Daily supplements of resveratrol for one month may improve sensitivity to insulin and reduce the spike in blood sugar after a meal, suggest new data from a pilot human trial.
Using capsules from Biotiva, LLC, researchers report that doses of between 1 and 2 grams of resveratrol per day were associated with improvements in sensitivity to insulin in older people with age-related glucose intolerance.
“This pilot study provides the first evidence in humans that resveratrol may possess clinically relevant effects on glucose metabolism and vascular function,” wrote researchers from Albert Einstein College of Medicine, New York, in the The Journals of Gerontology: Series A .
However, the results should be interpreted with caution, they said, since the study was not blinded and, being a pilot study, only included a small number of subjects.
“Future studies should include formal randomized placebo-controlled trials and efforts to explore the potential mechanisms for resveratrol’s cardiometabolic effects.”
Always making headlines…
Resveratrol, a powerful polyphenol and anti-fungal chemical, is often touted as the bioactive compound in grapes and red wine, and has particularly been associated with the so-called 'French Paradox'. The phrase, coined in 1992 by Dr Serge Renaud from Bordeaux University, describes the low incidence of heart disease and obesity among the French, despite their relatively high-fat diet and levels of wine consumption.
Other studies with only resveratrol have reported anti-cancer effects, anti-inflammatory effects, cardiovascular benefits, anti-diabetes potential, energy endurance enhancement, and protection against Alzheimer’s.
Interest in the compound has been impressive, but doubts and concerns were raised recently relating to some of the purported health benefits when results of a three-year investigation by the University of Connecticut alleged that the director of the institution’s Cardiovascular Research Center published falsified data on the red wine antioxidant over a seven year period.
One industry observer said that the unfolding scandal should raise the quality of research bar even higher as research in resveratrol is going to be scrutinized more closely than ever.
Pilot study details
Led by Jill Crandall, MD, the researchers recruited 10 people with age-related glucose intolerance and an average age of 72. The open label study assigned subjects to consume 1, 1.5, or 2 grams of resveratrol per day for four weeks.
Results showed that blood sugar (glucose) levels after a meal were significantly reduced as a result of resveratrol supplementation, compared to data from the subjects at the start of the study (baseline data).
In addition, insulin sensitivity increased following four weeks of supplementation. On the other hand, no effects were observed for body weight, blood pressure, or blood lipid levels.
“We were unable to detect differences within the narrow dose range studied and expect that a wider range of resveratrol doses will be necessary to reveal evidence of a dose-response,” said the researchers.
The supplement was found to be well-tolerated by the participants, but the researchers called for larger and longer trials to “appropriately assess safety concerns”.
“Together, these results suggest that resveratrol shows promise as a new therapeutic strategy for an important and highly prevalent age-related metabolic disorder”.
The study was funded by the the National Institute on Aging, the National Institutes of Health, and the Einstein Diabetes Research and Training Center.
Source: The Journals of Gerontology: Series A
Published online ahead of print, doi:10.1093/gerona/glr235
“Pilot Study of Resveratrol in Older Adults With Impaired Glucose Tolerance”
Authors: J.P. Crandall, V. Oram, G. Trandafirescu, M. Reid, P. Kishore, M. Hawkins, H.W. Cohen, N. Barzilai