Women who drink four or more cups of coffee a day can lower their risk of depression, a U.S. study out Tuesday showed.
Researchers from the Harvard School of Public Health, Boston, found that women who drink four or more coffees a day had a 20 percent lower risk of developing clinical depression than those who consumed one cup of coffee per week or less.
Women who consumed two to three cups per day had a 15 percent decreased risk of developing depression, according to the study.
The benefits only seem to be associated with drinking caffeinated coffees. There were no similar trends found with decaffeinated coffee, or other caffeinated drinks such as tea or soda.
"Our results support a possible protective effect of caffeine, mainly from coffee consumption, on risk of depression," lead author Michel Lucas said. "Further investigations are needed to confirm this finding and to determine whether usual caffeinated coffee consumption may contribute to prevention or treatment of depression."
The research, published in the Archives of Internal Medicine journal, was based on a 10-year study of 50,739 American women who took part in the Nurses' Health Study, a major health and lifestyle investigation.