a1 Department of Epidemiology and Prevention, Clinical Research Center, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan
a2 Department of Applied Biological Chemistry, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
a3 Faculty of Human Environmental Science, Fukuoka Women's University, Fukuoka, Japan
Objective To examine the association between the consumption of green tea, coffee and caffeine and depressive symptoms.
Design Cross-sectional study. Consumption of green tea and coffee was ascertained with a validated dietary questionnaire and the amount of caffeine intake was estimated from these beverages. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale. Multiple logistic regression analysis was performed to compute odds ratios and 95 % confidence intervals for depressive symptoms with adjustments for potential confounders.
Setting Two workplaces in north-eastern Kyushu, Japan, in 2009.
Subjects A total of 537 men and women aged 20–68 years.
Results Higher green tea consumption was associated with a lower prevalence of depressive symptoms. Compared with participants consuming ≤1 cup/d, those consuming ≥4 cups green tea/d had a 51 % significantly lower prevalence odds of having depressive symptoms after adjustment for potential confounders, with significant trend association (P for trend = 0·01). Further adjustment for serum folate slightly attenuated the association. Coffee consumption was also inversely associated with depressive symptoms (≥2 cups/d v. <1 cup/d: OR = 0·61; 95 % CI 0·38, 0·98). Multiple-adjusted odds for depressive symptoms comparing the highest with the lowest quartile of caffeine consumption was OR = 0·57 (95 % CI 0·30, 1·05; P for trend = 0·02).
Conclusions Results suggest that higher consumption of green tea, coffee and caffeine may confer protection against depression.
(Received September 03 2012)
(Revised November 30 2012)
(Accepted January 23 2013)
(Online publication March 04 2013)