Lee Swanson Research Update

Vegan Diet May Require Omega-3 and B-12 Boost

March 2011

People following a vegan diet may require additional omega-3 and vitamin B-12 supplementation to reduce an excess risk of heart disease, according to a new review.

The review authors said that although meat eaters are known for having a significantly higher combination of cardiovascular risk factors than vegetarians, people following strict vegetarian and vegan diets are not immune from risk, as their diets tend to lack several key nutrients, including iron, zinc, vitamin B-12 and omega-3.

Published in the Journal of Agricultural and Food Chemistry, the review suggests that people following a vegan lifestyle that is low in omega-3 and vitamin B-12 may have a high risk of developing blood blots and atherosclerosis—both of which increase the risk for heart attacks and stroke. As such, the authors suggest that an increased intake or supplementation of omega-3 polyunsaturated fatty acids (PUFAs) and vitamin B-12 may help to alleviate such risks.

"On the basis of the present data, it is suggested that vegetarians, especially vegans, could benefit from increased dietary intake of omega-3 PUFA and vitamin B-12 and thus improve the balance ratio of omega-3 to omega-6 PUFA and vitamin B-12 status…which may reduce any thrombotic tendency that might increase their generally low risk of cardiovascular disease," said the review author, Duo Li from Zhejiang University, China.

The review of over 30 years of studies for the biochemistry of vegetarianism noted that meat eaters are known to have a significantly higher incidence of certain cardiovascular risk factors compared with vegetarians.

Such risks include increased body mass index, waist to hip ratio, blood pressure, plasma total cholesterol, triacylglycerol levels and serum lipoprotein concentration.

However, Li said that compared with meat eaters, vegetarians and vegans have lower concentrations of serum vitamin B-12 and omega-3 polyunsaturated fatty acid levels in tissue membrane phospholipids.

Previous evidence has suggested vegetarians and vegans who do not take vitamin B-12 supplements often may have abnormally lower serum concentrations of vitamin B-12, which has been shown to be significantly correlated with plasma homocysteine levels.

Li said that the risks associated with low vitamin B-12 and omega-3 status include an increase in blood clotting (platelet aggregation) from raised levels of homocysteine and decreased levels of "good" HDL-cholesterol—all of which may be linked to an increased thrombotic and atherosclerotic risk.

As a result Li concluded that "it is suggested that vegetarians, especially vegans, should increase their dietary omega-3 PUFA and vitamin B-12 intakes."

Despite the fact that vegan diets exclude any foods from animal origin, in his recommendations Li outlined several sources of dietary omega-3 and vitamin B-12 sourced from animals; though he did add that "dietary supplements also can supply these nutrients."

Vegan sources of omega-3 EFAs include flax seed and hempseed; nuts like walnuts all contain omega-3s in the form of ALA. Flaxseed provides the richest plant source of ALA, and walnuts are the best nut source. An excellent vegan source of B-12 is spirulina, a blue-green vegetable plankton that is also a natural source of GLA (Gamma Linolenic Acid). Spirulina is the best known vegetable source of B-12 and delivers optimum levels of vitamins, minerals, trace elements, cell salts, amino acids and enzymes.

Journal of Agricultural and Food Chemistry 59(3):777-784, 2011

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