The Harvard study of nearly 51,000 nurses, average age 63, found that women who drank two to three cups a day had a 15 percent lower risk of depression as compared to those who drank a single cup a week. Those who drank four or more cups daily had a 20 percent lower risk.
Published this week in the Archives of Internal Medicine, the study examined whether drinking coffee or caffeinated beverages was associated with risk of depression. Previous research, including a small study of men, indicated there was a link.
None of the women were depressed at the start of the study in 1996. The researchers measured the women's caffeine consumption over 10 years and found a relationship between coffee intake and depression risk, but not with other sources of caffeine, like soda or tea. There was also no association with decaffeinated coffee.
Because depression affects twice as many women as men -- one out of every five women will suffer depression during her lifetime -- the researchers wrote that they were interested in identifying risk factors for depression among women, as well as new preventive strategies.
The authors caution that this observational study "cannot prove that caffeine or caffeinated coffee reduces the risk of depression, but only suggests the possibility of such a protective effect." After all, maybe women who drink more coffee engage in more activities, or are more social, or work longer hours, all of which might affect their risk of depression.
Still, combined with other research on coffee's health benefits, "there seem to exist no glaringly deleterious health consequences to coffee consumption."
Translation: Have a cup. It can't hurt.
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