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The Effects of Vitamins B₁₂ and B_12f on Growth, Kidney Hemorrhage, and Liver Fat in Rats Fed Purified Diets¹

Department of Biochemistry, University of Wisconsin, Madison

The choline-sparing activities of vitamins B₁₂ and B_12f have been investigated, using weanling male rats fed purified diets containing 9% or 18% casein. As judged by growth stimulation and prevention of hemorrhagic kidneys, vitamin B₁₂ is able to replace dietary choline almost completely. On the other hand, a suboptimum level of dietary choline is necessary for the demonstration of lipotropic activity. No evidence was obtained of a choline-sparing activity of vitamin B_12f.

Under the conditions used, methionine will not replace choline completely even in the presence of supplementary vitamin B₁₂. Rapid growth is not essential for the development of fatty livers, although the higher levels of liver fat were usually found in faster growing animals. Even with 0.1% choline chloride in the diet, liver fat in animals fed the 9% casein diet was considerably higher than that found in animals fed the 18% casein diet, indicating that casein may have lipotropic activity in addition to that due to its methionine content.

² National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Public Health Service, Federal Security Agency, Bethesda, Maryland, assigned to Department of Biochemistry, College of Agriculture, University of Wisconsin.

Manuscript received 25 August 1952.