Monounsaturated diet lowers LDL oxidisability in type IIb and type IV dyslipidemia without affecting coenzyme Q10 and vitamin E contents

The purpose of the present study was to evaluate the effects of MUFA vs PUFA enriched diets on the plasma and LDL lipid profile and antioxidant contents in mild hypercholesterolemic and triglyceridemic subjects. The study was divided in two consecutive diet periods. Two groups of 11 dyslipidemic patients each (type IIb and type IV) were recruited and during the first period (lasting four weeks) received a linoleic rich diet while during the following four weeks took an oleate rich diet. Both groups showed no significant changes in cholesterol and TG concentration either in plasma or in LDL. Coenzyme Q10 and vitamin E were also unaffected by the dietary treatments. LDL proneness to be oxidatively modified increased after dietary PUFA administration and markedly decreased following the virgin olive oil enriched diet. In fact, LDL from hypertrigliceridemic subjects on a oleate-enriched diet displayed a 26% (p < 0.05) longer lag-phase in conjugated dienes generation than during linoleate-enriched diet and at recruitment. In hypercholesterolemic subjects similar results were obtained: the lag-phase was 28% longer after MUFA diet that after PUFA diet. No differences were found in the maximum propagation rate and maximum concentration of conjugated dienes among dietary periods and at recruitment. Since we found that the vit. E and CoQ10 levels in plasma and in LDL particles remained unchanged during the course of the study, we may conclude that LDL proneness to undergo oxidative modifications is mainly the result of compositional change due to the enrichment from the different diets of the relative fats.