Association of Dietary Phytosterols with Cardiovascular Disease Biomarkers in Humans

Cardiovascular disease (CVD) is a leading cause of death worldwide. Elevated concentrations of serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) are major lipid biomarkers that contribute to the risk of CVD. Phytosterols well known for their cholesterol-lowering ability, are non-nutritive compounds that are naturally found in plant-based foods and can be classified into plant sterols and plant stanols. Numerous clinical trials demonstrated that 2 g phytosterols per day have LDL-C lowering efficacy ranges of 8–10%. Some observational studies also showed an inverse association between phytosterols and LDL-C reduction. Beyond the cholesterol-lowering beneficial effects of phytosterols, the association of phytosterols with CVD risk events such as coronary artery disease and premature atherosclerosis in sitosterolemia patients have also been reported. Furthermore, there is an increasing demand to determine the association of circulating phytosterols with vascular health biomarkers such as arterial stiffness biomarkers. Therefore, this review aims to examine the ability of phytosterols for CVD risk prevention by reviewing the current data that looks at the association between dietary phytosterols intake and serum lipid biomarkers, and the impact of circulating phytosterols level on vascular health biomarkers. The clinical studies in which the impact of phytosterols on vascular function is investigated show minor but beneficial phytosterols effects over vascular health. The aforementioned vascular health biomarkers are pulse wave velocity, augmentation index, and arterial blood pressure. The current review will serve to begin to address the research gap that exists between the association of dietary phytosterols with CVD risk biomarkers.     

Effect of Industrial Chemical Refining on the Physicochemical Properties and the Bioactive Minor Components of Peanut Oil

The effect of the industrial chemical refining process on the physicochemical properties, fatty acid composition, and bioactive minor components of peanut oil was studied. The results showed that the moisture and volatile matter content, acid value, peroxide value, and p‐anisidine value were significantly changed (P < 0.05) after the complete refining process. No significant variation (P > 0.05) in the iodine value was observed among all the peanut oil samples. Similar changes were observed in the DPPH radical scavenging activity and the total tocol content during chemical refining. In addition, chemical refining did not have much effect on the fatty acid composition, except for certain changes of several individual fatty acids. Moreover, the chemical refining resulted in 23.6, 23.1, and 9.5 % losses of squalene, total phytosterols, and total tocols (α, β, γ, δ‐tocopherols and α, β, γ, δ‐tocotrienols), respectively. The degumming–neutralization step caused the greatest overall reduction of these bioactive minor components. However, the concentrations of α‐tocotrienol and γ‐tocotrienol increased after full refining. Furthermore, chemical refining slightly changed the relative proportions of individual phytosterols and individual tocols.     

Effects of genotype and sowing date on phytostanol–phytosterol content and agronomic traits in wheat under organic agriculture

Cereals are an important source of sterols and stanols in the human diet. The present study underlines the effect of genotype and weather conditions in bread wheat, on total sterol and stanol content (TSS), agronomic traits, proteins and ash content under organic conditions. Variations in TSS as well as other characters between two sowing dates were observed. A broad genotypic variability was also reported since extreme genotypes differed by more than 30 mg 100 g⁻¹ DW for TSS, with total stanol content varying twofold. Moreover, two groups of genotypes that differed in agronomic production, ash and protein content were depicted, based on their response to an increase in temperature. This result suggests that the genotypic factor prevails over the sowing date factor for determining sterol and stanol traits in wheat cultivated under organic conditions. Nevertheless, a strong interaction exists between the two factors, which can be used to drive bioaccumulation of these molecules.     

Phytosterol oxidation in oil-in-water emulsions and bulk oil

Dietary plants sterols (phytosterols) have been shown to lower plasma cholesterol level in humans. Since phytosterols may protect against coronary heart diseases, they are being incorporated into functional foods. However, phytosterols are susceptible to oxidative degradation. The purpose of this study was to evaluate the formation of phytosterols oxidation products (POPs) in oil-in-water emulsions and bulk corn oil. The extent of lipid oxidation was monitored by measuring the lipid hydroperoxides and hexanal, whereas 7-keto derivatives of phytosterols were determined by gas chromatography to follow sterol oxidation. A higher POPs level and formation rate was found in the oil-in-water (o/w) emulsion than in the bulk oil. Interfacial tension measurements showed that phytosterols had a high degree of surface activity, which would allow them to migrate to the oil–water interface of the emulsion droplets where oxidative stress is high.     

Effect of phytosterol structure on thermal polymerization of heated soybean oil

This study determined the effect of phytosterol structure, including the degree of unsaturation and the presence of an ethylidene group in the side chain, on the thermal polymerization of heated soybean oil. Indigenous tocopherols and phytosterols were removed from soybean oil by molecular distillation. Pure phytosterols were added back to the stripped soybean oil at concentrations of 0.5, 1.0, and 5 mg/g oil (0.05, 0.1, and 0.5 wt-%). These oils were heated at 180 °C over a period of 8 h, and triacylglycerol dimers and polymers, fatty acid composition, and residual phytosterol content were determined. None of the phytosterols prevented triacylglycerol dimer and polymer formation when used at 0.5 mg/g; however, phytosterols with two or more double bonds, regardless of the presence of an ethylidene group in the side chain, provided slight protection when added at 1 mg/g. Ergosterol addition at 5 mg/g reduced polymer formation by 16–20% compared to the control oil, but at this level none of the other phytosterols provided protection of any practical significance. Thus, under the conditions used for this heating study, the degree of phytosterol unsaturation was more important for its anti-polymerization activity than the presence of an ethylidene group.     

新型功能性食品添加剂——植物甾醇类

植物甾醇,包括甾烷醇及其酯的形式,是一类具有降低血清胆固醇作用的功能因子。本文介绍了它的分类、物化性质、生理活性、产品开发方面的概况。     

植物甾醇生理功能及其研究进展

就植物甾醇中最主要的生理功能一降低血清胆固醇的研究与开发方面的历史和最新进展进行了综述，并对其作用机理、安全性评价作了介绍。     

Lipids and phytosterol oxidation products in commercial potato crisps commonly consumed in Sweden

The stability of frying oils and fried foods is mainly affected by the fatty acids present and by the types and levels of minor components such as phytosterols and tocopherols. This study assessed the current status of lipid composition and the occurrence of oxidised phytosterols as a parameter of lipid oxidation in potato crisps available in the Swedish market. Fatty acid composition and concentrations of tocopherols, sterols and phytosterol oxidation products (POPs) were determined in 16 commercial potato crisp samples of two types, distinguished by a high or low fat content. The fatty acid composition in most samples was dominated by saturated and monounsaturated fatty acids. The sum of α-tocopherol and γ-tocopherol content varied from undetectable levels to 10.2 mg/100 g potato crisps, with α-tocopherol dominating. Among the tocotrienols, α-tocotrienol and γ-tocotrienol were present in almost equal proportions, while δ-tocotrienol was present in all samples but in smaller amounts. Fatty acid composition, tocopherol and tocotrienol content, showed that all potato crisp samples were prepared in palm oil or a blend of palm oil and unspecified fats and oils. Total sterol content ranged from 10.2 to 93.1 mg/100 g sample, with β-sitosterol being the major sterol in all samples. The content of POPs ranged from 0.05 to 0.68 mg/100 g potato crisps. In general, there were no significant differences in content of POPs between high and low fat samples, and generally no correlations could be established between content of POPs and fatty acid, tocopherol, tocotrienol, and sterol content among the potato crisp samples.     

Changes in phytosterol contents during rape seed storage under conditions simulating industrial silos

During seed storage in tall silos the low layers of rape seeds are exposed to static pressure exerted by the upper layers. This may cause deformation and damage of seeds found in the lower layers and losses of biologically active compounds. The aim of this study was to simulate under laboratory conditions the actual ecosystem found in industrial plants and to evaluate the effect of not only the temperature and moisture content, but also static pressure on degradation of phytosterols contained in rape seeds in the course of storage. Changes in phytosterol levels were assessed using GC-MS. During storage in all samples of seeds (7–16% moisture content) under the adopted conditions of overpressure (20–60 kPa) and temperature (25–35 °C) the total content of phytosterols decreased by 3–57%. The smallest losses in the total phytosterol contents (3–4%) were recorded during storage of seeds with a 7% moisture content, irrespective of the applied storage temperature (25–35 °C) and overpressure variants (20–60 kPa). The greatest losses of phytosterols (43–57%) were observed during storage of seeds with a 16% moisture content at a temperature of 35 °C, while the higher the applied overpressure, the greater these losses were. The study showed that the greatest influence on sterol content during storage was increased seed moisture, and subsequently the temperature and the pressure. Experimental results also showed that for seeds with higher moisture contents (13 and 16%) an increase in storage temperature from 30 to 35 °C intensifies losses of individual phytosterols much more markedly that an increase in temperature from 25 to 30 °C. Moreover it was observed that overpressure over 20 kPa enhanced losses of investigated phytosterols.