Dietary Sources and Intakes of Non-extractable Polyphenols
The literature offers scattered and incomplete data on the content of bioactive compounds in certain foods. Estimations of dietary non-extractable polyphenol (NEPP) intake in complete diets are practically non-existent and few data are available regarding the NEPP contribution to our total dietary polyphenol (PP) intake. NEPP are generally not included in PP analysis of foodstuffs, although their content may be even higher than the extractable polyphenol (EPP) fraction. NEPP mainly comprise PP also found as EPP, such as proanthocyanins, other flavonoids, phenolic acids and hydrolysable tannins. The different classes of NEPP are widespread among the different families of plant foods, although some of them are particularly characteristic of specific food groups. Epidemiological and clinical studies report dietary PP intake in different population groups. However, NEPP have long been neglected in those studies. Only a few studies have estimated total dietary PP intake in Spanish diets, reporting values of between 1000 and 3000 mg person−1 day−1, with NEPP contributing about 40% of the total PP intake. The present chapter aims to provide an overview of the main dietary sources and intake of NEPP in the Spanish diet and to describe the methodology for isolating and analysing these compounds from plant foods and beverages.