A cup of coffee may cause a heart attack in some people within an hour of drinking it, according to a study reported in the journal Epidemiology (Transient Exposure to Coffee as a Trigger of a First Nonfatal Myocardial Infarction, (Volume 17, Issue 5, September 2006.) The risk was 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 her colleagues of Harvard School of Public Health surveyed participants about their coffee consumption in the hours and days before their heart attack. They also studied the participants socio-demographic characteristics, lifestyle, and medical history. They theorized that 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 that the moderate coffee drinkers, by having a cup of coffee, increased their risk of having a heart attack by 60%. There was little effect among heavy coffee drinkers, but light coffee drinkers increased their risk of heart attack by more than four times. This may be because lighter drinkers are less acclimated to the effects of caffeine.
Baylin and her team also found that patients with three or more risk factors for coronary heart disease more than doubled their risk.
"People at high risk for a heart attack who are occasional or regular coffee drinkers might consider quitting coffee altogether," comments Baylin, adding that for these individuals, a cup of coffee could be "the straw that broke the camel's back."
Coffee's effects on the human body have been studied for years. Baylin's study is unique in that it looks at immediate effects rather than those that impact people's health long-term. Although the study was conducted in Costa Rica, the researchers say that the results are relevant to the US as well, since Americans caffeine intake is comparable.
Epidemiology, published bimonthly by Lippincott Williams & Wilkins, is a peer-reviewed journal bringing important new developments in the field to epidemiologists, public health investigators, infectious disease specialists, and other health professionals. Its broad coverage spans from cancer, heart disease, and other chronic illnesses to reproductive, environmental, psychosocial, infectious-disease, and genetic epidemiology.
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