Chronic coffee consumption and respiratory disease: A systematic review.

PURPOSE: The widespread consumption of coffee means that any biological effects from its use can lead to significant public health consequences. Chronic pulmonary diseases are extremely prevalent and responsible for one of every six deaths on a global level.
METHODS: Major medical databases for studies reporting on the effects of coffee or caffeine consumption on a wide range of non-malignant respiratory outcomes, including incidence, prevalence, evolution or severity of respiratory disease in adults were searched. Studies on lung function and respiratory mortality were also considered.
RESULTS: Fifteen studies, including seven cohort, six cross-sectional, one case control and one randomized control trial were found. Coffee consumption was generally associated with a reduction in prevalence of asthma. The association of coffee with natural honey was an effective treatment for persistent post-infectious cough. One case-control study found higher risk of chronic obstructive pulmonary disease (COPD) with coffee consumption. No association was found with the evolution of COPD or sarcoidosis. Coffee was associated with a reduction in respiratory mortality, and one study found improved lung function in coffee consumers. Smoking was a significant confounder in most studies.
CONCLUSIONS: Coffee consumption was associated with some positive effects on the respiratory system. There was however limited available evidence, mostly from cross sectional and retrospective studies. The only prospective cohort studies were those reporting on respiratory mortality. These results suggest that coffee consumption may be a part of a healthy lifestyle leading to reduced respiratory morbidity.