ABSTRACT
This systematic review and meta-analysis of randomized controlled trials (RCTs) were conducted to determine the effects of grapes and grape products on inflammation and oxidative stress among adults. PubMed, Scopus, ISI Web of Science, and Cochrane Library databases were searched up to July 2020 to identify RCTs investigating the effects of grape and grape products on inflammatory and oxidative stress markers. Weighted mean differences (WMD) were pooled using a random-effects model. Of the 8,962 identified studies, 24 RCTs (27 arms) were included in the statistical analysis. Grape products significantly reduced serum C-reactive protein (CRP) levels (WMD: -0.35 mg/L; 95% CI: -0.62, -0.09, p = .008), but they had no significant effect on serum tumor necrosis factor-alpha (TNF-α) (WMD = -1.08 pg/ml; 95% CI: -2.29, 0.11, p = .07), interleukin-6 (IL-6) (WMD = 0.13 pg/ml; 95% CI: -0.35, 0.60, p = .60), total antioxidant capacity (TAC) (WMD = 0.15; 95% CI: -0.35, 0.65, p = .54), or malondialdehyde (MDA) (WMD = 0.14; 95% CI: -0.64, 0.92, p = .72). The analysis indicated possible decreasing effects of grapes and grape products on CRP, but they might not be able to change IL-6, TNF-α, TAC, and MDA concentrations. Nonetheless, further studies are warranted before definitive conclusions may be reached.
Subject(s)
Inflammation/drug therapy , Oxidative Stress/drug effects , Phytochemicals/therapeutic use , Vitis , Adult , Antioxidants/metabolism , Biomarkers/metabolism , Cytokines/metabolism , Dietary Supplements , Humans , Randomized Controlled Trials as Topic , Vitis/chemistryABSTRACT
The aim of this study was to perform a systematic review and meta-analysis of randomized clinical trials (RCTs) to examine the effect of grapes/grape products supplementation on glycemic indices in adults. Our systematic search to find relevant RCTs was performed up to February 2020 using PubMed, Scopus, ISI Web of Science, Cochrane Library, and Google Scholar. Based on the heterogeneity between included studies, a random effects or a fixed model was applied in the meta-analysis, and results were expressed as weighted mean differences (WMD) with 95% confidence intervals (CI). Twenty-nine clinical trials (1,297 participants) fulfilled the eligibility criteria of the present meta-analysis. Overall, the grapes/grape products supplementation significantly reduced homeostatic model assessment of insulin resistance (HOMA-IR) (WMD: -0.54, 95% CI: -0.91, -0.17, p = . 004) but did not affect fasting insulin levels (WMD: -0.90 µIU/ml, 95% CI: -1.04, 2.84, p = .362) and hemoglobin A1C (Hb1Ac) percentage (WMD: 0.00%, 95% CI: -0.10, 0.11, p = . 916) in the main analyses. In addition, changes to fasting blood glucose (FBG) levels were in favor of the control group (WMD: 1.19 mg/dl, 95% CI: 0.05, 2.34, p = .041). We found that giving grapes/grape products to adults might have beneficial effects on the HOMA-IR. Further, large-scale RCTs with longer duration are required to confirm these results.