Reliability of Data

There can be many different nutrient values for a given food. Various factors influence the amounts of nutrients in foods. Among these are mineral content of the soil, diet of an animal, fertilizers or growth hormones used, genetics of the plant or animal, season of harvest, and processing method.

Additional factors include the methods of analysis, differences in moisture content of samples, length and method of sample storage, number of samples tested, and varying methods of cooking or preparing the food.

As a result, even reliable sources will report different nutrient values for the same food item. When the USDA reports a single value for a nutrient, that value is usually the average of a range of data. In their more detailed reports, the number of samples and standard deviation of the data are noted.

Nutrient data should be viewed and used only as a guide – a close approximation of the true nutrient content.

To reduce missing and conflicting values, our staff researches thousands of additional sources: scientific journals and other publications, food composition tables from England and Canada, unpublished data from USDA and other research scientists, and information from other nutrient databanks.

Pre-label data from food manufacturers is also compiled to build the nutrient database for brand name food items.

When calculating estimates of nutrients in cooked foods from reported amounts in raw foods, or vice-versa, published retention factors are applied. In such cases, it is felt that calculated approximations are better than zeros or blanks. The USDA also uses this technique. When research sources report several different values for a single nutrient, many factors are taken into account when calculating an average value. Among these are analytical techniques used, moisture content of samples, and preparation technique used for the food. In addition, the average value is weighted for the number of samples that support each research report.

Blanks in the ESHA database represent cases where there is either no available data or a lack of reliable data. A zero value means that an item has been analyzed and there is no nutrient content.

Registered owners of Food Processor are notified as periodic updates are made to the database.