Plant Polyphenols in Obesity and Obesity-Associated Metabolic Disorders: A Narrative Review of Resveratrol and Flavonoids Upon the Molecular Basis of Inflammation

Background: The epidemic of obesity, metabolic syndrome, type 2 diabetes and non-alcoholic fatty liver disease is currently unsustainable for Public Health systems, and preventive and therapeutic approaches are urgently sought to improve health outcomes for affected individuals. Aim: In this study, we aim to further explore and synthetize available evidence on the effects of selected plant polyphenols (PP) upon molecular mechanisms associated with oxidative stress and inflammatory pathways. We also aim to briefly discuss PP supplementation as therapeutic tool for the prevention and management of prevalent obesity-associated metabolic disorders. Methods: This narrative review was performed in the PubMed database in June 2018 without restriction of publication period. Results: PP influence a broad range of cell signalling pathways; by modulating the activity of nuclear transcription factors, PP modulate gene expression and antioxidant responses, as well as inflammation and its resolution. Several interventional studies have investigated the effects of PP supplementation in a variety of sample populations, but no consensus has yet been reached regarding composition, dosage or course of treatment for therapeutic purposes. However, overall results tend to suggest a positive effect of PP in either improving metabolic profile or minimizing negative disease outcomes. Careful consideration on PP supplementation is paramount; adverse effects have already been described. Conclusion: The successful prevention and management or treatment of obesity-associated metabolic disorders may be achieved through an effective multidisciplinary approach to tackle their modifiable risk factors. A balanced diet, which includes naturally occurring sources of PP associated with lower consumption of ultra-processed foods, is a relevant approach for the positive health outcomes desired.