Resveratrol Lowers Blood Sugar Levels in Mouse Study
WebMD Health News
Reviewed By Louise Chang, MD
Oct. 9, 2009 -- The much touted compound resveratrol shows some promise as a future treatment for type 2 diabetes, but drinking wine or taking resveratrol supplements isn't likely to do diabetic people much good, researchers say.
Resveratrol, found in red wine, was found to lower blood sugar levels and improve insulin levels when injected directly into the brains of mice fed very high-calorie diets in a study conducted by researchers at the University of Texas Southwestern Medical Center (UTSW).
The finding suggests that the brain plays a key role in resveratrol's beneficial effect on diabetes and that the benefits may occur independently of diet and body weight.
If this is true, new type 2 diabetes treatments targeting the brain may be possible, lead researcher Roberto Coppari, PhD, tells WebMD.
But drinking red wine is not likely to improve blood sugar and insulin levels because resveratrol does not cross the blood-brain barrier very efficiently.
“We don't want to send the message that you can treat diabetes by drinking red wine,” Coppari tells WebMD. “Two or three glasses a day wouldn't be nearly enough for the brain to accumulate the amount of resveratrol delivered in our study. It would take many, many bottles, and clearly that wouldn't be good for you.”
Resveratrol: Fountain of Youth?
Resveratrol first made headlines several years ago when researchers identified it as the substance likely responsible for the health benefits to the heart attributed to red wine.
The buzz became almost deafening early this year, when the news program 60 Minutes aired a story suggesting that resveratrol-based drugs may one day succeed in slowing aging in humans.
Found mostly in the skin of red grapes and other dark fruits, resveratrol has been shown to protect against diabetes in studies involving mice, although very high doses of the molecule have been needed.
In the newly published study, Coppari and colleagues examined whether injecting resveratrol directly into the brains of diabetic mice would activate a group of proteins known as sirtuins, which have been shown to have anti-diabetes properties in earlier animal studies.
The UTSW researchers injected one group of diabetic mice with resveratrol, while a second group was given saline-containing placebo injections.
All the mice were fed a very high-fat diet throughout the study.
Despite this, insulin levels in the resveratrol-treated mice dropped significantly and were halfway to normal by the end of the five-week study. Insulin levels among the placebo-treated mice continued to rise.
Resveratrol Activates SIRT1
The resveratrol injections were found to activate SIRT1 proteins in the brain and they reduced brain inflammation related to the mice's high-calorie diets.
The study was published this week online and it will appear in the December issue of the journal Endocrinology.
“The brain appears to be a major player in diabetes,” Coppari says. “The treatments we have for diabetes target other organs like the liver. The brain hasn't really been on the map.”
If the findings are confirmed, Coppari believes the brain could become a target for not only diabetes treatments, but treatments for cardiovascular disease and obesity as well.
The study is not the first to show that resveratrol can prevent the deleterious consequences of a eating a high-fat diet.
In November of 2006, researchers from Harvard Medical School and the National Institute on Aging reported that obese mice fed a diet containing 60% of calories from fat lived significantly longer if they were treated with resveratrol.
The resveratrol-treated mice lived as long as lean mice, with a much better quality of life, as measured by motor skills tests.
“After six months, resveratrol essentially prevented most of the negative effects of the high calorie diet in mice,” study co-author Rafael de Cabo, PhD, of the National Institutes of Aging says in a news release.
Ramadori, G., Endocrinology, published online Oct 9, 2009.
Roberto Coppari, PhD, assistant professor of internal medicine, University of Texas Southwestern Medical Center, Dallas.
News release, University of Texas Southwestern Medical Center.
News release, Harvard Medical School.
News release, News Briefs from the Endocrine Society.
"Fountain of Youth in a Wine Rx," 60 Minutes, Jan. 25, 2009.
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