TUESDAY, Sept. 9, 2003 (HealthDayNews) -- Scientists have found another group of chemicals that may be responsible for red wine's cholesterol-lowering effects.
But don't plan a visit to the Napa Valley just yet, some experts say.
"It's always of interest to find naturally occurring compounds to decrease cholesterol levels, but one needs to keep it in context," says Alice H. Lichtenstein, Gershoff Professor of Nutrition at the U.S. Department of Agriculture's Human Nutrition Research Center at Tufts University in Boston.
The evidence supporting the new chemicals' worth is inconclusive, she explains.
Previous research has already shown an association between red wine and decreased incidence of heart disease. But much of the effect has so far been attributed to a molecule called resveratrol.
The new compounds, called saponins, have already been found in other foods, such as soy beans and peas, and are also thought to come from the skin of grapes, say the researchers, from the University of California, Davis.
They presented their findings Sept. 8 at the national meeting of the American Chemical Society in New York City.
For the study, the scientists compared the saponin content of six types of California wines -- four red and two white. They found red wine contains three to 10 times as much saponin as white wine. Red zinfandel topped the chart, followed by syrah, then pinot noir and cabernet sauvignon. (These last two had about the same amount of saponin. Merlot was not tested, but the researchers think it also has high saponin levels.)
The researchers also found that the higher the alcohol content, the higher the saponin levels.
Resveratrol, an antioxidant, is believed to act by blocking cholesterol oxidation. Scientists reporting in the August issue of Nature found a class of chemicals that includes resveratrol extended lifespan by 70 percent in yeast, worms and fruit flies.
Saponins are thought to work by preventing the absorption of cholesterol into the body.
Even if saponins do have an effect on cholesterol, the American Heart Association points out that alcohol and wine can have negative health effects, namely increasing triglyceride levels, raising blood pressure and providing extra calories that can contribute to obesity.
So take this wine news with a grain of salt.
"There are a number of naturally appearing compounds that can lower cholesterol levels but one needs to take into consideration how much a person is likely to get from normal consumption, and I don't have a good idea of the cholesterol response," Lichtenstein says. "It's unclear what the actual response is going to be in someone."