Scientists have claimed that drinking four cups of coffee a day could massively increase the risk of a heart attack for certain people.
A study of 4,028 people in Costa Rica found that those whose metabolism was slow to break down caffeine were 64 per cent more likely to suffer a heart attack if they drank four or more cups of coffee a day.
But those with the opposite genetic trait – known as ‘fast caffeine metabolisers’ – appeared to cut their chances of a heart attack by drinking coffee. The problem is that you won’t know which group you fall into, as only a genetic test can tell you.
One of the authors of the study, Ahmed el-Sohemy, from the University of Toronto, Canada, told a national newspaper: ‘It appears that one cup a day is not associated with any harm, regardless of your genetic make-up.
‘There may be some people in the population for whom several cups a day may not be harmful, but until such exceptions have been identified, moderation would appear to be best.’
Caffeine, which is found in coffee, tea and chocolate, causes blood vessels to constrict, which can trigger a rise in blood pressure. The longer caffeine remains in the bloodstream, the higher the risk that it will lead to a heart attack.
The study, published in the Journal of the American Medical Association, looked at 2,014 men and women who had had a non-fatal heart attack between 1994 and 2004 as well as a similar number of men and women who hadn’t suffered an attack.
Genetic tests were used to determine whether the participants were slow or fast to process caffeine, and they recorded their coffee consumption.
In the slow-metabolising group, people who drank two or more cups of coffee daily were about 36 per cent more likely to have a non-fatal heart attack, compared with those who drank little or no coffee.
But among fast metabolisers, those drinking two to three cups of coffee a day showed a 22 per cent reduction in risk of heart attack compared to other fast metabolisers who drank one cup a day or less.
Professor Peter Weissberg, medical director at the British Heart Foundation, said: ‘We know that the speed at which people break down different drugs varies from person to person, depending on their genetic make up.
‘This research suggests that heavy coffee drinkers who break down caffeine more slowly may have a slightly increased risk of having a heart attack. However, for most people other lifestyle choices, such as smoking, diet and exercise, are far more likely to affect their heart health than the occasional cup of coffee.’