Doctors have been telling us for years that a
glass of red wine at night may be good for our hearts. But they still can't
tell us why, exactly.
Does the answer lie in the antioxidants known
as polyphenols, which may or may not boost blood-vessel function, improve
cholesterol levels, and fight inflammation? Or does alcohol play the more
important role?
A small new study may provide a clue. To compare
the effect of polyphenols and alcohol on blood pressure, researchers instructed
67 older men at risk for heart disease to consume the same beverage every day
for one month at a time: red wine (about two glasses), non-alcoholic red wine,
or gin (about two shots).
The daily doses of alcoholic red wine and of
gin—which doesn't contain polyphenols—had no discernible effect on blood pressure.
By contrast, when the men drank the non-alcoholic red wine, theirsystolic
anddiastolic blood pressure fell by an average of 6 and 2 points, respectively,
over the course of the month. (Systolic pressure is the top number in a blood
pressure reading.)
Though modest, blood-pressure declines in the
same range have been shown to reduce the risk of heart disease and stroke by up
to 20%, according to the study, which was published today in the American Heart
Association journal Circulation Research.
"Our opinion is that [these] blood
pressure-lowering...effects should be attributed to the polyphenols contained
in wine," says senior author Dr. Ramon Estruch, M.D., Ph.D., a researcher
at the University of Barcelona, in Spain.
"Alcohol," he adds, "seems to
counteract the effects of the non-alcoholic fraction in red wine."
The researchers suspect that polyphenols
lowered blood pressure by raising blood levels of nitric oxide, which relaxes
the arteries and allows blood to circulate more freely. In the study, only
non-alcoholic red wine was associated with an increase in nitric oxide levels.
Despite the growing evidence of red wine's
heart benefits, doctors generally don't recommend it to their patients because of
the hazards associated with alcohol. Non-alcoholic red wine might be an option
for people who want to consume polyphenols without the alcohol, Estruch and his
colleagues say.
The study, however, left several questions
unanswered that will need to be addressed in future research.
It's not clear, for instance, whether the same
experiment would produce similar results in healthy people or in women. And the
researchers didn't measure the exact polyphenol content of the wines, raising
the possibility that some other property of the non-alcoholic wine helped lower
blood pressure.
Another important drawback is that the
researchers measured blood pressure on one day only, at the end of each
month-long period, says Dr. Sharonne Hayes, M.D., founder of the Women's Heart
Clinic at the Mayo Clinic in Rochester, Minnesota.
"Whether this [effect] would be sustained
with longer-term use is unknown," Hayes says.
Copyright Health Magazine 2011
Post by: Amanda Gardner - Health.com
Filed under: Health.com • Heart • Living Well |
