High serum nitric oxide metabolites and incident metabolic syndrome

Endothelial dysfunction, synonymous with reduced biological activity of nitric oxide, is related to all cardiovascular risk factors. Association between metabolic syndrome and nitric oxide metabolites (nitrite + nitrate = NO(x)) has been previously shown in cross-sectional studies. The aim of this study was to determine the ability of serum NO(x) levels in predicting the incidence of metabolic syndrome in a population-based study.

Serum NO(x) levels measured in 2098 adult subjects, participants of Tehran Lipid and Glucose Study, without metabolic syndrome at baseline. After 3.3 years follow-up, logistic regression analysis was used to calculate the odds ratio (OR) and 95% confidence interval for developing metabolic syndrome, with serum NO(x) quartiles as independent variables.

Incident metabolic syndrome was diagnosed in 23.0% of men and 16.3% of women after 3.3 years. Age-adjusted risk for developing metabolic syndrome in women who had higher NO(x) values (above 75th percentile vs. lower 75th percentile) at baseline, was significantly higher [OR: 1.59 (1.11-2.27), p = 0.011]; OR remained significant after multivariable-adjustment including adjustment for components of metabolic syndrome [OR: 1.75 (1.19-2.59), p = 0.005]. Serum NO(x) could not predict the incidence of metabolic syndrome in men.

High serum NO(x) level is an independent predictor of incident metabolic syndrome in women, but not in men, a finding which presents serum NO(x) level as a potential biomarker for assessing cardiometabolic disturbances.