Association between coffee and green tea intake and pneumonia among the Japanese elderly: a case-control study

A large prospective cohort study in the United States examined the association between coffee intake and overall and cause-specific mortality and showed a inverse association between pneumonia and influenza deaths and coffee intake. In Japan, the mortality rate of pneumonia in elderly people is high, and its prevention is an important issue. The present study investigated the association between coffee and green tea intake and pneumonia among the elderly. The design was a hospital-based case control study. The cases were patients over 65 years old newly diagnosed as pneumonia. As a control, patients with the same sex and age (range of 5 years) who visited the same medical institution around the same time (within 2 months after examination of the case) for a disease other than pneumonia were selected. There were two controls per case. Odds ratio (OR) and 95% confidence interval (CI) for pneumonia of coffee and green tea intake during the past month were calculated using a conditional logistic regression model. A total of 199 cases and 374 controls were enrolled. When compared to those who do not drink coffee, the OR for pneumonia of those who drink less than one cup of coffee per day was 0.69 (95% CI 0.39–1.21), OR of those who drink one cup was 0.67 (0.38–1.18), and OR of those who drink two or more cups was 0.50 (0.28–0.88) (Trend p = 0.024). No association was found between pneumonia and green tea consumption. This study suggested a preventive association between coffee intake over 2 cups per day and pneumonia in the elderly.