Vitamin B₁₂ absorption following human intestinal bypass surgery

Adaptation of vitamin B₁₂ absorption by small intestine has been suggested by experimental and clinical studies. Five partial ileal bypass patients and ten jejunoileal bypass patients were studied for adaptation of B₁₂ absorption following surgery. Adaptation of vitamin B₁₂ absorption could not be demonstrated in either group. Few of the patients on an individual basis demonstrated adaptation. Parenteral B₁₂ should be given to all patients who undergo bypass surgery unless evidence of persistent normal B₁₂ absorption has been obtained.