Methodology

How NutrientChart turns USDA data into rankings: which foods are in the pool, how a serving is chosen, how %DV is computed, and the exact formulas behind the nutrient-density and inflammatory-profile scores. Last updated 2026-10-16.

1. Data

All nutrient values come from USDA FoodData Central. The backbone is SR Legacy (final release April 2018; 7,793 foods with up to 150 nutrients each). Where USDA has since published new analytical values in Foundation Foods (April 2026 release, 395 foods), those values replace the SR Legacy value for the same food, matched by USDA's NDB number; 4,287 values across 122 food pages and the ranking pool were updated this way and are marked F on food pages. USDA reports every value per 100 g of edible portion. A nutrient that is absent from a food's record was not analysed; we never treat it as zero, and such foods are excluded from that nutrient's ranking.

2. The whole-food ranking pool

"Foods high in" lists rank 1,677 foods drawn from eight USDA groups: fruits, vegetables, legumes, nuts and seeds, cereal grains, finfish and shellfish, meat and poultry, and dairy and eggs. Excluded: spices and herbs, baby foods, powders, flours, bran and germ, dried and freeze-dried produce (except dates, figs, prunes and raisins), juices, syrups, items "with salt", fortified and ready-to-eat cereals, processed and cured meats, organ meats other than liver, fat trimmings, meat substitutes, and uncommon foods with no retail presence. Meats, fish, grains and legumes are ranked in their cooked form. Each food family (for example all forms of spinach, or all cuts of beef round) appears once per list, and no single plant or animal fills more than six places, so a list of 100 is 100 different foods.

3. Servings

Rankings are per common serving, not per 100 g, because per-100 g lists are led by cream of tartar, dried parsley and instant coffee powder. Servings are USDA household measures from the same database, chosen by rule: a medium fruit or 1 cup for fruit and vegetables; 1 cup cooked for legumes and grains; 1 oz for nuts, seeds and cheese; 3 oz cooked for meat, poultry and fish; 1 cup for milk and yogurt; 1 large egg; 1 tbsp for oils and butter; 2 tbsp for nut butters and hummus; 1 oz for dried fruit. When USDA lists no suitable measure, the standard portion (3 oz, 1 oz, 1 tbsp) is used and labelled as such. Food pages show every USDA portion for the food plus 100 g and 1 oz.

4. % Daily Value

%DV = amount per serving ÷ Daily Value × 100, using the FDA Daily Values for adults and children aged 4 and over (21 CFR 101.9): for example potassium 4,700 mg, magnesium 420 mg, iron 18 mg, calcium 1,300 mg, vitamin D 20 µg, vitamin C 90 mg, fiber 28 g, protein 50 g, sodium 2,300 mg, saturated fat 20 g. Vitamin A is in µg RAE, vitamin D in µg, folate in µg DFE. Following FDA labeling rules, 10 to 19% DV per serving is a "good source" and 20% or more is "high" or "excellent". Omega-3, lycopene, lutein, beta-carotene, caffeine and mono/polyunsaturated fat have no Daily Value and are shown as amounts only.

5. Nutrient density: NRF9.3

The Nutrient Rich Foods index NRF9.3 (Drewnowski, Am J Clin Nutr 2009) is computed per 100 kcal: the sum of %DV for nine nutrients to encourage (protein, fiber, vitamin A, vitamin C, vitamin E, calcium, iron, potassium, magnesium), each capped at 100%, minus the sum of %DV for three nutrients to limit (saturated fat, added sugars, sodium). USDA SR Legacy does not report added sugars, so total sugars are used as the proxy, which penalises fruit and milk slightly. Foods with fewer than 5 kcal per 100 g (water, tea, coffee) are not scored. Whole foods range from roughly −60 (butter, honey) to over 500 (cooked spinach).

6. Inflammatory profile score

The Dietary Inflammatory Index (Shivappa, Steck, Hurley, Hussey and Hébert, Public Health Nutrition 2014) assigns each of 45 dietary parameters an inflammatory effect score from a review of 1,943 studies: negative for anti-inflammatory (fiber −0.663, magnesium −0.484, beta-carotene −0.584, vitamin D −0.446, omega-3 −0.436, vitamin C −0.424, vitamin E −0.419, vitamin A −0.401, vitamin B6 −0.365, polyunsaturated fat −0.337, zinc −0.313, niacin −0.246, selenium −0.191, folate −0.190, omega-6 −0.159, thiamin −0.098, riboflavin −0.068, monounsaturated fat −0.009) and positive for pro-inflammatory (saturated fat +0.373, trans fat +0.229, cholesterol +0.110, vitamin B12 +0.106, iron +0.032). The index is designed for whole diets. Our single-food adaptation is: score = Σ wᵢ × (min(2, aᵢ / rᵢ) − 1), where aᵢ is the food's amount per 100 kcal and rᵢ is one twentieth of the reference daily amount (the FDA Daily Value, or the DII global mean intake for parameters without one: omega-3 1.06 g, omega-6 10.8 g, beta-carotene 3,718 µg, trans fat 3.15 g, MUFA 27 g, PUFA 13.9 g). A food supplying exactly its calorie share of every parameter scores 0; richer in anti-inflammatory nutrients is negative. Because it is per calorie, oils and fatty foods score high and leafy vegetables low. Labels ("strongly anti-inflammatory" to "pro-inflammatory profile") are percentile bands (20/40/60/80) among the 1,677 whole foods. Flavonoids and other polyphenols credited by the DII are not in USDA's standard nutrient data, so tea, berries, cocoa and olive oil are under-credited. This is a descriptive nutrient summary, not a measure of any food's effect on inflammation in a person.

7. "Healthiest" category pages

Each category's members are selected by USDA description (for example every item beginning "Bread," minus sweet breads and mixes) and ranked by NRF9.3 per 100 kcal, with a category-specific tiebreaker: 10% of the %DV per 100 kcal of sodium for bread, sugar for cereal, sodium and saturated fat for cheese and fast food, sugar and saturated fat for bars and milk. Energy drinks are ranked by sugar and calories per 8 fl oz because they contain almost no nutrients to score. Branded items are the products USDA analysed for SR Legacy (2018); recipes change, so check the current label.

8. Generated text

Every sentence that states a number (the summary at the top of each page, the comparison verdicts, the FAQ answers) is generated from the data by the same program that builds the tables, so text and tables cannot disagree. Pages carry the date of the last data change.

References

• U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, 2026. fdc.nal.usda.gov. Public domain (CC0 1.0).
• U.S. Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts Labels; 21 CFR 101.9.
• Drewnowski A. Defining nutrient density: development and validation of the Nutrient Rich Foods Index. J Am Coll Nutr 2009;28(4):421S–426S.
• Shivappa N, Steck SE, Hurley TG, Hussey JR, Hébert JR. Designing and developing a literature-derived, population-based dietary inflammatory index. Public Health Nutr 2014;17(8):1689–1696.
• Hébert JR, Shivappa N, Wirth MD, Hussey JR, Hurley TG. Perspective: The Dietary Inflammatory Index (DII): lessons learned, improvements made, and future directions. Adv Nutr 2019;10(2):185–195.