Hepatic Uptake and Intestinal Absorption of Co58-Labelled 5,6-dimethylbenzimidazolylcobamide Coenzyme.

Inhibitory Effect of Eggs on Vitamin B12 Absorption: Description of a Simple Ovalbumin 57Co‐Vitamin B12 Absorption Test

“…Although the malabsorption of vitamin B 1 2 from the ovalbumin 57Co-vitaminn B presumably also have impaired assimilation of vitamin B contents, being almost entirely dependent on the added vitamin B cobalamin (Chanarin, 1969), which are bound to animal proteins (Smith, 1965;Chanarin, 1969). The absorption of cyanocobalamin from the intestinal tract is essentially the same as that of hydroxocobalamin (Chosy et al, 1962;Adams et al, 1971), but superior to that of the coenzymes (Lee & Glass, 1961 Okuda et a!, 1973). During the processing and digestion of food the naturally occurring forms of vitamin B, 2 , being very labile substances, are presumably converted into hydroxocobalamin, in which form they may be absorbed (Lindstrand, 1971).…”

Absorption of cobalamins

“…These vitamin B12 analogues are absorbed largely unchanged (Okuda, Yashima, and Takamatsu, 1969), although some conversion of cyanocobalamin to deoxyadenosylcobalamin during absorption in the guinea pig has been demonstrated (Hoffbrand, Linnell, Matthews, and Peters, 1970). Further, the different vitamin B12 analogues are absorbed equally by man (Lee and Glass, 1961;Chosy, Killander, and Schilling, 1962), although when assessed by urinary excretion methods differences in plasma and tissue binding may result in lower urinary excretion with deoxyadenosyl B12 and hydroxocobalamin.…”