COFFEE drinkers who have more than three cups a day could significantly increase their chances of suffering a heart attack.

Research suggests that some people who carry a particular variation of a gene cannot process caffeine as quickly as other people. Such individuals could be 60 per cent more likely to have a heart attack if they drink large amounts of coffee.

It is not known how common the gene variation is in the British population. Some studies indicate that up to a third of Caucasians may carry it.

Canadian scientists have discovered that people with the slower metabolism gene variation, known as *1F, run a dramatically higher risk even if they drink only two cups a day.

Researchers found that heavy coffee drinkers under the age of 50 were four times as likely to have an attack compared with those who had one cup a day.

However, the study suggests conversely that people with a different variant of the same CYP1A2 gene, called *1A, could benefit from coffee. It found that for these individuals the drink might offer some protection against heart attacks, although the figures are less statistically significant. Drinking one cup a day appeared to halve the odds of a heart attack for these individuals, while drinking two or three cups cut the risk by about 40 per cent.

Ahmed El-Sohemy, Canada Research Chair in Nutrigenomics at the University of Toronto, told The Times that the study showed that coffee should, by and large, be drunk in moderation. He added that the suggested benefits of drinking coffee for *1A gene carriers explained why many previous coffee studies had offered apparently conflicting results.

High amounts of caffeine have long been blamed for overstimulating the nervous system. It contains ditrepenes, said to be responsible for raising levels in the blood of a stress hormone called homocysteine, which can lead to strokes.

Pregnant women have been urged not to drink more than three cups of coffee a day in case it increases the chances of miscarriage or stillbirth.

Some doctors have suggested that coffee can have health benefits. The antioxidants can ward off high blood pressure, according to a 12-year study by American scientists. Coffee has also been linked with a reduced risk of developing gallstones.

Previous research has also indicated that consumption of coffee and caffeine, the most widely consumed stimulant in the world, may be implicated in the development of cardiovascular diseases.

The latest study, carried out by Dr El-Sohemy and colleagues, and involving more than 4,000 people in Costa Rica, suggests that individuals with the specific variant gene who have two to three cups of coffee a day increase their chances of suffering a heart attack by 36 per cent. For those who drink four cups or more, the risk is raised by 64 per cent.

The study, published in the Journal of the American Medical Association, included 2,014 case patients with a first acute non-fatal heart attack and 2,014 controls, living in Costa Rica between 1994 and 2004. The “slow metabolism” genotype was found to be present in 55 per cent of the participants, who were Hispanic Americans.

However, coffee also contains other chemicals that have variable effects on the cardiovascular system, and it remains unclear whether caffeine alone affects the risk of heart attack or if other chemicals may be responsible.

“One cup a day is not associated with any harm, regardless of your genetic make-up,” Dr El-Sohemy said.

BEAN-COUNTING

All coffee is grown within a thousand miles of the Equator

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