Metabolic changes in golden hamsters fed vitamin B-12-deficient diets

Various metabolic changes were observed in male hamsters fed vitamin B-12-deficient diets with or without supplements of cobalt, methionine, and a previously untested cobalt-free pseudovitamin B-12. The effects observed after 31 weeks of consuming the vitamin B-12-deficient diets included a marked increase in the urinary excretion of both methylmalonic acid and formiminoglutamic acid, slight increases in red blood cell mean corpuscular volume, and higher tissue levels of glutathione and activities of glutathione reductase and glucose-6-phosphate dehydrogenase. Vitamin B-12 in the diet prevented these changes, as did inorganic cobalt. The cobalt-free pseudovitamin B-12 showed no vitamin B-12 activity, neither did it have any potent antagonistic effect. Methionine supplementation reversed some of the metabolic changes. Addition of inorganic cobalt to the diet resulted in a significant increase in tissue stores of vitamin B-12.