Metabolism of zinc, copper and iron as affected by dietary protein, cysteine and histidine.

Zinc, copper and iron utilization were examined in weanling male rats fed a 45% lactalbumin diet (HPro), a 15% lactalbumin diet (LPro), or 15% lactalbumin diets supplemented with: histidine (LProHis), cysteine (LProCys), or histidine and cysteine (LProHisCys). The histidine content and cysteine content of the supplemented diets were equal to the levels of these amino acids in the HPro diet. Zinc utilization was affected by the levels of protein, cysteine, and, to a lesser extent, histidine in the diets. The apparent absorption of zinc and the levels of zinc in their tibias were greater when the rats were fed the HPro, LProCys or LProHisCys diets rather than the LPro or LProHis diets. Liver copper levels were highest when rats consumed the LPro diet. Tissue levels of iron and fecal losses of iron were not affected by the dietary treatments.