ABSTRACT
Cyanocobalamin is the commercially available form of vitamin B-12. This form is stable and readily converted in the body to metabolically active vitamin B-12. Microorganisms are the source of all vitamin B-12 in nature. Hence, all plants and plant food are devoid of vitamin B-12 unless contaminated by microorganisms. In Zimbabwe, vitamin B-12 deficiency is the primary cause of megaloblastic anemia. Vegetarian diets have long been recognized to be deficient in vitamin B-12. Serum methylmalonic acid concentrations are elevated with a deficiency of vitamin B-12, but not by a folate deficiency. In the United States, blacks also had significantly higher serum vitamin B-12 concentrations than whites. Vitamin B-12 evaluations may be assisted by neutrophil hypersegmentation measurements, deoxyuridine suppression tests, or formiminoglutamic acid excretion levels. Measurements of both serum vitamin B-12 and holotranscobalamin II would provide the most useful information for the assessment of vitamin B-12 status.
