Dietary Reference Intakes (DRIs) are reference values that are quantitative estimates of nutrient intakes to be used for planning and assessing diets for healthy people. They include both recommended intakes and upper intake levels.

Although the reference values are based on data, the data are often insufficient or drawn from studies that had limitations in addressing the question. Scientific judgment is required in setting the reference values. 

• EAR - Estimated Average Requirement - a nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group.
• RDA - Recommended Dietary Allowance - the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a group.
• AI - Adequate Intake: a value based on observed or experimentally determined approximations of nutrient intake by a group of healthy people.
  Used when an RDA cannot be determined.
• UL - Tolerable Upper Intake Level - the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, the risk of adverse effects increases.