Coffee may brew heart attacks
2006-03-08 09:23
Washington - That extra cup of coffee may deliver a pleasant jolt to a sluggish nervous system, but for people who metabolise caffeine slowly, it could trigger a heart attack, according to a study released on Tuesday.
A research team led by Ahmed El-Sohemy of the University of Toronto conducted a study to determine whether there is an association between people with gene variations of the enzyme that metabolises caffeine in the liver, CYP1A2, consumption of coffee, and the risk of nonfatal heart attack.
The team found that the risk of heart attack increases for individuals who have a "slow" version of the enzyme as they increase coffee intake.
The study is to be published in the March 8 issue of the Journal of the American Medical Association.
Coffee, a major source of caffeine, is the most widely consumed stimulant in the world.
Previous studies looking at the link between coffee consumption and the risk of heart attack have been inconclusive, Jama said in a statement.
Costa Rica study
The Toronto-led team conducted a study of 4 018 people living in Costa Rica and found that the number of cups of coffee consumed and the age of the drinker made a difference for the "slow" caffeine metabolisers.
In that group, those who drank two to three cups of coffee a day had a 36% increased risk of a myocardial infarction (MI), or heart attack; that risk shot up to 64% with those who drank four or more cups a day.
Younger individuals in the group showed an increased risk: The chance of a heart attack risk doubled for those younger than 50 compared with those younger than 59.
"In summary, consistent with most case-control studies, we found that increased coffee intake is associated with an increased risk of nonfatal MI," the authors conclude.
The association between coffee and MI was found only among individuals with the slow (enzyme variant), which impairs caffeine metabolism, suggesting that caffeine plays a role in the association."