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Do vegans need to take B12?

Besvaret 26. oktober 2026

Yes. Natural food sources of vitamin B12 are limited to animal foods, so vegans have a higher risk of deficiency. Denmark's food agency, Fødevarestyrelsen, advises vegans and vegetarians to take a daily supplement of 4 µg of vitamin B12.

A systematic review found that most studies of vegans showed too low an intake, and on average 44 percent of the vegans in the studies were deficient, a figure that covers vegans both with and without supplements and ranged from 4 to 73 percent between studies. Its authors work for Unilever, which sells supplements and fortified foods. Deficiency can cause anaemia and nerve symptoms, and in children damage to the nervous system can last.

Neither plants nor humans can make B12 themselves. In cows and sheep it is made by a few kinds of bacteria in the rumen, which need enough cobalt in the feed. The B12 used in supplements and added to feed for all animal species is made by fermentation.

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  2. Officielle råd fra Fødevarestyrelsen om vegansk kost, 2025Samler mange studier · FaktaarkRåd til veganere og vegetarer, der kun spiser lidt æg og mejeriprodukter
  3. Gennemgang af 141 studier fra Unilever, 2021Samler mange studier · Systematisk gennemgang · 141 individuelle undersøgelserNutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review
  4. Gennemgang af 18 studier fra Nordic Nutrition Recommendations, 2023Samler mange studier · OversigtsartikelVitamin B12 - a scoping review for Nordic Nutrition Recommendations 2023
  7. Rapport fra EFSA's fodderpanel (FEEDAP), 2018Ét studie · RapportSafety and efficacy of vitamin B12 (in the form of cyanocobalamin) produced by Ensifer spp. as a feed additive for all animal species based on a dossier submitted by VITAC EEIG
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