Where our nutritional values come from, how we measure them, and what we do to make sure they're consistent and trustworthy.
Nutriofia draws on two authoritative, peer-reviewed nutrition databases to cover the full range of plant-based foods:
Published by Public Health England (now UKHSA), this is the UK's primary food composition reference and has been the gold standard for UK nutritional research since the 1940s. It uses UK measurement methods that align directly with UK food labelling regulations. CoFID is our first choice for every food it covers — principally UK-common foods, vegetables, fruits, grains, pulses, nuts, seeds, dairy, and meat & fish.
For foods not covered by CoFID — primarily tropical fruits, some US-origin grains (quinoa, teff, farro), fermented foods (tempeh), and other foods common in a modern plant-based diet — we draw on USDA FoodData Central Foundation Foods (2025 release). Before import, these values are adjusted to match UK conventions. The adjustments are documented below. You will see a 🇺🇸 badge on pages that use USDA data.
Every food page shows which database its values came from. We do not mix sources within a single food — every nutrient value for any given food comes from the same dataset.
We have a strict rule: every food entry uses exactly one primary source for all its nutrient values. We never fill a gap in a CoFID food with a USDA value, or vice versa.
The reason is straightforward. Different databases use different measuring methods. CoFID measures fibre one way; USDA measures it another. CoFID calculates carbohydrate by direct measurement; USDA calculates it by subtracting everything else from 100g (the "by-difference" method). If you mix values from both in a single food entry, the numbers will never add up correctly — and the apparent precision will be false.
Where a food has gaps in our primary source, the gap stays empty rather than being filled with a different source's value. This is why you may occasionally see a nutrient listed as "no data" even for a well-studied food.
Fibre is the nutrient most affected by measurement conventions, and it's worth explaining because the numbers you may have seen elsewhere could differ from ours.
CoFID uses Non-Starch Polysaccharides (NSP), the method developed by Dr Hans Englyst. NSP measures structural plant cell wall polysaccharides only. It does not include lignin or resistant starch. NSP values are the standard used in UK food labelling and form the basis of UK dietary guidelines. Typical NSP values are lower than AOAC values for the same food.
The USDA uses AOAC total dietary fibre, the method adopted by the US FDA. AOAC includes lignin, resistant starch, and some other components that NSP does not count. For a typical whole plant food, AOAC values run approximately 40–50% higher than NSP values for the same food. For example: walnuts are approximately 6.5g fibre per 100g on the AOAC measure, but approximately 3.5g on the NSP measure.
All fibre values in our database are in NSP (Englyst method) — consistent with UK labelling and UK dietary guidelines. When we import USDA fibre values, we multiply them by 0.7 before storing them, to convert from AOAC to approximate NSP. This is a population-average approximation; the actual conversion factor varies by food. We flag this conversion in the source tag on each value.
The practical consequence: our fibre numbers will often look lower than values you find on US nutrition sites or packaging. They are not wrong — they are simply measured differently, in accordance with UK standards.
CoFID reports available carbohydrate — the directly measured starch and sugars that are actually absorbed and raise blood glucose. The USDA "by-difference" method computes carbohydrate as whatever is left over after subtracting protein, fat, water, and ash from 100g. Because the USDA carbs figure includes fibre, it will be higher than CoFID's available carbs figure by the fibre amount.
When we import USDA carbohydrate values, we subtract the (already-converted) fibre value to arrive at available carbohydrate, which is then stored and displayed. All carbohydrate values on Nutriofia are therefore available (net) carbohydrate, consistent with CoFID convention and with UK food labelling.
Every nutrient value stored in our database carries a source tag recording exactly where it came from. You won't normally see these on the food page, but they're there for full audit traceability. The tags look like:
| Tag | Meaning |
|---|---|
| CoFID 2021 | Imported directly from the 2021 CoFID dataset. |
| CoFID 2021 (phase1 re-import) | Imported via the April 2026 mapping update, from the same CoFID dataset. |
| USDA FDC 2025 | From USDA FoodData Central Foundation Foods (2025), adjusted to UK conventions before import. |
| derived: salt = sodium × 2.5 / 1000 | Calculated from the stored sodium value. |
| derived: RAE = retinol + β-carotene/12 | Vitamin A in µg Retinol Activity Equivalents, computed from stored retinol and beta-carotene. |
| derived: kJ = kcal × 4.184 | Energy in kilojoules, computed from the kcal value. |
| CoFID 2021 (fibre gap-fill) | Fibre value added to complete a legacy record, sourced from CoFID 2021 NSP data. |
| manual: [citation] | Manually entered from a peer-reviewed publication. Citation included in the tag. |
| Nutrient | USDA convention | What we store |
|---|---|---|
| Fibre | AOAC total dietary fibre | USDA value × 0.7 → stored as NSP equivalent |
| Carbohydrate | By-difference (includes fibre) | USDA carbs − USDA fibre → available carbohydrate |
| Energy (kcal) | kcal, directly reported | Stored as-is |
| Energy (kJ) | Derived from kcal | Imported directly from the source where available; otherwise derived as kcal × 4.184. Note: CoFID and USDA both calculate kJ and kcal independently using Atwater factors — the 4.184 fallback is only used where the source does not supply a kJ figure directly. |
| Vitamin A | µg Retinol Activity Equivalents (RAE) | Stored as µg RAE — same convention |
| Folate | µg Dietary Folate Equivalents (DFE) | Stored as µg DFE; source tag notes US grain fortification applies. Note: CoFID reports folate as Total Folate (µg), not DFE. When comparing a USDA-sourced food (e.g. quinoa) with a CoFID-sourced food (e.g. lentils), the figures are not directly comparable — USDA DFE values are higher because synthetic folic acid has greater bioavailability than natural food folate. Both values are stored as reported by the source; no cross-database conversion is applied. |
| Sodium / Salt | Sodium in mg | Sodium stored; Salt derived as sodium × 2.5 / 1000 |
| All other nutrients | Same units as CoFID | Stored as-is — no conversion needed |
Where a straightforward conversion factor is inadequate (for example, folate forms with different bioavailability), we store the value with a note rather than applying an unreliable formula.
Nutriofia is built for a UK audience but the data is broadly reliable for users across Western and Northern Europe for the types of foods we cover. For raw vegetables, fruits, nuts, seeds, and legumes — our largest categories — typical country-to-country variation is around ±10%, which is within the natural variation of the foods themselves.
Where CoFID figures may diverge from other European databases is in fortified products. UK flour is mandatorily fortified with iron, calcium, and B-vitamins to levels above those common in mainland Europe. If you are using Nutriofia to analyse intakes from fortified breakfast cereals or bread products, the values will reflect UK fortification levels and may overstate the nutrient content of equivalent products bought in Germany, France, Italy or the Netherlands.
For US users: our fibre values will appear lower than US labelling because we use NSP, not AOAC. Our carbohydrate values will also differ because we show available (net) carbs rather than by-difference carbs. The values are not wrong — they reflect a different, equally valid measurement standard.
No automatic on-page conversions. Normalisation to UK conventions happens at import time and is already built into the stored values. When you read a fibre number on a food page, you are reading a stored NSP value — there is no further calculation happening in the browser.
No overwriting of source data. Once a value is imported from a primary source, it is never silently replaced by a value from a different source. Any correction to a stored value is documented with an updated source tag.
No invented values. If a nutrient is not in our database for a particular food, the page will show no data rather than a zero or an estimate. A zero value on a food page means the source database recorded zero; an absent value means the source database did not report it.
Coverage is visible, not hidden. Because we never gap-fill, the completeness of our data varies by nutrient — some compounds are measured for almost every food; others are measured for only a handful. Each nutrient page shows a coverage percentage telling you what proportion of our foods have a recorded value for that nutrient. This turns what could look like a weakness into something you can actually see and judge for yourself.
If you spot a value that looks wrong, or you'd like to suggest a correction with a published source, please contact us:
Argarth Collective Ltd
Company No. 16864945
Email: data@nutriofia.com
When reporting a suspected error, please include the food name, the nutrient in question, the value you saw, the value you believe is correct, and the source (publication or dataset) for the correct figure.