resveratrol

Resveratrol is a plant compound (a polyphenol) found in the skin of grapes, red wine, peanuts, and some berries. It is sold as a single-ingredient dietary supplement and is often marketed as an antioxidant.

Evidence is limited and far from conclusive. NCCIH describes only "low certainty evidence that resveratrol could be effective for glycemic control in people with diabetes," adding that "more research needs to be conducted before definitive conclusions can be drawn." In the studies it cites, resveratrol showed neutral effects on HbA1c and insulin resistance (with very low certainty) and did not improve triglyceride or HDL levels, though large doses were reported to significantly reduce fasting blood glucose and blood pressure. For antioxidants generally, MedlinePlus notes it "isn't clear" whether the benefits of antioxidant-rich diets come from the antioxidants themselves, something else in the foods, or other factors, and frames whether red wine and resveratrol are good for the heart as an open question rather than an established fact.

There is no established or government-recommended dose for resveratrol; supplement products vary widely, and the diabetes studies NCCIH cites used high doses (more than 1,000 mg) that may not reflect what is in typical products. Because the evidence is limited and resveratrol can affect blood sugar and interact with medications, talk to your doctor or pharmacist before starting it, especially if you have a health condition or take prescription drugs.

According to NCCIH, resveratrol "appears to be safe when used orally." However, long-term safety and the safety of high doses are not well established. People who are pregnant or breastfeeding, or who have a medical condition, should check with a clinician before use.

The reviewed NIH sources do not detail specific side effects of resveratrol; NCCIH characterizes oral use only as appearing safe, without listing adverse effects. As with any supplement, stop use and consult a clinician if you have an unexpected reaction.

NCCIH notes that resveratrol "may interact with other medications, especially anticoagulant/antiplatelet drugs and supplements" — categories that include blood thinners such as warfarin and antiplatelet agents such as aspirin — which could raise bleeding risk. Because resveratrol may also lower blood sugar, it could add to the effect of diabetes medications. Review your full medication and supplement list with a pharmacist before use.