take was chosen to avoid implying a possible beneficial effect. Instead, the term is intended to connote a level of intake that can, with high probability, be tolerated biologically. The UL is not intended to be a recommended level of intake, and there is no established benefit to healthy individuals if they consume a nutrient in amounts exceeding the recommended intake (the RDA or AI).
The UL is based on an evaluation conducted by using the methodology for risk assessment of nutrients (see Chapter 3). The need for setting ULs grew out of the increased fortification of foods with nutrients and the use of dietary supplements by more people and in larger doses. The UL applies to chronic daily use. As in the case of applying AIs, professionals should avoid very rigid application of ULs and first assess the characteristics of the individual and group of concern, such as the source of the nutrient, the physiological state of the individual, the length of sustained high intakes, and so forth.
For some nutrients, data are not sufficient for developing a UL for apparently healthy individuals. 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 safe monitoring of trial subjects.
In the derivation of the AIs in this report, 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 criterion may be deemed the most appropriate to determine the risk that an individual will become deficient in the nutrient whereas another criterion chosen may relate to reducing the risk of chronic degenerative disease, such as blood pressure in relation to hypertension.
In other reports providing DRIs for nutrients (IOM, 1997, 1998, 2000b, 2001, 2002/2005), as for those included in this report, each EAR or AI is described in terms of the selected criterion. The po-