Vetting the Vegan Diet
The Nutritional Implications of an Exclusively Plant-Based Diet
Note: You can listen to this article by clicking on the voiceover recording above.
As a health coach and nutrition writer, my purpose is to help people make informed choices. The only diet I wish to promote is a healthy one. This article unpacks the nutritional implications of the vegan diet, so that you may take this into account in shaping your own health.
The role of animal nutrients in human health is indisputable. Biologically, we are omnivores, evident in everything from our teeth, which are designed to tear animal flesh, to our cellular membranes, which are made of animal-based essential fatty acids. Our digestive systems are designed to unlock and assimilate animal fat and protein into our bodies. Certain critical micronutrients may also only be derived from animals.
Nature’s design is a given. But is it possible to edit, bypass, or transcend this evolutionary blueprint and achieve good health by other means?
It’s a question brushed off by many vegans for whom nutrition is simply not a priority. Rather, veganism is a choice often made for philosophical, ethical, environmental, or other personal reasons. Improving one’s own physical health is often superseded by a desire to protect animals and preserve the environment – noble and worthy causes – but does eating an exclusively plant-based diet accomplish these well-intended goals? This article explores that question as well.1
According to AI, vegans currently represent 1% of the population both in the U.S. and globally. While this does not sound like much, it translates to roughly 89-90 million people worldwide. Vegan surveys contend the national number is more like 3-4%, depending on how strictly the term “vegan” is defined and how accurately those surveyed self-assess. For many individuals, it’s a passing trend.
The available data also shows vegans are more than twice as likely to be urban dwellers.2 Most have never lived in a rural area, and curiously, very few have worked with animals or have close contact with nature. A theoretical mindset of “man over nature” is common, in which vegans believe we may override or improve upon nature’s design. Unfortunately, there is no scientific evidence to support this ideology – on the contrary, research increasingly reveals the opposite, that we have no choice but to harmonize with biology if we want to preserve our long-term health. But what does that mean?
It is widely believed that a plant-based diet is healthy, and compared to the average American diet, this is certainly true. Most Americans would do well to double or even triple the amount and type of vegetables they eat. Ideally, half your plate at every meal should be vegetables, mostly the non-starchy type. Most of us need more fiber, too, such as from whole grains and beans. And we all benefit from the thousands of phytonutrients found in plants, many of which have co-evolved with us to perform specific biochemical functions. Collagen protein from animals, for example, cannot be fully formed without vitamin C, which comes from plants.
For this reason, many vegans find their health improves when they give up meat, and are healthier than their meat-eating friends and family – in the short term. It’s hard to compare a vegan diet to one that includes factory-farmed meat, however – especially if either diet includes sugar, refined carbs, and ultra-processed food, either vegan or not. The implications of a meat-based diet will be the subject of a forthcoming article. For now, let’s examine the vegan diet on its own terms, and let the facts speak for themselves.
Plant-based and animal-based nutrients
The following crucial nutrients are derived from plants, or (with the exception of fiber) from the meat, dairy, and eggs of pasture-raised or wild animals that graze on plants:
Vitamin C
Vitamin K1
Carotenoids
Sulfides (from all types of onions)
Polyphenols (of which there are thousands)
Flavonoids
Lignans
Sterols (the basis of many hormones)
Fiber (not exactly a “nutrient” but necessary for healthy digestion and cholesterol regulation)
Without question, an optimal diet is largely plant-based. We all need more plants in our diets – including vegetables and fruits, whole grains, nuts, seeds, fruit oils, spices, and herbs. Mushrooms also fall into this broad category, though they are not plants. Fiber only exists in plants and fungi, and is the driver of good digestion, controlling the rate of macronutrient breakdown, the secretion of insulin, and the regulation of cholesterol. Fiber feeds good gut microbes that produce neurotransmitters, immune cells, and signaling molecules such as short-chain fatty acids. These fiber-loving bacteria also control neural networks through the gut-brain axis. Fiber is the first food I reach for at every meal.
The following nutrients are crucial for long-term human health, and may only be derived from animal sources:
• Vitamin K2 supports normal blood clotting and helps to usher calcium out of the vascular system and into the bones where it’s needed. Eggs, pasture-raised butter, cheese, and poultry are among the best sources. Japanese natto beans are one vegan source, but unless you live in Japan, natto is difficult to eat on a regular basis.
• Heme iron is derived from red meat such as beef, lamb, and pork. Heme iron is much more readily absorbed than non-heme iron from plants such as dark leafy greens and dried fruit. In order to be properly absorbed, plant-based sources of iron must be accompanied by an acidic food such as vinegar, citrus, or the amino acids in meat. Does too much heme iron put meat eaters at risk? In excess and in combination with refined carbs, yes – it has long been known that too much iron is dangerous, and possibly associated with cancer – a risk that has been exaggerated by proponents of veganism. In the context of a healthy diet, however, heme iron does not pose a risk.3
• Retinal, the usable form of vitamin A, may be easily derived from animal sources. Vitamin A is fat soluble, therefore absorption is aided by consuming it with fat. Sufficient retinal is critical for the eyes, and for fighting off certain viruses such as measles. It is poorly converted within the body from plant-based carotenes. Supplementation may also be problematic, as too much vitamin A is toxic. Cod liver oil is effective; care should be taken not to take too much, or to eat too much liver at once. Animal-derived foods are the best source.
• Vitamin D3 may be derived from muscle and organ meat, dairy, eggs, sunlight on your skin (depending on duration, time of year, latitude, and amount of cholesterol in your skin), or mushrooms that have been exposed to sunlight prior to cooking. Vitamin D from mushrooms, however, requires conversion within the liver from D2 to D3, which is not sufficient to meet your body’s needs. D3 plays many roles in the body, and is necessary for bone health, strong teeth, and robust immunity, especially against viruses and respiratory ailments. Vegans and the children of vegan mothers are known to be deficient in vitamin D, and to have weak bones and inferior tooth enamel.4
• Vitamin B12 is a critical nutrient for human health. Symptoms of B12 deficiency include anemia, fatigue, muscle weakness, intestinal problems, nerve damage, tremors, and mood imbalances. Both vegans and vegetarians tend to be deficient, as eggs and dairy contain very little, and cooking may also destroy it. Contrary to common belief, nutritional yeast does not contain a usable form of B12 unless it’s artificially fortified with cyanocobalamin, the same active ingredient found in B12 supplements. If there is one nutrient that is imperative to get from meat, this is it. Two postage-stamp-sized pieces (.3 oz) of liver, the most nutrient-dense food on the planet, provide a daily dose.
“A growing body of evidence that micronutrient insufficiency – not complete deficiency – contributes significantly to chronic disease. Studies suggest that even marginal B12 status may compromise resilience to metabolic stress, immune challenge, and accelerated aging.”5
• Omega-3 essential fatty acids (EFAs), derived from small fatty fish such as sardines, mackerel, herring, salmon, and anchovies, are the building blocks of your brain and crucial for cardiovascular health, cellular membranes, and reducing inflammation, among numerous other functions. It is widely believed (and marketed) that omega-3s may be derived from flax, chia, and hemp seeds. But the liver must first convert these into animal-based EFAs (DHA and EPA) in order to make them bioavailable. The process is slow and inadequate, converting only about 10% of plant-based EFAs. Algae-based omega-3 supplements claim to do this conversion for you. I’m skeptical; more research is needed. If you’re relying on algae-based supplements for omega-3s, you would be wise to get your levels tested.
The following nutrients are abundant in animal foods, and may be derived only in trace amounts from plants:
• Creatine, an amino acid found in grass-fed beef and wild-caught or regeneratively-farmed fish, is an important nutrient for cognition. Creatine tends to decline with age, even among meat-eaters. This underscores the importance of quality and source. Grain-fed, factory-farmed animals and fish cannot produce sufficient creatine.
• Taurine plays important roles in the body, helping to reduce cellular senescence (deterioration or loss of growth), protect against telomerase deficiency, suppress mitochondrial dysfunction, decrease DNA damage, reduce inflammation, lower LDL cholesterol, and even extend lifespan. Taurine also tends to diminish with age. It is abundant in almost all kinds of meat and seafood, with smaller amounts in dairy, and only trace amounts in seaweed. Human breast milk is especially rich in taurine, provided the mother is well-nourished, and plays a crucial role in determining her baby’s brain development and future health.
• Carnitine is necessary for heart health, cognition, and many other metabolic functions. Carnitine levels also diminish as we age. The typical vegan diet is said to provide less than 1/6th of what animal proteins provide. Carnitine is poorly absorbed from supplements.
• Glycine and proline are two amino acids that are necessary for building collagen. They are found in trace amounts in plants and algae, but their synthesis must be switched on by the presence of three other amino acids – leucine, isoleucine, and valine – which are found in adequate amounts only in animal-based foods. As the most abundant protein in the body, collagen plays critical structural and functional roles throughout the body, including bones, teeth, skin, hair, nails, tendons, ligaments, fascia, cartilage, eyes, blood vessels, clot formation, and scar tissue. Without sufficient collagen, structural integrity is impossible to form or maintain, especially in children, teens, athletes, pregnant women, and aging adults.
• Leucine is a critical amino acid for protein synthesis, and ideally should be present at every meal. Your body’s ability to synthesize protein is limited to the amount of leucine present. This “rate-limiting” amino acid must also be balanced with valine and isoleucine, also derived from animals. Leucine is present in soy and some other beans, but in order to get enough, one must consume excessive amounts of carbohydrates (and calories) that are present in legumes. (See my article Prioritize Your Proteins for more on this subject.) If you’re vegan, you might consider supplementing with branch-chain amino acids (BCAA’s): leucine, isoleucine, and valine, derived from fermented microbes. This is a poor substitute for food-based BCAAs and not a sufficient source, but perhaps better than nothing.
• Zinc is abundant in meat, poultry, and seafood. Legumes and whole grains contain zinc as well, but they also contain phytates that bind to the mineral, lowering its absorption. Zinc is necessary for fighting viral infections, maintaining healthy mucous membranes, and enabling normal taste and smell. Children and pets who are picky eaters may be deficient in zinc.
• Choline, an essential nutrient that helps control memory, mood, and muscle coordination, may be found in limited quantities in grains, legumes, and vegetables. Animal sources such as liver, egg yolks, red meat, and fish are rich in choline. Insufficient choline may lead to fatty liver disease, neurological disorders, and cardiovascular disease. Excess choline may also lead to cardiovascular disease through the production of TMAO, but as with heme iron, only in the context of an unhealthy, high-carb diet and sedentary lifestyle. (Buyer beware: protein drinks, shakes, and energy bars that are supplemented with carnitine or lecithin may also raise TMAO.) Whether from plant or animal-based foods, choline is converted to TMAO by gut bacteria. For both vegans and omnivores, the healthier your gut microbiome, the less TMAO.
• C15 is a powerful essential fatty acid that has only recently been discovered, with numerous benefits. It is found in grass-fed dairy products, and holds much promise for modulating metabolic health.
Rethinking animal welfare
Clearly, vegan diets are insufficient or deficient in many vital nutrients. To blithely claim our bodies can simply do without them is pure denial. Most vegans understand this very well when it comes to pet foods. A dog or a cat cannot live without meat, and (hopefully) would never be denied this necessity. Yet we, too, are animals. As members of the mammal kingdom, do we not also deserve to be healthy?
Not at the price of killing animals, my vegan friends would argue. As animals, our pets are innocent, and have no choice about what they must eat. But the truth is, neither do we. A strict, long-term vegan diet is a prescription for numerous health problems, especially as we age – including loss of bone density, sarcopenia (muscle wasting), poor immunity, weak connective tissue and joints, prematurely aging skin, dysregulated hormones (derived from cholesterol), cognitive decline, and diminished eyesight. Cellular membranes, the gatekeepers of our cells and their ability to function and reproduce normally, also depends on animal fat and protein; a long-term lack may therefore raise the risk of cancer or neuralgia. These outcomes are hardly beneficial to animals or the planet, much less our families, our healthcare system, or most of all, ourselves.
“Veganism is by definition a deficient diet.” – Dr. Mark Hyman
Though I deeply respect the heartfelt motivations of vegans, I cannot disagree with this quote. This conviction arises from years of nutrition research, not from any bias. It seems self-evident that any passion that is pursued to the point of self-harm may be considered destructive. All roads lead to this conclusion, including biological common sense.
Curiously, most people who have actually worked with farm animals choose an omnivorous diet. These people have close relationships with the animals they raise, and put a great deal of effort into their care. Individual cows, pigs, sheep, and goats may even be part of an extended family. Yet people who live with their fingers on the pulse of nature are seldom deterred from slaughtering and eating these animals, especially if doing so enables the farm to survive. One local farm near my home is only able to support their animals by selling a certain amount of meat. Their pigs, chickens, and cows live an ideal life up until the day they die. And while they are alive, they contribute immensely to the soil-food web, for the ecosystem needs grazing animals in order to be healthy.
It seems to me the true focus of animal welfare should be quality of life, not duration. For this reason, I am unalterably opposed to factory farming, and do not buy factory-farmed meat, dairy, eggs, or farm-raised fish. I believe how we treat animals is more important than how long they live. Nowhere in nature is any living creature guaranteed a full lifespan. When a human dies young, it’s viewed as a tragedy, but animals of prey have no such perspective. Trees suffer untimely deaths all the time, as do plants raised for consumption. Mass agriculture of wheat, corn, soy, palm oil, coconut oil, and oilseeds all destroy habitat, deplete or poison the soil-food web, and directly kill millions of birds, mammals, and other wildlife each year. Rice paddies are a major source of atmospheric methane. Birds are killed by airplanes, and fish by boat propellors – including those that transport foods around the planet, such as palm oil from Indonesia, which is rapidly destroying the tropical rainforests that are home to a number of endangered species. Palm oil is used in many vegan foods instead of saturated fat. Vaccines also contain animal ingredients, including chicken embryos, egg protein, porcine collagen, bovine serum, monkey kidney cells, and more. Cosmetics, perfumes, and even gummies also sometimes use scent glands, gelatin, or other substances derived from animals.
As for the impact of livestock on the environment, please see my article Eating for the Environment to explore this subject. Contrary to common belief, regeneratively-raised livestock do not contribute methane to the atmosphere, and actually sink carbon into the earth. This is another reason to boycott factory-farmed meat.
What about the suffering of plants? Evidence increasingly shows both plants and fungi are capable of experiencing distress, and can even emit sound signals beyond our range of audible perception. Slice a cabbage or a mushroom twenty minutes before cooking it, and its immune-boosting compounds will increase – in response to being cut, for its own protection. In a thousand myriad ways, life feeds on life. This is a fundamental, unavoidable fact of life. Every diet and all our modern lifestyles cause the death of animals and other living creatures, whether we see it or not.
Finding the middle way
There are many ways to fight for the well-being of animals and the preservation of our planet. Statistics show that the emissions of a single flight impacts the environment as much as six months of eating beef.6 Giving up your car may therefore do more to advance these causes than refusing to eat meat. Simply put, the belief that giving up animal-based food exonerates vegans from doing harm is hopelessly (or hopefully) reductionist. One way or another, directly or indirectly, we all contribute to the life and death of millions of creatures, and they to ours. The chain of cause and effect is unimaginably complex – more like a vast and intricate tapestry than a single chain. We are unavoidably knitted to every thread in that incredible weaving.
What worries me most as a health coach is the lack of awareness with which too many vegans embrace a selectively blind choice. Incestuous research within the vegan community waves off nutritional concerns, but these assertions are not grounded in credible science. And while young people may be able to withstand nutritional deficiencies in the short term, the effects of long-term veganism may be devastating. There have even been tragic cases where very young children raised on strict vegan diets suffered fatal malnutrition, and the parents were later charged or convicted in criminal proceedings.7
“Don’t let your ideology run over your biology.” – Ben Greenfield8
My plea is for the middle way, which gains traction in common sense and not an idealism disconnected from nature. Vegetarian and pescatarian diets are viable alternatives to veganism, with emphasis on plant-based eating patterns. In an ideal world, everyone should eat plant-based meals part time. If we omnivores could only limit our intake of meat, fish, dairy, and eggs to a healthy, moderate level, we would avoid the dangers of deficiencies and bring consumer demand down to a level that could be sustained by regenerative farming. America needs thousands of small farms to improve the soil-food web, the quality of life for farm animals, and the quality of food for all.
Food manufacturers as well as the massive agricultural industry are happy to promote veganism, for their own monumental profit: in 2024, the U.S. plant-based food industry was valued at about $8.1 billion, based on retail sales of products such as plant-based milk, meat substitutes, dairy alternatives, and other plant-derived packaged food items. Industry reports project this figure could grow to roughly $19 billion by 2030 if current trends continue.9 Vegans are the prized consumers of this industry, as they cannot make these foods at home – many of which are decidedly unhealthy. Plant-based meat substitutes are ultra-processed food-like substances, not real food. They contain unhealthy ingredients such as genetically engineered soy-based hemoglobin (fake blood), synthetic vitamins, and protein isolates that are not properly absorbed; binders; inflammatory oils; and emulsifiers that may cause leaky gut and insulin resistance. Manufactured vegan foods are by no means healthy.
“No traditional society has ever thrived on a purely plant-based diet, much less one based on isolates, binders, and other additives.” – Sally Fallon Morell, President of the Weston A. Price Foundation and author of Nourishing Traditions
In conclusion
“You can’t possibly care about animals if you kill them and eat them,” a vegan friend once told me. I considered this statement, and wondered therefore if it’s possible to care about the environment and still drive a car. Fossil fuel emissions, after all, are by far the biggest contributors to greenhouse gases. If caring about animals means never eating meat again, then it stands to reason that anyone who cares about climate change should cease to drive a car, ride a bus or train, fly in a plane, or consume anything imported from another continent.
In a world of relatives rather than absolutes, this sort of black-and-white thinking doesn’t serve. Caring about animals and choosing to eat meat are not mutually exclusive. How we treat animals and choose the meat we eat is what matters most. For our species, a diet of diverse plant and animal foods is the ideal.
A memory comes to mind of my youngest child’s seventh year, when she found a dead bird lying on our bluestone walkway. She knelt over the pretty little creature, and looked up at me with sad eyes. I explained to her that the bird had flown into the window, hit its head very hard, and died.
“You mean our house killed the bird?” she asked, incredulous.
“Well . . . yes,” I said, thinking of no other answer. Clear glass is simply not in a bird’s nature to recognize. This had happened before, and despite using curtains and stickers on our windows to warn the birds, I knew it would happen again. An estimated 300 million to 1 billion birds (with some estimates twice as high) are killed annually in the U.S. alone by colliding with glass windows.10 If we care about birds, should we give up our homes? Would anyone, vegan or not, give up even their second home to save birds? I think not. Few people are willing to change their lifestyle in order to save animals. Yet we are willing to give up vital nutrients, and even degrade our own health, to theoretically save a small portion of a single cow.
How small? Let’s break this down logically: a whole cow typically yields 400–430 lbs of packaged beef.11 Eating one serving (4oz) of ground beef per week – equivalent to 1 pound per month or 12 pounds per year – constitutes just 6% to 8% of the total ground beef produced by a single average steer. Giving up such moderate consumption of meat therefore saves only 1/8th of a single cow per year – but the price to that individual consumer’s health is huge. Even a weekly serving of grass-fed, nutrient-dense red meat would help to ameliorate the anemia and other chronic health conditions that result from a strict vegan diet.
As for the poor little dead bird, we laid it on a large rock beside our driveway. This way, a hungry raptor would see it and find a good meal. Vultures and owls, I explained to my daughter, live difficult lives, often faced with starvation. She brightened up at that thought. If our house killed the bird, it could also feed a hungry raptor.
Sure enough, the next morning the little bird was gone. And my daughter saw that life went on, with one life feeding another – and from a microbiological perspective, living on through it.
By contrast, a colleague of mine who grew up on a farm was traumatized as a child when she got off the school bus one day to find the family cow hanging from a butcher’s hook. Her parents did not prepare her or help her understand a larger context. She never got over it, and became a vegetarian at the age of 8 – hardly an age for making such a choice. With a little parental guidance, this child would have had an entirely different experience – and a more complete diet during her crucial developmental years.
Recently I bought a head of red-leaf lettuce that looked rather wilted by the time I got home. I stood the lettuce upright in a bowl of cold water, and within an hour it had perked up. Looking at its frilly leaves standing up like the petals of a flower, I could almost sense the plant’s relief. An hour later, I cut the lettuce up, made a salad, and ate it. I couldn’t help wondering: why did I help this plant, only to kill it? The child in me could not accept this, and railed against this insufferable reality.
The adult sees otherwise. Everywhere in nature, nutrients are assimilated, broken down, and recycled throughout the food chain, from creature to creature, from the energy of the sun to plants, from plants to microbes to fungi to animals and back again. We have scarcely begun to understand the unfathomably complex interplay among animal, plant, and fungal species. Even trees need animal nutrients, which they receive through nutrient cycling in the forest. For example, in Pacific riparian forests where salmon swim upstream, marine-derived nutrients from salmon carcasses left by bears are absorbed by redwoods and other trees. Oyster mushrooms are also carnivorous, engulfing and consuming nematodes (microscopic worms). There’s no escaping this vast and intricate web, and no need to. We are all part of the ever-changing dance of Creation.
I hope this article has given you the information you need to consider, and if you wish, to make adjustments in order to meet the challenges and deficiencies of a vegan diet. You need not turn your back on your principles – just do the best you can to preserve your own health without doing harm. There is not a reason under the sun to be an absolute purist, and in almost every other dietary choice – such as drinking alcohol or eating sweets – most people readily make exceptions without falling into an identity crisis or a moral quandary. Eating meat, dairy, fish, or eggs doesn’t make you an animal-hater or an animal-killer, any more than having a drink from time to time labels you an alcoholic. Let’s keep fine-tuning our choices as consumers, fighting for animal rights, and supporting sustainable and regenerative farming practices that benefit the earth and all its inhabitants.
To your good health –
Yael Bernhard
Certified Integrative Health & Nutrition Coach
Yael Bernhard is a writer, illustrator, book designer and fine art painter with a lifelong passion for nutrition and herbal medicine. She was certified by Duke University as an Integrative Health Coach in 2021 and by Cornell University in Nutrition & Healthy Living in 2022. For information about private health coaching or nutrition programs for schools, please respond directly to this newsletter, or email dyaelbernhard@protonmail.com. Visit her online gallery of illustration, fine art, and children’s books here.
Information in this newsletter is provided for educational – and inspirational – purposes only.
Have you seen my other Substack, Image of the Week? Check it out here, and learn about my illustrations and fine art paintings, and the stories and creative process behind them.
For a well-researched deep dive into this subject, see The Great Plant-Based Con by Jane Buxton.
Data from ChatGPT.
From my article Setting An Anti-Cancer Stage:
”It’s important to view these beliefs in context. A large percentage of Americans lean more toward heme iron deficiency (anemia) rather than excess. Too much heme iron can indeed lead to lipid peroxidation – but a healthy gut microbiome contains beneficial bacteria that neutralize this threat. As for the formation of free radicals from heme iron, this is driven by unhealthy strains of gut bacteria such as Bilophila wadsworthia that arise from a standard American diet of junk foods, excess refined carbohydrates, lack of fiber, industrial oils, alcoholic beverages, and consumption of substances that degrade the intestinal barrier. Only in this unhealthy environment does heme iron do damage.
Apple Podcast: Dhru Purohit – /oral-dysbiosis-is-driving-disease-popular-oral-care/id1381257272?i=1000708100203
Calculations from ChatGPT.
A quick search yields three documented cases in Florida, 2019; Belgium 2014; UK 2000.
https://drhyman.com/blogs/content/podcast-ep1067 Ben Greenfield is a prominent American biohacker, fitness coach, and New York Times bestselling author known for optimizing physical and mental performance.
https://simpsonsmeats.com/blogs/blog/how-much-meat-do-you-get-from-a-cow