Process of formulating USDA's Expanded Flavonoid Database for the Assessment of Dietary intakes: a new tool for epidemiological research.

The scientific community continues to be interested in potential links between flavonoid intakes and beneficial health effects associated with certain chronic diseases such as CVD, some cancers and type 2 diabetes. Three separate flavonoid databases (Flavonoids, Isoflavones and Proanthocyanidins) developed by the USDA Agricultural Research Service since 1999 with frequent updates have been used to estimate dietary flavonoid intakes, and investigate their health effects. However, each of these databases contains only a limited number of foods. The USDA has constructed a new Expanded Flavonoids Database for approximately 2900 commonly consumed foods, using analytical values from their existing flavonoid databases (Flavonoid Release 3.1 and Isoflavone Release 2.0) as the foundation to calculate values for all the twenty-nine flavonoid compounds included in these two databases. Thus, the new database provides full flavonoid profiles for twenty-nine predominant dietary flavonoid compounds for every food in the database. Original analytical values in Flavonoid Release 3.1 and Isoflavone Release 2.0 for corresponding foods were retained in the newly constructed database. Proanthocyanidins are not included in the expanded database. The process of formulating the new database includes various calculation techniques. This article describes the process of populating values for the twenty-nine flavonoid compounds for every food in the dataset, along with challenges encountered and resolutions suggested. The new expanded flavonoid database released on the Nutrient Data Laboratory's website would provide uniformity in estimations of flavonoid content in foods and will be a valuable tool for epidemiological studies to assess dietary intakes.