 However, as the food supply has evolved, and with the increasing demand for nutritional and related components, it has become more difficult for compilers to rely only on chemical analysis when compiling FCDBs.For example, in the UK the third edition of The Composition of Foods presented data on vitamin content of foods.However, due to the amount of information already available and in order to avoid the need to analyse every food for every vitamin, values from the scientific literature were included, although the tables are still predominately based on analytical data.