Polyphenols are widely consumed with fruits, vegetables and plant-derived beverages such as fruit juices, tea, coffee or wine. They form one of the most extensively studied families of food bioactives, with quite diverse biological properties including antioxidant, anti-inflammatory, antimutagenic, antiproliferating, or antiangiogenic effects, widely documented in preclinical studies. Many randomized clinical trials published over the last 10-15 years have shown some beneficial effects of polyphenols or polyphenol-rich foods on surrogate markers of cardiovascular diseases and diabetes, and on cognitive functions, providing a growing body of evidence to substantiate their protective role in the prevention of major chronic diseases and of functional declines associated to ageing.

In this issue, three papers discuss the role of polyphenols in the primary prevention or recurrence of colorectal cancer and in the reduction of total mortality, as studied in the EPIC and inCHIANTI cohorts. All authors stress the limits of current epidemiological evidence to support a protective role of polyphenols against colorectal cancer and other diseases and the need for more prospective studies with improved methodologies for measuring exposures to over 500 polyphenols scattered in a large diversity of foods. Such studies should contribute to the development of evidence-based recommendations for the general population or for specific groups of the population at risk of developing particular diseases.

The author is a staff member of the World Health Organization. The author alone is responsible for the views expressed in this editorial and they do not necessarily represent the decisions or the stated policy of the World Health Organization.

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