We all need the same nutrients, but the amounts we need depend on our age, sex, and a few other factors. For example, women who are pregnant or breastfeeding need more of most nutrients.

The Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences, a group of nutritional scientists from the United States and Canada, has established the Dietary Reference Intakes (DRIs), a set of recommendations for nutrient intake. The DRIs are age- and sex-specific.

With the exception of fats and carbohydrates (whose requirements depend only on our calorie needs), a separate DRI is set for each of the known nutrients for each of 10 different age groups. From the age of 9 years, males and females have separate DRIs, and additional DRIs are set for women who are pregnant or breastfeeding.

How did the nutrient recommendations originate? Concerned with the need to provide proper nutrition for newly drafted World War II soldiers, many of whom were undernourished, the Department of Defense commissioned the first set of nutrient recommendations (called the Recommended Dietary Allowances) in 1941.

Since then, nutrient recommendations have undergone periodic revision based on advances in our understanding of nutrition. Today, nutrition research addresses not only the prevention of nutritional-deficiency diseases but also the role of nutrients in reducing the long-term risk for diseases such as heart disease and cancer.

Taking into consideration the resulting expansion of scientific knowledge about the roles of nutrients in health since the first recommendations were established, the latest revision was begun in 1997.

The new Dietary Reference Intakes (DRIs) include the Recommended Dietary Allowance, the Estimated Average Requirement, the Adequate Intake, and the Upper Limit.

The Recommended Dietary Allowance (RDA) is the amount of each nutrient that is sufficient to prevent nutritional deficiencies in practically all healthy people. The Estimated Average Requirement (EAR) is the amount of a nutrient that is estimated to meet the requirement of half the population of an age- and sex-specific group.

For some nutrients, too little is known about them to establish an RDA. For these, an Adequate Intake (AI) is determined. This is the intake that should be adequate to meet the needs of most people. A safe Upper Limit (UL) has been established for some nutrients.

Establishment of this value reflects our growing recognition that some nutrients may help promote health and prevent disease in amounts that exceed the RDA. The UL is the maximal daily intake of a nutrient that is likely to be free of the risk of adverse health effects in almost all individuals in the designated group.

How are the DRIs used? They are the basis for all nutritional plans used by health care facilities and providers, food services, food manufacturers, and others who plan diets. As you will learn below, the Food Guide Pyramid, the research-based food guide developed by the government, is based on the DRIs.

In addition, the Daily Values, the information on food labels that helps you determine how a food contributes to your total nutrient intake, are based on the DRIs.