Nutrition Journal | 2021
The effect of grape products containing polyphenols on oxidative stress: a systematic review and meta-analysis of randomized clinical trials
Abstract
Background The literature showed that Grape Products Containing Polyphenols (GPCP) had anti-oxidant activity. However, the effects of GPCP on different biomarkers of oxidative stress are still controversial. In this regard, this systematic review and meta-analysis aimed to evaluate the effect of Grape Products Containing Polyphenols (GPCP) intake on oxidative stress markers. Methods PubMed, Scopus, Web of Science, and Google Scholar data bases were searched up to August 20, 2020. A random-effects model, weighted mean difference (WMD), and 95% confidence interval (CI) were applied for data analysis. Meta-analysis was conducted over 17 eligible RCTs with a total of 633 participants. The study registration number is CRD42019116696. Results A significant increase was observed in Total Antioxidant Capacity (TAC) (weighted mean difference (WMD)\u2009=\u20091.524\u2009mmol/L, 95% confidence interval (CI): 0.83, 2.21). Intake of GPCP enhanced Superoxide Dismutase (SOD) (WMD\u2009=\u20090.450\u2009mmol/L, 95% CI: 0.23, 0.66), TAC (WMD\u2009=\u20092.829\u2009mmol/L, 95% CI: 0.13, 5.52), and Oxygen Radical Absorbance Capacity (ORAC) (WMD\u2009=\u20090.524\u2009μmol/L, 95% CI: 0.42, 0.62) among healthy participants. Higher GPCP doses increased SOD (WMD\u2009=\u20090.539\u2009U/mgHb, 95% CI: 0.24, 0.82) and ORAC (WMD\u2009=\u20090.377\u2009μmol/L, 95% CI: 0.08, 0.67), whereas longer intervention periods enhanced ORAC (WMD\u2009=\u20090.543\u2009μmol/L, 95% CI: 0.43, 0.64). Conclusion GPCP intake may partly improve status of oxidative stress, but further well-designed trials are required to confirm these results.