Abstract
BackgroundThe 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.MethodsWe 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).ResultsSeventeen 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.ConclusionsTea consumption is inversely and linearly related to the risk of cognitive disorders. More studies are needed to further confirm our findings.
Highlights
In the rapidly aging societies around the world, cognition-related diseases, such as mild cognitive impairment, cognitive decline, dementia and Alzheimer’s disease (AD), are gradually increasing [1, 2]
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% confidence intervals (CIs): 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)
Summary
In the rapidly aging societies around the world, cognition-related diseases, such as mild cognitive impairment, cognitive decline, dementia and Alzheimer’s disease (AD), are gradually increasing [1, 2]. It has been indicated that the intake of certain diet and nutrients, such as fruit and vegetable [4], Mediterranean diet [5], omega-3 fatty acids [6], vitamin C [7], vitamin E [8], milk [9], coffee [10], and light to moderate amounts of alcohol [11], is related to the reduced risk of cognitive disorders and dementia. 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
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