Physical activity, dietary vitamin C, and metabolic syndrome in the Korean adults: the Korea National Health and Nutrition Examination Survey 2008 to 2012

Objectives: Metabolic syndrome is a global public health problem, and regular physical activity is a well-known critical factor in its management. A recent study suggests that the effect of exercise on metabolic syndrome may be enhanced by sufficient plasma vitamin C concentrations. We therefore examined the combined effect of physical activity and dietary vitamin C on the risk of metabolic syndrome in the general Korean population. Study design: Cross-sectional study. Methods: We analyzed data from 22,671 adults aged 20 years or older from the Korea National Health and Nutrition Examination Survey 2008-2012. Physical activity was computed as the total metabolic equivalent (METs-hr/week) summed from MET scores of walking, moderate activity, and vigorous activity. Vitamin C intake was assessed using a 24-h dietary recall. Participants were classified into four combined groups based on median values of physical activity and vitamin C intake. Results: After adjustment for potential confounders, the odds ratio (OR) for metabolic syndrome in individuals with both high physical activity and vitamin C intake (vs. both low physical activity and vitamin C intake) was 0.79 (95% confidence interval (CI), 0.71-0.87). The estimated combined effect was more than either high physical activity alone (OR, 0.81 (95% CI, 0.73-0.90)) or high vitamin C intake alone (OR, 0.89 (95% CI, 0.80-0.99)), although each of those was beneficial. Conclusions: Physical activity and dietary intake of vitamin C are both associated with a lower risk of metabolic syndrome. Our findings suggest further that a combination of physical activity and a diet rich in vitamin C may help in preventing metabolic syndrome. (C) 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.