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Effect of Vitamin B6 on the Growth of Rats Fed Diets Limiting in an Essential Amino Acid and on the Utilization of Isomers of Tryptophan, Methionine and Valine

1961; Elsevier BV; Volume: 74; Issue: 3 Linguagem: Inglês

10.1093/jn/74.3.289

1541-6100

Howerde E. Sauberlich,

Folate and B Vitamins Research

The influence of dietary supplements of pyridoxine on the activities of the L- and D-isomers of tryptophan, methionine, and valine for the growth of weanling rats was investigated. Diets were designed to be low in pyridoxine and the amino acid under investigation. Growth and efficiency of gains of the animals were improved by increased levels in the diets of either pyridoxine or the amino acid under study or both. The growth-promoting activities of both the L- and D-isomers of the amino acids studied were enhanced with increased amounts of pyridoxine in the diets. With an optimum amount of vitamin B6 in the diet, D-methionine and the hydroxy analogue of methionine were equal to L-methionine in promoting growth; D-tryptophan was about 50% as active as L-tryptophan; D-valine was less than one-third as effective as L-valine. Dietary pyridoxine levels were observed to influence the pattern of plasma free-amino acids.