In 1993, the Food and Nutrition Board’s Dietary Reference Intakes committee established 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 the:

• 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 for individuals, the amount of any one nutrient known to protect against deficiency.

• 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 mg to 1,000 mg for adults ages 31 to 50 as well as post-menopausal women taking estrogen supplements.

For post menopausal women not taking estrogen, the recommendation is 1,500 mg. The second DRI Panel 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 mcg 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.

As a result of the 1989 DRI Panel report, the FDA ordered food manufacturers to add folate to flour, rice, and other grain products. (Multivitamin products already contain 400 mcg 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.

And 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 (ages 50 to 70 and 71 and over).