Mediterranean diet supplemented with nuts reduces waist circumference and shifts lipoprotein subfractions to a less atherogenic pattern in subjects at high cardiovascular risk.

OBJECTIVE: The PREDIMED trial showed that Mediterranean diets supplemented with either extra-virgin olive oil or nuts reduced incident cardiovascular events compared to a control diet. Consumption of both supplemental foods has been associated with reduced LDL-cholesterol, but it is unknown whether they can shift lipoprotein subfractions to a less atherogenic pattern. We investigated changes in adiposity and lipoprotein subfractions after consumption of the PREDIMED diets. METHODS: In a PREDIMED sub-cohort (n = 169), lipoprotein subclasses (particle concentrations and size) were determined by nuclear magnetic resonance spectroscopy at baseline and after intervention for 1 year. RESULTS: Participants allocated to the Mediterranean diet supplemented with nuts showed significant reductions from baseline of waist circumference (mean [95% CI]; -5 cm [-7; -3]) and concentrations of medium-small (-27 nmol/l [-46; -8]) and very small LDL (-111 nmol/l [-180; -42]); decreased LDL particle number (a nuclear magnetic resonance-specific measurement) (-98 nmol/l [-184; -11]); and an increase of large LDL concentrations (54 nmol/l [18; 90]), with a net increase (0.2 nmol/l [0.1; 0.4]) of LDL size. The Mediterranean diets with olive oil and nuts increased large HDL concentrations (0.6 µM [0.0; 1.1] and 1.0 µM [0.4; 1.5], respectively). Compared to the other two intervention groups, participants in the nut-enriched diet showed significantly reduced waist circumference (p ≤ 0.006, both) and increased LDL size (p < 0.05, both). CONCLUSION: Lipoprotein subfractions are shifted to a less atherogenic pattern by consumption of Mediterranean diets enriched with nuts. The results contribute mechanistic evidence for the reduction of cardiovascular events observed in the PREDIMED trial.

Effect of dietary high-oleic-acid oils that are rich in antioxidants on microsomal lipid peroxidation in rats.

In contrast to other metabolic functions, the role of dietary antioxidants and oil on microsomal lipid oxidation has been less extensively studied. This study examines ascorbate-Fe(2+) and NADPH-induced lipid peroxidation of hepatic microsomes of rats that were fed for three weeks high-oleic-acid oils (high-oleic sunflower oil, HOSO; olive oil, OO; or olive pomace oil, OPO) containing different concentrations of the antioxidants alpha-tocopherol, erythrodiol, and oleanolic acid. The fatty acid composition of hepatic microsomes of Wistar rats that were fed for three weeks with the above-mentioned oils had lower proportions of C16:0, C18:2n6, and C22:6n3 and higher proportions of C18:0 and C18:1n9 than rats fed the control diet. Light emission by hepatic microsomes increased, in the first 180 min, 2-fold after ascorbate-Fe(2+) addition compared with NADPH addition. Both increases were less pronounced in microsomes of OPO-fed rats and to a smaller extent in microsomes of OO-fed rats. Smaller increases in light emission were associated positively with higher concentrations of dietary alpha-tocopherol, erythrodiol, and oleanolic acid but were not associated with changes in fatty acid composition of hepatic microsomes. Addition of alpha-tocopherol, erythrodiol, or oleanolic acid decreased light emission of hepatic microsomes with a greater inhibition in microsomes of rats fed the control diet. Our data suggest that erythrodiol and oleanolic acids partly explain the protective effect of dietary OPO on microsomal lipid peroxidation in rats.