What is known about the health effects of polyphenols from tea and cocoa?

Abstract

The study of the role of dietary polyphenols in protecting disturbances, associated with development of degenerative diseases, has benefited both recent advances in food databases for epidemiological studies, and the growing number of randomized controlled clinical trials with foods rich in flavonoids. To date, available scientific data suggest that flavan-3-ols from green tea and cocoa can reduce the risk of type 2 diabetes and cardiovascular diseases. The most convincing evidence concern the beneficial effects of green tea on LDL-cholesterol and those of flavan-3-ols rich cocoa on endothelial function and insulin sensitivity. However, these results need to be confirmed in other prospective cohort studies and through long term controlled clinical trials. In general, the clinical evaluation of purified flavonoids is also necessary to identify the active compounds and effective doses. For other diseases such as cancer or neurodegenerative diseases, the low number of clinical studies coupled with strong variations in their results does not allow to conclude for now on the effects of the consumption of tea or cocoa rich flavan-3-ols.