No abstract

The effects of zinc deficiency and testosterone on fatty acid composition of plasma lipids and microsomes of liver, intestine and testes were studied. The activities of fatty acid desaturase (delta 6 and delta 5) in rat liver and testes were also measured. A significant decrease in the level of arachidonic acid was observed in plasma of normal rats fed the zinc-deficient diet. Castration significantly decreased arachidonic acid but increased 20:3 fatty acid, which is negligible in normal rats. Testosterone and zinc administration restored arachidonic acid to normal values. Zinc deficiency does not significantly change the fatty acid profile in liver, but castration decreased both arachidonic and 22:6 fatty acid. Intestinal mucosal microsomes showed that the predominant fatty acid in this tissue, palmitic acid, is independent of zinc status, whereas polyunsaturated fatty acids 18:2 and 20:4 were decreased by zinc-deficient diet or castration. Zinc deficiency sharply decreased 22:5 fatty acid and to some extent, other polyunsaturated fatty acids in testis microsomes. These changes in fatty acids are in agreement with increased delta 9 desaturation and decreased delta 5 desaturase activity. In testes, both delta 6 and delta 5 desaturase activities are decreased in zinc deficiency. It appears that zinc influences the conversion of linoleic to arachidonic acid, whereas testosterone influences delta 6 desaturase activity. The data suggest that zinc deficiency may be one of the important factors in the causation of polyunsaturated fatty acid deficiency, which, in turn, may induce serum hypertriglyceridemia.

Premature infants have a lower selenium concentration in serum than full-term infants and children. The selenium concentration goes down quickly in infants treated for respiratory distress syndrome without supplementation. One premature infant with bronchopulmonary dysplasia had persistently low concentrations of selenium. Vitamin E supplements did not affect the serum selenium concentration in healthy premature infants. Supplementation with 3 µg/kg of selenium in parenteral fluids prevented the fall in the concentration seen in other infants not supplemented. Premature infants and especially those treated withoxygen may warrant selenium supplementation to the parenteral nutrition solution. Vitamin E supplements alone are apparently not sufficient to prevent selenium deficiency and potential oxygen toxicity.

Phytic acid has interested analytical chemists, biochemists, and nutritionists for several years. Brown et al( 1) recently supported Neuberg's proposed structure and concluded that of the 18 acid hydrogens in the Neuberg model, only 1 2 were available for titration in aqueous solution.Chicks fed purified diets containing sesame meal ( 2 ,3) or isolated soybean protein (4) as the sole source of protein developed zinc deficiency symptoms, although the diet contained more than the optimum level of zinc. *Arizona Agric. Exp. Station Journal Article 831.