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Daily 3 cups of tea decrease risk of depression

Research question:
Does tea consumption decrease depression risk?

Study design:
This meta-analysis (review article) contained 11 observational studies (22,817 participants with 4,743 cases of depression).

The Begg rank correlation test and the Egger linear regression test indicated no evidence of publication bias [Begg’s test: Z = 0.06, p = 0.951; Egger’s test: t = -0.1, p = 0.925].

Results and conclusions:
The researchers found in the meta-analysis of 22,817 participants with 4,743 cases of depression, a significant 31% decrease [RR = 0.69, 95% CI = 0.63-0.75, I2 = 41.9%] in the risk of developing depression for higher tea consumption compared with low tea consumption. Significant means, there is a relationship at a 95% confidence interval.

The researchers found overall, higher tea consumption had a protective effect against depression in all subgroups except for study location.

The researchers found a significant reduced risk of 32% [RR = 0.68, 95% CI = 0.62-0.75] in Asia populations for higher tea consumption compared with low tea consumption. Significant because RR of 1 was not found in the 95% confidence interval ranging from 0.62 to 0.75. RR of 1 means no relationship or risk.

The researchers found in the dose-response analysis consisted of 10,600 participants with 2,107 cases of depression a significant 37% decrease [95% CI = 0.55-0.71, I2 = 0.00%] in the risk of developing depression for every 3 cups/day increment in tea consumption.

The researchers concluded that higher consumption of tea was associated with lower risk of depression. The dose-response analysis identified a linear association between tea consumption, and the risk of depression, with every 3 cups/day increment in tea consumption associated with a 37% decrease in the risk of depression.

Original title:
Tea consumption and the risk of depression: a meta-analysis of observational studies by Dong X, Yang C, […], Lu Z.

Link:
http://journals.sagepub.com/doi/full/10.1177/0004867414567759

Additional information of El Mondo:
Find more studies/information on tea consumption right here.