Background: Although green tea or its constituents might reduce psychological stress, the relation between green tea consumption and psychological distress has not been investigated in a large-scale study.
Objective: Our aim was to clarify whether green tea consumption is associated with lower psychological distress.
Design: We analyzed cross-sectional data for 42,093 Japanese individuals aged >/=40 (40 and older) from the general population. Information on daily green tea consumption, psychological distress as assessed by the Kessler 6-item psychological distress scale, and other lifestyle factors was collected by using a questionnaire. We used multiple logistic regression analyses adjusted for age, sex, history of disease, body mass index, cigarette smoking, alcohol consumption, time spent walking, dietary factors, social support, and participation in community activities to investigate the relation between green tea consumption and psychological distress.
We classified 2,774 (6.6%) of the respondents as having psychological distress (Kessler 6-item psychological distress scale 13/24 or more).
There was an inverse association between green tea consumption and psychological distress in a model adjusted for age and sex.
Although the relation was largely attenuated when possible confounding factors were adjusted for, a statistically significant inverse association remained.
The odds ratio (with 95% CI) of developing psychological distress among respondents who consumed 5 or more cups of green tea a day was 0.80 (0.70, 0.91) compared with those who consumed less than 1 cup a day. [Note an odds ratio of 0.1 would indicate no difference. The OR of 0.80 indicates those who drank more tea were 20% less likely to be distressed on average.]
These relations persisted when respondents were stratified by social support subgroups or by activities in communities.
Conclusion: Green tea consumption was inversely associated with psychological distress [more tea, less distress] even after adjustment for possible confounding factors.
Source: American Journal of Clinical Nutrition, Sep 30, 2009. PMID: 19793850, by Hozawa A, Kuriyama S, Nakaya N, Ohmori-Matsuda K, Kakizaki M, Sone T, Nagai M, Sugawara Y, Nitta A, Tomata Y, Niu K, Tsuji I. Division of Epidemiology, Department of Public Health and Forensic Medicine, and Department of Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai, Japan. [E-mail: firstname.lastname@example.org]