Deliberations and evaluations of approaches, endpoints and paradigms for determining zinc dietary recommendations

The work group considered past and future Recommended Dietary Allowances (RDAs) for zinc. Past RDAs were based in large part on metabolic balance data. Balance measurements are technically difficult and it is uncertain that they reflect true requirements. Therefore other methods should be used to determine requirements and the RDA. The best approach at this time is the factorial method. In the future, data from measurements of zinc kinetics, in relation to diet and physiological functions will provide useful insights. Future RDAs should provide for at least three levels of bioavailability: low, moderate and high. Whether adjustments should be made in the RDA to account for life style factors is a matter of philosophy. The importance of the differences (gaps) between the RDA and usual intakes of zinc by persons who are apparently in good health, or between the RDA and other dietary guidelines, is an issue for consideration.