Over the last decade, a polyphenol compound with the tongue-twisting name resveratrol has garnered a great deal of attention. Organisms such as yeast, worms, fruit flies and fish live longer when they ingest resveratrol. So far, though, studies have not shown that people consuming this compound live longer. It may provide some other health benefits, however. What do you know about the pros and cons of resveratrol?
Pros and Cons of Resveratrol:
Q. We have heard many good things about resveratrol. But before I start taking it, I’d like to know more about the pros and cons of resveratrol. What can you tell us?
A. Certain plants produce resveratrol to defend themselves against pathogens or in response to injury. Grape and peanut skins are both rich in this polyphenol. So are many berries. Consequently, foods made from grapes such as red wine or wine vinegar are relatively good sources of the compound. On the other hand, people metabolize it relatively quickly, so blood levels of metabolites may be higher than those of the parent chemical. Please note: a five-ounce glass of Pinot Noir wine provides only half a milligram of resveratrol. To get a reliable amount, you’d need a supplement.
Blood Sugar and Blood Pressure:
Studies show that this antioxidant can increase insulin sensitivity and improve blood glucose control (Nutrition & Metabolism, Sept. 22, 2017). Resveratrol also improves blood vessel flexibility and may help lower blood pressure modestly (International Journal of Molecular Sciences, April 30, 2019).
Other Pros and Cons of Resveratrol:
New research indicates that resveratrol might improve blood flow in the brain and help cognitive function in older women (Nutrients, March 20, 2020). Previous studies, however, had not shown significant improvement in cognitive tests (Pharmacological Research, Feb. 2018).
Resveratrol for Hemorrhoid Relief:
Q. I watched a health show that suggested resveratrol for hemorrhoids and varicose veins. I started taking 250 mg a day with no effect.
A few months later, the experts on the show said if you have bad varicose veins or hemorrhoids to take 500 mg a day. After seven weeks at the higher dose, my hemorrhoids were gone!
A. We appreciate your testimonial. Although scientists have acknowledged the possibility that hemorrhoids might respond to resveratrol in combination with a high fiber diet, we could not find clinical trials to support such an approach (Anatomical Record, Nov. 2017).
Adverse Effects and Interactions:
This compound does have some downsides. Like many antioxidants, resveratrol can have pro-oxidant effects in some situations (International Journal of Molecular Sciences, March 2020). This could in theory have negative consequences, although human volunteers in resveratrol studies have not reported serious side effects.
Taking resveratrol before exercising could interfere with the benefits from physical activity. Other side effects may include nausea, diarrhea, itchy bottom and allergic reactions.
One reader wrote us to report:
“Recently I started taking resveratrol supplements because they are supposed to be good for you. Then I developed severe ankle pain and swelling, much like tendinitis. I was shocked to learn that resveratrol can cause this side effect.
“I’ve stopped the resveratrol now and the pain and swelling are completely gone. I wondered if you have heard of this side effect of resveratrol. My doctor wasn’t aware of it.”
Another reader had a similar reaction:
“Reservatrol gave me tennis elbow after only one pill. My elbow hurt for about two months afterward.”
We too were unaware of this problem until we heard from our reader. We found some anecdotal reports of tendinitis, but no studies in the medical literature.
Interactions with Resveratrol:
The compound may boost effects of warfarin, leading to unexpected anticoagulation and potentially bleeding. At the same time, resveratrol might interact with drugs metabolized by the enzyme CYP3A4. This is the same enzyme inhibited by grapefruit. Anyone taking resveratrol supplements should ask the pharmacist to check on potential drug interactions.