Middle-aged and elderly people drink coffee in the morning, which may cause heart disease.

Brown University professor Anna? Behring reported in the journal epidemiology that middle-aged and elderly people who drank little coffee had a significantly higher risk of stroke one hour after drinking coffee in the morning, and those who had three or more risk factors for heart disease, such as diabetes, high blood pressure, smoking and little exercise, had a higher risk.

However, people who drank more than four cups of coffee a day did not have an increased risk of heart disease. Behring's team believes that heavy coffee drinkers may have become accustomed to caffeine, so cardiovascular effects are not affected.

The study involved 503 Costa Ricans who suffered their first stroke between 1994 and 1998. Coffee consumption and overall diet in the hours and days before stroke, as well as medical history, lifestyle habits and background, were all included in the study.

People who drank less than one cup of coffee a day on average had four times the normal risk of having a heart attack an hour after drinking coffee in the morning. Drinking two or three glasses a day increases your chances by 60%. Those who drank more than four drinks were no worse off.

The research team believes that the stimulating effects of caffeine may promote nervous system activity, causing fat deposits in the arterial wall to shed, blocking blood flow to the heart and causing heart disease.

Behring said morning coffee could be the "last straw" for people with heart disease risk factors who don't drink much coffee, and that this group should consider giving up coffee.