Greibe E, et al. - This study was performed to investigate the effect of 8-week daily supplementation with 3 μg of cyano-B12 (CN-B12) or hydroxo-B12 (HO-B12) on markers of the vitamin B12 (B12) status in a B12-deficient Indian population. Compared to 3 μg hydroxo-B12, 8-week supplementation with 3-µg cyano-B12 elevated serum cobalamin more. However, in both groups, all other biomarkers changed similarly. In individuals with nutritional vitamin B12 deficiency, supplementation with 3 μg vitamin B12 did not reverse the low status.