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Where to find food composition data
Evaluation of data from various sources

Obtaining data from other sources, sometimes called "borrowing" data, refers to using data originally generated or gathered by someone else. This is the most frequent way of obtaining data for many special-purpose data bases, with the usual sources being the large reference data bases (such as those of the USDA [96], the United Kingdom [59], etc.). One problem with the data of others is that they are often incompletely described. However, borrowing of data is not only justified but essential when analyses are impractical (i.e., allocation of resources is not justified) and "good" data are available elsewhere. See Jacob [39] for an overview of this problem from the point of view of some social scientists.

Given the decision that certain data are needed and cannot be generated de novo, the two basic tasks facing the compiler are finding and evaluating the data.