Resveratrol for Blood Sugar
Resveratrol arrived with an unusually good story — the polyphenol in red wine, the sirtuin activator, the explanation for the French paradox. Twenty years of human trials have been considerably less exciting than the story, and the honest summary is that the results conflict.
Evidence tier 3. Mechanistically interesting, human glucose data thin and inconsistent.
Table of Contents
An Umbrella Review Is the Right Tool Here
When a field has produced many small trials and many meta-analyses of those trials, the useful next step is an umbrella review — a review of the meta-analyses. Zeraattalab-Motlagh and colleagues did exactly that in the American Journal of Clinical Nutrition in 2021, identifying 11 meta-analyses covering 29 outcomes in 1,476 people with type 2 diabetes, plus separate bodies of work in metabolic syndrome and non-alcoholic fatty liver disease.
That structure is itself informative. Eleven meta-analyses of the same question is a sign of a field re-analysing a limited pool of small trials rather than generating new large ones, and it is a pattern that tends to produce conflicting conclusions from overlapping data. Zhu and colleagues' earlier 2017 meta-analysis in Nutrition & Metabolism is one of the component analyses worth reading directly.
The practical reading: resveratrol's glucose effects, if present, are small and inconsistent enough that competent analysts looking at largely the same trials reach different conclusions.
The Red Wine Problem
Resveratrol's fame comes from red wine, and the arithmetic there is worth stating plainly. Trial doses run to hundreds of milligrams a day. A glass of red wine contains on the order of a milligram. Reaching a trial dose by drinking would require an amount of alcohol whose harms would dwarf any polyphenol benefit many times over.
Whatever red wine does or does not do for cardiovascular risk, it is not delivering a pharmacological dose of resveratrol, and this page is not an argument for drinking.
Bioavailability
Resveratrol is absorbed reasonably well and then almost immediately conjugated: circulating free resveratrol is very low, with the sulfate and glucuronide metabolites dominating. As with quercetin and curcumin, much of the mechanistic work uses the free form at concentrations plasma does not reach.
Cautions
- It lowers blood glucose, and so does your medication. The effects add. With insulin or a sulfonylurea this is a hypoglycemia risk, and dose changes belong with the prescriber — see hypoglycemia awareness and prevention.
- Antiplatelet activity at supplemental doses — relevant with anticoagulants and before surgery.
- Possible oestrogenic activity; caution with hormone-sensitive conditions.
- Gastrointestinal upset is common at gram doses.
- Measure, do not assume. Adding a supplement without measuring means you learn about an interaction from a symptom rather than from a number.
Key Research Papers
Every DOI below was checked against Crossref and the abstract read for support before it was listed.
- Zeraattalab-Motlagh S, Jayedi A, Shab-Bidar S. The effects of resveratrol supplementation in patients with type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease: an umbrella review of meta-analyses of randomized controlled trials. American Journal of Clinical Nutrition, 2021;114(5):1675–1685.
- Zhu X, Wu C, Qiu S, Yuan X, Li L. Effects of resveratrol on glucose control and insulin sensitivity in subjects with type 2 diabetes: systematic review and meta-analysis. Nutrition & Metabolism, 2017;14:60.