Do vegetables and fruits reduce the risk of chronic obstructive pulmonary disease? A case-control study in Japan

Objective. To investigate the relationship between vegetable and fruit consumption and the risk of chronic obstructive pulmonary disease (COPD), a case-control study was conducted in central Japan in 2006. Methods. A total of 278 referred patients with COPD diagnosed within the past four years and 340 community-based controls undertook spirometric measurements of respiratory function. A structured questionnaire was administered face-to-face to obtain information on demographics, lifestyle and habitual food consumption. Results. The mean vegetable and fruit intakes of cases (155.62 (SD 88.84) and 248.32 (SD 188.17) g/day) were significantly lower (p<0.01) than controls (199.14 (SD 121.41) and 304.09 (SD 253.72) g/day). A substantial reduction in COPD risk was found by increasing daily total vegetable intake, p for trend=0.037. The prevalence of breathlessness also decreased with vegetable consumption, the adjusted odds ratio being 0.49 (95% CI 0.27-0.88) for the highest versus lowest quartile of intake. However, the effects of fruit consumption were not significant. Among the nutrients contained in vegetables and fruits, vitamin A was particularly significant (p=0.008) with an estimated 52% reduction in COPD risk at the highest level of intake. Conclusion. The study provided evidence of an inverse association between vegetable consumption and the risk of COPD for Japanese adults. (C) 2009 Elsevier Inc. All rights reserved.