Effect of a traditional Mediterranean diet on apolipoproteins B, A-I, and their ratio: a randomized, controlled trial.

OBJECTIVES: Apolipoprotein (Apo)B, ApoA-I, and their ratio could predict coronary heart disease (CHD) risk more accurately than conventional lipid measurements. Our aim was to assess the effect of a traditional Mediterranean diet (TMD) on apolipoproteins. METHODS: High-cardiovascular risk subjects (n=551, 308 women and 243 men), aged 55-80 years, were recruited into a large, multicenter, randomized, controlled, parallel-group, clinical trial (The PREDIMED Study) aimed at testing the efficacy of TMD on primary cardiovascular disease prevention. Participants assigned to a low-fat diet (control) (n=177), or TMDs (TMD+virgin olive oil (VOO), n=181 or TMD+nuts, n=193) received nutritional education and either free VOO (ad libitum) or nuts (dose: 30 g/day). A 3-month evaluation was performed. RESULTS: Both TMDs promoted beneficial changes on classical cardiovascular risk factors. ApoA-I increased, and ApoB and ApoB/ApoA-I ratio decreased after TMD+VOO, the changes promoting a lower cardiometabolic risk. Changes in TMD+VOO versus low-fat diet were -2.9 mg/dL (95% CI, -5.6 to -0.08), 3.3mg/dL (95% CI, 0.84 to 5.8), and -0.03 mg/dL (-0.05 to -0.01) for ApoB, ApoA-I, and ApoB/ApoA-I ratio, respectively. CONCLUSIONS: Individuals at high-cardiovascular risk who improved their diet toward a TMD pattern rich in virgin olive oil, reduced their Apo B and ApoB/ApoA-I ratio and improved ApoA-I concentrations.

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 Prevención con Dieta Mediterránea [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. Trial Registration isrctn.org Identifier: ISRCTN35739639.

Postprandial and short-term effects of dietary virgin olive oil on oxidant/antioxidant status.

It is generally believed that virgin olive oil consumption has beneficial effects, but little is known about its effects postprandially on oxidant/antioxidant status. The aim of this study was to determine changes in oxidative stress biomarkers and lipid profile after a single dose of virgin olive oil and after 1 wk of daily consumption. Sixteen subjects (9 men, 7 women) ingested 50 mL of virgin olive oil in a single dose. Blood samples were collected from 0 to 24 h. Thereafter, 14 participants (8 men, 6 women) followed a 1-wk 25 mg/d virgin olive oil dietary intervention. Blood samples were collected at the end of this period. Serum TAG (P = 0.016), plasma FA (P < 0.001), and lipid peroxidation products in plasma (P< 0.001) and VLDL (P = 0.007) increased, reaching a peak at 4-6 h, and returning to baseline values at 24 h after oil ingestion. The opposite changes were observed in plasma glutathione peroxidase (P = 0.001) and glutathione reductase (GR) (P = 0.042). No changes in LDL lipid peroxidation or resistance to oxidation were observed postprandially. At 24 h, plasma oleic acid remained increased (P < 0.05) and resistance of LDL to oxidation improved (P < 0.05). After 1 wk of virgin olive oil consumption, plasma oleic acid (P = 0.031), resistance of LDL to oxidation (P< 0.05), and plasma GR activity (P = 0.005) increased. These results indicate that changes in oxidant/antioxidant status occur after oral virgin olive oil. Virgin olive oil consumption could provide short-term benefits for LDL resistance to oxidation and in glutathione-related enzyme activities.