The new study, performed with mice, found that resveratrol may activate two molecules that play a role in cell signaling and the breakdown of fats in the liver: AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). These molecules are reportedly inhibited by alcohol, leading to fat build-up and fatty liver.
Although expert advice is clearly to avoid excessive alcoholic consumption altogether, the results suggest alcoholics could benefit from upping their intake of resveratrol-rich foods.
Researchers from the University of South Florida report their findings in the American Journal of Physiology-Gastrointestinal and Liver Physiology.
Previous research has linked the potential health benefits of wine to resveratrol, a powerful polyphenol and anti-fungal chemical that occurs naturally under the skin of red wine grapes.
It is often touted as the bioactive compound in grapes and red wine, and has particularly been associated with the so-called 'French Paradox', a phrase used to describe the low incidence of heart disease and obesity among the French, despite their relatively high-fat diet and levels of wine consumption.
The protective properties of compounds found in red wine are the focus of numerous studies today as industry and academia investigate dietary mechanisms to stem the growing tide of diseases such as obesity, heart disease and diabetes.
The researchers, led by Joanne Ajmo, studied the effects of resveratrol at a molecular level. Mice were divided into groups and all of them were fed a low-fat diet. One group of the mice had their diets supplemented with resveratrol, one group was supplemented with resveratrol plus alcohol (ethanol), one group with only ethanol, and one group consumed only the diet (control group). The researchers used two different dose levels of resveratrol.
At the end of the experiment, Ajmo and her co-workers report that, as they expected, resveratrol increased the expression of SIRT1 and stimulated the activity of AMPK in the livers of alcohol-fed mice.
Furthermore, these increases were associated with changes in the levels of other molecules that control fat metabolism, including adiponectin, a hormone produced by fat cells, which helps control obesity.
Such changes are reported to prevent the accumulation of fat in the mouse liver by both reducing the production of fat and increasing the burning of the fat already present.
The study’s senior author, Dr. Min You, said that it was interesting that the combination of alcohol with resveratrol appeared to enhance the positive effects of resveratrol.
"Our study suggests that resveratrol may serve as a promising agent for preventing … human alcoholic fatty liver disease," concluded the authors.
The study was financed by the National Institute on Alcoholism and Alcohol Abuse.
A recent study in California, for example, found low doses of freeze-dried grape powder could inhibit the development of colorectal cancer thanks to the polyphenol resveratrol and synergistic effects between the grape compounds.
Previous studies have also linked resveratrol to bearing a positive effect on extending survival rates of mice and preventing the negative effects of high-calorie diets. It has also been linked to diabetes, heart health and obesity.
In red wine, the amount of resveratrol in a bottle can vary between types of grapes and growing seasons, and can vary between 0.2 and 5.8 milligrams per litre. But nearly all dark red wines - merlot, cabernet, zinfandel, shiraz and pinot noir - contain resveratrol.
Source: American Journal of Physiology – Gastrointestinal and Liver Physiology Published online ahead of print, doi:10.1152/ajpgi.90358.2008“Resveratrol Alleviates Alcoholic Fatty Liver in Mice”Authors: J.M. Ajmo, X. Liang, C.Q. Rogers, B. Pennock, M. You