The AI is defined as a value based on observed or experimentally determined estimates of nutrient intake by a group of people who are apparently healthy and assumed to be maintaining an adequate nutritional state. Examples of adequate nutritional states include normal growth, maintenance of normal levels of nutrients in plasma, and other aspects of nutritional well-being or general health. The AI is obviously derived differently from the EAR/RDA, and a distribution of requirements cannot be offered.
As intake increases above the UL, the potential risk of adverse effects may increase; it is a level above which the risk for harm begins to increase. The UL is the highest average daily nutrient intake level likely to pose no risk of adverse health effects for nearly all people in a particular group. The need to set a UL grew out of two major trends; increased fortification of foods with nutrients and the use of dietary supplements by more people in larger doses (IOM, 2006).
The UL is not a recommended level of intake, but rather the highest intake level that can be tolerated without the possibility of causing adverse effects in most people. The value applies to chronic daily intake among free-living persons in the community (IOM, 2006). It has often been misused as a determination of levels to be allowed in controlled clinical trials. However, ULs are not defined to fit this purpose, and higher levels may be approved for controlled research purposes if there is a rationale for the levels to be used and if monitoring and other safety precautions are put in place. Rather, the UL is meant for public health protection. The biggest challenge in establishing ULs is the paucity of data indicating the effects of chronic intakes of high levels of nutrients. Experimental animal data as well as observational data are useful and relevant under these circumstances.
The application of the DRIs in real world settings has been the subject of detailed IOM reports (IOM, 2000a, 2003). The EAR is the foundation of DRI development and is relevant to the planning and assessing of diets as they relate to population groups. The EAR is a reference value often important to the government sponsors of the report who may use requirement distributions to set national food policy, establish criteria for food programs, and make decisions about the adequacy of the food supply.
An individual’s nutrient requirement cannot be readily determined, and the use of DRIs for the purposes of assessing and planning diets of individuals is challenging. If an individual’s daily intake is typically below the