Does the Form of Vitamin B12 Matter?
By Reed Mangels, PhD, RD
I was recently asked about the form of vitamin B12 that vegans should be using. There are several different forms of vitamin B12 including cyanocobalamin, methylcobalamin, and adenosylcobalamin. Note that cobalamin means vitamin B12. The cobalamin molecule is bound to different side groups. For example, methylcobalamin has cobalamin attached to methyl (CH3).
Cyanocobalamin, in which cobalamin is bound to a cyanide side group, is the most common form of vitamin B12 in supplements. It is also the most stable form. This means that it is less likely to deteriorate with time and that the amount of B12 that you’re getting from a cyanocobalamin supplement is likely to be similar to the amount said to be in the supplement. This stability is one reason why vegan nutrition experts recommend using the cyanocobalamin form (1-3). Yes, cyanocobalamin does contain cyanide, but the amount is very, very small and does not appear to pose a risk to most people (4).
The exception may be people with poor kidney function who apparently have a compromised ability to separate the cobalamin from the cyanide so that the cobalamin (vitamin B12) can be used. Those with poor kidney function may also not be as able to excrete the cyanide. For most people, though, cyanocobalamin is the form of vitamin B12 that is recommended.
Methylcobalamin and adenosylcobalamin are not as stable as cyanocobalamin so that higher doses of these forms may be needed.
References
- Vitamin B12. VeganHealth.org. https://veganhealth.org/daily-needs/#Vitamin-B12
- Messina, G. Vitamin B12: A Vegan Nutrition Primer. TheVeganRD.com https://www.theveganrd.com/vegan-nutrition-101/vegan-nutrition-primers/vitamin-b12-a-vegan-nutrition-primer/
- Greger M. Vitamin B12 Recommendations. NutritionFacts.org https://nutritionfacts.org/optimum-nutrient-recommendations/
- Vitamin B12 and Cyanide. VeganHealth.org https://veganhealth.org/vitamin-b12/elevated-vitamin-b12-levels-and-mortality/#Vitamin%20B12%20and%20Cyanide
To read more about vitamin B12 see:
Do Vegetarians Have To Take Vitamin B12 Supplements?
