ABSTRACT
The growing use of nutrient supplements as well as the popularity of lowcalorie but often nutritionally inadequate diets gives rise to concern about interactions between vitamins and minerals. Such interactions are very different in their biochemistry but can occur by two fundamental mech anisms: (1) one micronutrient directly affects the absorption of another micronutrient, and (2) deficiency or excess of one micronutrient within the organism affects the metabolism of another micronutrient. Examples of the first type of interaction are the interactive effects of ascorbic acid on iron absorption and the potential interaction between negatively charged folates and positively charged trace elements, such as zinc. The second type of interaction is exemplified by the effect of zinc deficiency on retinol binding protein (RBP) and vitamin A metabolism and the effect of high doses of ascorbic acid on copper metabolism. The effects of negative mi cronutrient interactions need to be considered when single nutrient sup plements are used. In addition, the need for supplementing populations at risk for one micronutrient deficiency with other micronutrients that would be affected by the primary deficiency must be assessed.
