NHANES-III found the median intakes of zinc of women, 60-69 years old, was about 60% of the RDA, suggesting many are at risk of zinc deficiency. Zinc nutriture may affect neuropsychological performance, protein status, energy metabolism, and potassium homeostasis. Therefore our primary objective is to determine if zinc repletion improves neuropsychological performance of women 65-70 years old, with mild zinc deficiency; and our secondary objectives are to determine if zinc repletion also improves the other above listed functions. Design: eight week, double blind, randomized controlled zinc treatment trial. Subjects: thirty women, 65-70 years old, without disability, who are identified by a three stage screening procedure. First, about 300 women will be screened for health and dietary intake of zinc. Second, about 100 women with zinc intakes <6mg from diets of relatively low bioavailability, will be screened by granulocyte and lymphocyte zinc concentrations and the percent of CD8+ lymphocytes that are positive for CD73 antigen. Third, about 50 individuals who are low in either laboratory index will be screened by zinc kinetics to identify 30 subjects with a low 24 hour exchangeable zinc pool. Treatments: Based on the RDA, 15 experimental subjects will be given 12mg zinc daily with micronutrients; and 15 control subjects will be given micronutrients alone. Outcomes: change from baseline in neuropsychological performance, protein status, basal metabolic rate and respiratory quotient and total body potassium. Results: positive findings will imply that low zinc nutriture caused the abnormalities that were corrected by zinc repletion and will provide a basis for dietary recommendations and research on mechanisms.
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