The Synergistic Effect of Dietary Acid Load Levels and Cigarette Smoking Status on the Risk of Chronic Obstructive Pulmonary Disease (COPD) in Healthy, Middle-Aged Korean Men

Abstract

We investigated whether cigarette smoking and dietary acid load (DAL) are associated with a risk of chronic obstructive pulmonary disease (COPD) in healthy, middle-aged Korean men. Healthy men without diagnosed chronic disease (aged 40-64 years) from the KNHANES-VI (2013-2015) were included in the analysis (n = 774) and were subdivided by smoking status and DAL levels, as estimated using the quartile of net endogenous acid production (NEAP). The current smokers tended to have a higher risk of COPD than the never-smokers before and after adjustment. When divided by the DAL quartile, the Q4 group tended to have a higher risk of COPD than the Q1 group. Additionally, the current smokers with lower (Q2), modest (Q3), and the highest NEAP scores (Q4) showed risks of COPD that were more than fourfold higher than those of the never-smokers with the lowest NEAP scores (Q1). The ex-smokers with higher NEAP scores (Q3 and Q4) showed risks of COPD that were more than fourfold higher than those of the Q1 group. Interestingly, the risk of COPD was also more than sixfold higher in the never-smokers with the highest NEAP scores compared to that in the Q1 group. The NEAP scores and smoking status synergistically increased the risk of COPD in healthy, middle-aged Korean men. This suggests that DAL levels are an important factor in the prevention and management of COPD.

Keywords: KNHANES; chronic obstructive pulmonary disease; dietary acid load; net endogenous acid production.

Figure 1

Flow chart of the study population. FFQ: food frequency questionnaire; KNHANES: Korean National Health and Nutrition Examination Survey.

Figure 2

ORs and 95% CIs for the risk of COPD according to the NEAP score quartiles (Q1–Q4) and the smoking status. The odds ratios (confidence intervals) were determined via the logistic regression model. Reference groups: never-smoker; Q1 group. ORs were calculated with adjustments for age, body mass index, total calorie intake, household income status, education status, and alcohol drinking. CI—confidence interval; COPD—chronic obstructive pulmonary disease; OR—odds ratio.