Sept. 23, 2011 -- Red wine (in moderation) is as good for your health as it is to your palate. At least that’s what we’re consistently told.
Red wine and heart health have long been linked, with studies suggesting a glass or two a day lowers heart disease risk.
The heart-healthy benefits are often credited to antioxidants called polyphenols. Experts have different opinions, however, about exactly how the polyphenols may benefit the heart.
Now, Dutch researchers have found that the polyphenols don't seem to promote heart health by reducing blood pressure.
"Our findings do not support [the idea] that potential cardiovascular benefits of red wine consumption result from blood pressure lowering by polyphenols," says researcher Ilse Botden, MD, a PhD student at Erasmus Medical Center in Rotterdam, Netherlands.
The findings don't suggest red wine isn't still heart-healthy -- just that it doesn't seem to work by lowering blood pressure, Botden says.
The benefit of red wine and heart health, she says, ''apparently occurs in a blood pressure-independent manner."
Botden is due to present the findings today at the American Heart Association's High Blood Pressure Research 2011 Scientific Sessions in Orlando.
Red Wine and Heart Health: Study Details
Botden asked 61 men and women, average age 61, to drink three types of dairy beverages. One drink contained placebo. The other two contained either 280 milligrams or 560 milligrams of red wine polyphenols. That is equal to about what is found in two or fourglasses of red wine.
They were randomly assigned to drink one of the three choices every day for four weeks.
The researchers measured blood pressures after each four-week study period. Blood pressures were taken in the office and using 24-hour measurements while the people went through their day wearing a monitor.
However, in the new study, neither dose of the polyphenols lowered blood pressure.
Is it possible that something else in the wine may be needed to interact with the polyphenols, that they can't act alone?
"No," Botden says. "I don't think something else in red wine causes a decrease in blood pressure since previous human studies showed no effect of red wine drinking on blood pressure."
The same polyphenols she tested in people, when tested in animals, did produce a blood pressure decrease, she says.
In other studies done in people, polyphenols from red wine seem to work by improving the health of the cells lining the blood vessels, in turn improving blood flow and heart health. One possibility, she says, is that perhaps more severe problems in the health of the blood vessel linings may be needed before the red wine polyphenols affect the blood pressure.
Red Wine and Heart Health: Another Expert's View
The findings don't surprise Arthur Klatsky, MD, a senior consultant in cardiology at Kaiser Permanente Northern California. He has researched the relationship between drinking alcoholic beverages and health since 1977.
"I don't think there is any substantial thought by experts that lowering of blood pressure is the mechanism for [red wine reducing] heart disease," he tells WebMD. He reviewed the findings for WebMD but was not involved in the study.
Among other explanations, experts say substances in red wine may benefit heart health by increasing good (HDL) cholesterol or producing anti-clotting actions, Klatsky says.
Looking at the big picture, "polyphenols may play a subsidiary function in reducing the risk of coronary artery disease," Klatsky says. He says they may be less important than the alcohol.
What is known, he says, is that heavy drinking raises blood pressure. Studies about light drinking and blood pressure lowering have mixed results, he says. Most show no effect, although some show a slight reduction.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.