Vegan diets are acclaimed for their health benefits, owing to their high content of fiber, vitamins C and E, and folic acid. Compared to other diets, vegan diets tend to be low in fat, calories, and cholesterol. Vegans also have a reduced risk of obesity, heart disease, high blood pressure, and diabetes .
However, there are many other nutrients obtained from animal sources that vegans lack unless they take supplements. They are all important for health, and some deficiencies can have adverse effects .
Whatever diet you think is healthy, vegan diets are missing many healthful components that can become a serious problem in the long run for vegans.
This post is bringing down many of these components that are missing.
These nutrients are so important that I have a post on most of them and will soon have a post on all of them.
The Cancer vs Autoimmune Tradeoff
People with cancer and autoimmune disease have very different immune systems. Generally, cancer is caused by a lowered immune system and autoimmune disease is caused by an overactive immune system.
People who are predisposed to cancer are more likely to do well with a more plant-rich Mediterranean diet (not vegan), while people who are predisposed to autoimmunity are better served with a higher protein, meat, and seafood-based diet (see lectin avoidance diet).
The Worst Part About Vegetarian/Vegan Diets
For me, the worst part of a vegan diet is the immunostimulatory agents in grains, beans, nuts, seeds, and plant-based foods.
The effects that I get are somewhat dose-dependent and on a vegan diet, the immune stimulation is way too much for me. My body melts down, no matter how organic or high-quality the foods are. Raw plant-based foods are often worse because they contain more of these immune stimulatory agents.
For most people, an omnivorous diet is fine, but a vegan diet is too much for most of the population.
I’ve identified some common substances found in plant-based foods that can be problematic when people have autoimmune issues. They are:
- Trypsin Inhibitors
- Sulfites, Benzoates, and MSG
- Non-protein amino acids
- Alkaloids [includes solanine, chaconine]
- Phytic Acid [Also Called Phytate]
Vegetarians also often get too much copper, which can cause some health issues.
Vegan Diets Do Not Contain Adequate Amounts of:
1) Pre-formed Omega-3 Fatty Acids DHA and EPA
Aside from being sources of energy, essential fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) serve as structural components of cell membranes and precursors to eicosanoids, which play a role in regulating blood pressure and inflammation .
EPA & DHA also have protective roles in a wide range of diseases [e.g., cancer, asthma, depression, heart disease, ADHD, and autoimmune disorders] . DHA is a very important component of neurons and for healthy nervous system function.
The major dietary sources of EPA and DHA are seafood, red meat, and dairy products. Although it is possible for plant food acids to be converted to EPA and DHA, the conversion levels are below 10% and not sufficient .
Compared to meat eaters, vegans have 53% lower levels of EPA and nearly 59% lower levels of DHA .
2) Vitamin B12
Vitamin B12 is an essential nutrient that is vital for cell division, carbon metabolism, and maintenance of the nervous system. Because natural sources are only found in meat, vegans are frequently vitamin B12 deficient .
Vitamin B12 deficiency can cause weakness, numbness, and an increase in an amino acid called homocysteine. High homocysteine levels can increase the risk of heart disease, dementia and Alzheimer’s disease [6, 7].
B12 deficiency can lead to the destruction of nerve endings [peripheral neuropathy] and brain fog [cognitive impairment] which eventually may lead to Alzheimer’s, vascular dementia, and Parkinson’s Disease [8, 9].
Because the liver can store vitamin B12, it can take years before low B12 consumption becomes full-on B12 deficiency . During this time, your B12 levels may be considered “normal” by your doctor, but suboptimal for health. If you follow a plant-based diet or used to be plant-based for many years, you want to keep your B12 and homocysteine levels optimal.
3) Vitamin D3
Vitamin D3 is essential for bone health .
Vegans’ dietary intake of vitamin D is below the recommended range. Inadequate intake can decrease bone mineral density and cause bone abnormalities. In a prospective longitudinal study of 181 Asian women, 73% of vegans compared to 46% of omnivores had vitamin D deficiency. However, veganism was not associated with bone loss or fracture [13, 14, 15].
Vitamin D is critical to many processes in the body, especially the immune system. Many people develop autoimmune or inflammatory diseases after years of being vitamin D deficient.
4) Vitamin A/Retinol
Vitamin A promotes healthy immune function and helps with reproduction, skin health, and eyesight. Retinol (the bioactive form of vitamin A) is found in seafood, meat, liver, eggs, and dairy products [16, 17, 18].
Plants contain beta-carotene, which can be converted to active Vitamin A (retinol), but there are multiple factors that can affect the conversion rate and beta-carotene absorption. Therefore, it is possible for vegans to be vitamin A deficient [19, 20, 21].
Zinc deficiency in adults is uncommon but can be an issue for children. Inadequate zinc intake in children can cause anorexia, poor growth, and problems with the immune system. In adults, zinc deficiency can cause liver disease .
Vegetarians have a lower intake of zinc .
I was severely deficient in Zinc at one point when consuming a plant-based diet.
If you have gut problems [IBD, IBS, etc..], your zinc absorption will be significantly worse.
Choline is an essential nutrient that is needed for brain function, cell transmission, and metabolism. Inadequate choline intake can cause high cholesterol, as well as liver, heart, and brain disorders .
Calcium has many other important uses as well. In many cases, vegans don’t get nearly enough calcium. While many plant-based foods contain plenty of calcium, they also contain oxalate and phytate, both of which inhibit calcium absorption .
The Dietitian’s Guide to Vegetarian Diets  lists 45 studies that have surveyed vegetarians’ calcium intakes in Appendix G. The daily calcium intakes in these studies are about:
- Vegans: 500 – 600 mg
- Lacto-Ovo vegetarians: 800 – 900 mg
- Non-vegetarians: 1,000 mg
American adults need anywhere from 1,000 – 1,300 mg of calcium and vegans are falling short of this by 2.5X.
|Table 4. U.S. DRI for Calcium|
|0 – 6 mos||200|
|6 – 12 mos||260|
|1 – 3 yrs||700|
|4 – 8 yrs||1,000|
|9 – 18 yrs||1,300|
|19 – 50 yrs||1,000|
|51 – 70 yrs (male)||1,000|
|51 – 70 yrs (female)||1,200|
|14 – 18 pregnant/lactating||1,300|
|19 – 50 pregnant/lactating||1,000|
Iron deficiency, especially in young children, can cause behavioral problems and brain impairments .
Heme iron is only found in meat and is more easily absorbed than the iron found in plant foods [31, 32, 33]. Plant-based non-heme iron needs to be converted into a soluble form [Fe3+ to Fe2+] before they can be absorbed. This process is dependent on the enzyme ferric reductase, which requires sufficient amount of stomach acid .
Therefore, vegans are more prone to anemia than meat eaters and have lower iron stores in their body .
People with gut problems such as IBD and IBS can’t absorb iron that well as it is. And women are often anemic when they are consuming normal diets.
I have a lot of clients who have very low ferritin levels. A vegan diet can be dangerous in this instance.
Iodine is an important micronutrient that is needed for all stages of life. Insufficient iodine intake can cause mental retardation, thyroid dysfunction, and other health problems .
Iodine is more commonly found in animal food products than those of plant origin. One study showed that 80% of vegans suffer from iodine deficiency compared to 9% of those who ate both meat and plants .
Eating a lot of vegetables and soy products that are goitrogenic can make things worse, even though you are using iodized salt.
I was deficient in iodine after being on a vegan diet for a while.
Selenium plays a role in thyroid and reproductive function, and also has antioxidant and anti-inflammatory effects. Low levels of selenium are associated with cognitive decline, poor immune system function, and an increased risk of death .
Women that partook in a vegan diet exhibited lower levels of selenium compared to women on a regular diet .
Vegetarians usually have lower cholesterol levels . Low cholesterol levels are not always healthy.
Too low cholesterol levels are associated with:
- Severe depression 
- Anxiety 
- Suicidal thoughts and attempts 
- increased risk of death from stroke, heart disease, and cancer 
If I don’t consume foods with cholesterol, my cognitive function and motivation reliably go down.
When I consumed a whole food, plant-based vegan diet, I thought I was getting early-stage Alzheimer’s, I had zero motivation and almost no cognitive horsepower.
After taking pregnenolone, I was able to function on some level, but this didn’t solve the other deficiencies.
Compared to non-vegetarians, vegetarians have lower muscle carnitine levels and a reduced capacity to transport carnitine into the muscle .
High levels of carnosine in muscles are linked to reduced muscle fatigue and improved athletic performance .
Carnosine is only found in meat and dairy products but can be formed in the body from the amino acids histidine and beta-alanine. Vegetarians have less carnosine in their muscles than meat eaters [54, 55].
Vegans don’t ingest as much glycine from the diet as meat eaters [even though their blood levels are higher] .
15) Amino Acids
Compared to fish eaters, vegetarians, and meat eaters, vegans have the lowest concentrations of methionine, tryptophan, lysine, leucine, cysteine, proline, tyrosine, phenylalanine, serine, alanine, threonine, isoleucine and valine, all of which are essential amino acids .
It would take a book to describe why each of these amino acids is important, but I will just name the most common reasons why people supplement with these amino acids.
Essential amino acids, especially leucine, are vital for making proteins in muscle. These amino acids may also contribute to maintaining muscle mass .
- Leucine, isoleucine, and valine are BCAAs that stimulate metabolism and muscle growth.
- Methionine is a precursor to SAM, which is important for methylation.
- Tryptophan is critical for serotonin synthesis, and therefore melatonin synthesis.
- Cysteine is important for creating glutathione and hydrogen sulfide.
- Lysine is important for immune function and can reduce anxiety.
- Tyrosine and phenylalanine are important for dopamine synthesis.
- Proline is important for collagen production and joints.
I had to supplement with many amino acids on a vegan diet.
Creatine is a nutrient that enhances endurance, strength building, and brain function. Although it is not necessary to obtain creatine from dietary sources, there are studies that show that creatine supplements can provide health benefits .
Vegetarians are also more responsive to creatine supplementation with regard to physical performance than nonvegetarians. Vegetarians who took creatine had a greater increase in lean muscle tissue and total work performance compared to non-vegetarians .
Taurine is only found in animal products such as seafood, poultry, and dairy products .
Taurine has many benefits. One study claims that taurine is one of the most essential substances in the body. The authors wrote :
“Considering its broad distribution, its many cytoprotective attributes, and its functional significance in cell development, nutrition, and survival, taurine is undoubtedly one of the most essential substances in the body.”
Vegans have lower levels of taurine than meat eaters .
18) Vitamin B6/Pyridoxine
One study says that 58% of vegetarians are deficient in vitamin B6 .
Another study says ~29% of vegetarians are deficient in vitamin B6 and the study concludes that vegetarians should be considered as a vulnerable group for vitamin B6 deficiency .
19) Vitamin B2/Riboflavin
Vegetarians have a lower intake of vitamin B2/riboflavin [70,].
A high prevalence of riboflavin deficiency was found in 24.2% of the vegetarians and a study concludes that vegetarians should be considered as the vulnerable group for vitamin B2 deficiency [69, 71].
20) Vitamin B3/Niacin
In one study, 34% of vegetarians were deficient in niacin .
The Vegan Argument – and Counterpoints
The key vegan argument centers around what is strictly enough to prevent a deficiency and in cases where there’s no other option, they supplement. The problem with that reasoning is twofold:
- Some people in the population need more of a certain nutrient.
- Many people in the population do better with taking more of a certain nutrient, even if they are not strictly defined as “deficient” in it. That’s why there’s a supplement industry that sells them in higher dosages and people take them for a variety of conditions. I would recommend reading my posts on these nutrients to see what benefits taking extra has.
1) DHA, EPA: yep, eat some flax, chia, and walnuts every day. Limit your vegetable oil. Not so hard. If you still test too low, take some algae supplements.
Counterpoint: ALA found in flax/chia/walnuts does not convert well into DHA  and you will never get the optimal levels of DHA. And when it comes to DHA, we’re not getting enough. All you need to do is read my post about DHA to understand why you need to get optimal levels of this.
“The majority of evidence from isotopic tracer studies show that the conversion of ALA to DHA is of the order of 1% in infants, and considerably lower in adults” .
There’s a reason why vegans have 59% less DHA .
2) Vitamin B12: Veganism 101, supplement B12.
Counterpoint: Not a problem if vegans supplement.
3) Vitamin D3: take some sun? If you feel fancy eat some UV treated mushrooms or just take a pill. This nutrient is a problem for everyone who doesn’t get much sun.
Counterpoint: people don’t get nearly enough sun, and I would also venture to say that dietary and vitamin D from the sun get circulated to different tissue differently.
4) Vitamin A/Retinol: the plant version is harmless, the animal version is toxic at too high dosage
Counterpoint: Toxic in excess that no one would consume in a diet. Many people require real vitamin A because of poor conversion.
5) Zinc: eat some pumpkin seeds and legumes.
Counterpoint: Zinc is one of those nutrients that people do better with it in levels over the RDA. Pumpkin seeds and legumes didn’t cut it for me and I was severely deficient.
6) Choline: present in plants in a non-dangerous version. The animal version is linked with cancer risk.
Counterpoint: This is a nutrient that some people need more of – it depends on your genetics, as mentioned.
7) Calcium: kale? Other leaky greens? Buy a supplemented plant milk. Getting 700mg is important.
Counterpoint: The RDA is 1000mg or more and kale won’t give you that [in addition to the calcium being less bioavailable in kale].
8) Iron: eat nuts and legumes with a vitamin C source and you’ll be fine. It can increase the absorption up to 6 fold. Funny how they never say that. Funny how they also never say that heme iron is linked to cancer.
Counterpoint: It’s a fact that many women and people are anemic and aren’t getting enough iron. I’ve has hundreds of clients who were anemic even after trying to consume a lot of meat. The point is that you need to measure your iron status and if it’s low [as was the case with me even though I ate tons of vitamin C], eating nuts and legumes won’t cut it. If you’re adequate then you don’t need to worry, because more iron isn’t better [ferritin should be over 70].
9) Iodine: buy iodized salt. Eat some seaweed. Unless you are deficient, the goitrogenic effect of vegetables shouldn’t a problem.
Counterpoint: Vegans can get around this if they’re smart, but the fact is that one study shows that 80% of vegans suffer from iodine deficiency compared to the 9% of those who ate both meat and plants .
10) Selenium: seriously? Eat some brazil nuts.
Counterpoint: True, except that vegans need to pay attention and eat brazil nuts.
As mentioned, women who partook in a vegan diet exhibited lower levels of selenium compared to women on a regular diet .
11) Cholesterol: No – just no. The only source is about how we use cholesterol to make sex hormones. Good thing you produce your own and you don’t need to eat any. Eating too much is bad for you, because yes it’ll increase your blood cholesterol and – yes – this will increase your risk for heart disease.
Counterpoint: Cholesterol production isn’t enough in some people. Many people report doing better on diets with higher cholesterol – and dietary cholesterol doesn’t increase the risk of heart disease, according to a systematic review and meta-analyses .
12) Carnitine: you produce it
Counterpoint: This is a case where more can be better. Read carnitine post.
13) Carnosine: non-essential antioxidant. We eat plenty of other types and probably more in total than your average omnivore.
Counterpoint: This is a case where more can be better. See carnosine post.
14) Glycine: like all amino acids you can get as much as you want from plants
Counterpoint: This is a case where more can be better. See glycine post.
15) Amino Acids: seriously? That’s just another way of saying protein. Yes, they are important but it’s also true that most people eat too much protein which is disastrous for your health. Vegans having less of those is not a bad thing at all.
Counterpoint: Many people do better with more.
16) Creatine: not essential.
Counterpoint: Many people do better with more. It’s not essential if you’re not interested in intelligence. As I mentioned, IQ went up in vegans who supplemented.
17) Taurine: not essential.
Counterpoint: Many people do better with more.
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