Vegan and vegetarian diets are becoming more popular as the health and environmental benefits are more widely known. Many studies have shown that there are health benefits to eating a plant-based diet. Whatever your reason for considering a vegan or vegetarian diet, you are wise to do some research first so you understand how to go about making this transition in a healthy way.

 

For those of you here contemplating going vegan/vegetarian, let’s first go over what exactly these diets include and don’t include: 

 

A vegetarian diet consists primarily of fruits, vegetables, grains, legumes, plant-based oils, and some dairy products. Vegetarians don’t eat meat of any kind, including fish and poultry.

 

A vegan diet is the more restrictive of the plant-based diets, eliminating all meats as well as dairy products, eggs, and honey. As you may have guessed, because vegan diets are more restrictive, vegans have a greater likelihood of becoming deficient in some key nutrients. 

 

 

Vegetarian and vegan diets are particularly high in some nutrients compared to omnivorous diets. This study found that vegetarians had higher levels of magnesium, potassium, folate, antioxidants such as vitamins C and E, and phytochemicals. The same study concluded that “vegetarians have been reported to have lower body mass indices than non-vegetarians, as well as lower rates of death from ischemic heart disease, lower blood cholesterol levels, lower blood pressure, and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.” The summary of two large longitudinal studies was that vegetarians and vegans have a 11-19% lower risk of all cancers compared to meat-eating study participants. 

 

 

We should absolutely hold these health benefits in high regard, but we can’t ignore that cutting animal products out of the diet can limit intake of important nutrients. As with any kind of diet there is a right and a wrong way to approach it. We often falsely think of vegetarians as the epitome of health. As a naturopathic doctor, I have seen a number of patients on a vegetarian diet who eat primarily nutrient-poor grains, breads, and potatoes. These people are well-meaning and under the assumption that they are making a good choice for their health but their diets lack nutrient-dense foods. Even vegetarians and vegans who are great about eating a wide variety of nutrient-dense plants can become deficient in certain nutrients. That being said, it is possible to be healthy on a vegan or vegetarian diet as long as you are making informed food choices. 

 

For people already consuming or those considering a vegetarian or vegan diet, supplements may be a good option to replenish nutrients that may become deficient. Here are the top 6 supplements to consider, along with a list of other important nutrients to be aware of. 

 

Nutrients Most Likely Low in a Vegan or Vegetarian Diet: 

 

The data is mixed on which nutrients vegetarians should consider supplementing and research on vegan nutrient deficiencies is lacking. This recent study concluded that, “The nutrients of concern in the diet of vegetarians include vitamin B(12), vitamin D, omega-3 fatty acids, calcium, iron, and zinc.” Several other studies (referenced below) corroborate these findings. “Although a vegetarian diet can meet current recommendations for all of these nutrients, the use of supplements and fortified foods provides a useful shield against deficiency.” For this article, we will primarily focus on these nutrients. Secondarily, I will touch on nutrients that had mixed info in the research regarding deficiencies in vegetarians and vegans.   

 

It should be noted that the studies I’m referencing were done with healthy non-pregnant adults. Some people have increased nutrient needs and dietary-induced nutrient deficiencies may be more profound in these populations: children, pregnant/lactating women, athletes, people with digestive impairment, people with chronic diseases.   

 

1) Vitamin B12 

 

Hands down, vitamin B12 is the most prevalent nutrient deficiency in vegetarians and vegans. The top 5 foods containing vitamin B12 are: sardines, salmon, tuna, cod, and lamb. While some plant foods, like seaweeds (i.e. spirulina) and mushrooms, contain small amounts, none have consistently enough B12 to keep B12 levels in the optimal range for long-term vegans and vegetarians.    

 

 

This article from Nutrients Journal summarized that deficient vitamin B12 levels can contribute to fatigue, osteoporosis, cognitive decline, cardiovascular disease, neural tube defects (important for women of childbearing age), vision loss, diminished strength, muscle wasting, and increased vulnerability to stressors. 

 

The cardiovascular risks are of particular importance and have been emphasized in the research. Low levels of vitamin B12 can increase an amino acid in the body called homocysteine. Homocysteine is used as a marker for cardiovascular disease. This effect was shown to be more pronounced in vegans (66%) as opposed to 45-50% of vegetarians and omnivores. This may be because vegans have more significant B12 deficiencies and are also more prone to being deficient in B2, another B vitamin that has synergistic effects with B12.

 

There is strong evidence indicating that elevated homocysteine levels are a major independent biomarker and/or a contributor to chronic conditions, such as cardiovascular disease. A deficiency of vitamin B12 can elevate homocysteine. This study goes on to say that the most common form of B12 in supplements, cyanocobalamin, is not a reliably effective way to increase the body’s B12 levels. Most naturopathic doctors recommend the higher quality forms of B12 for supplementation – methylcobalamin, hydroxycobalamin, or adenosylcobalamin. 

 

 

Finally, this study goes so far as to say that “vitamin B12 deficiency may negate the cardiovascular disease prevention benefits of vegetarian diets. In order to further reduce the risk of cardiovascular disease, vegetarians should be advised to use vitamin B12 supplements.”

 

Here is a great source of highly absorbable vitamin B12

 

2) Vitamin D 

 

Most people know that humans primarily get vitamin D from the sun but the food sources are also important. Recent research has indicated that many people are chronically low in vitamin D. The top 5 food sources of vitamin D are: salmon, sardines, tuna, fortified cow’s milk (not recommended), and eggs.

 

 

This study found that blood vitamin D levels were lower in vegetarians and vegans than in omnivores. This disparity was particularly pronounced in the winter months. 

 

Vitamin D plays an important role in immunity, metabolic syndrome (obesity and diabetes), cancers, renal disease, memory, and neurological dysfunction. There is also some evidence to show that vitamin d levels have an effect on blood pressure, risk of heart attack, and risk of heart disease. 

 

Here is a great quality vegan vitamin D (Many vitamin D supplements are derived from animal products). 

 

 

3) Omega 3 Fatty Acids 

 

As fish oil supplements have been hugely popular over the past decade, omega 3 fatty acids have received a lot of attention. The highest food sources of omega 3 fatty acids are: flax, walnuts, sardines, salmon, and beef. 

 

Although it seems easy enough to get plenty of flaxseed and walnut in a vegetarian diet, this study found that these plant-based sources of omega 3 do not convert to DHA (docosahexaenoic acid) at all. DHA is a critical nutrient for brain health and cardiovascular health. 

 

 

Thankfully, this study found that plant-based algae omega 3 fatty acids are easily absorbed and converted into DHA. Blood tests of participants who had taken algae sources showed sufficient levels, unlike those who were consuming nuts and seeds for their primary omega 3 source. 

 

Deficient omega 3 levels are associated with cardiovascular disease, age-related dementia/Alzheimer’s disease, metabolic issues, and fetal abnormalities.

 

Here is a great quality vegan algae omega 3 product.  

 

4) Zinc

 

Zinc is another nutrient that is low in vegetarian diets. It is most concentrated in: beef, lamb, sesame seeds, pumpkin seeds, and lentils. It seems easy enough to get lentils, pumpkin seeds, and sesame seeds in a plant-based diet, but zinc is one of the nutrients that has different forms and not all are bioavailable. 

 

This meta-analysis summarized the results from 34 studies and found that dietary zinc consumption and serum zinc concentrations were significantly lower in vegetarians vs omnivorous subjects. It appears as though this disparity is larger in women, children, and elderly populations. The authors concluded that vegans and vegetarians should consider supplementing with zinc to bring serum concentrations up to optimal levels. 

 

Zinc deficiency is associated with problems with immunity, reproduction (particularly sperm health in men), skin health (rashes, acne), sense of taste, thyroid health, and eye health. 

 

 

Here is a great quality vegan zinc supplement 

 

5) Calcium

 

Particularly for vegans, research shows that low calcium levels in the diet lead to an increased fracture risk. This study did not find an increased risk of fracture in vegetarians. Furthermore, this study found that vegetarian children who ate dairy and eggs had similar bone health to omnivorous children. These studies seem to point to the conclusion that dairy intake provides sufficient calcium in most vegetarian diets but the plant-based sources of calcium may not be enough to maintain healthy bones in vegans. 

 

 

The top 5 food sources of calcium are: tofu, sardines (with bone-in), sesame seeds, yogurt, and collard greens. Clearly there are vegan sources of calcium on this list but calcium is yet another nutrient that has multiple forms and bioavailability seems to be higher in the non-vegan forms. 

 

Calcium deficiency can cause problems with bone health, muscle and nerve conduction, and acid/base balance. 

 

Here is a great vegan calcium supplement. Because calcium works synergistically with other nutrients to build bones, this product also contains other key nutrients. 

 

6) Iron

 

This meta-analysis concluded that vegetarians are more likely to have low iron stores compared with non-vegetarians. This study went on to demonstrate that this deficiency was more likely in pre-menopausal women vs post-menopausal women. Food sources of iron come in 2 forms: heme iron and nonheme iron. Non-heme iron is found in plant foods and iron-fortified food products. Heme iron is found in meat, seafood, and poultry. Our bodies do not absorb non-heme iron as well as heme iron. Vitamin C helps with absorption of either form of iron but still does not make non-heme iron as easy to absorb as heme iron (animal source). 

 

 

The top food sources of heme iron are: meat, seafood and poultry.

 

The top food sources of non-heme iron are: soybeans, lentils, spinach, sesame seeds and garbanzo beans.

 

Iron-deficiency anemia can cause fatigue, reduced physical endurance, cognitive impairment, hair loss, difficulty in regulating temperature, and decreased resistance to infection. 

 

If you suffer from these symptoms, you’ll want to get blood tests including a full iron panel (CBC, iron, TIBC, & ferritin) before supplementing. Taking iron when you don’t need it can be harmful. 

 

Here is a great quality iron supplement. 

 

Other Nutrients to Consider Supplementing:

 

There are a few other nutrients that show up in the research that may be lower in vegan and vegetarian populations. Data is mixed or limited on these but they are worth mentioning. 

 

• Amino acids – especially carnitine, carnosine, & taurine 
• Vitamin A 
• Vitamin B2
• Vitamin K2 
• Iodine
• Selenium 

 

While vegan and vegetarian diets have some clear and documented health benefits, they aren’t always the healthiest choice for everyone. Naturopathic doctors prefer to use an individualized approach when making dietary recommendations, understanding that diet is not a one-size-fits-all approach. Long-term vegetarian and vegan diets can contribute to micronutrient deficiencies and should be approached with an understanding that supplementing these key nutrients may be appropriate to maintain health. The choice to adopt a vegan or vegetarian diet is something that should be done after plenty of research and a conversation with your healthcare provider(s). 

 

Resources: 

 

Health and Sustainability – Benefits of vegetarian and vegan diets

https://pubmed.ncbi.nlm.nih.gov/30487555/ 

Nutrition concerns and health effects of vegetarian diets. 

https://pubmed.ncbi.nlm.nih.gov/21139125/

Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets

https://pubmed.ncbi.nlm.nih.gov/12826028/

Vegetarian and Vegan nutritional biomarker measurements

https://pubmed.ncbi.nlm.nih.gov/26840251/ 

 

Long term vegetarian and vegan health 

https://pubmed.ncbi.nlm.nih.gov/26707634/

 

Diet types and cancer rates

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4844163/ 

 

Lower BP veg 

https://pubmed.ncbi.nlm.nih.gov/22230619/ 

 

Nutrients and food sources 

http://www.whfoods.com/foodstoc.php 

 

Nutrient Table: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4844163/table/t0020/?report=objectonly 

 

Vegan mothers and children
https://pubmed.ncbi.nlm.nih.gov/30577451/ 

 

Italian position paper on supplementation in vegetarian diets https://pubmed.ncbi.nlm.nih.gov/29174030/ 

 

Health Effects of Vegan Diets

https://www.ncbi.nlm.nih.gov/pubmed/19279075 

 

Vegan Athletes

https://pubmed.ncbi.nlm.nih.gov/28924423/ 

 

Institute of Medicine – Dietary Reference Intake – Vitamins 

https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t2/?report=objectonly

 

Institute of Medicine – Dietary Reference Intake – Elements 

https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t3/?report=objectonly 

 

B12

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257642/ 

https://pubmed.ncbi.nlm.nih.gov/16988496/ 

https://pubmed.ncbi.nlm.nih.gov/25998928/ 

 

Vitamin D 

https://pubmed.ncbi.nlm.nih.gov/20854716/ 

https://pubmed.ncbi.nlm.nih.gov/28742648/ 

https://pubmed.ncbi.nlm.nih.gov/21646368/ 

 

Omega 3 

https://pubmed.ncbi.nlm.nih.gov/28417511/ 

https://pubmed.ncbi.nlm.nih.gov/24261532/ 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3262608/ 

 

Zinc

https://pubmed.ncbi.nlm.nih.gov/23595983/ 

http://www.whfoods.com/genpage.php?tname=nutrient&dbid=115#function

 

Calcium 

http://www.whfoods.com/genpage.php?tname=nutrient&dbid=45#function 

https://pubmed.ncbi.nlm.nih.gov/29414859/ 

https://pubmed.ncbi.nlm.nih.gov/17299475/ 

 

Iron

https://pubmed.ncbi.nlm.nih.gov/27880062/

https://pubmed.ncbi.nlm.nih.gov/30783404/

https://pubmed.ncbi.nlm.nih.gov/20509117/

https://pubmed.ncbi.nlm.nih.gov/16635664/

https://ods.od.nih.gov/factsheets/Iron-Consumer/

https://www.ncbi.nlm.nih.gov/books/NBK230103/ 

Amino acids 

https://pubmed.ncbi.nlm.nih.gov/26395436/ 

 

Carnitine 

https://pubmed.ncbi.nlm.nih.gov/25612929/

https://pubmed.ncbi.nlm.nih.gov/21753065/ 

 

Iodine

https://www.ncbi.nlm.nih.gov/books/NBK230108/