Not just any red wine will do, it seems.
In the current issue of the Journal of the American College of Cardiology, German researchers say wines from their country probably aren't as good at reducing the risk of heart disease as French wines are.
"French wines are richer in flavonoids, polyphenols and phytoalexins than are German wines tested in this study," explains lead author Dr. Ulrich Forstermann, head of pharmacology at Johannes Gutenberg University in Mainz.
An enzyme called endothelial nitric oxide synthase (eNOS) protects blood vessels from clotting and from plaque buildup. This enzyme is dysfunctional in many disorders, such as diabetes, high cholesterol and high blood pressure, and also with cigarette smoking, Forstermann says.
To see if alcohol could increase the amount of eNOS available in the body, Forstermann and his team cultured cells from human umbilical cords and then exposed them to six French red wines, three German red wines and pure alcohol or nothing as controls.
The researchers found that some of the French wines caused eNOS expression to quadruple, while the German wines showed little change when compared to the controls. Pure alcohol had no effect on the eNOS present in the cells.
"Good red wines contain ingredients that are able to stimulate eNOS gene expression and eNOS activity. Therefore, they have the potential to protect against atherosclerosis (hardening of the arteries)," Forstermann says.
French wines probably aren't the only ones that would have this beneficial effect. Any wine rich in flavonoids and other heart-healthy compounds, such as those found in Italy, California and South Africa, would probably produce similar findings, he says.
The reason some wines are so rich in these substances comes from the way they are grown, especially the soil they are grown in, he adds.
The researchers also tested to see if the way the wine is fermented had any effect -- it didn't. Wine matured in oak barrels or steel tanks showed the same beneficial effects.
"This study doesn't tell us much about what happens when people drink," comments Dr. Robert Vogel, a professor of medicine at the University of Maryland Hospital, who wrote an accompanying editorial to the study. "It's an interesting study, but it's not clinically relevant. They incubated human cells in wine concentrations. What that means to human beings is still unknown."
However, Vogel adds, the study may point to a reason why there have been so many conflicting studies on the benefits of red wine. He says that studies done in America have tended to show little difference between red wine and other forms of alcohol in protecting heart health, while many European studies have found that red wine is superior.
The bottom line, says Vogel, is that one or two drinks a day will probably help prevent heart disease for people over 40.
Forstermann agrees: "One or two glasses of red wine in the evening are good for you. Besides the relaxing, calming and stress-reducing effect of a moderate dose of alcohol, good red wines contain compounds with protective effects on the cardiovascular system."
Vogel cautions, however, that too much of a good thing can be bad for you. "Too many people drink a lot, and the ravages of alcohol are devastating," he notes.