An occasional cup of coffee might trigger first
heart attacks in some people, a new study suggests.
"One cup or less of coffee per day may set
off heart attacks in people with a sedentary lifestyle
or with three or more risk factors for heart disease,"
said study author Ana Baylin, an assistant professor
in the Department of Community Health at Brown
University, in Rhode Island.
This latest finding will most likely keep the
coffee debate percolating among health experts.
Previous research has suggested that coffee does
not raise heart risks, and might even protect
against high blood pressure and diabetes. As a
matter of fact, only decaffeinated coffee has
been shown to possibly boost the chances of cardiovascular
trouble.
Baylin and her colleagues from Harvard's School
of Public Health looked at 503 nonfatal heart
attack cases that occurred between 1994 and 1998
in Costa Rica. Their study, expected to be published
in the September issue of Epidemiology,
found light (one cup daily) and moderate (two
to three cups daily) coffee consumption was linked
to a higher incidence of first, nonfatal heart
attacks when compared with heavy (four cups or
more daily) coffee consumption. Most people in
the study reported drinking two to three cups
of coffee per day.
"We don't know, but think it may be caffeine,
because that is the active component in coffee
that we know increases sympathetic nerve activity,
which raises blood pressure," Baylin speculated.
She stressed the study focused only on the short-term
effects of coffee; the researchers only looked
at the first hour after coffee was consumed. "The
acute effect of coffee as a trigger for heart
attack is modified by habitual consumption. People
who drink it regularly are still at risk. Only
heavy drinkers are not at risk," she said.
And, she cautioned, the findings don't apply
to the general population, only for people who
are already at risk for heart attacks. Some risk
factors include high blood pressure, high cholesterol,
obesity, diabetes and smoking. "People who
don't have these risk factors don't need to limit
their coffee intake," she said.
Dr. Robert Eckel, immediate past president of
the American Heart Association,
said he is "unconvinced" about the coffee-heart
attack link. "Most heart attacks occur in
the morning, a time that might coincide with coffee
consumption for the once-a-day drinker,"
he noted, adding that the small size of the study
and low number of cardiac events reported also
pointed up the need for further research.
"There were only nine cases of heart attack
in the one-cup-or-less-a-day group. Like any other
study, it's observation and association, although
[the study] might give rise to further research,"
he said.
Also, it's unclear why heavy coffee drinkers
would be immune from the effect, Eckel added.
Like most of the research on coffee, "this
is all opinion and theory, [there's] nothing one
could say that would be convincing here,"
Eckel said.
It may be "people with more heart disease
are more at risk for that occasional cup of coffee,
but this study doesn't prove that. There may be
an effect, but there's no validation or reproducibility,"
he said.
