Dietary Fiber Intake and Risk of Chronic Obstructive Pulmonary Disease: A Prospective Cohort Study of Men

The limited literature suggests that dietary fiber intake from whole grains, fruits, and vegetables is negatively associated with chronic obstructive pulmonary disease (COPD) via fiber's anti-inflammatory properties. Therefore, we investigated the association between total fiber and fiber sources and risk of COPD in the population-based prospective Cohort of Swedish Men (45,058 men, ages 45-79 years) with no history of COPD at baseline.

Dietary fiber intake was assessed with a self-administered questionnaire in 1997 and was energy adjusted using the residual method. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (95% CIs) adjusted for potential confounders.

During a mean follow-up of 13.1 years (1998-2012), 1,982 incident cases of COPD were ascertained via linkage to the Swedish health registers. A strong inverse association between total fiber intake (≥36.8 vs. <23.7 g/day) and COPD was observed in current smokers (hazard ratio [HR] = 0.54; 95% confidence interval [CI] = 0.43, 0.67) and ex-smokers (HR = 0.62; 95% CI = 0.50, 0.78) but not in never smokers (HR = 0.93; 95% CI = 0.60, 1.45; P interaction = 0.04). For cereal fiber, HRs for highest versus lowest quintile were 0.62 (95% CI = 0.51, 0.77; P trend < 0.001) in current smokers and 0.66 (95% CI = 0.52, 0.82; P trend < 0.001) in ex-smokers; for fruit fiber, the HR was 0.65 (95% CI = 0.52, 0.81; P trend < 0.001) in current smokers and 0.77 (95% CI = 0.61, 0.98; P trend = 0.17) in ex-smokers; and for vegetable fiber, it was 0.71 (95% CI = 0.57, 0.88; P trend = 0.003) in current smokers and 0.92 (95% CI = 0.71, 1.19; P trend = 0.48) in ex-smokers.

Our findings indicate that high fiber intake was inversely associated with COPD incidence in men who are current or ex-smokers.