CLINICAL ASPECTS OF TRACE-ELEMENTS - ZINC IN HUMAN-NUTRITION - ZINC REQUIREMENTS

The body requires certain levels of essential nutrients, such as zinc, to maintain lift. Intake less than the required levels can cause impa ired function, disease and death. Every essential nutrient has a uniqu e range of tissue concentration and intake necessary for proper physio logical and biochemical functioning. Many criteria have been used to s et dietary intake levels for nutrients. For trace elements, however, a limited number of investigative approaches are currently employed by researchers due to inadequate information on individual requirements a nd intake levels. Further, a clear lack of satisfactory biochemical me thods to measure zinc nutritional status continues to hinder formulati on of dietary guidelines. Thus, many assumptions have to be made, and large safety margins have to be added to assumed daily requirements in order to compensate for this absence of information. Numerous barrier s to a full understanding of what constitutes an adequate dietary reco mmendation for;inc still exist. Zinc is incompletely absorbed, and thi s absorption can be greatly influenced by the chemical form in which z inc is bound; interactions with other nutrients also affect absorption . Part three of this five-part review presents the current Canadian re commended nutrient intakes for zinc for various sex and age categories and provides a rationale for the suggested values. The important nutr ient interactions that affect the bioavailability of zinc, including t hose with phytates, copper, cadmium, tin and iron, are discussed.