Trace element bioavailability as exemplified by iron and zinc

Plant foods can be improved as sources of essential micronutrients either by increasing the concentrations of nutrients in the food, increasing the bioavailability of micronutrients in the food, or both of these, Quantities of minerals in edible portions of crops are influenced by numerous complex, dynamic and interacting factors, including plant genotype, soil properties, environmental conditions and nutrient interactions. Similarly, numerous dietary and host factors interact to affect the bioavailability to animals and people of mineral nutrients in plant foods. Micronutrient bioavailability apparently can be improved by either increasing the quantity of substances within plant foods that enhance the absorption and utilization of micronutrients or by decreasing the quantity of dietary antinutrients that inhibit micronutrient absorption; however, processes that control and regulate the bioavailability of trace elements in plant foods consumed in mixed diets are not fully understood. Use of either stable or radioactive isotopes incorporated intrinsically into edible portions of plant feuds during plant growth will likely provide the most reliable estimates of thr bioavailability of micronutrients consumed in mixed diets. Increasing the dietary supply of staple plant foods rich in trace elements combined with increased knowledge of micronutrient bioavailability from these foods will meaningfully improve the nutritional health and well being of people. (C) 1999 Elsevier Science B.V. All rights reserved.