Background and aims: During the past three decades the relationship between habitual coffee drinking and coronary heart disease (CHD) has been assessed in numerous studies, with conflicting results. The aim of this study was to systematically examine the data published on the association between habitual coffee consumption and risk of CHD.
Methods and results: Thirteen case-control and 10 cohort studies were included. Case-control studies incorporated 9487 cases of CHD and 27,747 controls, and cohort studies included a total of 403,631 participants that were followed for between 3 and 44 years. The summary of odds ratios (OR) for the case-control studies showed statistically significant associations between coffee consumption and CHD for the highest intake group (>4 cups/day), OR 1.83 (95% CI 1.49-2.24; P<0.0001), and for the second highest category (3-4 cups/day), OR 1.33 (95% CI 1.04-1.71; P<0.0001), while no significant association emerged for low daily coffee intake (< or =2 cups/day), OR 1.03 (95% CI 0.87-1.21; P=0.45). The analysis of long-term follow-up cohort studies did not show any association between the consumption of coffee and CHD, with a relative risk (RR) of 1.16 (95% CI 0.95-1.41; P=0.14) for the highest category, and 1.05 (95% CI 0.90-1.22; P=0.57) and 1.04 (95% CI 0.90-1.19; P=0.60) for the second and third highest categories, respectively. These results did not differ substantially when controlling for region of origin, fatal and non-fatal events, year of publication, and number of years of follow-up.
Conclusions: Despite a significant association between high consumption of coffee and CHD reported among case-control studies, no significant association between daily coffee consumption and CHD emerged from long-term follow-up prospective cohort studies.