THE RECOMMENDED DIETARY ALLOWANCE FOR

ABSTRACT Although the recommended dietary allowance provides an estimate for vitamin C ingestion in humans, optimal vitamin C requirements are unknown. We define optimal vitamin C requirements operationally based on the following: dose-func-tion relations, availability in the food supply, steady state concen-trations in plasma and tissues achieved at each dose of vitamin C, urinary excretion, bioavailability, toxicity, and epidemiologic ob-servations. Optimal vitamin C requirements can be estimated when information is available for at least some of these criteria. Am J Clin Nutr l995;62(suppl): 1347S-56S. KEY WORDS Vitamin C, ascorbic acid, recommende