The aim of the study was to systematically review and analyze results from observational studies on coffee, caffeine, and tea consumption and association or risk of depression.
METHODS AND RESULTS:
Embase and Pubmed databases were searched from inception to June 2015 for observational studies reporting the odds ratios (ORs) or relative risks (RRs) and 95% confidence intervals (CI) of depression by coffee/tea/caffeine consumption. Random-effects models, subgroup and dose-response analyses were performed. Twelve studies with 23 datasets were included in the meta-analysis, accounting for a total of 346,913 individuals and 8146 cases of depression. Compared to individuals with lower coffee consumption, those with higher intakes had pooled RR of depression of 0.76 (95% CI: 0.64, 0.91). Dose-response effect suggests a non-linear J-shaped relation between coffee consumption and risk of depression with a peak of protective effect for 400 ml/d. A borderline non-significant association between tea consumption and risk of depression was found (RR 0.70, 95% CI: 0.48, 1.01) while significant results were found only for analysis of prospective studies regarding caffeine consumption (RR = 0.84, 95% CI: 0.75, 0.93).
This study suggests a protective effect of coffee and, partially, of tea and caffeine on risk of depression.