Women with heart disease who down a few cups of coffee each day tend to live as long as those who avoid the beverage, according to a study.
The results, reported in the American Journal of Clinical Nutrition, add to already mixed findings on whether caffeinated coffee is a hazard for people at high risk of cardiovascular problems.
The study, which followed nearly 12,000 U.S. nurses with a history of heart disease or stroke, found that those who regularly drank caffeinated coffee were no more likely to die than non-coffee drinkers during the study period, which spanned more than 20 years for some participants.
In fact, no link was found between a woman's coffee intake and her risk of death from heart attack, stroke or any other cause—and this was true of even of women who drank four or more cups of coffee each day.
"Our results suggest that coffee drinking is okay for patients with cardiovascular disease, but it would be desirable to replicate our results in other populations," said lead researcher Esther Lopez-Garcia, of Universidad Autonoma de Madrid in Spain.
The results came from the long-running Nurses' Health Study, which began tracking more than 100,000 female nurses in 1976. The researchers focused on 11,697 women who developed heart disease or had a stroke sometime between 1976 and 2002.
Of those women, 62 percent continued to drink caffeinated coffee after their diagnosis.
Overall, 1159 women had died by 2004. That risk was no greater among coffee drinkers than non-drinkers, including women who drank at least four cups a day.
One possibility is that women in relatively worse health might choose to avoid caffeinated coffee, the study authors noted. But they found no evidence that changes in women's coffee intake after their heart complication or stroke explained the findings.
They also accounted for factors like age, weight, high blood pressure and diabetes, and still found no association between coffee consumption and the risk of death.
The findings, Lopez-Garcia said, support the idea that people with heart disease who already drink coffee don't have to give it up.
But she noted that one problem with the current study is that all of the subjects were nurses, so they might not be representative of women with heart disease in general.
The study also can't discount coffee as a possible cause of cardiovascular problems, at least in some people.
"What this study shows is that, in a general population, there's no obvious harm, or benefit, to consuming coffee after a heart attack," said Ahmed El-Sohemy, an associate professor at the University of Toronto who has studied coffee intake and cardiac health.
"What this study doesn't tell us is who might coffee be harmful to, and who might benefit from it."
Some research has linked coffee drinking to increased risks of high blood pressure in people who are naturally slow metabolizers of caffeine. But the reverse pattern has been seen in people who quickly process caffeine—more coffee, lower heart risks.
Recent studies have pointed to the importance of genetics, El-Sohemy added, cautioning that it's hard to make individual recommendations on coffee intake because of these genetic variations in metabolizing.
"I don't see how any results can be interpreted from studies that don't take this genetic difference into account."