Polyphenols Effect on Circulating Lipids and Lipoproteins: From Biochemistry to Clinical Evidence

Background: Polyphenols are a family of natural antioxidants that in recent years have been studied and tested for their potential benefits towards cardiovascular diseases. Objective: The aim of this review is to focus the attention on the presumed lipid-lowering and atheroprotective effects of polyphenols, administered either as individual molecules (nutritional supplements) and as functional foods, on the basis of the evidence coming from randomized controlled trials (RCTs) and their meta-analyses. Method: A search strategy was conducted to identify studies in PubMed (January 1980 to September 2016); in particular, we have included human clinical trials, reviews and meta-analyses when they offered suitable insights and elucidations regarding the action of polyphenols on lipid profile and cardiovascular disease risk. Results: Literature data on polyphenols suggest that they potentially could exert an effect on lipid profile, especially by reducing the oxidation of LDL-C. Polyphenols from cocoa, grape, green tea, berries and soy are the ones that have shown more clinically relevant effect. However, quantitative data on cholesterol reduction are still unclear and often conflicting. Conclusion: Polyphenols, if taken in adequate dosages, can exert in some cases a positive effect on the prevention of cardiovascular risk and lipid oxidation, despite an unclear effect on lipid levels.