The phytochemicals in cocoa have been characterised and investigated. A number of these phytochemicals appear to have antioxidant effects and are bioavailable in humans. In particular cocoa is rich in a group of flavonoids called proanthocyanidins. Proanthocyanidins belong to the flavonoid group of phytochemicals. Structurally they are polymers of another subgroup of flavonoids called flavanols or flavan-3-ols, which are also found in high quantities in tea and apples. Cocoa is not a widely consumed food in terms of quantity, with the richest foods sources of cocoa being dark chocolate and cocoa powder. Consumption of 100 grams of dark chocolate has been shown to improve insulin resistance, and concomitantly reduce blood pressure and decrease blood levels of low density lipoprotein (LDL). These physiological changes may relate to cocoa’s antioxidant effects, because while oxidative stress has been shown to play a role in insulin resistance, it has also been shown to play a role in high blood pressure.
Cocoa may also be able to stimulate the release of insulin. Cocoa containing foods for example have been shown to increase the release of insulin by about 30 % compared to low cocoa alternatives. Because cocoa appears to stimulate insulin release and improve insulin sensitivity, insulin levels do not drop, at least in short term studies, following consumption of cocoa. The fall in blood pressure and fall in LDL seen following cocoa consumption suggests that cardiovascular risk would reduce with cocoa consumption. In this regard, the proanthocyanidins in cocoa can also decrease the aggregation of platelets, making the blood less ‘sticky’ and this can reduce the risk of a myocardial infarction. Studies testing the effects of cocoa on cardiovascular disease show large reductions in risk, and this is a likely a reflection of the multiple ways in which the food can improve risk factors (lowering blood pressure, reducing LDL and inhibiting platelet aggregation).
