The Reference Daily Intake (RDI) is a nutrient intake level that is sufficient to meet the nutritional needs of nearly all (97–98%) healthy individuals in a particular life stage and sex group. RDIs are based on the best available scientific evidence and are set by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine.
RDIs are used to determine the Daily Value (DV) of foods, which is printed on nutrition facts labels in the United States and Canada. The DV is a percentage of the RDI that is found in a single serving of a food. For example, if a serving of cereal contains 10% of the DV for vitamin C, then it contains 10% of the RDI for vitamin C for that particular life stage and sex group.
RDIs are not the same as Recommended Dietary Allowances (RDAs). RDAs are based on the estimated average requirement (EAR) for a nutrient, which is the amount of the nutrient that is needed to meet the requirements of half of the healthy individuals in a particular life stage and sex group. RDIs are set higher than RDAs to account for individual variability in nutrient needs and to provide a margin of safety.
The RDI for a particular nutrient varies depending on age, sex, and other factors such as pregnancy and lactation. For example, the RDI for iron for women aged 19–50 is 18 milligrams per day, while the RDI for iron for men aged 19–50 is 8 milligrams per day.
To get enough of all the essential nutrients, it is important to eat a variety of foods from all food groups. The 2020–2025 Dietary Guidelines for Americans recommend that people eat a variety of nutrient-dense foods, including fruits, vegetables, whole grains, lean protein, and low-fat or fat-free dairy products.
Here are some examples of RDIs for common nutrients:
- Vitamin C: 90 milligrams per day for adult men and 75 milligrams per day for adult women
- Calcium: 1,000 milligrams per day for adult men and women aged 19–50
- Iron: 18 milligrams per day for adult women aged 19–50 and 8 milligrams per day for adult men aged 19–50
- Protein: 0.8 grams per kilogram of body weight per day for adults
If you have any questions about your individual nutrient needs, talk to your doctor or a registered dietitian.