Association Between Dietary Fiber Intake and Prevalence of Chronic Obstructive Pulmonary Disease in a Middle-Aged and Elderly Population: a Study Based on the National Health and Nutrition Examination Survey Database.

OBJECTIVE: This study aimed to investigate dietary fiber (DF) intake with prevalence of chronic obstructive pulmonary disease (COPD) in the middle-aged and elderly population through analysis of the National Health and Nutrition Examination Survey (NHANES) data.

METHODS: The study utilized data from three cycles of NHANES database (2007-2012). The exposure variable was DF intake, and the outcome variable was COPD prevalence. Weighted logistic regression was utilized to construct relationship models between the two variables. Confounding factors were adjusted, and subgroup analysis was to explore association of DF intake with COPD. Restricted cubic spline (RCS) analysis investigated non-linear relationship between DF intake and COPD. Finally, mediation analysis was performed to determine whether the influence of DF intake on COPD prevalence is mediated through alteration of white blood cell (WBC) counts.

RESULTS: This study included a total of 7,301 eligible participants aged >40 years. The results of the study indicated that an increase in DF intake significantly reduced the prevalence of COPD (OR: 0.98, 95% CI: 0.96-0.99, p<0.001), and DF intake was correlated with lung function indicators (FEV1). Stratified analysis revealed that an increased DF intake significantly reduced the risk of COPD in male individuals, middle-aged individuals (aged 40-59 years), those with BMI≤30 kg/m2, individuals with a history of smoking, and alcohol consumers (p<0.05). Through RCS analysis exploring the nonlinear association between DF intake and COPD prevalence, the critical threshold for the impact of DF intake on COPD prevalence was 15.10 gm. When DF intake was ≥15.10 g/d, it effectively reduced the prevalence of COPD. Mediation analysis results indicated that the WBC count partially mediated the association between DF intake and COPD, with a mediation proportion of 9.89% (p=0.006).

CONCLUSION: Increased DF intake was linked to decreased prevalence of COPD, particularly in men and middle-aged people. WBC counts may be an important pathway linking DF intake and COPD.