Gene Contribution in Coffee Heart Risks

Recent research has uncovered why one or two cups of coffee a day may be harmful to some, but beneficial to others. This appears to be linked to a gene that determines how fast caffeine is metabolized.

Ahmed El-Sohemy, researcher at the University of Toronto and one of the study's lead authors, says these results may also explain the mixed results in previous studies investigating the effects of caffeine on the cardiovascular system. There are many studies that have proved coffee increased blood pressure over short term, but there is also evidence that caffeine consumption did not cause a long-term increase in blood pressure, at least in women.

Unfortunately, there is no commercially available test to determine whether you are a slow or a fast caffeine metabolizer, and nobody can actually feel how fast the body is eliminating caffeine.

The liver enzyme cytochrome P450 1A2, responsible for metabolizing caffeine, has a slow 1F version and a fast 1A version, according to this study.

The study, conducted with researchers from Harvard's School of Public Health and the University of Costa Rica, involved 4,024 participants living in coffee-rich Costa-Rica between 1994 and 2004. Slightly more than half of them were found to have the slower version of the gene, while the others had the faster version; half had had a non-fatal heart attack, and half had not.

Individuals who had the slower version of the gene were found to have a 36% increased risk of heart disease if they consumed two-three cups of coffee a day. If they consumed more than three cups of coffee a day, their risk increased b 64%.

"For those who had the fast version of the gene, there was no increased risk, even with four or more cups a day", Dr. El-Sohemy said.

The most surprising finding, however, was that in individuals under 50 years of age who had the fast-acting version of the gene the consumption of 1-3 cups of coffee a day had beneficial effects on heart health, reducing the risk of cardiovascular disease by 22%. Those who had a higher consumption of caffeine had no decrease in the risk.

The study, published in today's issue of the Journal of the American Medical Association, was the first to take into account genetic differences in a body's ability to break down caffeine. "Perhaps in the future we'll be making different (dietary) recommendations based on people's genetic makeup", Dr. El-Sohemy adds.

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