Effects of resveratrol supplementation on multiple health outcomes: an umbrella review of systematic reviews and meta-analyses of randomized controlled trials

Sun JN, Yang R, Fu L, Li YJ, Wu QJ · Nutrition Journal

The field graded rather than summarised. All 45 reviews rated moderate-to-high on AMSTAR, 26 of them high, median score 8 of a possible range 5 to 10. Of 35 significant associations, GRADE rated four high certainty, 23 moderate, five low and three very low. The four high-certainty effects are metabolic and small: waist circumference down 0.80 cm (95% CI 1.40 to 0.20), total cholesterol in overweight adults down 0.19 mmol/L (0.32 to 0.06), and in type 2 diabetes diastolic pressure down 3.55 mmHg (5.18 to 1.93) and systolic down 7.97 mmHg (10.63 to 5.31). High-certainty nulls are recorded too: no effect on mean arterial pressure, pulse pressure, alkaline phosphatase, total bilirubin or albumin overall, none on waist circumference or HDL in type 2 diabetes, and none on HDL or triglycerides in overweight adults. Working memory improved by a standardised mean difference of 0.20 (0.03 to 0.36) on moderate certainty. Excluding trials at high risk of bias left 27 of the moderate-to-high associations standing, downgraded 15 to low certainty and three to very low.

Population

45 systematic reviews and meta-analyses of randomised trials of resveratrol supplementation, covering 129 associations across 68 human health outcomes

Intervention

Oral resveratrol supplementation, doses and durations as reported by the pooled trials

Comparator

Placebo

Limitations

An umbrella review inherits its inputs: no joint or cartilage outcome appears among the 68, because no meta-analysis of one exists to include. The four high-certainty findings sit in different populations from each other, so they do not describe one responsive group. The review notes its own AMSTAR downgrades came mainly from reviews not listing their excluded studies.