How We Make These Pages

Where the Food Figures Come From

Food amounts come from USDA FoodData Central, the food composition database of the US Department of Agriculture, through the Caltide food library. Each figure is an average of measured samples, given per 100 g, so a few percent either way is normal for any one apple or steak.

Rankings draw on the whole Caltide food catalogue, one plain entry per food, leaving out mixed dishes, powders, spices and fortified products. Foods that have their own page in the Caltide food library link to their full nutrition facts; the others are listed by name. A food nobody measured for a nutrient is left out, never shown as zero. Per-portion tables and sample days use only foods with a calorie page.

Where the Daily Amounts Come From

The daily amount at the top of each page is what adults aged 19 and over need, as the US National Academies set it: the Recommended Dietary Allowance (RDA), or an Adequate Intake where there is not enough evidence for an RDA. It is shown as a range when men and women differ. Tables lower on the page give the amounts by age and sex, and for pregnancy.

Food pages show a different figure: the EU nutrient reference value (NRV) printed on food labels, one value for an average adult. It is the right yardstick for a label claim such as "high in vitamin C", but not a personal target.

How Foods Are Ranked

Foods are ranked by the amount per 100 g. A food is listed as high in a nutrient only when 100 g gives at least 15% of the daily reference, the level the EU sets for a food to be called a source of it. For nutrients without a reference, a food needs at least a tenth of what the richest food has. A list shows at most 3 foods of one kind, such as oils or beans, so it is not filled by foods that are nearly the same. Each page also shows what a usual portion gives, because nobody eats 100 g of seeds.

How the Text Is Written and Checked

Pages are written from public health sources: the NIH Office of Dietary Supplements fact sheets, EFSA scientific opinions, the WHO, the NIH National Center for Complementary and Integrative Health (NCCIH) for herbs and supplements, and USDA FoodData Central. Every figure and claim is then checked against those sources in two separate passes. Anything a source does not support is removed rather than guessed.

For supplements, herbs and mushrooms, each page says how strong the human evidence is, such as a few small trials or results only in animals, and never gives a dose that the sources do not report as studied. The sources behind each page are listed at its end, with the date it was last reviewed.

What These Pages Are Not

They are general information, not medical advice. Needs change with pregnancy, illness and medicines, and some supplements interact with medicines. Ask a doctor or pharmacist before starting a supplement or changing your diet for a health condition.

Report a Mistake

If a figure or claim looks wrong, tell the team through the contact page. Corrections are checked against the sources and the page's review date is updated.