by Jack Norris, Registered Dietitian
Vegan dietitians have typically recommended the cyanocobalamin form of vitamin B12 for vegans; it’s well-studied, stable, and inexpensive. The coenzyme forms, methylcobalamin and adenosylcobalamin, have been heavily marketed but poorly studied, with typical recommendations of 1,000 µg/day based more on caution than evidence.
A 2026 randomized trial (MATCOBIND) from India and Nepal offers the best evidence yet on methylcobalamin dosing. In 531 predominantly vegetarian pregnant women with low B12 status, both 250 µg/day and 50 µg/day of a methylcobalamin-only supplement substantially increased holotranscobalamin, the active form of B12. The 50 µg/day group reached a mean holotranscobalamin of 65.3 pmol/L, well within healthy range. This suggests that 50 µg/day of methylcobalamin as a stand-alone supplement is likely adequate for most people, though MMA was not measured (Nagpal, 2026).
There’s reason for caution about methylcobalamin in multivitamins. A stability study found that in solution, methylcobalamin degrades substantially in the presence of vitamin C, thiamin, and niacin, all common multivitamin ingredients, with losses of 48-76%. Sorbitol added as a stabilizer significantly reduced these losses, so a multivitamin containing sorbitol may be more reliable (Hadinata Lie, 2020).
More info at Coenzyme Supplements: Methylcobalamin and Adenosylcobalamin.
References
Nagpal J, Mathur M, Rawat S, et al. Maternal supplementation of vitamin B12 in predominantly vegetarian pregnant women improves their vitamin B12 status and the neurodevelopment of their infants: the MATCOBIND multicentric double-blind randomised control trial. BMJ Paediatr Open. 2026 Mar 18;10(1):e004112.
Hadinata Lie A, V Chandra-Hioe M, Arcot J.Hadinata Lie A, V Chandra-Hioe M, Arcot J. Sorbitol enhances the physicochemical stability of B12 vitamers. Int J Vitam Nutr Res. 2020 Oct;90(5-6):439-447.
