It may seem rather self-evident that a hot cup of tea would be the perfect de-stresser. Now, a group of researchers from the University of Tokyo has tested the idea that tea - specifically green tea - reduces stress, and found some surprising results.

Niu et al., writing in the December 2009 issue of the American Journal of Clinical Nutrition, looked at the association between green tea and depressive symptoms in 1,058 elderly Japanese subjects age 70 or greater.¹ A self-administered questionnaire was used to determine green tea intake. The 30-item Geriatric Depression Scale was used to evaluate depressive symptoms. 

The odds ratios for mild and severe depressive symptoms were 0.96 for those subjects who drank two to three cups of green tea per day (95 percent confidence interval [CI], 0.66 - 1.42). For those subjects who consumed four or more cups of green tea per day, the odds ratios were 0.56 (95 percent CI, 0.39 - 0.81; P = 0.001).

According to the researchers, "A more frequent consumption of green tea was associated with a lower prevalence of depressive symptoms in the community-dwelling older population."

Another study from the same research group, published a month earlier in the same journal, showed similar results.² In this second study, researchers analyzed data on daily green tea consumption for 42,093 Japanese individuals age 40 or greater. Psychological distress was measured on the Kessler 6-item psychological distress scale. Information on other lifestyle factors was also collected with the questionnaire. Overall, 6 percent of the respondents were rated as having psychological distress.

The researchers found an inverse association between green tea consumption and psychological distress in fact, the odds of subjects who drank five or more cups per day of green tea developing psychological distress was significantly lower than among those who consumed one cup or less per day. In this study, the researchers concluded, "Green tea consumption was inversely associated with psychological distress even after adjustment for possible confounding factors."

So the next time you are feeling yourself getting frazzled, brew up some green tea. It will do you a world of good.

References

1. Niu K, Hozawa A, Kuriyama S, et al. Green tea consumption is associated with depressive symptoms in the elderly. Am J Clin Nutr 2009 Dec;90(6):1615-22.
2. Hozawa A, Kuriyama S, Nakaya N, et al. Green tea consumption is associated with lower psychological distress in a general population: the Ohsaki Cohort 2006 Study. Am J Clin Nutr 2009 Nov;90(5):1390-6.