Dietary intake and bioavailability of trace elements.

In order to assess the nutritional importance of trace elements, it is relevant to consider the factors regulating their metabolism. One of the most important factors is the true intake level. Conventional techniques such as diet history and interview studies in conjunction with standard food tables do not provide the true intake levels from prepared meals. Employing the duplicate portion technique, we have investigated the dietary intake of trace elements in prepared meals consumed by children, adults, and elderly in Sweden. The results indicate that the intake of potassium, magnesium, zinc, copper, and selenium is low when compared with the present recommended dietary allowance (RDA) values. It appears that a marginal deficiency of a number of trace elements may exist in the general population of affluent countries. When the dietary intakes are known, it is necessary to consider the bioavailability. This depends on the chemical form as well as the concentration of other dietary constituents such as fiber, phytate, carbohydrates, macrominerals, and vitamins in the diet. Knowledge of these interactions are important to improve the overall nutritional status of the population in general and patients in particular.