Vitamin B 12 deficiency in the elderly.

Vitamin B 12 deficiency is usually a disease of older persons, and much controversy has surrounded the significance of the deficiency of this vitamin in these patients. This article explores the mechanism of action of vitamin B 12, the clinical and laboratory features of vitamin B 12 deficiency, and a rational treatment plan. Once vitamin B 12 deficiency is recognized and diagnosed, it can be easily treated, usually with gratifying results.