| Protein AMDR | 10–35% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Carbohydrate AMDR | 45–65% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Total Fat AMDR | 20–35% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Fiber AI — Adult Women (19–50) | 25 grams per day (National Academies of Sciences, Engineering, and Medicine) |
| Fiber AI — Adult Men (19–50) | 38 grams per day (National Academies of Sciences, Engineering, and Medicine) |
| Reference calorie level (general adult) | 2,000 calories/day (Used as basis for FDA Nutrition Facts label % Daily Values) |
What Are Dietary Reference Intakes?
Dietary Reference Intakes (DRIs) are the evidence-based standards used by U.S. federal agencies to define how much of each nutrient most healthy adults need each day. Developed by the National Academies of Sciences, Engineering, and Medicine, DRIs serve as the scientific backbone of nutrition labels, school meal programs, and clinical dietary guidelines.
The DRI framework includes several distinct values you may encounter:
- Recommended Dietary Allowance (RDA): The average daily intake sufficient to meet the needs of roughly 97–98% of healthy individuals in a given life stage and sex group.
- Adequate Intake (AI): Used when an RDA cannot be established; based on observed intake in apparently healthy populations.
- Tolerable Upper Intake Level (UL): The highest daily intake unlikely to cause harm. Exceeding this level — particularly through supplements — may pose health risks.
- Estimated Average Requirement (EAR): The intake estimated to meet the needs of half the healthy individuals in a group; used more in research and policy than in personal planning.
Recommended Dietary Allowance (RDA)
The average daily dietary intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a specific life stage and sex group. It is set above the Estimated Average Requirement to cover population variability.
Adequate Intake (AI)
A reference value used when sufficient evidence is not available to establish an RDA. It is based on observed or estimated nutrient intake by apparently healthy populations and is considered a reasonable goal.
Tolerable Upper Intake Level (UL)
The highest average daily nutrient intake likely to pose no risk of adverse health effects for almost all individuals. Intakes above the UL increase the potential for harm, especially from supplements.
Acceptable Macronutrient Distribution Range (AMDR)
The range of intake for each macronutrient — protein, carbohydrate, and fat — expressed as a percentage of total daily calories, associated with a reduced risk of chronic disease while providing adequate essential nutrients.
DFE (Dietary Folate Equivalent)
A unit that accounts for differences in absorption between naturally occurring food folate and synthetic folic acid found in supplements and fortified foods. One mcg of food folate equals 1 mcg DFE.
Dietary Reference Intake (DRI)
An umbrella term for a set of reference values — including RDA, AI, UL, and EAR — used to plan and assess nutrient intakes for healthy populations in the United States and Canada.
These values are set for general healthy adult populations and do not account for individual medical conditions, pregnancy, or older age-related changes. Always consult a registered dietitian or healthcare provider for guidance tailored to your specific circumstances.
Key Macronutrient Reference Values
Macronutrients — protein, carbohydrates, and fat — supply the calories your body runs on. Federal guidelines express their recommended ranges as Acceptable Macronutrient Distribution Ranges (AMDRs), stated as a percentage of total daily calorie intake. These ranges support adequate nutrient intake while reducing the risk of chronic disease.
| Protein AMDR | 10–35% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Carbohydrate AMDR | 45–65% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Total Fat AMDR | 20–35% of daily calories (National Academies of Sciences, Engineering, and Medicine) |
| Fiber AI — Adult Women (19–50) | 25 grams per day (National Academies of Sciences, Engineering, and Medicine) |
| Fiber AI — Adult Men (19–50) | 38 grams per day (National Academies of Sciences, Engineering, and Medicine) |
| Reference calorie level (general adult) | 2,000 calories/day (Used as basis for FDA Nutrition Facts label % Daily Values) |
For a deeper look at what each macronutrient does in the body and how to identify quality sources, see our plain-language guide to macronutrients.
Fiber, while technically a carbohydrate, is tracked separately. The AI for dietary fiber is 25 grams per day for adult women and 38 grams per day for adult men (ages 19–50), based on National Academies guidance. Most Americans consume well under these amounts.
Total fat guidelines do not specify a single RDA, but the AMDR of 20–35% of calories reflects evidence linking very low and very high fat intakes to health concerns. Saturated fat should be limited, and trans fats minimized, according to the 2020–2025 Dietary Guidelines for Americans.
Selected Vitamin and Mineral Reference Values
Micronutrients — vitamins and minerals — support everything from immune function to bone density to nerve signaling. The table below summarizes RDAs or AIs for key micronutrients for adults aged 19–50. Values differ by sex and shift further during pregnancy, lactation, and older adulthood.
90%+
Americans not meeting potassium AI
According to federal dietary surveillance data cited in the 2020–2025 Dietary Guidelines for Americans, potassium is among the most widely under-consumed nutrients.
~40%
U.S. adults with insufficient vitamin D status
Analysis of NHANES data suggests a substantial share of American adults have serum vitamin D levels below recommended thresholds, with higher rates in certain demographic groups.
16 g
Average daily fiber intake for U.S. adults
Dietary survey data show Americans consume roughly 16 grams of fiber daily on average, well below the AI of 25–38 grams depending on sex and age.
| Nutrient | Adult Women (19–50) | Adult Men (19–50) | Type |
|---|---|---|---|
| Vitamin D | 600 IU (15 mcg) | 600 IU (15 mcg) | RDA |
| Calcium | 1,000 mg | 1,000 mg | RDA |
| Iron | 18 mg | 8 mg | RDA |
| Vitamin C | 75 mg | 90 mg | RDA |
| Folate | 400 mcg DFE | 400 mcg DFE | RDA |
| Potassium | 2,600 mg | 3,400 mg | AI |
| Magnesium | 310–320 mg | 400–420 mg | RDA |
| Vitamin B12 | 2.4 mcg | 2.4 mcg | RDA |
Several of these nutrients — including vitamin D, calcium, potassium, and magnesium — are identified as nutrients of public health concern in federal dietary guidance because Americans consistently fall short. Our article on micronutrients Americans commonly fall short on covers practical food sources for each.
Values Shift With Age, Sex, and Life Stage
The reference values shown here apply to adults aged 19–50 under typical healthy conditions. Requirements for calcium, vitamin D, and several B vitamins change meaningfully after age 50. Pregnancy and lactation also substantially alter needs for folate, iron, iodine, and choline. The National Academies publishes detailed DRI tables by life stage group at no cost on its website.
If you follow a plant-forward eating pattern, certain nutrients require extra attention. Our article on plant-based eating trade-offs covers what to watch for.
This article is for general informational and educational purposes only. It is not a substitute for personalized medical or dietary advice. Consult a qualified healthcare provider or registered dietitian before making significant changes to your diet.