American Journal of Clinical Nutrition, Vol 12, 180-193, Copyright © 1963 by The American Society for Clinical Nutrition, Inc.

Effect of Some Physiologic Factors on the Absorption of Vitamin B₁₂ in Rats

¹ From the Department of Biochemistry, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland

Prefeeding of a soybean diet and resin can enhance vitamin B₁₂ absorption in rats. This enhancement is probably due to the reduction of the rate of passage of vitamin B₁₂ adsorbed to food or resin in the gastrointestinal tract. The hypothesis is supported by the fact that the administration of Pro-banthine slows down the vitamin B₁₂ passage in the gastrointestinal tract and also enhances its absorption.

Vitamin B₁₂ absorption is enhanced when animals are exposed to cold temperatures but not to starvation or semistarvation.

Our preliminary data suggest that vitamin B₁₂ can be absorbed against a concentration gradient. Administration of adenosine triphosphate increases the absorption of vitamin B₁₂, whereas the administration of 2,4-dinitrophenol results in an impairment. These findings, taken as a whole, suggest that active transport may be involved in the complicated processes in vitamin B₁₂ absorption.