Habitual Tea Drinking is Associated with Reduced Odds of Restrictive Spirometry Pattern in Non-smokers

Background: Restrictive spirometry pattern (RSP) is found to be associated with an increased risk of all-cause and cardiovascular mortality. This study was aimed to examination of the association between tea consumption and RSP in smokers and non-smokers.MethodsA total of 14,997 eligible subjects were analyzed after excluding individuals with (1) age <20 years, (2) a history of asthma, lung cancer, tuberculosis, or any chest structural deformities, or (3) a history of connective tissue diseases. RSP was defined as FVC<80% of the predicted value and an FEV1/FVC ratio ≥ 70%. One traditional Chinese teapot containing 120ml was defined as one “cup.” Habitual tea consumption was defined as 120mL/d or more for at least 1 year. To evaluate the effects of cumulative dosage of tea over time, the variable “cup-year” was obtained by multiplying the number of daily cups of tea by the number of years one has consumed. ResultsThe amount of daily tea consumption and the prevalence of habitual tea drinking were significantly higher in the non-RSP group (65 ± 191 vs. 110 ± 242 mL, p < 0.001; 15.1% vs. 24.0%, p< 0.001). In multiple logistic regression, habitual tea drinker (OR = 0.75, CI 0.63-0.89, p < 0.01) and tea consumption no less than 3 cup-year (OR = 0.74, CI 0.61-0.89, p < 0.01) were associated with a lower risk of RSP in non-smoking group while the association was insignificant in the smoking group.ConclusionHabitual tea drinking and tea consumption of at least three cup-years were associated with a reduced risk of RSP in the non-smokers, but not in the smokers.