Influence of Vitamin Bi2 and Folacin on the Synthesis of Choline and Methionine by the Rat.

Abstract

A diet deficient in both choline and methionine supplemented with homocystine was fed to weanling rats to study the effect of vit. B12 and/or folacin on the synthesis of both choline and methionine in the presence or absence of a dietary source of labile methyl. In the presence of adequate methyls vit. B12 alone was as effective for methionine and choline synthesis as when combined with folacin. When the methyl supply was limited, both folacin and vit. B12 were essential. As a methyl donor for the synthesis of methionine from homocystine, betaine was at least as effective as choline, mole per mole. Under the conditions employed, the rate of synthesis of the methyl group or utilization of methanol for the methylation of homocystine to methionine and aminoethanol to choline was not fast enough to support normal development.