(e.g., vitamin E), it may refer only to intakes from supplements, food fortificants, pharmacological agents, or a combination of the three. For some nutrients, such as β-carotene and other carotenoids, there may be inconsistent and insufficient data on which to develop ULs. This indicates the need for caution in consuming amounts greater than the recommended intakes; it does not mean that high intakes pose no risk of adverse effects.

The safety of routine, long-term intake above the UL is not well documented. Although members of the general population should be advised not to routinely exceed the UL, intake above the UL may be appropriate for investigation within well-controlled clinical trials. Clinical trials of doses above the UL should not be discouraged as long as subjects participating in these trials have signed informed consent documents regarding possible toxicity and as long as these trials employ appropriate safety monitoring of trial subjects.

Determination of Adequacy

In the derivation of the EAR or AI, close attention has been paid to the determination of the most appropriate indicators of adequacy. A key question is, Adequate for what? In many cases, a continuum of benefits may be ascribed to various levels of intake of the same nutrient. One indicator may be deemed the most appropriate to determine the risk that an individual will become deficient in the nutrient, while another may relate to reducing the risk of chronic degenerative disease such as common neurodegenerative diseases, cardiovascular disease, cancer, diabetes mellitus, cataracts, or age-related macular degeneration.

Each EAR or AI is described in terms of the selected criterion or outcome. The potential role of vitamin C, vitamin E, selenium, and β-carotene and other carotenoids in the reduction of disease risk was considered in developing the EARs for this group of nutrients. With the acquisition of additional data relating intake to chronic disease or disability, the choice of the criterion for setting the EAR may change. These nutrients, their role in health, and the types of evidence considered are discussed in Chapter 2.

PARAMETERS FOR DIETARY REFERENCE INTAKES

Life Stage Categories

The life stage categories described below were chosen by keeping in mind all the nutrients to be reviewed, not only those included in this report. Additional subdivisions within these groups may be add-



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