Zinc, Copper and Iron Concentrations in Hair and Other Tissues: Effects of low zinc and low protein intakes in rats

Abstract

The effects of purified diets containing 2 to 4 ppm of zinc upon concentrations of zinc in liver, kidney, pancreas, spleen, small intestine and in hair were studied in rats. Pair-fed controls received 20 or 30 ppm of zinc. Casein and gelatin served as sources of protein. Among the visceral organs studied, only the small intestine showed consistent and significantly decreased concentrations of zinc compared with the controls. The zinc concentration in hair was found to decrease substantially within 40 days after the low zinc diets started to be fed, and decreased progressively thereafter. During the same intervals, the concentration of zinc in the hair of control rats increased considerably. The combined effects of low zinc with low protein (7.4%) intakes were studied. No effect upon tissue zinc concentrations which could be attributed to the low protein intake was demonstrated. However, low intakes of protein, either with or without zinc supplementation, were associated with significantly elevated concentrations of copper in liver. In contrast, low intakes of zinc had no demonstrable effect upon the concentration of copper in the tissues studied. Iron concentration in the hair of weanling rats was uniform within litters but differed markedly between litters. The differences disappeared with time. No relationship of iron in hair to zinc nutrition was detected.