Vitamin B12 synthesis by human small intestinal bacteria.
Albert MJ, et al. Nature. 1980.
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In man, physiological amounts of vitamin B12 (cyanocobalamin) are absorbed by the intrinsic factor mediated mechanism exclusively in the ileum. Human faeces contain appreciable quantities of vitamin B12 or vitamin B12-like material presumably produced by bacteria in the colon, but this is unavailable to the non-coprophagic individual. However, the human small intestine also often harbours a considerable microflora and this is even more extensive in apparently healthy southern Indian subjects. We now show that at least two groups of organisms in the small bowel, Pseudomonas and Klebsiella sp., may synthesise significant amounts of the vitamin.
PMID 7354869 [Indexed for MEDLINE]
Free intrinsic factor in the small intestine in man.
Kapadia CR, et al. Gastroenterology. 1976.
Vitamin B12 production by the gastro-intestinal microflora of baboons fed either a vitamin B12 deficient diet or a diet supplemented with vitamin B12.
Uphill PF, et al. J Appl Bacteriol. 1977.
Vitamin B12 absorption–a study of intraluminal events in control subjects and patients with tropical sprue.
Kapadia CR, et al. Gut. 1975.
Absorption of vitamin B12 in pancreatic insufficiency.
von der Lippe G, et al. Scand J Gastroenterol Suppl. 1974.
Vitamin B12 in health and disease: part I–inherited disorders of function, absorption, and transport.
Kapadia CR, et al. Gastroenterologist. 1995.