June 16, 2011 (Madrid, Spain) — Previous studies on the influence of coffee consumption on cardiovascular disease have shown conflicting results, but a new analysis from the massive Nurses' Health Study suggests that coffee has no effect on the cardiovascular risk of women with known cardiovascular disease .
"The results of this study support the idea that people with heart disease who drink coffee do not need to stop drinking it, because this beverage does not increase their risk of having a fatal event," study lead author Dr Esther Lopez-Garcia (Universidad Autonoma de Madrid, Spain) told heartwire .The study is published online May 13, 2011 in the American Journal of Clinical Nutrition.
Lopez-Garcia and colleagues note that heavy coffee consumption was shown to increase the risk of sudden cardiac death in a population case-control study , but another study of all-cause mortality in patients hospitalized for acute myocardial infarction (MI) found a strongly protective effect of heavy coffee consumption after three months but not at four years . A three-year study found no association between the cumulative consumption of nonfiltered coffee and the risk of a second cardiovascular event , and a 10-year prospective study in Sweden found that filtered coffee consumption in the year prior to an acute MI appeared to reduce the risk of all-cause mortality after the event . As reported by heartwire , a small study in Germany showed that drinking coffee improved markers of subclinical inflammation and oxidative stress, while increasing HDL-cholesterol levels.
Lopez-Garcia et al looked at two years of follow-up data from 11 697 women in the long-running Nurses' Health Study to determine whether there was a link between filtered caffeinated coffee consumption and all-cause and cardiovascular mortality. Coffee consumption is tracked on the study's food-frequency questionnaire, which is repeated every two to four years, so the study was able to track coffee consumption both before and after an adverse event. The subjects were categorized by how often they drank an 8-oz cup of coffee: one or less per month, one to 16 per month, five to seven per week, two to three cups per day, or four or more cups per day.
In the study group, there were 1159 deaths, including 579 attributed to cardiovascular disease. The relative risk of all-cause mortality was about the same across categories of cumulative coffee consumption (p for trend=0.91), as was the risk of cardiovascular mortality (p for trend=0.76). There was also no association between caffeine intake and either total or cardiovascular mortality.
This study adds to previous studies of coffee and heart disease because it focused on women with less severe heart-disease symptoms--usually just angina alone--and it was the first such study to look at coffee drinking both before and after an event, study coauthor Dr Kenneth Mukamal (Beth Israel Deaconess Hospital, Boston, MA) told heartwire . This study finds "that coffee is quite neutral for typical women with CVD who primarily have angina or have undergone revascularization," Mukamal said. "It's still possible that people with acute MI have some benefit from coffee, but the bulk of the evidence increasingly seems to be that coffee has little benefit or harm in secondary-[prevention] populations like this."
Lopez-Garcia added that "because of the long follow-up and large size of the cohort, we had statistical power to detect even small detrimental effects of coffee, and we did not find any increase in the risk of death among coffee drinkers."
The study looked at female nurses because the Nurses' Health study is a large available data set. But nurses are a "special population because of their knowledge of diseases and lifestyles," Lopez-Garcia said. "So extrapolation of the results to the general population must be done with caution." Also, although some previous studies have assessed the effect of coffee on healthy people, "we need more research on the effect of coffee among patients with a diagnosed disease [and] more research on the effect of specific types of coffee on the risk of diseases, because we now know that filtered coffee is different from unfiltered, and they may affect health in a different way," she said.
Lopez-Garcia also cautioned that, although coffee does not appear to contribute to cardiovascular risk, "these patients still need to check with their doctor if they have insomnia, anxiety, or uncontrolled blood pressure--problems that can be worsened by coffee. Because of these side effects of coffee, it is prudent to recommend moderate coffee consumption."
The study was supported by the National Institutes of Health, the Ministry of Health in Spain, and the American Heart Association.
Heartwire from Medscape © 2011 Medscape, LLC
Cite this: Coffee Consumption Generally Safe in Women With CV Disease - Medscape - Jun 17, 2011.