Preferably, food composition data should come from chemical analyses by accredited laboratories.  Analyses performed by order of NEVO are mixed samples with several brands of the same product. In case of fresh foods these are bought in several shops. Other data sources include foreign food composition tables, scientific publications and food label information. These are carefully judged by our personnel.

Missing values are filled in, if possible,  by deriving the composition from the ingredients of the food. We calculate a recipe based on the ingredients. Also we can borrow values from similar foods or by logical deduction, e.g. 'vegetable product: vit B12 = 0'. Some nutrients and energy are calculated based on other nutrients with a formula, e.g. 'vegetable protein=total protein-animal protein'.

For each value, a reference is known. You can see these for each food in the Product details screen, which you enter by clicking on the food name in NEVO-online. For every nutrient the reference is shown. With this information you can judge the quality of the nutritional value of the food yourself.

The references and reference id's are available in  the download. The data sources are documented according to the EuroFIR European Food Information Resource (European Food Information Resource) value documentation, and so also people who are not Dutch can use it.