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In 1993, the Food and Nutrition Board’s Dietary Reference Intakes committee set up several panels of experts to review the RDAs and other recommendations for major nutrients (vitamins, minerals, and other food components) in light of new research and nutrition information. The first order of business was to establish a new standard for nutrient recommendations called the Dietary Reference Intake (DRI). DRI is an umbrella term that embraces several categories of nutritional measurements for vitamins, minerals, and other nutrients. It includes

 Estimated Average Requirement (EAR): The amount that meets the nutritional needs of half the people in any one group (such as teenage girls or people older than 70). Nutritionists use the EAR to figure out whether an entire population’s normal diet provides adequate amounts of nutrients.

 Recommended Dietary Allowance (RDA): The RDA, now based on information provided by the EAR, is still a daily average that meets the needs of 97 percent of a specific population, such as women age 18 to 50 or men age 70 and older.

 Adequate Intake (AI): The AI is a new measurement, providing recommendations for nutrients for which no RDA is set. (Note: AI replaces ESADDI.)

 Tolerable Upper Intake Level (UL): The UL is the highest amount of a nutrient you can consume each day without risking an adverse effect.

The DRI panel’s first report, listing new recommendations for calcium, phosphorus, magnesium, and fluoride, appeared in 1997. Its most notable change was upping the recommended amount of calcium from 800 milligrams to 1,000 milligrams for adults age 31 to 50 as well as postmenopausal women taking estrogen supplements; for postmenopausal women not taking estrogen, the recommendation is 1,500 milligrams.

The DRI panel’s second report appeared in 1998. The report included new recommendations for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. The most important revision was increasing the folate recommendation to 400 micrograms a day based on evidence showing that folate reduces a woman’s risk of giving birth to a baby with spinal cord defects and lowers the risk of heart disease for men and women. (See the sidebar “Reviewing terms used to describe nutrient recommendations” in this chapter to brush up on your metric abbreviations.)

As a result of the 1998 DRI panel’s report, the FDA ordered food manufacturers to add folate to flour, rice, and other grain products. (Multivitamin products already contain 400 micrograms of folate.) In May 1999, data released by the Framingham Heart Study, which has followed heart health among residents of a Boston suburb for nearly half a century, showed a dramatic increase in blood levels of folate. Before the fortification of foods, 22 percent of the study participants had folate deficiencies; after the fortification, the number fell to 2 percent.

A DRI report with revised recommendations for vitamin C, vitamin E, the mineral selenium, beta carotene, and other antioxidant vitamins was published in 2000. In 2001, new DRIs were released for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. In 2004, the Institute of Medicine (IOM) released new recommendations for sodium, potassium, chloride, and water, plus a special report on recommendations for two groups of older adults (age 50 to 70 and 71 and over). By 2005, the Food and Nutrition Board had established an AI of 600 IU (international units) vitamin D for men and women older than 71. Put all these findings together, and they spell out the recommendations you find in this chapter.

Table 3-1 shows the most recent RDAs for vitamins for healthy adults; Table 3-2 shows RDAs for minerals for healthy adults. Where no RDA is given, an AI is indicated by an asterisk (*) by the column heading.