Effect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and vegetarians with a marginal deficiency: A randomized controlled trial

BACKGROUND & AIMS: Vegetarians and vegans are more vulnerable to vitamin B12 deficiency with severe risks of megaloblastic anemia, cognitive decline, neuropathy, and depression. An easy and simple method of supplementation consists of taking one weekly dosage of 2000 μg. However, single large oral doses of vitamin B12 are poorly absorbed. The present research evaluates the ability of two different sublingual dosages of vitamin B12 (350 μg/week vs 2000 μg/week) in improving cyanocobalamin (vitamin B12) nutritional status in vegans and vegetarians with a marginal deficiency. METHODS: A 12-week randomized, double-blind, controlled, parallel intervention trial was performed. Forty subjects with marginal vitamin B12 deficiency were enrolled and randomly divided into two groups: test group Ld (low dose, 350 μg/week) and control group Hd (high dose, 2000 μg/week) vitamin B12 supplementation. Blood samples were collected at baseline and after 15, 30, 60, and 90 days from the intervention for the determination of vitamin B12, related metabolic markers, and blood cell counts. RESULTS: Two-way analysis of variance showed a significant effect of time (P < 0.0001) and of time × treatment interaction (P = 0.012) on serum concentration of vitamin B12 that increased after 90-day supplementation (Ld and Hd) compared to baseline. Both the supplements increased (P < 0.0001, time effect) the levels of holotranscobalamin, succinic acid, methionine and wellness parameter, while decreased (P