Clues to the functions of flavanols are provided by the following study results.
Scientific studies
Flavanols contained in cocoa have a blood pressure-lowering effect. This was the conclusion of a study by the Rijksinstituut voor Volksgezondheid en Milieu (RIVM) of the Netherlands, in which older men participated. Those men who had consumed the least cocoa had twice the risk of dying from a heart attack than those who had consumed the most cocoa – assuming a minimum amount of 4 grams per day. Even after adjustment for other factors such as smoking, physical activity and body weight, the risk remained reduced. This may be explained by the positive effect of flavan-3-ols on the function of the endothelium (the cells lining blood vessels).
Flavanols can increase blood levels of nitric oxide (NO = endothelium derived relaxing factor) and thus exert positive effects on the vascular system. In a double-blind cross-over study, 12 male and 6 female smokers, who had no adverse health effects, were administered a flavanol-rich (176 to 185 mg) cocoa drink on one day and a flavanol-poor (< 11 mg) cocoa drink on the other day. There was a significant increase in blood NO levels after ingestion of the flavanol-rich cocoa drink. NO indirectly causes relaxation (slackening) of vascular smooth muscle by increasing cGMP (cyclic guanosine monophosphate), resulting in vasodilatation and thus lowering cardiac afterload and blood pressure. Numerous drugs are based on this mechanism of action. Increasing circulating levels of nitric oxide in the blood through a flavanol-rich diet can help maintain a healthy vascular system. The elasticity of blood vessels is improved.
Randomized clinical trials indicate that flavanols also have the following functions:
- Protect against UV radiation and improve the condition of the skin.
- Reduce insulin resistance
- Inhibit platelet aggregation