Tea Consumption and Risk of Chronic Obstructive Pulmonary Disease in Middle-Aged and Older Singaporean Adults

Objective: The anti-oxidant and anti-inflammatory actions of phytochemicals and the smooth muscle relaxant actions of theophylline present in tea may confer pulmonary protection and reduce COPD risk. We investigated tea consumption (black, oolong, or green) association with COPD risks in a population-based cohort study of older adults aged >= 55. Methods: GOLD criteria was used to identify prevalent and incident cases of COPD (FEV1 /FVC <0.70) among 4617 participants and 920 participants free of COPD at baseline who were assessed at follow-up 4.5 years later. Results: Prevalent cases of COPD consumed less tea than their non-COPD counterparts. Estimated odds ratio (OR) and 95% confidence intervals (95% CI) of association with prevalent COPD, adjusted for age, sex, ethnicity, housing type, smoking, alcohol, physical activity and BMI declined across tea consumption levels (p-trend=0.048), and was lowest for >= 3 cups/day (OR=0.77, 95% CI=0.61-0.96). The cumulated incidence of COPD declined across tea consumption categories (p-trend=0.012) and the lowest OR of association (OR=0.35, 95% CI=0.17-0.69) with consuming >= 3 cups/day after co-variate adjustment. Conclusion: Different kinds of tea showed similar non-significant trends of associations but appeared to be strongest for green tea. Tea consumption in this Asian population was associated with lowered COPD prevalence and incidence.