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.
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From the aUnit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; bNutrition Research Laboratory, Department of Human Nutrition, Warsaw University of Life Sciences–SGGW, Warsaw, Poland; cProgram in Epidemiology, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA; dUnit for Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; eLung Allergy Clinic, Karolinska University Hospital New Karolinska Solna, Stockholm, Sweden; and fDepartment of Surgical Sciences, Unit of Orthopedics, Uppsala University, Uppsala, Sweden.
Submitted September 13, 2016; accepted September 5, 2017.
This study was supported by a research grant from the Swedish Research Council/Infrastructure, the Karolinska Institutet’s Distinguished Professor Award (Alicja Wolk) and the Swedish Heart Lung Foundation and from King Gustaf V’s and Queen Victoria’s Freemason Research Foundation (Anders Linden). Federal funding was obtained in accordance with the the Stockholms Läns Landsting (ALF) agreement, from Stockholms Läns Landsting (Anders Linden).
The authors report no conflicts of interest.
J.K. had full access to all data in the study and takes responsibility for the integrity of the data analysis; J.K., A.L. and A. Wolk study concept and design; J.K. and A. Walin performed the statistical analysis; all authors helped to write to the manuscript; H.H., A.L., and A. Wolk participated in the 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 A. Wolk (PI). Investigators may apply to access the study’s deidentified data through contact with the PI.
Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).
Correspondence: Joanna Kaluza, Nutrition Research Laboratory, Department of Human Nutrition, Warsaw University of Life Sciences – SGGW, 159C Nowoursynowska Street, 02-776 Warsaw, Poland. E-mail: email@example.com.