Article Text

Download PDFPDF
Vitamin B12 by mouth


The small quantity of vitamin B12 in a normal diet is absorbed by a complex process involving the liberation of the vitamin from food proteins, its combination with a glycoprotein secreted by the gastric mucosa (‘intrinsic factor’), its uptake by the ileal mucosa and its transfer to the blood stream.1 Vitamin B12 in very large amounts, and probably some of that present in liver and kidney, is absorbed mainly by direct diffusion without the participation of intrinsic factor.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.