| Food composition databases provide detailed information on the nutritional composition of foods, usually from a particular country. These databases may be available in different formats e.g. paper-based, often referred to as food composition tables, or electronic versions, often known as nutrient databases or databanks. Food composition databases provide values for energy and nutrients (e.g. protein, vitamins and minerals) and for each of the foods listed. These values are based on chemical analyses which are carried out in analytic laboratories or are estimated from other appropriate data. The table below shows an extract from the UK Food Composition Tables, as an example.
Inorganic constituents per 100g edible portion
|
No |
Food |
Protein g |
Fat g |
Carbo-hydrate g |
Energy kcal |
Energy kJ |
|
952 |
Grapefruit, raw |
0.8 |
0.1 |
6.8 |
30 |
126 |
|
953 |
Grapefruit, canned in juice |
0.6 |
Tr* |
7.3 |
30 |
120 |
|
954 |
Grapefruit, canned in syrup |
0.5 |
Tr* |
15.5 |
60 |
257 |
|
956 |
Grapes, average |
0.4 |
0.1 |
15.4 |
60 |
257 |
|
955 |
Guava, raw |
0.8 |
0.5 |
5.0 |
26 |
112 |
* Trace amount of nutrient
Source: FSA (2002) McCance and Widdowson’s The Composition of Foods, 6th Summary Edn. Cambridge: Royal Society of Chemistry.
© Crown copyright. Reproduced with the permission of the Controller of HMSO.
As well as energy and basic nutrients (e.g. protein, vitamins and minerals), some food composition databases contain values for other food components as well. For example, the USDA National Nutrient Databank now contains values for some bioactive compounds e.g. isoflavones for around 200 foods listed in the database. Other food components that may be found in some databases include:
- Carotenoids e.g. lycopene
- Other bioactive compounds
- Different types of fatty acids e.g. n-3 fatty acids, trans fatty acids
- Fibre
- Peptides
- Plant sterol and stanol esters
One of the objectives of EuroFIR is to try to identify and provide new data on these many different food components, many of which have putative health benefits.
The number of foods found in a food composition database can vary enormously and will largely depend on whether the database contains values for many composite foods, recipes or manufactured products in addition to individual food items. Composite foods are foods comprised of a number of ingredients, e.g. lasagne. For these foods, food composition values are either based on chemical analyses which are carried out in analytical laboratories or are derived from the nutrient composition of the individual ingredients. For example, the nutrient value of pasta, minced beef, tomatoes and other ingredients can be used to estimate the composition of 100g of lasagne.
There are approximately 150 food composition tables and electronic databases in existence across the world. The values for a food item may vary between these databases, for a number of reasons, for example:
- there may be some genuine differences between the nutrient composition of the foods selected for sampling. For example, the selenium content of cereals will vary depending on the selenium content of the soil in which they were grown.
- the nutrient value of more commonly consumed foods may also have changed, perhaps because of new varieties, new farming practices and feeding regimens, or new preparation techniques.
- different technologies or methods may have been used to analyse the data. For example, over time the precision of methods has improved, which can affect the value attained.
- the ‘statistical treatment’ or analytical values may differ. For example data may be expressed as ‘edible matter only’ or ‘as purchased’.
The UK Food Composition Tables (McCance and Widdowson) contain around 3500 foods, whereas the US Department of Agriculture (USDA) National Nutrient Databank contains around 6000 foods.
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