U.S. scientists say they've determined a single cup of coffee might cause a heart attack in some people within an hour of drinking it.
Researchers say the risk is highest among people with light or occasional coffee intake, and those with a sedentary lifestyle or other risk factors for coronary heart disease.
Studying 503 cases of non-fatal myocardial infarction in Costa Rica, Ana Baylin of Brown University and colleagues at the Harvard School of Public Health theorize caffeine causes short-term increases in blood pressure and sympathetic nervous activity that could affect a vulnerable atherosclerotic plaque, and trigger a heart attack.
The researchers found moderate coffee drinkers, by having one cup of coffee, increased their risk of having a heart attack by 60 percent. There was little effect among heavy coffee drinkers, but light coffee drinkers increased their risk of heart attack by more than four times. That, the researchers said, might be because lighter drinkers are less acclimated to the effects of caffeine.
Baylin and her team also found patients with three or more risk factors for coronary heart disease more than doubled their risk.
The research is detailed in the journal Epidemiology.
Copyright 2006 by United Press International
Explore further: Immigrant children given adult dose of hepatitis A vaccine