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Abbreviations: PBMC, peripheral blood mononuclear cells; TCR, T cell receptor; Th, T helper
Cocoa, a product derived from the beans of the Theobroma cacao plant, has been consumed since 600 BC, first by ancient civilisations, such as the Mayans and Aztecs(1). Cocoa consumption in Europe dates from the 16th century when Hernán Cortés introduced it to the Iberian Peninsula; from there its use spread rapidly to Western Europe(2). Cocoa powder is a rich source of fibre (26-40 %), proteins (15-20 %), carbohydrates (about 15 %) and lipids (10-24 %; most, 10-12 %), and it contains minerals (for example, Ca, Mg, K) and vitamins (A, E, B and folic acid) (Table 1).
Table 1
Cocoa powder: nutritional information per 100 g(93)
Cocoa has become a subject of increasing interest because of its high content of polyphenolic antioxidants, particularly flavonoids. Cocoa powder is reported to contain up to 70 mg polyphenols/g (expressed as catechin)(3). A serving size portion of certain cocoa-derived products provides more phenolic antioxidants than beverages and fruits such as tea and blueberries, traditionally considered high in antioxidants(4,5). Cocoa mainly contains the monomers ( - )-epicatechin and catechin, and various polymers derived from these monomers, known as procyanidins (Figs. 1 and 2). Monomer content ranges from 0·20 to 3·50 mg/g, depending on the type of product, with epicatechin content being higher than (+)-catechin in most cocoa products(3,6). Procyanidins are the major flavonoids in cocoa and chocolate products, with reported levels ranging from 2·16 to 48·70 mg/g(6). Methylxanthines have also been identified in cocoa powder, and account for 0·5-2 % of the DM(7).Fig. 1
Chemical structure of the main cocoa flavonoids. (a) R1 = OH corresponds to ( - )-epicatechin and R2 = OH to (+)-catechin. (b) Dimeric procyanidin (4β [arrow right] 8).
Fig. 2
Flavonoids (a) and non-flavonoid phenols (b) contained in cocoa(94,95).
Bioavailability of cocoa flavonoids
The biological effects of flavonoids depend on the bioavailability of the compound. The various manners and rates in which flavonoids are...