Coffee consumption and risk of coronary heart diseases: a meta-analysis of 21 prospective cohort studies.

Background: A large amount of cohort studies addressed coffee consumption and risk of coronary heart disease (CHD) and yielded inconsistent results. We conducted a meta-analysis to estimate the pooling effects.
Methods: We searched for all published English articles indexed in MEDLINE or PubMed from January 1966 to January 2008. Twenty-one independent prospective cohort studies, which tested CHD risk by coffee consumption, were identified. A general variance-based method was used to pool the relative risks (RR). 15,599 cases from 407,806 participants were included in pooling the overall effects.
Results: As compared to the light coffee consumption (<1 cup/d in US or <or=2 cups/d in Europe), under the random-effects model, the pooled CHD RRs (95% CI) for all studies combined were 0.96 (0.87-1.06), 1.04 (0.92-1.17) and 1.07 (0.87-1.32) for the moderate (1-3 or 3-4 cups/d), heavy (4-5 or 5-6 cups/d) and very heavy (>or=6 or >or=7 cups/d) categories of coffee consumption (all p>0.05); Moderate coffee consumption showed significantly lower CHD RR (95% CI) of 0.82 (0.73-0.92) (p<0.001) in women, and of 0.87 (0.80-0.86) (p=0.001) in men and women followed <or=10 years.
Conclusion: Our findings do not support the hypothesis that coffee consumption increases the long-term risk of coronary heart disease. Habitual moderate coffee drinking was associated with a lower risk of CHD in women.