TORONTO - Red wine has been touted as beneficial for cardiovascular
health, but new research suggests that while one glass of that favourite Merlot
or Shiraz may indeed be heart healthy, two or more could actually do more harm
than good over time.
Furthermore, those good and bad effects on the heart and blood vessels aren't
restricted just to red wine, but also apply to any kind of alcoholic drink, says
principal investigator Dr. John Floras, director of cardiology research at the
Peter Munk Cardiac Centre in Toronto.
Several large population studies have suggested light or moderate alcohol
drinking has a protective effect on the heart; red wine, which contains
antioxidant polyphenols, is thought to have particular benefits.
These studies found lower rates of heart disease, despite high-fat diets, among
some European populations that regularly consume red wine. Widely known as the
"French paradox," the phenomenon has created huge interest in how the libation
might stave off cardiovascular disease.
In the Toronto study, Floras said tests on volunteers showed that drinking a
single glass of red wine or an amount of ethanol (pure alcohol) equal to that
found in a beer or a serving of spirits did indeed have potentially helpful
effects on the heart and blood vessels.
"One standard drink of both the red wine and the alcohol causes the blood
vessels to dilate (widen), which could be considered a good thing," he said. "It
would make it easier for blood to flow through the vessels and reduce the work
of the heart."
"But what happened after two drinks is the nervous system got turned on. And
when the nervous system got turned on, that led to an increase in the impulses
going to the blood vessels, which acted as a brake on further blood vessel
dilation."
Floras said after two drinks, subjects' heart rates rose and their hearts began
pumping more blood than necessary.
"So it suggests that there may be a physiological underpinning to this
relationship in populations where one drink a day seems to be more beneficial
than two drinks a day. And it may be that over time, revving up the nervous
system, increasing the heart rate, increasing the pumping action of the heart
may be part of the reason heavy drinking has been shown to have adverse
effects."
Dr. George Fodor, head of research for the University of Ottawa Heart
Institute's Minto Prevention and Rehabilitation Centre, said the findings
provide a solid challenge to "the nonsensical statement that the French have low
levels of heart disease because they drink red wine."
"The bottom line is if there is any benefit in alcohol, the range is very
narrow," Fodor said Tuesday from Ottawa, commenting on the research. "So this
study, I think, is a warning against trying to justify the drinking of alcohol
for alleged health benefits."
Toronto cardiologist Beth Abramson, a spokeswoman for the Heart and Stroke
Foundation, said that although the study looked at only a small number of
subjects, it is important because it gives insights into how the heart, blood
vessels and body react when exposed to alcohol.
"This is another piece of evidence - and it's done very elegantly - that
suggests that just because a small amount of alcohol may be beneficial, more of
it can actually be harmful," said Abramson, who was not involved in the study.
"Although it is enticing to think that alcohol would be a quick fix ... it
actually isn't."
To conduct the study, published in the February issue of the American Journal of
Physiology: Heart and Circulatory Physiology, researchers enrolled 13 healthy,
non-smoking adults who were not heavy drinkers or total abstainers.
Participants attended three separate morning sessions, two weeks apart, during
which "standard" drinks of red wine, ethanol or water were randomly
administered. A 120-millilitre glass of wine and a 44-millilitre shot of spirits
is considered a standard drink. The study used a moderately priced pinot noir
with a high polyphenol content.
While agreeing the study is small, Floras said it is unique because it compares
three different drinks - water, ethanol and red wine - in the same individuals
on separate occasions, looking at different doses.
And because his lab contains a variety of testing methods, the researchers were
able to simultaneously measure heart rate, blood pressure, blood vessel diameter
and electrical impulses sent from the brain to the heart and the rest of the
circulatory system.
"It would appear that following two or more drinks, the alcohol seems to turn on
systems that do stress the circulation," he said.
"And our concern is if these stressful actions are repeated on a daily basis in
individuals who have high alcohol consumption, they ultimately may be at higher
risk of a heart attack or stroke or high blood pressure because of this
potential mechanism."
Source : The Canadian Press
