A meta-analysis of three large studies on coffee consumption, published in the World Journal of Biological Psychiatry, found that drinking two to four cups of caffeinated coffee daily was associated with a 50 percent reduced suicide risk among adults, compared to drinking one cup or less of caffeinated coffee, or decaf.
Drinking more than four cups a day did not lead to any further decrease in suicide risk. In all, the studies included more than 208,000 Americans, whose caffeine consumption was analyzed from a variety of sources, including coffee, tea, soda and chocolate. Coffee accounted for 71 percent of the total caffeine consumed. According to the authors:
“These results from three large cohorts support an association between caffeine consumption and lower risk of suicide.”