Answer:
The four classes of Dietary Reference Intakes (DRIs), which are nutrition goals set for healthy Americans, are:
1. **Estimated Average Requirement (EAR)**: This is designed for about half of the healthy individuals in a specific life stage and gender group. It represents the average daily nutrient intake level estimated to meet the requirements of half of the healthy individuals in a particular group.
2. **Recommended Dietary Allowance (RDA)**: This is designed to meet the needs of nearly all (97%–98%) healthy individuals in a specific life stage and gender group. RDAs are based on the EARs but set higher to cover the needs of most people.
3. **Adequate Intake (AI)**: This is used when there isn't enough scientific evidence to establish an EAR and, subsequenly, an RDA. The AI is based on observed or experimentally determined estimates of nutrient intake by a group (or groups) of healthy people.
4. **Tolerable Upper Intake Level (UL)**: This represents the highest level of nutrient intake that is likely to pose no risk of adverse health effects for almost all individuals in the general population. The UL is not intended as a recommended level of intake but rather as a level of intake that should not be exceeded.
These classes of DRIs help guide individuals and health professionals in assessing and planning nutrient intake to promote overall health and well-being.
