But the results of a new study published in the January 2001 issue of the Journal of Epidemiology and Community Health suggest that risk may be far higher than previously thought. The same study, however, indicates that coffee may protect against bladder cancer, especially among smokers. Coffee-drinking smokers, on the other hand, were only three times more at risk.
Coffee thus appears to somehow dilute the harmful effect of tobacco use on the bladder.
Previous studies have suggested that caffeine might discourage mutations from forming, perhaps by inducing activity in an enzyme known as CYP1A2. But only further research will reveal exactly how coffee consumption protects against this disease.