Coffee may do more than merely perk you up in the morning: Over time, it might also reduce your risk of depression. A new Harvard study reports that women consuming two or three cups of regular coffee per day were 15% less likely to develop depression over a follow-up period of 10 years than those drinking one cup a day or less. Those drinking four cups a day were at 20% lower risk.
Tammy Scott, PhD, an assistant professor at the Friedman School and adjunct scientist at Tufts HNRCA Nutrition and Neurocognition Laboratory, says, Very little is known about the health consequences of long-term coffee consumption. This study is significant in that its the first prospective large-scale study of the effects of caffeine and coffee on mental health in women.
Caffeine is the most frequently used central nervous system stimulant in the world, and approximately 80% of consumption is in the form of coffee. An earlier study among men in Finland suggested an association between coffee consumption and reduced depression risk. But women are at twice the risk of depression as men-about one in five US women will suffer symptoms during their lifetime-so researchers sought to test whether coffee might also benefit women.
Michel Lucas, PhD, RD, of the Harvard School of Public Health, and colleagues compared caffeine habits and depression symptoms among 50,739 women, average age 63, who participated in the Nurses Health Study. The women were free of depression at the start of the study in 1996. Researchers measured caffeine consumption, from coffee and other sources, through questionnaires completed from 1980 through 2004. During a 10-year follow-up period, researchers identified 2,607 new cases of depression.
The benefits of very high levels of coffee intake couldnt be accurately studied because only a tiny fraction of participants drank more than six cups daily. Decaffeinated coffee was not linked to lower risk.
Despite the implication that caffeine counters depression, the scientists cautioned that their study cant prove a cause and effect relationship.
Is the evidence strong enough that women who dont drink coffee should consider taking up the habit-and one-cup daily drinkers should up their intake? Tufts Scott cautions, Although the results are promising, its too soon to recommend that women either start or increase their consumption of coffee. More studies are needed before we can establish that caffeinated coffee has a protective effect against depression.
TO LEARN MORE: Archives of Internal Medicine, Sept. 26, 2011; abstract at archinte.ama-assn.org/cgi/content/short/171/17/1571.