In 1941 the Food and Nutrition Board of the National Research Council established R-D-A's, or Recommended Dietary Allowances to prevent deficiencies in calories, protein, vitamins and minerals. Since then scientific knowledge about nutrients has increased dramatically and 'Dietary Reference Intakes,' or D-R-I's are used, which provide more of an emphasis on decreasing the risk of chronic diseases, such as cancer and heart disease. The D-R-Is are a set of four reference values: Estimated Average Requirements (E-A-R), which is a value estimated to meet the needs of 50 percent of the population; Recommended Dietary Allowances (R-D-A), the intake level of a nutrient to prevent a deficiency; Adequate Intakes (A-I), the goal intake for nutrients that don't have an R-D-A; and Tolerable Upper Intake Levels (U-L), the highest level of a nutrient that won't cause adverse health effects. Nutrition labels refer to these as a'Percentage of Daily Value,' based on a 2,000-calorie diet.
