Mario Kratz

Effects of dietary fatty acids on the composition and oxidizability of low-density lipoprotein.

Objective: The objective of this study was to compare the effects of dietary monounsaturated fatty acids (MUFA), n-6 and n-3 polyunsaturated fatty acids (PUFA) on LDL composition and oxidizability.Design, setting and subjects: Sixty-nine healthy young volunteers, students at a nearby college, were included. Six subjects withdrew because of intercurrent illness and five withdrew because they were unable to comply with the dietary regimen.Interventions: The participants received a 2-week wash-in diet rich in saturated fatty acids (SFA) followed by diets rich in refined olive oil, rapeseed oil or sunflower oil for 4 weeks. Intakes of vitamin E and other antioxidants did not differ significantly between the diets.Results: At the end of the study, LDL oxidizability was lowest in the olive oil group (lag time: 72.6 min), intermediate in the rapeseed oil group (68.2 min) and highest in the sunflower oil group (60.4 min, P<0.05 for comparison of all three groups). Despite wide variations in SFA intake, the SFA content of LDL was not statistically different between the four diets (25.8–28.5% of LDL fatty acids). By contrast, the PUFA (43.5%–60.5% of LDL fatty acids) and MUFA content of LDL (13.7–29.1% of LDL fatty acids) showed a wider variability dependent on diet.Conclusions: Enrichment of LDL with MUFA reduces LDL susceptibility to oxidation. As seen on the rapeseed oil diet this effect is independent of a displacement of higher unsaturated fatty acids from LDL. Evidence from this diet also suggests that highly unsaturated n-3 fatty acids in moderate amounts do not increase LDL oxidizability when provided in the context of a diet rich in MUFA.Sponsorship: This work was supported by the Central Marketing Agency of the German Agricultural Industry (CMA), the German Union for the Promotion of Oil- and Protein Plants (UFOP), the Austrian Science Foundation, project F00709 (to P.M.A.) and the Brökelmann Ölmühle Company, Hamm, Germany.

Mediterranean diet, olive oil and health

The traditional Mediterranean diet is characterised by an abundance of plant foods (fruits, vegetables, cereals, legumes); olive oil is the principle source of fat. Dairy products, mainly yoghurt and cheese, are eaten in low to moderate amounts, as well as fish and poultry. Red meat is eaten only in small amounts. The Mediterranean diet contains wine in moderation, usually consumed with meals. These food patterns lead to a nutrient composition with low contents of unfavourable or undesirable nutrients (saturated fatty acids, trans fatty acids, cholesterol), with high contents of desirable and health-beneficial nutrients (dietary fibre, complex carbohydrates, monounsaturated fatty acids, vitamins, minerals, minor components), and with a low energy density. Due to its specific food patterns and its favourable nutrient composition the Mediterranean diet has undoubtedly contributed to the low rates of numerous chronic diseases observed in the Mediterranean region and has been proven as a model for healthy nutrition. In particular, a large body of evidence documents the beneficial relationship between the traditional Mediterranean diet, cardiovascular risk factors, such as hyperlipidaemia, hypertension, diabetes and obesity, and coronary heart disease. Furthermore, there is evidence that the Mediterranean diet plays a role in cancer prevention.

Similar serum plant sterol responses of human subjects heterozygous for a mutation causing sitosterolemia and controls to diets enriched in plant sterols or stanols.

Objective:We investigated the serum phytosterol responses of heterozygous relatives of sitosterolemia patients to diets enriched in phytosterols or stanols.Design:Randomized double-blind crossover design.Setting:Muenster, Germany.Subjects:Eight heterozygous and 13 control subjects were recruited. One heterozygote and three controls dropped out.Interventions:Seven heterozygotes and 10 controls received daily portions of margarine containing 2 g of plant sterols, 2 g of stanols or a control margarine for 6 weeks each in a randomized order. These phases were intercepted by wash-out periods of 6 weeks each.Results:Compared to the control period, serum phytosterol concentrations increased overall by more than 20% when subjects consumed the plant sterol margarine (F(1,15)=8.719, P=0.01), with no significant difference between heterozygotes (mean +14.5 (s.d. 17.2) μmol/l, +23.0%) and controls (+4.9 (9.9) μmol/l, +20.5%; F(1,15)=2.168, P=0.162), but decreased when subjects consumed the stanol-enriched margarine (F(1,15)=12.124, P=0.003), again to a similar extent in heterozygotes (−34.2 (41.2) μmol/l, −54.2%) and controls (−12.2 (9.2) μmol/l, −50.6%; F(1,15)=2.729, P=0.119). The lowest total serum concentrations of cholesterol and phytosterols were seen after the diet enriched in stanols. Serum stanol concentrations increased on this diet, but on a very low level and never exceeded 0.05% of serum cholesterol levels in any subject.Conclusions:Serum phytosterol concentrations increased only moderately in heterozygotes consuming a diet enriched in phytosterols, indicating that they retained considerable capacity to excrete phytosterols even at higher intakes.Sponsorship:Supported by a grant of the Stifterverband für die Deutsche Wissenschaft (project number TS022/12372/2002) to MK.