Studies on Intestinal Absorption of Vitamin B₁₂ in Totally Gastrectomized Patients

Abstract

It has been well known that vitamin B₁₂ is absorbed from the intestinal tract in the presence of intrinsic factor. Suggestions have been made that liver B₁₂ is absorbed without intrinsic factor, and that lack of B₁₂ merely represents maldigestion in the stomach. This communication deals with our study to clarify the role of intrinsic factor in vitamin B₁₂ absorption in subjects without stomach, and digestibility and absorbability of liver bound B₁₂. Liver containing ⁵⁷Co-B₁₂ was prepared by repeated injection of the vitamin to rats, and was fed to test subjects. In addition, a patient with an intestinal fistulae was used for study.
The following results were obtained;
1) Vitamin B₁₂ malabsorption in patients with total gastrectomy was due mainly to absence of intrinsic factor.
2) No evidence was obtained that absorption of liver bound B₁₂ was superior to that of aqueous B₁₂. Hence, liver proteins have no intrinsic factor-like activity.
3) Following oral administration of hog intrinsic factor, the activity continued to be demonstrable in the small intestine for at least two hours.
4) A patient who had had total gastrectomy and showed normal absorption of vitamin B₁₂ has been described.