Women who drink four or more cups of coffee a today are less likely to develop depression, new research suggests.
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.
The study was conducted by questioning 50,739 women who participated in the Nurses' Health Study. The study tracked the health of the women from 1980 to 2004, using detailed questionnaires to keep a record of their coffee consumption. Just over 2,600 women developed depression during this time.
The study also suggests women who drink three cups of coffee a day were 15 percent less likely to develop depression than those who drank one cup or less a week.
Decaffeinated coffee does not appear to have the same effect, nor do other sources of caffeine, including soft drinks and tea.
Publishing their findings in the Archives of Internal Medicine, the study authors wrote: "In this large prospective cohort of older women free of clinical depression or severe depressive symptoms at baseline, risk of depression decreased in a dose-dependent manner with increasing consumption of caffeinated coffee."
NHS figures suggest that about one in four women will require treatment for depression at some point during their lives.