Green Tea Lowers the Risk of Depression, at least in Japan

Green tea is becoming more popular in Western countries, as its healthful properties become more widely recognized.  A Japanese study has just shown that increased green tea consumption by older people is associated with a lower prevalence of depressive symptoms.  The report is in the American Journal of Clinical Nutrition. 

Over 1,000 community-dwelling Japanese aged 70 or more were surveyed by questionnaire.  Green tea intake was assessed based on replies to specific questions, and depressive symptoms were measured using a 30-item scale (the Geriatric Depression Scale).  Subjects were assumed to behave depressive symptoms if they were taking antidepressant medication.  A score of 11 on the scale indicated mild to moderate depressive symptoms, and a 14 or more score meant severe depressive symptoms.

Mild to moderate depressive symptoms were found in 34% of the enrollees, and severe symptoms in 20%.  The likelihood of mild to moderate symptoms were slightly, but not significantly, decreased in those people who drank to 3 cups of green tea daily, compared with those who drank one or less cups a day.  However, in those subjects who drank 4 or more cups of tea daily, the likelihood was almost halved (56% less).  Similar results were found for severe depressive symptoms.

You probably noted we haven’t talked about ‘depression’, but ‘depressive symptoms’.  This is because the Geriatric Depression Scale isn’t designed to make a clinical diagnosis of depression.  But the findings are not really changed by these semantic differences.  Green tea, in fairly large amounts (4 or more cups a day), seems to reduce the likelihood of depressive symptoms by almost half.  Now we need a prospective study or randomized trials are needed to place this finding on a firmer footing.