TOKYO, Dec 21 (Reuters Life!)

Elderly people who drink several cups of green tea a day are less likely to suffer from depression, probably due to a "feel good" chemical found in this type of tea, Japanese researchers said.

Several studies have linked drinking green tea to lessening psychological problems.

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

Green tea is widely consumed in many Asian countries, including China and Japan.

Niu and the team investigated 1,058 relatively healthy elderly men and women. About 34 percent of the men and 39 percent of the women had symptoms of depression, according to the study that was published in the December issue of the American Journal of Clinical Nutrition.

A total of 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 rest reported having one or fewer cups daily.

According to the researchers, the apparent effect of drinking more green tea on alleviating symptoms of depression did not fade after they factored in social and economic status, gender, diet, history of medical problems and use of antidepressants.

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 tranquillising 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 needed to confirm whether greater green tea intake actually has antidepressant effects, the researchers said.