A new study by the Harvard School of Public Health seems to show that coffee drinkers have a lower risk of suicide than non-coffee drinkers.
Researchers reviewed data from three large caffeine studies and found that the risk of suicide for adults who drank two to four cups of caffeinated coffee per day was about half that of those who drank decaffeinated coffee or very little or no coffee.
The lower risk of depression and suicide in coffee drinkers can be explained by the fact that caffeine acts as a mild antidepressant. It boosts certain neurotransmitters in the brain like serotonin, dopamine and noradrenaline. Caffeine also stimulates the central nervous system.
The risk of suicide is reduced by about 50 percent in coffee drinkers, researchers found. However, researchers did not find any major difference in suicide rates among those drinking more than four cups a day — although they admit that the sample size of those drinking more than four cups and committing or attempting suicide was small.
However, in a previous HSPH coffee-depression study published in JAMA Internal Medicine, the investigators observed a maximal effect among those who drank four or more cups per day. One large Finnish study showed a higher risk of suicide among people drinking eight or nine cups per day. Few participants in the two HSPH studies drank such large amounts of coffee so the impact of six or more cups/day of coffee was not addressed in these two studies.