Effect of Chromium and Tungsten on L-Ascorbic Acid Metabolism in Rats and Chicks

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Abstract
The effects of dietary chromium and tungsten on the growth rate and also on ascorbic acid metabolism in rats and chicks were studied. Chromium at a dose of 10 ppm stimulated the growth rate of rats. In rat and goat liver systems in vitro, addition of chromium, and in rats both dietary chromium and tungsten at either low or high concentrations stimulated the conversion of L-gulonolactone to L-ascorbic acid. In the case of chicks, however, there was inhibition of the enzyme L-gulonolactoneoxidase when chromium was fed orally. Both chromium and tungsten increased the oxidative breakdown of L-ascorbic acid by rat liver enzymes, but in chicks oral administration of chromium showed no effect on the catabolism of L-ascorbic acid. Only tungsten increased the biosynthesis of L-xylulose in rats. Chromium supplementation to the control diet resulted in an increase in the concentration of ascorbic acid in the spleen and adrenal gland, whereas tungsten at low concentration increased the ascorbic acid reserve of the liver, kidney and spleen and at a higher concentration diminished the ascorbic acid status in the adrenal. In chicks the ascorbic acid content went up in the spleen after oral administration of chromium.