Elderly men and women who sip on several cups of green tea a day may be less likely to have the blues, hint findings of a study from Japan.

Dr. Kaijun Niu, at Tohoku University Graduate School of Biomedical Engineering in Sendai, and colleagues found men and women aged 70 and older who drank four or more, versus one or fewer, cups of green tea daily were 44 percent less likely to have symptoms of depression.

Several prior studies have linked green tea consumption to reduced levels of psychological distress. This led Niu and colleagues to look at associations between drinking green tea and symptoms of depression in 1,058 relatively healthy elderly individuals.

About 34 percent of the men and 39 percent of the women had symptoms of depression, according to a report in the American Journal of Clinical Nutrition. These symptoms were severe in about 20 percent of the men and in about 24 percent of the women.

Overall, 488 participants said they drank four or more cups of green tea a day, 284 said they downed two to three cups daily and the remaining 286 reported having one or fewer cups daily.

According to the investigators, the apparent protective effect of greater green tea consumption on symptoms of depression did not fade after they factored in social and economic status, gender, diet, history of medical problems, use of antidepressant medications, smoking, and physical activity.

By contrast, there was no association between consumption of black or oolong tea, or coffee, and lower symptoms of depression.

A green tea component, the amino acid theanine, which is thought to have a tranquilizing effect on the brain, may explain the "potentially beneficial effect" shown in the current study, Niu noted in an email to Reuters Health.

However, further studies are necessary to confirm whether greater green tea intake actually has antidepressant effects. Therefore, Niu shied away from recommending greater green tea intake to minimize depression among the elderly.