Measures of oxidized low-density lipoprotein and oxidative stress are not related and not elevated in otherwise healthy men with the metabolic syndrome.

OBJECTIVE The metabolic syndrome predisposes to the development of cardiovascular diseases. Oxidative stress and elevated circulating oxidized low-density lipoprotein (LDL) concentrations are related to cardiovascular disease and proposed to be features of the metabolic syndrome. F2-isoprostanes are lipid peroxidation products and considered the most reliable biomarkers of oxidative stress. METHODS AND RESULTS Plasma oxidized LDL (oxLDL) and urinary 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha; the major F2-isoprostane) were analyzed in a cross-sectional study of 289 healthy men (62 to 64 years of age). Individuals completed a 7-day dietary record, and fasting plasma insulin, lipid, and lipoprotein concentrations, LDL particle size, and inflammatory markers were determined. National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATPIII) criteria were used to define the metabolic syndrome and individuals were grouped according to the number of risk factors for the metabolic syndrome (0, [n=88; 30%]; > or =1, [n=179; 62%], metabolic syndrome [n=22; 8%]). Group comparisons revealed no differences for oxLDL, 8-iso-PGF2alpha, or reported intake of macronutrients, whereas C-reactive protein and interleukin-6 were increased in the metabolic syndrome. LDL cholesterol strongly determined oxLDL in univariate and multivariate analysis, but no relationship to 8-iso-PGF2alpha was found. In turn, 8-iso-PGF2alpha was related to reported intake of fat, fatty acids, and dietary antioxidants. CONCLUSIONS There were no increases in plasma oxLDL or measures of oxidative stress (urinary 8-iso-PGF2alpha) in these otherwise healthy 63-year-old men with the metabolic syndrome. Furthermore, no relationship between oxLDL and 8-iso-PGF2alpha was found, but our results suggest a role for dietary factors in oxidative stress.