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nance of bone health, its role is still not well understood. A number of studies have demonstrated a beneficial effect of chromium on insulin action and circulating glucose levels; however, further information is needed to relate the intake of chromium to the prevention and reversal of diabetes. Although information on vitamin K and chromium is insufficient, even less information is available for the other nutrients, and therefore EARs are based on indicators other than functional ones.

Adverse Effects

Considering these micronutrients as a group, only a few studies have been conducted that were explicitly designed to address adverse effects of chronic high intake. For four nutrients—vitamin K, arsenic, chromium, and silicon—data were insufficient to set a Tolerable Upper Intake Level (UL). Because of insufficient human data, the UL for three nutrients—boron, molybdenum, and vanadium—were based on animal data. Thus, information on which to base a UL is extremely limited for some micronutrients.


Five major types of information gaps were noted: (1) a lack of data demonstrating a role of some of these nutrients in human health, (2) a dearth of studies designed specifically to estimate average requirements in presumably healthy humans, (3) a lack of data on the nutrient needs of infants, children, adolescents, the elderly, and pregnant women, (4) a lack of studies to determine the role of these nutrients in reducing the risk of certain chronic diseases, and (5) a lack of studies designed to detect adverse effects of chronic high intakes of these nutrients.

Highest priority is given to research that has the potential to prevent or retard human disease processes and to prevent deficiencies with functional consequences. The following four areas for research were assigned the highest priority (other research recommendations are found at the ends of Chapters 4 through 13):

  • studies to identify and further understand the functional (e.g., cognitive function, regulation of insulin, bone health, and immune function) and biochemical endpoints that reflect sufficient and insufficient body stores of these micronutrients;

  • studies to further identify and quantify the effect of interactions between nutrients and interactions between micronutrients and

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