New research from Harvard School of Public Health shows that drinking 2-4 cups of caffeinated coffee each day can lower suicide risk among adults.
The study, published in The World Journal of Biological Psychiatry, compared three extensive U.S. health studies that included a total of 43,599 men enrolled in the Health Professionals Follow-Up Study (HPFS) from 1988 to 2008; 73,820 women in the Nurses’ Health Study (NHS) from 1992 to 2008, and 91,005 women in the Nurses’ Health Study II (NHSII) from 1993 to 2007.
Consumption of caffeine (from tea, soda and chocolate), coffee and decaffeinated coffee was evaluated among study participants every four years through a questionaire. Amoung all three studies, coffee accounted for the majority of caffeine consumed at 71% of the total.
Cause of death was tracked during the study period and by reviewing death certificates; a total of 277 deaths were the result of suicide.
The study showed that the risk of suicide among adults drinking 2-4 cups of coffee (the equivalent of about 400 mg of caffeine) a day was 50% less than those who drank decaffeinated coffee or less of caffeinated coffee.
Lead researcher Michel Lucas, from the Department of Nutrition at the Harvard School of Public Health, said in a statement: “Unlike previous investigations, we were able to assess association of consumption of caffeinated and non-caffeinated beverages, and we identify caffeine as the most likely candidate of any putative protective effect of coffee.”
Although, drinking more than 4 cups of coffee didn’t drop the suicide risk lower.
“Overall, our results suggest that there is little further benefit for consumption above 2-3 cups/day or 400 mg of caffeine/day,” the authors wrote.
However, in a prior HSPH coffee-depression study, scientists observed a maximal effect among those who drank four or more cups per day, reports PsychCentral. Finnish researchers actually found a higher risk of suicide among people drinking eight or nine cups per day. Few participants in the two HSPH studies drank that much coffee, so the studies did not address the impact of six or more cups of coffee per day.
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