A cup of coffee can get you going in the morning? and it could increase your risk of a non-fatal heart attack if you have a specific gene.
A study published in the Journal of the American Medical Association looks at the DNA sequence of the genes responsible for how the body breaks down caffeine. One gene breaks down the caffeine rapidly. Another is a slow version.
Lead author Ahmed El-Sohemy and colleagues at the University of Toronto, Harvard University and University of Costa Rica compared the genes and coffee drinking habits of 4,000 people. Half had had heart attacks.
Study participants were also evenly divided between those with the fast gene and those with the slow gene. El-Sohemy says the difference was significant. "We found in individuals who had the slow version of this gene, as little as two cups of coffee a day is associated with an increased risk of heart disease," he says. "For those who had the fast version of the gene, there was no increased risk, even with four or more cups a day."
El-Sohemy says coffee drinking even had beneficial effects for those under 50 who were fast metabolizers. "Consumption of as little as one to three cups a day was associated with a lower risk of heart disease," he says.
El-Sohemy says you can't tell which gene you have by the way you feel. And, until a commercial test is developed, he recommends drinking no more than four cups of caffeinated coffee a day.