▪ Abstract  Vitamin B₁₂ deficiency is estimated to affect 10%–15% of people over the age of 60, and the laboratory diagnosis is usually based on low serum vitamin B₁₂ levels or elevated serum methylmalonic acid and homocysteine levels. Although elderly people with low vitamin B₁₂ status frequently lack the classical signs and symptoms of vitamin B₁₂ deficiency, e.g. megaloblastic anemia, precise evaluation and treatment in this population is important. Absorption of crystalline vitamin B₁₂ does not decline with advancing age. However, compared with the younger population, absorption of protein-bound vitamin B₁₂ is decreased in the elderly, owing to a high prevalence of atrophic gastritis in this age group. Atrophic gastritis results in a low acid-pepsin secretion by the gastric mucosa, which in turn results in a reduced release of free vitamin B₁₂ from food proteins. Furthermore, hypochlorhydria in atrophic gastritis results in bacterial overgrowth of the stomach and small intestine, and these bacteria may bind vitamin B₁₂ for their own use. The ability to absorb crystalline vitamin B₁₂ remains intact in older people with atrophic gastritis. The 1998 recommended daily allowance for vitamin B₁₂ is 2.4 μg, but elderly people should try to obtain their vitamin B₁₂ from either supplements or fortified foods (e.g. fortified ready-to-eat breakfast cereals) to ensure adequate absorption from the gastrointestinal tract. Because the American food supply is now being fortified with folic acid, concern is increasing about neurologic exacerbation in individuals with marginal vitamin B₁₂ status and high-dose folate intake.