Life stage and gender were considered to the extent possible, but for some nutrients, the data did not provide a basis for proposing different requirements or upper levels for men and women or for adults in different age groups. In all cases, data were examined closely to determine whether reduction of risk of a chronic degenerative disease or developmental abnormality could be used as a criterion of adequacy. The quality of studies was examined, considering study design, methods used for measuring intake and indicators of adequacy, and biases, interactions, and confounding factors. After careful review and analysis of the evidence, including examination of the extent of congruence of findings, scientific judgment was used to determine the basis for establishing the values. The setting of a UL does not indicate that nutrient intakes greater than the RDA or AI are recommended as being beneficial to an individual.
Many individuals are self-medicating with nutrients for curative or treatment purposes.
It is beyond the scope of the model at this time to address the possible therapeutic benefits of higher nutrient intakes that may offset the risk of adverse effects. The UL is not meant to apply to individuals who are being treated with the nutrient or food component under medical supervision. In the case of nutrients, it is exceedingly important to consider the possibility that the intake of one nutrient may alter in detrimental ways the health benefits conferred by another nutrient.