Nitrogen utilization, enzyme activity, glucose intolerance and leukocyte chemotaxis in human experimental zinc depletion.

We previously reported significant decreases in plasma, whole blood, urinary, seminal and fecal zinc in six young men consuming a semipurified formula diet providing 0.28 mg zinc and 0.8/kg protein per day for 4-9 weeks. During a one-week baseline period, 15.7 mg of zinc (as ZnSO4) were fed; three of the men were repleted with 6.0, 23.2 or 46.3 mg zinc for 2-5 weeks. Biochemical and functional measures of zinc status other than tissue zinc levels were also monitored. No one parameter appeared to parallel dietary zinc status in all subjects, although significant mean changes were seen in serum and leukocyte alkaline phosphatases. Inconsistent changes were noted in erythrocyte delta-amino levulinic acid dehydratase, plasma alkaline ribonuclease and the serum alkaline phosphatase isoenzymes. Nitrogen balance was unaffected by zinc nutritional status. However, alterations in hair root growth phase and morphology, decreases in lymphocyte counts and in transferrin levels during depletion suggest impairment in protein synthesis. Impaired leukocyte chemotaxis and clinical signs indicative of decreased resistance to infection were also noted.