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, aged 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 vs. 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; 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.
Financial support: This study was supported by a research grant from the Swedish Research Council/Infrastructure, the Karolinska Institutet’s Distinguished Professor Award (AW) and the Swedish Heart Lung Foundation and from King Gustaf V’s and Queen Victoria’s Freemason Research Foundation (AL). Federal funding was obtained in accordance with the ALF agreement, from Stockholms Läns Landsting (AL).
Conflict of interest: There is no conflict of interest.
Authors contributing: JK had full access to all data in the study and takes responsibility for the integrity of the data analysis; JK, AL and AWo study concept and design; JK and AWa performed the statistical analysis; all authors helped to write to the manuscript; HH, AL and AWo critical revision of the manuscript for important intellectual content.
The data and the computer code are stored on a highly secure institutional server under the supervision of Prof. Alicja Wolk (PI). Investigators may apply to access the study’s deidentified data through contact with the PI.
*Correspondence Joanna Kaluza – email: firstname.lastname@example.org Tel: +48 22 59 37 114 Fax.: +48 22 59 37 117
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