Coffee May Up Heart Risks for Some

March 7, 2006 -- Drinking a lot of coffee may raise the risk of heart attack in people with a particular gene variation.

That finding comes from researchers including Ahmed El-Sohemy, PhD, of the University of Toronto's nutritional sciences department.

However, drinking one cup of coffee per day shouldn't raise heart risks, El-Sohemy tells WebMD. However, his study -- published in The Journal of the American Medical Association -- doesn't make recommendations about coffee consumption.

"At this point, I don't think most people would make recommendations on the basis of a single study," Tufts University nutrition professor Alice Lichtenstein, DSc, tells WebMD.

"I think it's an interesting study," says Lichtenstein, who studies lifestyle factors that affect heart disease. "It's certainly very well done, but it raises a lot of questions." She didn't work on El-Sohemy's study.

How Much Coffee?

El-Sohemy's team compared about 2,000 people who had had their first nonfatal heart attack to a similar group of people who hadn't had heart attacks.

Participants, who all lived in Costa Rica, completed surveys about their diets, including coffee and other caffeine sources (chocolate, tea, and cola beverages). The researchers focused on people who drank fully caffeinated coffee.

Participants rated how much coffee they drank, ranging up to more than six daily cups. They also noted how they made their coffee; almost all drank paper-filtered coffee.

The researchers also screened participants for a gene that governs the metabolism, or breakdown, of caffeine. About half of both groups of participants had the "slow" variant of that gene, meaning that caffeine lingers longer in their blood.

Heart Attack Findings

Coffee intake was linked to higher risk of heart attack in people with slow caffeine metabolism and who were younger than 59, the study shows.

The study doesn't prove that caffeine caused any heart attacks. Also, coffee intake was actually linked to a lower risk of heart attack in people with fast caffeine metabolism.

"We find that the increased risk is in only those who cannot get rid of it very quickly," says El-Sohemy. He and his colleagues found "absolutely no increased risk in fast caffeine metabolizers. "In fact, there was even a protective effect [for those people], at moderate intakes," El-Sohemy says.

"I think one of the take-home messages is that not everybody responds in the same manner," he observes. "We apply a one-size-fits-all model to advice that we give, but what we're finding is that some people can respond in the opposite direction than others."

"In terms of the specifics of coffee and heart disease, it appears that drinking one cup a day is not associated with any harmful effects, regardless of what a person's genetic makeup is," El-Sohemy says. "And drinking four or more certainly doesn't have any beneficial effects for anybody" -- at least, in this particular study.