A randomized, double-blind, placebo-controlled study of oral vitamin B12 supplementation in older patients with subnormal or borderline serum vitamin B12 concentrations.( Jan 2002)

Cyanocobalamin supplementation of 50 microg but not 10 microg daily produced a significant increase in serum vitamin B12. This result has implications for the management of patients with subnormal or borderline serum vitamin B12 concentrations and for food fortification with vitamin B12.
PMID: 12028259