Effect of a traditional mediterranean diet on lipoprotein oxidation -: A randomized controlled trial

Background: Despite the richness in antioxidants of the Mediterranean diet, to our knowledge, no randomized controlled trials have assessed its effect on in vivo lipoprotein oxidation. Methods: A total of 372 subjects at high cardiovascular risk ( 210 women and 162 men; age range, 55-80 years), who were recruited into a large, multicenter, randomized, controlled, parallel-group clinical trial ( the Prevencion con Dieta Mediterranea [ PREDIMED] Study) directed at testing the efficacy of the traditional Mediterranean diet ( TMD) on the primary prevention of coronary heart disease, were assigned to a low-fat diet ( n = 121) or one of 2 TMDs ( TMD + virgin olive oil or TMD + nuts). The TMD participants received nutritional education and either free virgin olive oil for all the family ( 1 L/wk) or free nuts ( 30 g/d). Diets were ad libitum. Changes in oxidative stress markers were evaluated at 3 months. Results: After the 3-month interventions, mean ( 95% confidence intervals) oxidized low-density lipoprotein ( LDL) levels decreased in the TMD + virgin olive oil (-10.6 U/L [-14.2 to -6.1]) and TMD + nuts (-7.3 U/L [-11.2 to -3.3]) groups, without changes in the low-fat diet group (-2.9 U/L [-7.3 to 1.5]). Change in oxidized LDL levels in the TMD + virgin olive oil group reached significance vs that of the low-fat group ( P = .02). Malondialdehyde changes in mononuclear cells paralleled those of oxidized LDL. No changes in serum glutathione peroxidase activity were observed. Conclusions: Individuals at high cardiovascular risk who improved their diet toward a TMD pattern showed significant reductions in cellular lipid levels and LDL oxidation. Results provide further evidence to recommend the TMD as a useful tool against risk factors for CHD.