Century BCE.

On the one hand, recent concern about the nutritional gaps in plant-based diets has led to a number of alarming headlines, including a warning that they can stunt brain development and cause irreversible damage to a person’s nervous system. Back in 2016, the German Society for Nutrition went so far as to categorically state that – for children, pregnant or nursing women, and adolescents – vegan diets are not recommended, which has been backed up by a 2018 review of the research. In Belgium, forcing a vegan diet on your offspring could land you a spell in prison.

But on the other, if abstaining from meat had any real impact on our brains, you would think that we would already have noticed. So is it really damaging our intellects, or is this all just fear of the unknown?

Ideally, to test the impact of the vegan diet on the brain, you would take a randomly selected group of people, ask half to stop eating animal products – then see what happens. But there isn’t a single study like this.

There are several important brain nutrients that simply do not exist in plants or fungi

Instead, the only research that comes close involved the reverse. It was conducted on 555 Kenyan schoolchildren, who were fed one of three different types of soup – one with meat, one with milk, and one with oil – or no soup at all, as a snack over seven school terms. They were tested before and after, to see how their intelligence compared. Because of their economic circumstances, the majority of the children were de facto vegetarians at the start of the study.

Surprisingly, the children who were given the soup containing meat each day seemed to have a significant edge. By the end of the study, they outperformed all the other children on a test for non-verbal reasoning. Along with the children who received soup with added oil, they also did the best on a test of arithmetic ability. Of course, more research is needed to verify if this effect is real, and if it would also apply to adults in developed countries, too. But it does raise intriguing questions about whether veganism could be holding some people back.

In fact, there are several important brain nutrients that simply do not exist in plants or fungi. Creatine, carnosine, taurine, EPA and DHA omega-3 (the third kind can be found in plants), haem iron and vitamins B12 and D3 generally only occur naturally in foods derived from animal products, though they can be synthesised in the lab or extracted from non-animal sources such as algae, bacteria or lichen, and added to supplements.

Others are found in vegan foods, but only in meagre amounts; to get the minimum amount of vitamin B6 required each day (1.3 mg) from one of the richest plant sources, potatoes, you’d have to eat about five cups’ worth (equivalent to roughly 750g or 1.6lb). Delicious, but not particularly practical.

To get your daily requirement of vitamin b6, you would need to eat around 1.5lbs of potatoes

And though the body can make some of these vital brain compounds from other ingredients in our diets, this ability isn’t usually enough to make up for these dietary cracks. For all of the nutrients listed above, vegetarians and vegans have been shown to have lower quantities in their bodies. In some cases, deficiency isn’t the exception – it’s completely normal.

For now, the impact these shortcomings are having on the lives of vegans is largely a mystery. But a trickle of recent studies have provided some clues – and they make for unsettling reading.

“I think there are some real repercussions to the fact that plant-based diets are taking off,” says Taylor Wallace, a food scientist and CEO of the nutrition consulting firm Think Healthy Group. “It’s not that plant-based is inherently bad, but I don’t think we’re educating people enough on, you know, the nutrients that are mostly derived from animal products.”

One of the most well-known challenges for vegans is getting enough vitamin B12, which is only found in animal products like eggs and meat. Other species acquire it from bacteria which live in their digestive tracts or faeces; they either absorb it directly or ingest it by snacking on their own poo, but unfortunately (or fortunately, depending on how you look at it) humans can’t do either.

Later in life, the amount of B12 in a person’s blood has been directly correlated with their IQ

“There are some tragic cases of children whose brains failed to develop because of their parents being ill-informed vegans,” says David Benton, who studies the link between our diets and brain chemistry at Swansea University. In one example, the child was unable to sit or smile. In another, they slipped into a coma.

Later in life, the amount of B12 in a person’s blood has been directly correlated with their IQ. In the elderly, one study found that the brains of those with lower B12 were six times more likely to be shrinking.

Even so, low B12 is widespread in vegans. One British study found that half of the vegans in their sample were deficient. In some parts of India, the problem is endemic – possibly as a consequence of the popularity of meat-free diets.

Another nutrient that’s scarce in the typical vegan diet is iron. Though we often associate it with blood, iron also plays prominent role in brain development, and is essential for keeping the organ healthy throughout our lives. For example, one 2007 study found that giving young women iron supplements led to significant intellectual gains. In those whose blood iron levels increased over the course of the study, their performance on a cognitive test improved between five- and seven-fold, while participants whose haemoglobin levels went up experienced gains in their processing speed.

It is important for vegans to take supplements to replace the essential elements found in animal products, experts say

It’s surprisingly easy to slip into iron deficiency, even though it makes up 80% of the inner mass of the planet we live on. Up to two billion people are thought to have a shortage of the element worldwide, making it the most common nutritional inadequacy. Vegans are particularly prone, because the form that’s most readily absorbed by the body is “haem iron”, which is only found in animal proteins. One German study found that 40% of the vegans they looked at were consuming less than the recommended daily amount.

Other common deficiencies among vegans include D3, omega-3, selenium, folate and iodine. Though the body can make D3 when the skin is exposed to sunshine, this doesn’t make up for the extra that vegans are missing from their diets. In the winter months, when the sun is weaker, omnivores living in the UK have nearly 40% more vitamin D3 in their blood than vegans.

Of course, some of these things can easily be acquired from supplements. But others are so obscure, vegans are unlikely to have even heard of them – let alone realise they could be missing out.

The holes in our current understanding of what the brain needs to be healthy could potentially be a major problem for vegans

One example is taurine. This enigmatic amino acid is one of the most plentiful in the human brain, where it’s thought to underpin several important processes, such as regulating the number of neurons. It’s often added to caffeinated energy drinks, because of the (possibly mistaken) belief that it can provide an immediate cognitive boost.

Though there are small amounts of taurine in some dairy products, the main dietary sources are meat and seafood. “Some species have the ability to make all the taurine they need,” says Jang-Yen Wu, a biomedical scientist at Florida Atlantic University. “But humans have a very limited capacity to do this.”

For this reason, vegans tend to have less taurine in their bodies. No one has looked into how this might be affecting their cognitive abilities yet, but based on what we know about its role in the brain, Wu says vegans should be taking taurine tablets. “People can become deficient when they restrict their diets, because vegetables have no taurine content,” he says.

In fact, the holes in our current understanding of what the brain needs to be healthy could potentially be a major problem for vegans, since it’s hard to artificially add a nutrient to your diet, if scientists haven’t discovered its worth yet.

It’s hard to artificially add a nutrient to your diet, if scientists haven’t discovered its worth yet

“There are so many unknowns,” says Nathan Cofnas, a biologist from Oxford University. “And when you deviate from the typical diet for your species, to one which has not been tested and properly established to be healthy or good for the brain, you are conducting an experiment and you are taking a risk.”

Take choline: in the brain, it’s used to make acetylcholine, which is involved in a number of tasks, including relaying messages between nerve cells. It’s fundamental to our ability to think – even insects have it in their tiny brains – and the body can’t produce enough of it on its own.

And yet: “It’s a very understudied nutrient,” says Wallace. “I believe we’ve only considered it essential [something you have to get from your diet] since the late 1990s.”

Recently creatine has started to attract a fanbase as a smart drug

There are small amounts of choline in lots of vegan staples, but among the richest sources are eggs, beef and seafood. In fact, even with a normal diet, 90% of Americans don’t consume enough. According to unpublished research by Wallace, vegetarians have the lowest intakes of any demographic. “They have extremely low levels of choline, to the point where it might be concerning,” he says.

For vegans, the picture is likely to be bleaker still, since people who eat eggs tend to have almost double the choline levels of those who don’t. And though the US authorities have set suggested intakes, they might be way off.

Wallace points to a 2018 study, which found that the babies of women who consumed twice the amount considered “adequate” – around 930mg each day – in the last third of pregnancy enjoyed a lasting cognitive edge. For comparison, the average vegetarian gets roughly a fifth of that amount.

Vegans can get the protein they need from alternatives such as soya, but it won’t give them essential elements such as choline and creatine (Credit: Getty Images)

In other cases, our understanding is even murkier.

The latest nutrient in question is creatine – a white, powdery substance often found in fitness shakes. Its natural function in the body is to supply our cells with energy, so it’s revered by gym obsessives as a way to improve their endurance.

But it’s also important to the brain – and studies have shown that increasing your intake can provide a range of benefits, such as a better recognition memory and reduced mental fatigue. Recently it’s started to gain traction as a smart drug.

It’s well-established that vegans and vegetarians have significantly lower levels in their bodies, because plants and fungi don’t contain any.

This has led scientists to wonder whether a creatine deficit could be holding some people back. For one study, researchers tested how the intelligence of vegetarians and omnivores changed after five days on supplements. “We found that the vegetarians seemed to benefit particularly,” says David Benton from Swansea University, who led the research.

In contrast, the omnivores were relatively unaffected. This hints that, unlike the vegetarians, they already had the appropriate amount of creatine in their brains.

It can make quite a substantial difference in your life, whether your intelligence is one standard deviation above the mean or two – Nathan Cofnas

However, Caroline Rae, who led another study, says there isn’t enough evidence to back taking creatine yet. It may come with unintended consequences, such as reducing the brain’s ability to make its own – leading to “creatine withdrawal”. “I’ve always hypothesised that it could be useful if you wanted to cram for an exam, but it would be interesting to see if people then got slower after they stopped.”

Finally, the brain largely makes its own supply, so it’s not clear if vegans actually need any extra. Instead of being a major source, the creatine in our diets might only be used by the brain in “extreme” conditions, like when we’re stressed.

Creatine, carnosine, taurine, omega-3, heme iron and vitamins B12 and D3 only occur naturally in foods made from animal products (Credit: Getty Images)

Nevertheless, Cofnas finds the potential creatine deficits in vegans disturbing. “It can make quite a substantial difference in your life, whether your intelligence is one standard deviation above the mean or two,” he says, referring to the small-yet-significant intellectual gains made by vegetarians on creatine supplements.

So what’s the verdict?

“I think we need a lot more research into vegan nutrition and health,” says Heather Russell, a dietitian from The Vegan Society. “As far as we can tell, it’s possible to lead a healthy life as a vegan – certainly there are people who thrive on a vegan diet.” Though it’s important to take supplements, she explains that a person’s cardiovascular and brain health are inextricably linked, and vegans tend to have healthier hearts.

“I tell people all the time, if you’re going to be a vegan or vegetarian, that’s fine,” says Wallace. “I’m certainly not advocating against it. But there are 40 or something essential nutrients. So, I mean, it really would take a lot of research for vegans to get everything the brain needs,” he says. Some nutrients that a typical vegan diet is low or lacking in, like choline, creatine, carnosine and taurine, are extremely bulky, so just taking a standard vitamin tablet won’t be enough. Instead, they need to be taken individually.

Without question, veganism can cause B12 and iron deficiencies, and without question they affect your intelligence – Nathan Cofnas

Benton agrees. “I’m sure that if you are knowledgeable, careful, and obsessive about it – and you have all the right personality characteristics to be this way – then it is possible to have a healthy diet as a vegan,” he says. “But it is distinctly possible that you could have deficiencies.”

Cofnas takes a harsher view. Though vegans can take supplements, he thinks it’s unrealistic to expect that they all will. Consequently, he finds the recent shift towards plant-based diets troubling, though he’s sympathetic to the arguments for doing so. “Without question, veganism can cause B12 and iron deficiencies, and without question they affect your intelligence,” he says.

As for Gandhi, he eventually abandoned his illicit relationship with meat, and went back to vegetarianism. But his experiments with nutrition didn’t end there. He also ditched salt, then went back to it, and attempted veganism – though after a bout of dysentery practically reduced him to a living skeleton, he decided that milk products were necessary, in order for a person to be healthy.

Whatever the truth is, isn’t it about time we found out?

EXTRA DEBATE ON VEGANISM: PRO AND CON

Is vegan healthy?

THE CASE FOR NO…

Recently, I’ve received a few emails from readers who’ve asked me, “I’m so confused about a healthy diet! Is vegan healthy? I’ve read/seen [enter vegan book or documentary here] promoting a vegan lifestyle, but I know that you eat many animal products.”

Food is complicated, but let’s start with the many aspects of a balanced diet on which everyone agrees – even the vegans and paleos! This includes:

  • Enjoy an abundance of freshly prepared vegetables
  • Minimized processed foods and instead cook meals from scratch
  • Eat mindfully and slowly
  • Source local, organic foods and support small farms

But what about the question of eating animals products? I firmly believe that properly-sourced animal products are essential to both the health of the human race and the health of the planet. Here are 10 reasons why I will never be a vegan.

1. A vegan diet never sustained any traditional culture

Dr. Weston Price, a dentist with a passion for nutrition, traveled the globe to discover the secrets of healthy, happy people. He recorded his findings in the 30’s in the landmark book, Nutrition and Physical Degeneration. From the Inuit in Alaska to the Maori in New Zealand, Dr. Price revealed that the diets traditional to each culture, although dependent on geography, followed a strict set of dietary laws.

Perhaps the most striking commonality is an unerring reverence for animal foods. No traditional culture subsisted on a vegan diet, a fact that Dr. Price found particularly interesting.

Some cultures, such as the Masai tribe in Africa, consumed almost exclusively animal products. The Masai ate meat, milk and blood from their cattle, experiencing profound health and incredible bone structure (which is an indicator of generational health). Cultures – such as the Inuit – that didn’t practice animal husbandry caught wild meat or fish. Groups who had the least access to animal products would forage for grubs and bugs.

The China Study (which is a book title, not a study) has been used to promote the idea that primarily vegan cultures experience better health than omnivorous cultures. T. Campbell, the author, notoriously cherry-picked data to arrive at a specific conclusion. Denise Minger, author of Death by Food Pyramid, published a scathing critique of Cambell’s work in her article, The China Study: Fact or Fiction.

Read more and sources: Nutrition and Physical Degeneration, Nourishing Traditions, The China Study: Fact or Fiction

2. Vegan diets do not provide fat-soluble vitamins A and D

Contrary to popular belief, you can’t get vitamin A from carrots. Vegetables provide carotene, a precursor to vitamin A, while animal sources such as liver and pastured egg yolks provide true vitamin A. Many people believe that carotene can be converted into vitamin A, but this conversion is usually insignificant. First, it takes a huge amount of carotene to convert to a moderate amount of vitamin A. Second, when there is poor thyroid function, impaired digestion or a a lack of healthy fats in the diet, this conversion won’t happen.

In the same way, useable vitamin D (natural vitamin D3) is only found in animal products such as pastured egg yolks, cod liver oil and dairy products from grass-grazing animals. Traditionally, ancient cultures that lived in darker environments relied heavily on these vitamin-D rich foods (for example, Scandinavians ate copious amounts of salmon and grassfed butter). The myth that we can obtain vitamin D from mushrooms is false… mushrooms contain vitamin D2, which is extremely poorly absorbed.

Vitamin A and Vitamin D are particularly essential for immune regulation, digestion, fertility and hormone balance.

Read more and sources: True Vitamin A Foods, The Vitamin A SagaVitamin D in Mushrooms?

3. Vegan diets often rely heavily on soy

Soy, soy, the magical fruit. The more you eat, the more… your hormones go berserk!

10 years ago, a vegan diet equated to vegetables interspersed with soy milk, soy cheese, soy bacon, soy protein, soy cereal, tofu, and tempeh. Now, the health problems with chronic soy consumption are becoming more mainstream anedemame 2d many vegans have reduced their soy consumption. Even so, a vegan diet often relies on a moderate amount of soy products  – especially soy protein powders and soy protein bars.

The primary concern with consuming soy in any form is the phytoestrogen content. Phytoestrogens can mimic estrogen in the body, causing a chain reaction of hormone imbalances. Although studies showing the hormonal effects of consuming soy are controversial, I believe the research indicates that we should play it safe rather than sorry. For example, one study showed that infants consuming soy formula had concentrations of blood estrogen levels 13,000 to 22,000 times higher than normal estrogen levels!

Read more, studies and sources: Exposure of infants to phyto-oestrogens from soy-based infant formulaStudies showing the adverse affects of dietary soyIs Soy Bad for You or Good For You?  (a great summary of research on soy and why it may be biased)

4. Vegan diets do not provide vitamin K2

Vitamin K2 is the shuttle that transports calcium into your bones. You can eat as much calcium as you want but it won’t strengthen your bones unless it is accompanied by vitamin K2. This is one reason why calcium supplementation has beencheese slice shown to increase the risk of plaque formation – the body can’t use the calcium for building bones so it stores it in the arteries.

Unlike vitamin K1, plants do not provide vitamin K2. (The one and only exception to this rule is natto, a fermented soybean product. One problem, however, is that natto is, for the majority of humans and animals, repulsive to eat). Like other fat-soluble vitamins, Vitamin K2 is found fatty sources – Mother Nature packages the vitamin with the cofactors required to absorb it. You’ll get vitamin K2 in pastured egg yolks, milk and cheese from grassfed animals, liver, beef, and chicken.

Read more and sources: Vitamin K2 and The Calcium Paradox

5. Ethical omnivorism supports a healthy planet

What is ethical omnivorism? I define it as choosing sustainably-raised animal products from small, local producers. With a little planning and careful selection, can be relatively budget-friendly. I think people should eat less meat, but a much higher quality to support the demand for pasture-raised meats. $1 hamburgers have no place in an ethical omnivore world. 

Our ecosystem relies on a self-regulating balance of  predators and prey. This system worked well with humans and their prey until we began inhumane farming practices that compromise the wellbeing of animals, the health of humans, and the health of the planet.

But just like Confined Feeding Animal Operations aren’t the answer to a healthy planet, neither is veganism. Vegan diets ten to demand a higher quantity of cereal grains and soy, crops which wreak havoc on our ecosystem due to mass farming techniques. On the other hand, grass-grazing animals can nourish stripped soil and even reverse desertification!

Read more and sources: Joel Salatin on Grassfed Beef (video), Reversing Desertification with Grassfed CowsEat the Yolks.

6.  Real Food > Fake Food

How do you create cheese, milk and meat without cheese, milk and meat? With a slew of non-foods including stabilizers, gums, thickeners and highly processed protein extracts. Yummy.

Let’s consider the example of Earth Balance, a non-dairy butter often used in vegan diets.

  • Ingredients in a Earth Balance: Palm fruit oil, canola oil, safflower oil, flax oil, olive oil, salt, natural flavor, pea protein, sunflower lecithin, lactic acid, annatto color.
  • Ingredients in butter: butter.

Humans have been eating butter for thousands of years. We only started producing canola oil in the last century. Butter is real food, but canola oil is a freak of nature. Similarly, pea protein and natural flavors are highly processed non-foods.

Fortunately, more and more people are becoming aware that processed vegan products are just that – highly processed. Still, many vegans reach for these options on a regular basis.

Read more: 7 reasons to never use canola oil6 reasons to avoid non dairy milks.

7.  Vegan isn’t the answer to autoimmune disease

Autoimmunity is a 21st century epidemic, with 50 million people suffering with an autoimmune disease in America (according to AARDA) But did you know that you can address autoimmunity with diet? I’m living proof that it works! Three years ago, my ulcerative colitis was so advanced that my doctors wanted to remove my colon. Instead, I decided to do whatever it took to heal myself naturally. Now, I’m completely symptom free (and colon intact!) thanks to my dietary changes.

All disease begins in the gut, and all disease must be addressed by improving gut health. In the case of autoimmunity, the intestines are permeable to bacterial toxins and undigested proteins (leaky gut), which cause an problematic immune response.

To heal leaky gut, specific foods must be removed from the diet and nutrient-dense foods should be emphasized. The two leaders in leaky gut dietary treatment – Dr. Natasha Campbell McBride and Sarah Ballantyne – both agree that animal products are a nonnegotiable, essential part of healing leaky gut to address autoimmunity.

Read more and sources: The Gut and Psychology Syndrome Diet, The Paleo Approach, Breaking the Vicious Cycle.

8.  You must take life to have life

Many people choose veganism because they think it cruel to take a life, but something dies no matter what you eat. For example, field mice were demolished in order to grow the corn for a box of vegan cereal.

Further, plants are living beings, capable of communicating with each other and the world around them. Controversial but intriguing research, discussed in this documentary, indicates that plants can even sense and respond to human emotions!

Nutritional Therapist Liz Wolf sums it up perfectly in her book Eat the Yolks:

If we truly believe that no living thing should have to die for our dinner, we shouldn’t eat at all. If we truly believe that all life deserves equal respect, why not equalize ourselves by embracing the elegant fact that we are all, as Nelson writes, “driven by the same hungers that motivate any other creature— the squirrel in the forest, the vole in the meadow, the bear on the mountainside, the deer in the valley”?

Read more and sources: The Secret Life of Plants (free documentary on Youtube), Eat the Yolks, The Intelligent Plant.

9. Vegan diets are deficient in vitamin B12 and iron

Like vitamin A, D and K2, the readily-absorbed form of vitamin B12 and iron is found only in animal sources (are you seeing a pattern here?). Testing with the most up-to-date methods show that 83% of vegans are B12 deficient, compared to 5% of omnivores.

What about spirulina and brewer’s yeast as a source of B12? Chris Kresser has an excellent post on vegan diets and vitamin deficiencies in which he addresses this question:

A common myth amongst vegetarians and vegans is that it’s possible to get B12 from plant sources like seaweed, fermented soy, spirulina and brewers yeast. But plant foods said to contain B12 actually contain B12 analogs called cobamides that block the intake of, and increase the need for, true B12. (4)

Chris also discusses iron in his post. While plants such as lentils and leafy greens do provide some iron, it is not as well-absorbed as animal-based iron. He explains,

Vegetarians and vegans have lower iron stores than omnivores, and […] vegetarian diets have been shown to reduce non-heme iron absorption by 70% and total iron absorption by 85%. (6, 7)

Read more and sources: Why You Should Think Twice About Vegetarian and Vegan Diets, Eat the Yolks

10. Animal fats offer unique nutrients

Have you heard that flax seeds, walnuts, hemp seeds and chia seeds are all excellent sources of omega-3? That may be true, but these plant sources provide a form of omega-3 that is not well absorbed by the body.

The omega-3 in plant sources, such as flaxseed and walnuts, is ALA. ALA must be converted to EPA or DHA in the body to be useable. Unfortunately, the conversion between ALA and EPA/ DHA is extremely low. One study showed that women convert about 21% of ALA to EPA and 9% to DHA. The conversion rates for men are even lower.

Further, as Chris Kresser points out in his article on vegan nutrient deficiencies, “the conversion of ALA to DHA depends on zinc, iron and pyridoxine—nutrients which vegetarians and vegans are less likely than omnivores to get enough of.”

Fats from sustainably-raised animals provide unique health benefits not found in plant sources:

  • EPA and DHA, the active forms of omega-3 vital for cognitive function, are found only in animal sources such as fatty fish.
  • Fat soluble vitamins A, D and K2 are found in fatty animal products (discussed above).
  • Cholesterol, a vital ingredient for healthy hormones, can be dietarily obtained only through animal sources. Yes, the body can produce cholesterol, but dietary cholesterol is a key part of wellness including memory, liver health, and digestion.

But don’t cholesterol-rich saturated fats cause heart disease? Nope! Saturated fats were wrongly blamed for heart disease with the help of poor research and sleazy food politics. Now, even mainstream sources are acknowledging the science.  For example, the 2014 June cover of Time Magazine announced, “Eat butter. Scientists labeled fat the enemy. Why they were wrong.”

THE CASE FOR YES…

1. A vegan diet never sustained any traditional culture

To which I would reply: so what? The computer you’re reading this post on right now never existed in a traditional culture either.
This bullet point seems to be a direct appeal to tradition (and/or possible nature). This is considered a fallacy, because of course traditional things aren’t invariably good (and unnatural things aren’t invariably bad) and the appeal to tradition assumes this is the case. Ebola, malaria, dying of starvation are all about as natural as one c an get. Slavery, patriarchy, discrimination based on sexual orientation certainly are traditional. Any takers to argue in favor of those things?

2. Vegan diets do not provide fat-soluble vitamins A and D

Without a study demonstrating that vegans end up deficient, this is just an appeal to your emotions. Vitamin D3 actually isn’t only found in animal products, you can get a vegan D3 supplement if you’d like. If you’re tempted to say “hey, supplements aren’t natural!”, please refer to my previous point about appeals to nature/tradition.
It’s true that you do need more D2 or veggy vitamin A precursors than retinyl palmitate, this article substantially overstates the difficulty of reaching your daily requirements. Refer to: https://en.wikipedia.org/wiki/Vitamin_A#Equivalencies_of_retinoids_and_carotenoids_.28IU.29

3. Vegan diets often rely heavily on soy: Soy, soy, the magical fruit. The more you eat, the more… your hormones go berserk!

No, no they don’t. https://en.wikipedia.org/wiki/Soybean#Health_risks
There isn’t really any credible scientific evidence to back up the author’s doom-and-gloom claims here. Phytoestrogens aren’t the same as actual estrogen, and the effect is quite weak. At normal levels of consumption, issues are pretty unlikely. Soy foods can actually have beneficial health effects too. (For example, a reduction in the risk of prostate cancer for me.)
And of course there’s no *requirement* that vegans consume soy. So arguing against soy, even if the article met a reasonable burden of proof to demonstrate that soy is harmful is *not* equivalent to an argument against veganism.

4. Vegan diets do not provide vitamin K2

You can take a vitamin K2 supplement if you want. However, your body can synthesize K2 from precursors like K1, you also absorb some from intestinal bacteria. Vitamin K deficiency is considered rare.

5. Ethical omnivorism supports a healthy planet

Each time you go up a link in the food chain, you lose roughly 90% of energy from the previous level. Eating high on the food chain is inherently inefficient. Scale that inefficiency up to 7 billion people and the environmental effects are very significant, even if the individual contribution is small.
Producing animal based foods also require much more water, animals produce large amounts of greenhouse gases that contribute to climate change.
Our ecosystem relies on a self-regulating balance of predators and prey.
Hard to tell what the author is advocating here. Clearly 7 billion hunter gathers isn’t feasible, though.
Vegan diets ten to demand a higher quantity of cereal grains and soy, crops which wreak havoc on our ecosystem due to mass farming techniques.
The top three crops produced in the US are soy, corn, and alfalfa. Of those, 80% or more are fed to animals.

6. Real Food > Fake Food

Appeal to nature fallacy here.

7. Vegan isn’t the answer to autoimmune disease

Um, okay? Going vegan certainly isn’t a panacea. It’s a method by which you can reduce the harm you cause, both environmental and to other individuals.

8. You must take life to have life

Not all life is equivalent. A plant isn’t sentient: it cannot suffer, it cannot be deprived of its happiness, it doesn’t establish preferences, is incapable of emotional states, does not form social bonds.
Many people choose veganism because they think it cruel to take a life, but something dies no matter what you eat. For example, field mice were demolished in order to grow the corn for a box of vegan cereal.
Going vegan is about reducing the harm you cause. Eliminating it entirely is the ideal, but generally not practical to reach. Since the majority of many plant-based crops are fed to animals, eating that animal therefore compounds your harm since all the same criticisms apply.
Further, plants are living beings, capable of communicating with each other and the world around them.
Plants are more complex than many people give them credit for, they can signal to each other and react to stimuli. This doesn’t imply that they are capable of feeling in the way that humans and many animals are, though.
Controversial but intriguing research, discussed in this documentary, indicates that plants can even sense and respond to human emotions!
The linked documentary is based on The Secret Life of Plants, which in pure bunk. It’s pseudoscience: https://en.wikipedia.org/wiki/The_Secret_Life_of_Plants
The author here does themselves a serious disservice. Any critical reader should have serious doubts at this point. When such an unreliable source is cited without blinking, one has to wonder about the veracity of the author’s other references.
Finally, even if plants were exactly as sentient as animals, what do you think any animal you contemplate eating ate itself? It ate either other animals or it ate plants. Due to the inefficiency of trophic levels (90%, remember) eating any animal is indirectly eating far more plants than if you simply ate some plants directly. So again: harm reduction.

9. Vegan diets are deficient in vitamin B12 and iron

First, B12 doesn’t actually come from animal foods. It’s produced by bacteria exclusively. Vegans definitely do need to supplement B12. Many common foods like soy/almond/coconut milk are fortified.
Testing with the most up-to-date methods show that 83% of vegans are B12 deficient, compared to 5% of omnivores.
This is the actual study that was indirectly referenced: http://ajcn.nutrition.org/content/78/1/131.long
The results are substantially more nuanced and ambiguous than the other here implies. The total number of vegans in the study was 29. Of those, only 59% actually supplemented their diet with B vitamins. It doesn’t seem like the authors of the study knew exactly which B vitamins were supplemented or what doses the test subjects were taking. Without controlling for those variables, and given the pretty small sample size it doesn’t seem reasonable to draw a definitive conclusion here.
There also seems to be abiguity in the markers the researchers used. There are other possible causes for changes in those markers. Additionally:
“The incidence of pathologically abnormal indexes of vitamin B-12 status was clearly related to the type of diet, because it was considerably higher in the vegans than in the other 2 groups. It was not clear in the current study whether the slightly better vitamin B-12 status in the LV-LOV subjects taking vitamins was attributable to vitamin B supplements or to the weak statistical power resulting from the small number of subjects in this group (Table 1⇑). Therefore, subjects taking vitamins were excluded from further analysis.”
It’s not completely clear exactly which results this applies to, but the researchers said that they specifically *excluded* test subjects that took vitamins in some cases.
Chris also discusses iron in his post. While plants such as lentils and leafy greens do provide some iron, it is not as well-absorbed as animal-based iron.This only matters if you aren’t getting sufficient iron to meet your nutritional needs.

10. Animal fats offer unique nutrients:

Have you heard that flax seeds, walnuts, hemp seeds and chia seeds are all excellent sources of omega-3? That may be true, but these plant sources provide a form of omega-3 that is not well absorbed by the body.
Again, this only matters if you don’t get an adequate amount. It is also possible to supplement with algae-derived omega3 if you think your intake is inadquate for some reason.
Yes, the body can produce cholesterol, but dietary cholesterol is a key part of wellness including memory, liver health, and digestion.
The author seems to have neglected to back up this claim with any reputable scientific evidence.
Read more, studies and sources: 5 Reasons Why Butter is a Superfood, Cholesterol and Heart Disease, 2010 meta-analysis on saturated fat consumption, 2014 meta-analysis on saturated fat consumption, study on ALA conversion, Nourishing Traditions, Why You Should Think Twice About Vegetarian and Vegan Diets.
There are a number of links, here, but they are primarily to other blogs. That doesn’t really meet the required standard. Given the titles, it seems like bias is rather likely.