other food components, the food matrix, food processing, and age on nutrient bioavailability and therefore dietary requirement;
studies to further investigate the roles of arsenic, boron, nickel, silicon, and vanadium in human health; and
studies to investigate the influence of non-nutritional factors (e.g., body mass index, glucose intolerance, infection) on the biochemical indicators for micronutrients such as iron and vitamin A that are currently measured by U.S. and Canadian nutritional surveys.
Because of a lack of sufficient data, a Tolerable Upper Intake Level (UL) could not be established for vitamin K, arsenic, chromium, and silicon. Furthermore, there was a lack of data from humans to establish a UL for boron, molybdenum, and vanadium, and therefore a UL was based on animal data. Thus, research is needed concerning the ULs for these micronutrients. However, it was concluded that higher priority should be given to the areas listed above because of low suspicion of toxicity at intakes consumed from food and supplements in the United States and Canada.