BMC Public Health 2007, 7:149 http://www.biomedcentral.com/1471-2458/7/149 We found no association between early menopause and alcohol or coffee consumption. However, the crude OR showed that coffee consumption is associated with an early onset of menopause, which is consistent with Nagata et al.'s findings [9]. Nagata et al. adjusted for a number of factors, but not educational level or smoking, which we found to be important confounders of coffee consumption. When we adjusted for these factors, coffee was no longer associated with the onset of menopause, which is consistent with the findings of other studies [17,33]. Other studies have reported that a moderate intake of alcohol is associated with later menopause [10,12,33]. However, only one of these studies adjusted for both smoking and education. Our analysis showed that educa- tion is an important confounder of the association between alcohol consumption and early menopause. If adjusted only for smoking and coffee consumption, alco- hol was associated with early menopause (adj. OR, 0.56; 95% CI, 0.32–0.98, data not shown), but this association was no longer significant when adjusted for educational level. Conclusion Our study showed an association between current smok- ing and early onset of menopause, and that the earlier a woman stops smoking, the more protection she derives with respect to an early onset of menopause. Passive smoking and alcohol or coffee consumption were not sig- nificantly associated with early onset of menopause. Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions TFM, SGI, JS and EB participated in the design of the study and in writing the manuscript. TFM performed the statistical analyses All authors read and approved the final manuscript. 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