Adequate intake is a specific component of the dietary reference intake. Initiated in 1997 by the U.S. National Academy of Sciences, the dietary reference intake is a program of strategic nutritional recommendations, consisting of four specific values for each nutrient, that, when followed, result in adequate nutrition for most individuals. The four recommendations that make up the dietary reference intake are the estimated average requirements, the adequate intake, the tolerable upper intake levels, and the recommended dietary allowances. Based on experimental data and approximations of intake by healthy individuals, the adequate intake is a recommended average daily intake level of a given nutrient assumed to be satisfactory.
The estimated average requirements, calculated from data obtained in a review of the scientific literature, are designed to fulfill the dietary needs of at least 50 percent of individuals in a given age group. Determined only when there is inadequate evidence to establish an estimated average requirements, an adequate intake is expected to fulfill or surpass the quantity needed to maintain normal growth or maintenance of certain circulating blood levels of a nutrient in virtually all members of a specific healthy demographic. It is established as a suggested guidepost for a proper level of intake of a nutrient. In most cases, the adequate intake level exceeds the quantity that would have been established experimentally. With certain nutrients that can be potentially toxic in large quantities, the tolerable upper intake levels warn against overindulgent supplementation, while the recommended dietary allowances indicate those levels of a nutrient that the Food and Nutrition Board considers sufficient for greater than 95 percent of average individuals in each demographic group.
In the dietary reference intake reports, the adequate intake levels are estimated using a number of different tactics. Some adequate intake levels are established by observing the average nutrient intake of people who meet certain criteria for health. Since the data are collected in various ways, and the adequate intake is derived from various formulas, it is difficult to make broad assertions regarding the diet of a population using the adequate intake value. When the adequate intake is based directly on consumption levels of healthy groups, it is valid to assume that nutrient consumption in other groups matching or surpassing that of the reference group is adequate.