Effect of Bacteria on Intestinal Uptake of Vitamin B12

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Abstract
Preincubation in vitro of intrinsic-factor-(IF-)bound vitamin B12 with populations of Escherichia coli and Bacteroides fragilis reduced intestinal uptake and absorption of the vitamin from the mixture in rats, as compared to application of vitamin not exposed to living bacteria. Strains of Streptococcus faecalis and Bifidobacterium were without such effects. In vitro uptake of IF-bound vitamin B12 by E. coli and B. fragilis was high, while the uptake by Str. fœcalis and Bifidobacterium was minimal. The results suggest that uptake by intestinal bacteria of IF-bound vitamin B12 may contribute to the malabsorption of the vitamin in the blind-loop syndrome.