Resveratrol is one of the most popular dietary supplements. It is an antioxidant found in red grape skin, Japanese knotweed, blueberries and other berries. Resveratrol is available as dietary supplements from red wine extracts, grape seed extracts, Japanese knotweed extracts and other plants. The amount and purity of resveratrol in supplements varies significantly; absorption in the gut is low.
While, for many supplements, there is no or very little research, this one has a huge amount. So, has reseveratrol any proven health effects demonstrated in clinical trials?
The answer is encouraging.
This abstract provides a useful summary:
Resveratrol is a polyphenolic nutraceutical that exhibits pleiotropic activities in human subjects. The efficacy, safety, and pharmacokinetics of resveratrol have been documented in over 244 clinical trials, with an additional 27 clinical trials currently ongoing. Resveretrol is reported to potentially improve the therapeutic outcome in patients suffering from diabetes mellitus, obesity, colorectal cancer, breast cancer, multiple myeloma, metabolic syndrome, hypertension, Alzheimer’s disease, stroke, cardiovascular diseases, kidney diseases, inflammatory diseases, and rhinopharyngitis. The polyphenol is reported to be safe at doses up to 5 g/d, when used either alone or as a combination therapy. The molecular basis for the pleiotropic activities of resveratrol are based on its ability to modulate multiple cell signaling molecules such as cytokines, caspases, matrix metalloproteinases, Wnt, nuclear factor-κB, Notch, 5′-AMP-activated protein kinase, intercellular adhesion molecule, vascular cell adhesion molecule, sirtuin type 1, peroxisome proliferator-activated receptor-γ coactivator 1α, insulin-like growth factor 1, insulin-like growth factor-binding protein 3, Ras association domain family 1α, pAkt, vascular endothelial growth factor, cyclooxygenase 2, nuclear factor erythroid 2 like 2, and Kelch-like ECH-associated protein 1. Although the clinical utility of resveratrol is well documented, the rapid metabolism and poor bioavailability have limited its therapeutic use. In this regard, the recently produced micronized resveratrol formulation called SRT501, shows promise. This review discusses the currently available clinical data on resveratrol in the prevention, management, and treatment of various diseases and disorders. Based on the current evidence, the potential utility of this molecule in the clinic is discussed.
This is a comprehensive review but it fails to critically assess the quality of the clinical trials. Once we do that, we are likely to get disappointed. Many studies are just not up to the mark.
And if we consult a Cochrane review, our enthusiasm for resveratrol disappears completely: Currently, research is insufficient for review authors to evaluate the safety and efficacy of resveratrol supplementation for treatment of adults with T2DM [type 2 diabetes mellitus]. The limited available research does not provide sufficient evidence to support any effect, beneficial or adverse, of four to five weeks of 10 mg to 1000 mg of resveratrol in adults with T2DM. Adequately powered RCTs reporting patient-relevant outcomes with long-term follow-up periods are needed to further evaluate the efficacy and safety of resveratrol supplementation in the treatment of T2DM.
So, for the time being, I might just continue to obtain my resveratrol in very small but regular doses from red wine, I think.