The health benefits of anthocyanins: an umbrella review of systematic reviews and meta-analyses of observational studies and controlled clinical trials

Anthocyanins (ACNs) are phenolic compounds present in foods and have undefined health benefits. The present umbrella review aimed to analyze the effects of ACNs on multiple aspects of human health (from systematic reviews and meta-analyses [SRMs] of randomized controlled trials [RCTs]), and the associations of ACNs with the risk of various diseases (from SRMs of observational studies [OSs]). Following the PRISMA methodology, the PubMed, SCOPUS, and Cochrane databases were searched up to November 1, 2020 for OS-SRMs and RCT-SRMs that examined the effects of ACNs on health. The risk of bias of RCT-SRMs was assessed using the AMSTAR 2, and that of OS-SRMs was assessed using the Joanna Briggs Institute methodology. Based on 5 OS-SRMs (57 studies and 2 134 336 participants), ACNs of various sources were significantly associated with a reduction in the risks of hypertension and type 2 diabetes mellitus. According to 8 RCT-SRMs (139 interventions and >4984 participants), ACNs improved plasmatic lipids, glucose metabolism, and endothelial function, without affecting blood pressure. No associations between ACNs and breast or gastric cancer risks were found. ACN intake opens new pathways for the management of glucose metabolism, the plasmatic lipid profile, and the improvement of endothelial function in humans.