Do vegetables and fruits reduce the risk of chronic obstructive pulmonary disease? A case–control study in Japan Fumi Hirayama a , Andy H. Lee a, ⁎, Colin W. Binns a , Yun Zhao a , Tetsuo Hiramatsu b , Yoshimasa Tanikawa c , Koichi Nishimura d , Hiroyuki Taniguchi e a School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, GPO Box U 1987, Perth, WA 6845, Australia b Department of Respiratory Medicine and Allergy, Komaki City Hospital, Komaki, Aichi, Japan c Department of Respiratory Medicine and Clinical Immunology, Toyota Kosei Hospital, Aichi Prefectural Welfare Federation of Agricultural Cooperatives, Toyota, Aichi, Japan d Department of Respiratory Medicine, Murakami Memorial Hospital, Asahi University, Gifu, Japan e Department of Respiratory and Allergic Medicine, Tosei General Hospital, Seto, Aichi, Japan abstract article info Available online 23 June 2009 Keywords: Breathlessness Chronic obstructive pulmonary disease Fruit Risk Vegetable 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 meanvegetable and fruit intakes of cases (155.62 (SD 88.84) and 248.32 (SD 188.17) g/day) were significantly lower (p b 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. © 2009 Elsevier Inc. All rights reserved. Introduction Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in the world (Murray and Lopez, 1997). Cigarette smoking has been established as the principal risk factor (Celli and MacNee, 2004; McKenzie et al., 2003; Pauwels and Rabe, 2004). According to a review study, while 95% of COPD patients are, or have been, cigarette smokers, about 20% of smokers develop COPD (Madison and Irwin, 1998), implying that other factors may protect against or contribute to the development of this disease. In particular, the risk of COPD may be reduced through an appropriate diet (Sridhar, 1995). A high intake of fruits is inversely associated with the risk of COPD (Celik and Topcu, 2006; Van Duyn and Pivonka, 2000; Watson et al., 2002) and respiratory symptoms (Butler et al., 2004; Tabak et al., 2001a,b). A large cohort study in Singapore found that non-citrus fruit (apples, pears and grapes) intake could decrease cough with phlegm, and soy foods appeared to reduce the development of chronic respi- ratory symptoms, especially productive cough (Butler et al., 2004). A cross-sectional study in the Netherlands similarly observed that solid fruits (apples and pears) were inversely related to the prevalence of COPD symptoms namely chronic cough and breathlessness (Tabak et al. 2001a), whereas an increased fruit consumption (N 180 g/day) appeared to reduce the prevalence of these respiratory symptoms (Tabak et al. 2001b). The favourable effect of vegetables was also noted in the lite- rature (Celik and Topcu, 2006; La Vecchia et al., 1998; Watson et al., 2002). Two reviews concluded that a high level of fruit and vegetable consumption could enhance ventilatory function and reduce airway obstruction (Schunemann et al., 2001; Smit et al., 1999). Based on the available evidence, it is likely that vegetables can lower the COPD risk, even among smokers (Van Duyn and Pivonka, 2000). On the other hand, two large studies conducted in the Netherlands and Singapore showed no relationship between Preventive Medicine 49 (2009) 184–189 ⁎ Corresponding author. Fax: +61 8 92662958. E-mail address: Andy.Lee@curtin.edu.au (A.H. Lee). 0091-7435/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2009.06.010 Contents lists available at ScienceDirect Preventive Medicine journal homepage: www.elsevier.com/locate/ypmed