Objective: Airflow obstruction often results from the chronic inflammation caused by cigarette smoke. It has been concluded that cigarette smoke-induced oxidative damage is prevented by ascorbic acid on a cellular level. The purpose of the current study was to explore the effect of vitamin C intake on pulmonary function in established smokers (100 or more cigarettes) and never-smokers in a Korean population.
Methods: The 2974 enrolled men and women over the age of 40 in the Korea National Health and Nutrition Examination Survey IV 2008 were divided into 4 groups based on smoking patterns (never-smoker vs established smoker) and vitamin C intake from dietary assessment (higher vs lower; median value: 77.18 mg/day).
Results: Univariate analysis showed associations between forced expiratory volume in 1 second (FEV1), FEV/forced vital capacity (FVC) and age, gender, body mass index (BMI), pack-years, vitamin C intake, and additional micronutrient intake. On multiple logistic regression analysis, the odds ratios (95% confidence interval) for FEV1 < 80% predicted were 1.000 (never-smokers, higher vitamin C intake), 1.067 (0.823, 1.383; never-smokers, lower vitamin C intake), 1.224 (0.871, 1.721; established smokers, higher vitamin C intake), and 1.479 (1.057, 2.072; established smokers, lower vitamin C intake). The odds ratios for FEV1/FVC < 0.70 were 1.177 (0.821, 1.687; never-smokers, lower vitamin C intake), 1.637 (1.094, 2.445; established smokers, higher vitamin C intake), and 2.093 (1.403, 3.122; established smokers, lower vitamin C intake) after adjusting for confounding factors (p < 0.001).
Conclusions: Korean smokers with adequate vitamin C intake showed a preferable pulmonary function test.
Keywords: antioxidants; ascorbic acid; pulmonary function test; smoking.