Article
A, E, C: where every nutrient value comes from
Every figure in the FSVO database carries a letter: A for measured, E for estimated, C for calculated. That small marker says how the value was obtained: in a laboratory, by estimation or by calculation. Here is what it means, and what it changes when you read a food page.
A, E, C: three ways to obtain a figure
On every food page a value never comes alone: it carries a letter stating its origin, that is, how the figure was obtained.
- A · measured: the component was analysed, with no derivation in the source. The protein in polished rice, raw, 7.4 g per 100 g, is one of those.
- E · estimated: the figure comes from sources considered reliable (another composition database, a very similar food) rather than from an analysis of the food itself. The water in raw cucumber, 96.3 g, is an estimate.
- C · calculated: the figure results from a documented calculation, either an automatic conversion or a reconstruction from the ingredients. The energy of raw polished rice, 352 kcal, is calculated.
None of the three is a flaw. They are three levels of precision, shown in the same place so you always know where a figure comes from.
The real split: 26,570 values
The site publishes 1,216 generic foods across 19 families, with up to 22 components per food. Counting every cell that actually holds a figure gives 26,570 published values, each with its origin marker. The count is almost complete: 1,216 foods × 22 components make 26,752 possible cells, and 26,570 of them hold a value.
| Marker | Meaning | Number of values | Share |
|---|---|---|---|
| A | Measured | 8,961 | 34% |
| E | Estimated | 3,594 | 14% |
| C | Calculated | 14,015 | 53% |
Shares are rounded to the nearest percentage point. So one third of the database rests on direct measurement, one value in seven is estimated, and more than half is calculated. That is not a flaw: it follows from the way a composition database is built. The marker appears on every page reachable from the full list of foods.
Why calculated values dominate
Three mechanisms produce most of the C markers.
Energy. It is almost never measured directly; it is derived from the components of the food. For raw polished rice, protein carries an A while energy (352 kcal) carries a C.
Conversions. Parmesan cheese shows 650 mg of measured sodium and 1.6 g of calculated salt: salt is derived from sodium rather than analysed separately.
Cooked foods and composed dishes. These are rebuilt from the raw food and the recipe. Whole dried lentil shows 24.4 g of measured protein; once cooked, its 8.8 g of protein is calculated. For polished rice cooked in water, energy, water, protein and carbohydrate all carry a C. A ranking such as the highest-protein foods therefore mixes all three origins.
Traces, “less than”, n/a: what the site never rounds
Three wordings sometimes replace the figure. They do not mean the same thing, and none of them means zero.
- traces (235 cells): the component is present, but in an amount too small to be quantified.
- a value preceded by the “less than” sign (144 cells): the content sits below a threshold and cannot be pinned down further.
- n/a (182 cells): the value is not available in the source. The food was not analysed for that component.
The site carries these wordings over unchanged and never replaces them with a 0. Writing 0 would claim a certainty that does not exist: “n/a” means “not known”, not “none present”. In the food comparison, a cell without a value therefore stays empty instead of counting as zero.
What this changes when you read a value
A single page can mix all three origins. Farmed salmon, raw shows 19.9 g of measured protein, 15.9 g of estimated fat and 2.1 g of calculated omega-3 side by side.
Small gaps therefore deserve caution. Raw spinach shows 1.8 mg of measured iron; steamed spinach, 1.9 mg of calculated iron. The two figures do not have the same standing: the second is a reconstruction, not the measurement of a difference. In the ranking of iron-rich foods, two neighbours are not necessarily comparable to the decimal.
A practical rule: a calculated value is fine for an order of magnitude, weaker for separating two similar foods. How the markers are carried over from the source is set out in the methodology; to relate these contents to your own benchmarks, the needs calculator uses the adult reference values.