Vitamin B₁₂, the gastrointestinal system and aging

Vitamin B₁₂ deficiency appears to be an under recognized problem in the geriatric age group. A complex pathway pertinent to the gastrointestinal system is the basis for absorption of the micronutrient; numerous etiological factors are recognized to cause malabsorption of the vitamin. A discussion emphasizing the physiological alterations and pathological states involving the gastrointestinal tract that result in cobalamin deficiency follows.