Boston, MA - A large study attempting to shed light on the risks posed by coffee suggest that coffee consumption does not increase the risk of coronary heart disease [1]. Researchers found no risk in men or women, and no association was observed for total caffeine intake, decaffeinated coffee, or tea, providing strong evidence that concerns about the risks of CHD associated with long-term caffeine consumption are unwarranted.

"The bottom line is that coffee is not a risk factor for heart disease," senior investigator Dr Frank Hu (Harvard Medical School, Boston, MA) told heartwire. "People should not make a decision regarding coffee consumption based on a perception of heart-disease risk. People who are regular coffee drinkers don't need to give up coffee to reduce their cardiovascular risk factors. For people who don't drink coffee, I don't think we want to encourage them to pick up the habit, but it's really a nonissue for cardiovascular disease."

Dr Esther Lopez-Garcia (Universidad Autonoma de Madrid, Spain) is the lead author of the study; results are published online April 24, 2006 in Circulation.

The debate over the possibly adverse effects of coffee has been going on for some time. Since the 1970s, when some of the first case-control studies found an increased risk of heart disease among coffee drinkers, researchers have studied the relationship between coffee consumption and cardiovascular disease. Subsequent cohort studies did not find an association between coffee consumption and the risk of CHD, Hu notes, but many of these studies were short term. Results from recent epidemiological studies have been mixed, he added.

In light of these discrepancies, including recent findings suggesting that coffee consumption might protect against diabetes mellitus, the researchers sought to assess the association between coffee intake and risk of CHD in the Health Professionals Follow-up Study (HPFS) and Nurses' Health Study (NHS), two large, ongoing, cohort studies. Coffee consumption was first assessed by questionnaire in 1986 for men and in 1980 for women and repeated every two to four years. After excluding patients with cardiovascular disease or cancer at baseline, investigators followed 44 005 men and 84 888 women until 2000.

Overall, there was no indication of an increase risk of CHD with coffee consumption. Stratification by smoking status, alcohol consumption, history of type 2 diabetes, and body-mass index gave similar results. There appeared to be a slight protective effect with high coffee consumption (>6 cups/day), but this finding lacked statistical significance and must be considered hypothesis-generating for future studies, said Hu. There was also a slight decrease in risk for fatal CHD in both men and women who consumed large amounts of coffee, but again, Hu said the number of fatal CHD events is too small to be significant.

An analysis looking only at recent coffee consumption showed no association between shorter-term intake and CHD risk. Investigators also looked for an association between decaffeinated coffee, tea, and non-paper-filtered coffee and CHD risk, but none was observed.

In addition, investigators found no adverse effects of coffee consumption—caffeinated or decaffeinated—on the lipid profile of approximately 1000 men and women studied. Hu said these findings are reassuring in light of previous data, presented at the American Heart Association 2005 Scientific Sessions and reported by heartwire at that time, suggesting that decaffeinated coffee raised LDL-cholesterol levels. While coffee is known to cause adverse effects, Hu suspects many of these effects are transient.

"Caffeine has been shown to increase blood pressure, heart rate, and blood sugar levels in the short term, but it is possible that people get used to coffee very quickly and develop tolerance," said Hu. "This is why it has always been difficult to extrapolate short-term studies long term."

Recently, a study published in the Journal of the American Medical Association, also reported by heartwire, showed that slow metabolizers of caffeine were at an increased risk of nonfatal MI [2]. These data suggested that a genetic polymorphism appears to make some individuals, and not others, susceptible to the detrimental effects of caffeine consumption. Hu said he was intrigued by these findings and that his group plans to go back to look for the same genetic interaction in various cohorts. In the meantime, he said those findings have not been validated and it is still too early to recommend against coffee consumption based on genotype.