Effect of CLA supplementation on factors related to vascular dysfunction in arteries of orchidectomized rats

The vascular endothelium is a monolayer of flat epithelial cells located between the circulating blood and the underlying connective tissue. It conveys key functions that when impaired, lead to endothelial dysfunction. This condition is responsible for the pathogenesis of vascular diseases. The cardioprotective effect of sex hormones is widely known; hence, a murine orchidectomized model has been employed to study the effects caused by their deficiency. In the search for approaches to maintain vascular health, the effect of dietary fatty acids as CLA on cardiovascular diseases has been studied. Some proven beneficial properties of CLA are antioxidant, antiatherogenic and anti-inflammatory. Our objective was to evaluate the effect of a diet supplemented with 1.8 % (w/w) of CLA, administered during eight weeks, on the amount of cholesterol oxidation products (COPs) produced by orchidectomy and on factors related to vascular dysfunction in the aorta and the mesenteric arteries. The diet with CLA prevented the increase in prostanoids formation and maintained the normal physiological conditions of NO and antioxidant activity. In addition, it prevented the increase in cholesterol and COPs at the vascular wall. CLA-supplemented diet prevented the orchidectomy-induced alterations on prostanoids, NO and COPs and also improved the antioxidant activity. These findings could contribute to understand the mechanisms of actions of CLA involved in the prevention of cardiovascular diseases.

Oxysterols formation: A review of a multifactorial process

Dietary sterols are nutritionally interesting compounds which can suffer oxidation reactions. In the case of plant sterols, they are being widely used for food enrichment due to their hypocholesterolemic properties. Besides, cholesterol and plant sterols oxidation products are associated with the development of cardiovascular and neurodegenerative diseases, among others. Therefore, the evaluation of the particular factors affecting sterol degradation and oxysterols formation in foods is of major importance. The present work summarizes the main results obtained in experiments which aimed to study four aspects in this context: the effect of the heating treatment, the unsaturation degree of the surrounding lipids, the presence of antioxidants on sterols degradation, and at last, oxides formation. The use of model systems allowed the isolation of some of these effects resulting in more accurate data. Thus, these results could be applied in real conditions.

Cholesterol and stigmasterol within a sunflower oil matrix: Thermal degradation and oxysterols formation

The characteristics of the lipid matrix surrounding sterols exert a great influence in their thermal oxidation process. The objective of this work was to assess the oxidation susceptibility of equal amounts of cholesterol and stigmasterol within a sunflower oil lipid matrix (ratio 1:1:200) during heating (180°C, 0-180min). Remaining percentage of sterols was determined and seven sterol oxidation products (SOPs) were analysed for each type of sterol along the heating treatment. Evolution of the fatty acid profile and vitamin E content of the oil was also studied. Overall oxidation status of the model system was assessed by means of Peroxides Value (PV) and TBARS. PV remained constant from 30min onwards and TBARS continued increasing along the whole heating treatment. Degradation of both cholesterol and stigmasterol fitted a first order curve (R(2)=0.937 and 0.883, respectively), with very similar degradation constants (0.004min(-1) and 0.005min(-1), respectively). However, higher concentrations of oxidation products were found from cholesterol (79μg/mg) than from stigmasterol (53μg/mg) at the end of the heating treatment. Profile of individual oxidation products was similar for both sterols, except for the fact that no 25-hydroxystigmasterol was detected. 7α-Hydroxy and 7-keto-derivatives were the most abundant SOPs at the end of the treatment. PUFA and vitamin E suffered a significant degradation along the process, which was correlated to sterols oxidation.

Effect of Microwave Heating on Phytosterol Oxidation

The oxidative stability of phytosterols during microwave heating was evaluated. Two different model systems (a solid film made with a phytosterol mixture (PSF) and a liquid mixture of phytosterols and triolein (1:100, PS + TAG (triacylglycerol))) were heated for 1.5, 3, 6, 12, 20, and 30 min at 1000 W. PS degraded faster when they were microwaved alone than in the presence of TAG, following a first-order kinetic model. Up to 6 min, no phytosterol oxidation products (POPs) were generated in both systems. At 12 min of heating, the POP content reached a higher level in PSF (90.96 μg/mg of phytosterols) than in PS + TAG (22.66 μg/mg of phytosterols), but after 30 min of treatment, the opposite trend was observed. 7-Keto derivates were the most abundant POPs in both systems. The extent of phytosterol degradation depends on both the heating time and the surrounding medium, which can impact the quality and safety of the food product destined to microwave heating/cooking.