The Recommended Dietary Allowance (RDA) is the average daily dietary intake level of a nutrient that is sufficient to meet the nutrient requirements of nearly all (about 97.5%) healthy individuals in a specific age and sex group. It is designed to cover the needs of the vast majority of the population to prevent nutrient deficiencies and maintain health

. Key points about RDA include:

• It accounts for factors affecting nutrient absorption and utilization, such as the conversion of precursors to active nutrients (e.g., carotenoids to vitamin A) and differences in absorption efficiency (e.g., heme vs. nonheme iron)

• The RDA is typically about 20% higher than the Estimated Average Requirement (EAR), which meets the needs of 50% of individuals in the group

• RDAs are established only when sufficient scientific data exist; otherwise, Adequate Intakes (AIs) are provided as a less certain estimate of nutrient needs

• The RDA is used for planning diets for individuals and populations, developing food products, and guiding public health policy

In summary, the RDA represents a scientifically determined nutrient intake goal intended to ensure nutritional adequacy for almost all healthy people within a defined demographic group