Resveratrol Reconsidered

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As we pointed out last week here at Diabetes Flashpoints, red wine has long been associated with a number of health benefits — including reduced insulin resistance and a lower risk of developing Type 2 diabetes — along with the risks inherent in drinking alcohol (which can include addiction and abuse, as well as higher blood triglyceride levels in some people). But the main study we discussed in last week’s post, published earlier this month by the journal JAMA Internal Medicine, found no reduction in overall mortality, or any other health benefits, from consuming higher levels of resveratrol — a compound in red wine that, in the context of the study, was a good marker for how much red wine the participants were drinking over the nine-year study period. This study cast doubt on the benefits of drinking red wine and, in particular, of consuming resveratrol, which is touted by some proponents as a wondrous health-enhancing, life-extending chemical.

But another new study, also published earlier this month, takes a very different perspective on resveratrol. This research review, published in the journal European Endocrinology, notes that resveratrol may have several beneficial effects in people with Type 2 diabetes, including enhancing the effect of the oral drug metformin. According to an article on the review at, a series of clinical trials at New York City’s Albert Einstein College of Medicine between 2005 and 2014 examined some of the diabetes-related effects of the chemical. In one study, a daily 500-milligram dose of resveratrol (in pill form) was found to slow the progression of prediabetes into full-blown Type 2 diabetes. Another study found that taking 1–2 grams of resveratrol daily improved glucose metabolism. In people with Type 2 diabetes who take metformin, taking additional resveratrol supplements was found to increase insulin sensitivity and lower blood glucose levels compared with metformin alone.

The authors of the review note that resveratrol has been widely studied in animals and cell cultures, and that human clinical trials have found a very low rate of adverse side effects associated with taking resveratrol supplements, along with measurable benefits. But as the Web site Quackwatch points out, most studies of resveratrol in humans have been short-term trials; the long-term effects of taking resveratrol supplements haven’t been widely examined. Moreover, the doses of resveratrol that have been shown to be beneficial in studies of humans are far greater than what a typical person — or probably any person — would consume through food and beverages. A five-ounce glass of red wine — the most concentrated dietary source of resveratrol — typically contains between 0.3 and 1.07 milligrams of the chemical. This means that even if your red wine contained the highest possible levels of resveratrol, you’d have to drink between 467 and 1,869 glasses of it each day to match the doses studied in clinical trials.

So maybe last week’s study found no longevity-enhancing effect because participants’ doses of resveratrol simply weren’t high enough. Or maybe taking supplements of the chemical doesn’t, in fact, reduce overall mortality; only long-term clinical trials can effectively answer this question. Such trials, however, are expensive and unlikely to be conducted anytime soon.

In the meantime, have you considered taking a resveratrol supplement (in consultation with your doctor, of course)? In the absence of long-term clinical trials, is it irresponsible for medical professionals to have an opinion on taking resveratrol? Should doctors encourage their patients, in cases like this, to weigh the potential risks and benefits of taking a supplement? Are you more comfortable with the idea of getting resveratrol from food and beverages, even if this means much lower doses than those found to be helpful in clinical trials? Leave a comment below!

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