Phenolic compounds in fruits and beverages consumed as part of the mediterranean diet: their role in prevention of chronic diseases

The objective of this review was to assess, based on human data, the role of phenolic compounds in selected plant foods consumed as part of the Mediterranean diet in the prevention of chronic diseases (CDs) like cardiovascular disease, cancer and neurodegenerative conditions. Fruits and vegetables are rich sources of phenolic compounds and based on scientific data it would be expected that their consumption, as part of the diet, would be responsible for their documented preventive role of chronic diseases. The results of the review of scientific literature on human clinical trials revealed that in some studies polyphenols exert a positive effect in the prevention of cardiovascular disease, essentially blood pressure and arterial dilation, certain types of cancer and neurodegenerative disorders. However, such effects are not consistent with other clinical studies in which no effect has been found. Therefore, the level of evidence for a beneficial effect in humans of phenols on the prevention of CDs is weak and need to be strengthened by additional studies addressing potential confounding factors, such as interaction of phenols with other bioactive substances in foods and potential pro-oxidant effects.