Flavan-3-ols, anthocyanins, and inflammation

The process of inflammation constitutes a reactive response of the organism to tissue damage and is an important factor making part of a number of degenerative pathologies as insulin resistance, dyslipidemia, and hypertension, all of them comprised in the metabolic syndrome. There is an increasing interest in plant products rich in flavan-3-ols and anthocyanins because of their potential beneficial effects observed in epidemiological studies against inflammatory-related diseases. Their anti-inflammatory effects are exerted by modulation of cell redox status and inhibition of signaling pathways as NF-κB activation. The effects depend on their concentrations in target tissues and hence the bioavailability pathways followed by each particular compound. In this sense, in vitro studies performed with parental compounds at doses exceeding to those found in vivo may be drawing erroneous conclusions about their real efficacy. Contradictory results have been observed in human intervention trials, which may be ascribed to the type of population studied, length of study, source of flavan-3-ol/anthocyanin, and dose provided. Human studies are required to confirm the positive effects found in vitro and in animal models. Future research should be focused on the understanding of dose/flavonoid intake-response relationship with pharmacokinetic studies, evaluating proper biomarkers of intake. Long-term dietary interventions are necessary to observe effects on markers of late activation as well as the possible preventive effects of these compounds on long-term inflammation-related diseases.