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.