Vegan diets increase the risk of vitamin B₁₂ deficiency Original paper

Cobalamin (vitamin B₁₂) is crucial for good health, notably through its role in DNA synthesis. It is primarily found in animal-based foods, so vegans are at an increased risk of deficiency — which can lead to megaloblastic anemia and peripheral neuropathy (nerve damage).

In this 4-week randomized controlled trial, 53 healthy people aged 18–60 were tasked to follow either a meat-rich diet or an unsupplemented vegan diet. They were told how to prepare a balanced diet based on their group assignment, according to the guidelines of the German Nutrition Association. B₁₂ status was assessed by measuring serum B₁₂, holotranscobalamin (holo-TC), methylmalonic acid (MMA), and total plasma homocysteine (tHcy).

The vegan group saw a decrease in B₁₂ intake, serum B₁₂, and holo-TC. MMA and tHcy metabolites were unaffected. The authors suggest that holo-TC may be a fast-responding marker of B₁₂ status, which is consistent with previous studies.

It takes 2–5 years to exhaust liver and kidney stores of B₁₂ and thus become deficient in this vitamin.