Self-reported intake of fruit and vegetables and risk of chronic obstructive pulmonary disease: A nation-wide twin study.

BACKGROUND: Although smoking is the major risk factor for chronic obstructive pulmonary disease (COPD) many patients with obstructive lung function suggesting COPD are never-smokers. Therefore, other lifestyle factors have been suggested as risk factors.

AIMS: i) To examine the association between self-reported intake of fruit and vegetables and risk of COPD and ii) to examine whether the association between these traits are due to underlying genetic factors.

METHODS: 12,449 twins, aged 40-80, from the Danish Twin Registry were recruited. The participants completed a questionnaire on medical history and lifestyle factors and participated in clinical examination. COPD was defined according to ATS/ERS recommendations. Multivariate logistic regressions were used to estimate the risk of COPD in individuals with a low intake of fruit and vegetables. Co-twin control analyses were performed to examine whether the association between fruit and vegetables and COPD is explained by genetic factors. Self-reported physician-diagnosed asthmatic individuals were excluded.

RESULTS: Of the 11,458 individuals were included in the analyses, 48% of the participants were males. Mean age was 58.9 (years)±SD 9.6, mean BMI (kg/m2 )26.6 ± SD 4.4. A multivariate logistic regression, including sex, age and BMI showed that both smoking, no and heavy drinking and physical inactivity were independent predictors of COPD. There was a significant frequency-pendent association between intake of fruit and vegetables and increased risk of COPD. Conditional logistic regression analyses showed that the association might be controlled by genetic factors.

CONCLUSIONS: This study shows that low intake of fruit and vegetables is associated with an increased risk of COPD and the association might be under influence of genetic factors.