Association between tea consumption and risk of cognitive disorders: A dose-response meta-analysis of observational studies
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Xueying Liu1,2, Xiaoyuan Du3, Guanying Han4 and Wenyuan Gao1
1School of Pharmaceutical Science and Technology, Tianjin University, Nankai District, Tianjin 300072, China
2Department of Pharmacy, The Third Affiliated Hospital of Jinzhou Medical University, Jinzhou 121001, China
3Department of Pathology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121001, China
4Department of Pharmacy, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121001, China
Wenyuan Gao, email: firstname.lastname@example.org
Keywords: tea consumption, cognitive disorders, dose-response, meta-analysis
Received: February 15, 2017 Accepted: March 29, 2017 Published: April 26, 2017
Background: The epidemiological evidence for a dose-response relationship between tea consumption and risk of cognitive disorders is sparse. The aim of the study was to summarize the evidence for the association of tea consumption with risk of cognitive disorders and assess the dose-response relationship.
Methods: We searched electronic databases of Pubmed, Embase, and Cochrane Library (from 1965 to Jan 19, 2017) for eligible studies that published in the international journals. A random-effects model was used to pool the most adjusted odds ratios (ORs) and the corresponding 95% confidence intervals (CIs).
Results: Seventeen studies involving 48,435 participants were included in our study. The meta-analysis showed that a higher tea consumption was associated with a significant reduction in the risk of cognitive disorders (OR=0.73, 95% CI: 0.65-0.82). When considering the specific types of tea consumption, the significantly inverse association is only found in green tea consumption (OR=0.64, 95% CI: 0.53-0.77) but not in black/oolong tea consumption (OR=0.75, 95% CI: 0.55-1.01). Dose-response meta-analysis indicated that tea consumption is linearly associated with a reduced risk of cognitive disorders. An increment of 100 ml/day, 300 ml/day, and 500 ml/day of tea consumption was associated with a 6% (OR=0.94, 95% CI: 0.92-0.96), 19% (OR=0.81, 95% CI: 0.74-0.88), and 29% (OR=0.71, 95% CI: 0.62-0.82) lower risk of cognitive disorders.
Conclusions: Tea consumption is inversely and linearly related to the risk of cognitive disorders. More studies are needed to further confirm our findings.
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