Understanding the role of oxidative stress in the incidence of metabolic syndrome and obstructive sleep apnea

BACKGROUND: Understanding the causes and risk factors of metabolic syndrome is important for promoting population health. Oxidative stress has been associated with metabolic syndrome, and also obstructive sleep apnea. These are two diseases which have common prognostic characteristics for heart disease. The aim of this study was to examine the role of oxidative stress in the concurrent presence of metabolic syndrome and obstructive sleep apnea in a working population. METHODS: Participants were 163 artisan bakers in Shahroud, Iran, routinely exposed to significant heat stress and other oxidative stress indicators on a daily basis as part of their work. Using a cross-sectional design, data relevant to determining metabolic syndrome status according to International Diabetes Federation criteria, and the presence of obstructive sleep apnea according to the STOP-Bang score, was collected. Analyses included hierarchical binary logistic regression to yield predictors of the two diseases. RESULTS: Hierarchical binary logistic regression showed that oxidative stress - alongside obesity, no regular exercise, and smoking - was an independent predictor of metabolic syndrome, but not obstructive sleep apnea. Participants who were obese were 28 times more likely to have metabolic syndrome (OR 28.59, 95% CI 4.91-63.02) and 44 times more likely to have obstructive sleep apnea (OR 44.48, 95% CI 4.91-403.28). Participants meeting metabolic syndrome criteria had significantly higher levels of malondialdehyde (p < 0.05) than those who did not. No difference in oxidative stress index levels were found according to obstructive sleep apnea status. CONCLUSIONS: Our findings suggest that oxidative stress contributes to the onset of metabolic syndrome, and that obstructive sleep apnea is involved in oxidative stress. Whilst obesity, exercise, and smoking remain important targets for reducing the incidence of metabolic syndrome and obstructive sleep apnea, policies to control risks of prolonged exposure to oxidative stress are also relevant in occupations where such environmental conditions exist.