Methodology

Daily intake reference values

Recommended daily intakes on this site come from two authoritative families: Dietary Reference Intakes (DRIs) set by the U.S. National Academies and republished by the NIH Office of Dietary Supplements, and the Dietary Guidelines for Americans for narrative limits where no scalar DRI exists (saturated fat). Each per-nutrient page cites its source publication and snapshot date.

DRIs are not personalized. They cover the needs of approximately 97–98% of healthy individuals in a life-stage group. Real requirements vary with body size, activity, illness, medications, genotype, and pregnancy status. The values on this site are population-level reference ranges, not clinical targets.

Values do not change between site builds. When a source body publishes a revision, the change is captured by an explicit pipeline rebuild and reflected in the snapshot date below.

Recommended Dietary Allowance (RDA)

The RDA is the average daily intake sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a life-stage group. It is set at roughly the EAR plus two standard deviations of the requirement distribution. RDA is the default value used on per-food and per-nutrient pages whenever it is available.

Adequate Intake (AI)

An AI is a recommended average daily intake based on observed or experimentally determined approximations of intakes by healthy people. AIs are used when an RDA cannot be set because evidence is insufficient to estimate the average requirement — examples include vitamin K, choline, biotin, pantothenic acid, fluoride, and most infant nutrients. AIs are intended to cover or exceed the actual requirement of nearly all individuals in the group, but with less confidence than an RDA.

Tolerable Upper Intake Level (UL)

The UL is the highest average daily intake likely to pose no risk of adverse health effects to almost all individuals in the general population. Routine intake above the UL increases the potential risk of adverse effects.

For folate, niacin, and vitamin E, the UL applies only to specific supplemental forms — folic acid, nicotinic acid, and supplemental alpha-tocopherol respectively — not to the food forms reported by USDA. These ULs are flagged with a methodology footnote on the page where they appear.

Estimated Average Requirement (EAR)

The EAR is the daily intake estimated to meet the nutrient requirement of half the healthy individuals in a life-stage group. It is the median of the requirement distribution and is used in research and population-level planning rather than personal targets. The site shows EAR alongside RDA on the per-nutrient demographic page so the underlying distribution is visible.

DRI vs. FDA Daily Value

The "Daily Value" (DV) printed on US Nutrition Facts labels is a single label-format figure derived (mostly) from the DRIs but adjusted for general public communication. DVs do not vary by life-stage. This site uses the underlying life-stage DRIs directly, which is why a single nutrient may appear with different recommended intakes for adult men, adult women, pregnancy, etc.

Where the FDA has set a DV but no DRI exists (notably added sugars), the FDA value is recorded as the canonical reference for that nutrient and the page is flagged as DRI-exempt.

Pregnancy and lactation default age range

Pregnancy and lactation values on this site default to the 19–30 age band. The DRI tables publish three pregnancy/lactation rows (14–18, 19–30, 31–50); 19–30 is the most representative for adult use and matches what NIH ODS factsheets surface first. Per-nutrient pages where the values differ between pregnancy age bands surface the additional rows in the demographic table.

DRI source snapshots

Each nutrient's reference values come from the source publication listed below, captured on the snapshot date shown. The snapshot is the version we transcribed; subsequent revisions to the source require an explicit rebuild before they appear on the site.

Display group taxonomy

Reference values are organized into 14 standard life-stage groups: infants 0–6 months, infants 7–12 months, children 1–3, children 4–8, four pre-adolescent and adolescent age × sex bands (9–13 and 14–18 for males and females), four adult age × sex bands (19–50 and 51+ for males and females), pregnancy (19–30), and lactation (19–30).

Some source publications use coarser bands (e.g. "Adults 19+") that span multiple display groups. In those cases the same source value is shown for every covered display group, and the per-nutrient table records which source label generated the row. This is the only form of inheritance the pipeline performs — values are never extrapolated, averaged, or invented for unstated bands.

Acceptable Macronutrient Distribution Range (AMDR)

The AMDR is a range, expressed as a percentage of total daily energy, within which intake of a macronutrient is associated with reduced risk of chronic disease while providing essential nutrients. AMDRs apply to carbohydrates (45–65%), protein (10–35%), and total fat (20–35% for adults). They are not directly comparable to per-100g food values because they are expressed relative to total energy intake, so the percentage cells on per-food pages do not apply to AMDR.

Chronic Disease Risk Reduction (CDRR)

The CDRR is a relatively new DRI category, established in 2019 specifically for sodium. It is the intake level at and below which the National Academies expect a measurable reduction in chronic disease risk for the general population. Unlike a UL, the CDRR is not framed around acute toxicity; it replaces sodium's previous UL because the original UL was set without strong chronic-disease evidence. Sodium intake above the CDRR (2,300 mg/day for adults) is framed as a target to lower, not a hard ceiling.

Folate and Dietary Folate Equivalents (DFE)

Folate exists in food as natural folate and in fortified foods and supplements as folic acid. Folic acid is roughly 1.7× more bioavailable than natural food folate, so the National Academies express the folate RDA in Dietary Folate Equivalents (DFE): 1 µg DFE = 1 µg natural folate = 0.6 µg folic acid from fortified foods or supplements taken with meals.

USDA reports food folate as DFE (FDC nutrient ID 1190), which matches the basis used by the RDA. The folate UL of 1,000 µg/day applies only to folic acid from fortified foods and supplements, not to natural food folate, which has no UL. Per-food pages do not show a "% of UL" for natural food folate intake.

Vitamin A and Retinol Activity Equivalents (RAE)

Vitamin A reaches the body in two forms: preformed retinol from animal foods, and provitamin-A carotenoids (mainly beta-carotene) from plant foods, which the body converts to retinol at a lower and variable rate. The National Academies express the vitamin A RDA in Retinol Activity Equivalents (RAE): 1 µg RAE = 1 µg retinol = 12 µg dietary beta-carotene.

USDA reports food vitamin A as RAE (FDC nutrient ID 1106), which matches the basis used by the RDA, so per-food percentage-of-needs values use the food's RAE directly. The vitamin A UL (3,000 µg/day for adults) applies only to preformed retinol from animal foods, fortified foods, and supplements; provitamin-A carotenoids have no UL. Per-food pages therefore show "% of RDA" against RAE but do not compute "% of UL", because a food's RAE value combines both forms.

Niacin and Niacin Equivalents (NE)

The body can convert excess dietary tryptophan to niacin: roughly 60 mg of tryptophan yields 1 mg of niacin. The National Academies therefore express the niacin RDA in Niacin Equivalents (NE): NE = preformed niacin (mg) + tryptophan (mg) / 60.

Where USDA reports both niacin and tryptophan, this site computes NE for each food. Where tryptophan is missing in the source data, the page shows preformed niacin only and flags it with a footnote linking back here, because the food's true NE value cannot be calculated.

The niacin UL of 35 mg/day applies only to supplemental nicotinic acid taken in pharmacological doses; it does not apply to niacin or tryptophan from food.

Essential amino acid 70 kg body-weight basis

The National Academies publish essential amino acid RDAs as milligrams per kilogram of body weight per day. To present absolute values comparable to per-100g food data, this site multiplies each amino acid's mg/kg/day RDA by a reference body weight of 70 kg, the convention used in NIH ODS materials.

For an individual whose body weight differs materially from 70 kg, the absolute requirement scales linearly: a 60 kg adult needs 60/70 of the listed value, and so on. The mg/kg/day basis is preserved in the per-nutrient page's source-value column for direct reference.

Combined-RDA amino acids: methionine and phenylalanine

The 2005 DRI report sets RDAs not for methionine and phenylalanine individually but for combined sulfur-containing amino acids (methionine + cysteine) and combined aromatic amino acids (phenylalanine + tyrosine), because each pair is metabolically interconvertible. USDA reports each amino acid separately.

To avoid implying that the methionine or phenylalanine RDA can be met by methionine or phenylalanine alone, this site shows the absolute combined-RDA value on the methionine and phenylalanine pages but does not compute "% of RDA" for any food. The per-food pages explicitly note this constraint.

Limit-only nutrients: total sugars, saturated fat, total fat

Some nutrients have no scalar daily target — their public-health framing is a limit or range, not a daily allowance.

• Total sugars: no DRI exists. The 50 g Daily Value on US food labels applies only to added sugars. USDA total-sugars data combines naturally occurring and added sugars and is not directly comparable to the FDA added-sugar limit. Per-food pages show the value with no percentage.
• Total fat: no scalar RDA exists. The AMDR for adults is 20–35% of energy, expressed relative to total daily intake.
• Saturated fat: the Dietary Guidelines for Americans recommend limiting intake to less than 10% of total daily energy. There is no scalar DRI.

For each of these, per-food pages display the absolute value per 100g without a percent-of-needs computation, with a link to this section.