Methionine, Homocystine, Choline, Folic Acid and Vitamin B12 in the Nutrition of the Mouse

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Abstract
Weanling mice fed a methionine-free, choline-free basal diet, supplemented with homocystine, died or failed to grow when either folic acid or vitamin B12 was added. The addition of both vitamins permitted survival but little growth. Further supplementation with glycine, serine and threonine resulted in 50% of normal growth. The addition of choline alone to the homocystine-supplemented basal diet permitted only slight growth, whereas about 50% of normal growth was obtained with betaine. The addition of folic acid in the presence of either choline or betaine resulted in nearly normal growth. The further addition of vitamin B12 had only a slight effect. Methionine alone permitted nearly normal growth which was improved slightly by the presence of choline, folic acid and vitamin B12. The liver choline oxidase activity was markedly reduced in mice fed the basal diet supplemented with homocystine. The reduction in activity was largely prevented by dietary supplements of folic acid and partially with vitamin B12. Choline was also effective, whereas betaine was ineffective. Liver transmethylase activity was reduced when choline, folic acid, and vitamin B12 were omitted from the basal-homocystine diet. The activity was improved when folic acid and vitamin B12 were added to the diet. When choline was present in the diet, supplements of folic acid permitted normal activity while partial improvement was noted with supplements of vitamin B12. Extremely fatty livers were observed in mice fed the basal-homocystine diet, either in the presence or absence of folic acid and vitamin B12. When choline or betaine was present, the liver fat was greatly reduced. Normal values were obtained when choline, folic acid and vitamin B12 were fed.

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