Effect of Major Dietary Constituents on Growth Response of Rats to Vit B 12 . ∗

Summary

1) Rats born to dams maintained on Vit. B₁₂ deficient diets from mating to weaning were fed rations high in carbohydrate, fat, protein, and protein and fat with and without Vit. B₁₂. 2) The greatest degree of deficiency was consistently observed in rats on high protein and high protein-high fat rations. Since Vit. B₁₂ increased ability of rats to utilize excess protein, one of the important functions of this vitamin appears to be the metabolism of excess amino acids for non-protein functions. 3) Differences in growth on various diets, however, may be due to degree of intestinal synthesis of Vit. B₁₂ and extent of coprophagy.