Sterol content in sunflower seeds (Helianthus annuus L.) as affected by genotypes and environmental conditions

Phytosterols play essential roles in many plant cell mechanisms. They are of industrial interest since, as part of the diet, they can reduce low density lipoprotein cholesterol. An increase in plant sterol contents, by improved crop varieties or crop management, could help to answer industrial demands and also to develop environmentally friendly extraction methods. The aim of this study was to evaluate genotypic variability of sterol content in cultivated sunflower and, in particular, effects of sowing date. Results showed large variability among a collection of sixteen sunflower inbred lines and hybrids. Total sterols varied almost twofold between extreme genotypes. A delay of sowing, giving higher temperatures during seed formation, induced a general increase in total sterol concentration by up to 35%, as well as variation in sterol composition according to genotype. These results are considered with an aim of improving sterol content by sunflower breeding programmes.     

食品加工对植物甾醇影响

本文论述植物甾醇天然来源、存在形式及食品加工对其影响,以利于控制食品加工条件,最大限度地使甾醇得以保留。     

Key points for maximum effectiveness and safety for cholesterol‐lowering properties of plant sterols and use in the treatment of metabolic syndrome

According to the American Diabetes Association and the Adult Treatment Panel III, the starting point for treating metabolic syndrome (MS) is a change of lifestyle. In addition, action on the main symptoms of MS by means of dietary supplements, can be helpful in view of the chronic course of the disease. The term ‘phytosterols’ refers to sterols and stanols composed of lipophilic triterpenes, a family that is widely distributed in the plant kingdom and whose cholesterol‐lowering properties have been amply demonstrated. In the light of the recent literature, the key points for maximum effectiveness and safety of sterols are the following. (A) Plant sterols should be taken with meals: clinical trials have shown that when plant sterols are consumed close to mealtimes, low‐density lipoprotein cholesterol may decrease by 9.4%, while when they are taken between meals, the reduction is about 6%. (B) The optimal dosage is 2–2.5 g day^?1 in a single dose. More than 3 g day^?1 has not been found to have any additional beneficial effect and increases the risk of side effects. (C) The food matrix used to dissolve the phytosterols should contain a certain amount of fat. A milk‐based matrix appears optimal from this point of view. © 2013 Society of Chemical Industry     

Dietary fat quality and circulating cholesterol levels in humans: a review of actions and mechanisms

Consumption of saturated fats contributes to elevated circulating cholesterol levels, whilst either polyunsaturated or monounsaturated fats are linked to depressed levels. Since elevated serum cholesterol is a risk factor for coronary heart disease, it is of interest to understand the factors responsible for the responses elicited by dietary fat quality. Changes in faecal sterol excretion, exogenous cholesterol absorption, lipoprotein composition, and lipoprotein catabolism can coincide with changes in fat intake but may not necessary cause them. Whether or not rates of whole-body cholesterol synthesis respond to dietary fat quality is not known. To date, animal studies suggest that shifts in LDL receptor-mediated cholesterol transport are to blame for responses of circulating cholesterol levels to dietary fat.     

Plant Sterols in Soybean Hulls

Using gas chromatography techniques after lipid extraction, soybean hulls were analyzed for their plant sterol components. Soybean hulls contained 7.46% and 2.02% moisture and lipid components, respectively. Three plant sterols, campestrol, stigmasterol, and β-sitosterol, were quantified in the ratios of 1: 1.5: 2. The use of soybean hulls as food ingredients was discussed for their potential serum cholesterol reducing effects.     

Lucerne saponins. 3. Effect of lucerne saponins on larval growth and their detoxification by various sterols

The role of sapogenins in the antibiological effects exerted by lucerne saponins has been studied. Data are presented, showing that lucerne sapogenins are more toxic towards Tribolium castaneum larvae than their respective saponins, from which they are isolated. Medicagenic acid and to a lesser extent a new, hitherto unidentified sapogenin are the main growth-depressing factors, the soyasapogenols being almost harmless in this respect. When cholesterol is also included in the diet, the negative influence of the sapogenins is completely abolished. The counteraction found with cholesterol, as well as with various plant sterols, of the growth inhibition of the larvae caused by dietary saponin extracts (SE) was studied quantitatively with different SE: sterol ratios. It is shown that the amount of cholesterol needed to counteract fully the growth impairment depends on the toxicity of the SE preparation and its concentration in the diet. The counteracting property of plant sterols on larval growth depression leads to the conclusion that a built-in defence mechanism exists in lucerne against the antibiological effects of saponins.     

食品加工对植物甾醇的影响

血脂过高引起的心血管病已成为威胁人类健康的第一杀手，植物甾醇因其具有显著的降血脂作用而倍受关注。论述了植物甾醇的天然来源、存在形式及食品加工对其影响，以利于控制食品加工条件，最大限度地使甾醇得到保留。     

Modification of the sterol profile in milk through feeding

The fortification of milk with phytosterols is an increasingly common practice to enhance the sterol profile and offer consumers potential health benefits. This study investigated whether cattle feed can influence the profile of phytosterols and cholesterol in the milk produced as an alternative to direct fortification of milk. Five experiments were performed using feeds commonly used by Australian dairy farmers and selected formulated rumen-protected feeds. Statistical significances were observed for some individual plant sterols and cholesterol in milk under these differing feeding regimens compared with the respective controls. In the case of the phytosterols, where the daily recommended consumption is typically 2 g per day, the total phytosterols were <0.12 mg/100 mL of milk. An experiment using a rumen-protected feed with high phytosterol levels suggested a decreased transfer of cholesterol to the milk by as much as 20%, although further work is required to confirm these preliminary results. Overall, the study suggests that different feeding practices have minimal effect on the resulting sterol profile of the milk.     

Hypocholesterolemic activity of onion is mediated by enhancing excretion of fecal sterols in hamsters

Onion has been shown to favorably modify the lipoprotein profile. However, research on its underlying mechanism is lacking. The present study investigated the interaction of dietary onion powder with the protein expression of key receptors and enzymes involved in cholesterol metabolism. Thirty-six male hamsters were randomly divided into three groups and fed a high-cholesterol control diet or the two experimental diets supplemented with 1% onion powder (OP-1) or 5% onion powder (OP-5), for a period of 8 weeks. It was found that onion dose-dependently decreased plasma total cholesterol (TC) level. The change in plasma lipoprotein profile was accompanied by a greater excretion of both fecal neutral and acidic sterols. Western blot analysis revealed that onion up-regulated sterol regulatory element binding protein 2 (SREBP-2), liver X receptor alpha (LXRα) and cholesterol-7α-hydroxylase (CYP7A1) with no effect on 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and LDL receptor (LDL-R). It was concluded that the hypocholesterolemic activity of onion powder was mediated by enhancement of fecal sterol excretion and up-regulation of LXRα and CYP7A1.     

茶树花对大鼠肥胖病和高脂血症预防作用研究

目的:研究茶树花对大鼠肥胖病和高脂血症的预防作用.方法:将40只大鼠分为5组,即:基础饲料组、高脂饲料组、茶树花2.5％、5％、7.5％3个剂量组.每两天测量体重和摄食量1次,24d后断头取血,测定总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C).取体脂(肾及睾丸周围脂肪)称重.结果:与基础饲料组相比,高脂饲料组大鼠体重、脂肪系数、TC、TG、LDL-C、动脉粥样硬化指数(AI)显著增加;3个剂量茶树花添加组大鼠体重、脂肪系数、TC、TG、LDL-C、AI均低于高脂饲料组,且呈显著或极显著差异;中、高剂量组大鼠体重、脂肪系数、TC、TG、LDL-C、HDL-C、AI与基础饲料组无明显差异.结论:茶树花对大鼠肥胖病和高脂血症有一定的预防作用,3个剂量组中添加5％茶树花效果最好,可开发为降脂减肥的纯天然保健食品.     

Mutations in the nucleotide-binding domain of putative sterol importers Aus1 and Pdr11 selectively affect utilization of exogenous sterol species in yeast

Sterol uptake in the yeast Saccharomyces cerevisiae is mediated by two plasma membrane ATP-binding cassette transporters, Aus1 and Pdr11. Their expression is regulated by oxygen and is triggered by anaerobic growth conditions. Under these conditions, internal ergosterol synthesis is arrested and utilization of exogenous sterol is vital for yeast cells. Here, we demonstrate that Aus1 is the major importer of non–yeast sterols, mammalian cholesterol, and plant sterols under anaerobic conditions. In contrast, uptake of yeast native sterol, ergosterol, is relatively low. This uptake could not be enhanced by overexpression of either of the transporters. Interestingly, overexpression of the minor importer Pdr11 resulted in a substantial import of non–yeast sterols. We show that mutation of the conserved residue in one of the ABC characteristic motifs—the H-loop in Aus1 and Pdr11—lowered their ATPase activity. The residual activity was sufficient to import exogenous sterols and to preserve cell viability. Importantly, the reduction of sterol import was dramatic for mammalian cholesterol and plant sterols, whereas import of yeast ergosterol was decreased only slightly indicating substrate selectivity of the sterol utilization process.     

Effect of probiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis on lipid profile in individuals with type 2 diabetes mellitus

The purpose of this study was to investigate the effects of probiotic and conventional yogurt on the lipid profile in type 2 diabetic people. In a randomized double-blind controlled trial, 60 people (23 males and 37 females) with type 2 diabetes and low-density lipoprotein cholesterol (LDL-C) greater than 2.6 mmol/L were assigned to 2 groups. Participants consumed daily 300 g of probiotic yogurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 or 300 g of conventional yogurt for 6 wk. Fasting blood samples, anthropometric measurements and 3-d, 24-h dietary recalls were collected at the baseline and at the end of the trial. Probiotic yogurt consumption caused a 4.54% decrease in total cholesterol and a 7.45% decrease in LDL-C compared with the control group. No significant changes from baseline were shown in triglyceride and high-density lipoprotein cholesterol (HDL-C) in the probiotic group. The total cholesterol:HDL-C ratio and LDL-C:HDL-C ratio as atherogenic indices significantly decreased in the probiotic group compared with the control group. Probiotic yogurt improved total cholesterol and LDL-C concentrations in type 2 diabetic people and may contribute to the improvement of cardiovascular disease risk factors.     

摄食鱿鱼对人体血脂的影响

探讨高胆固醇海产品的摄食对正常人群血脂的影响。选取33名年龄在22～28岁之间的健康实验人员,每天食用100g鱿鱼,持续20d,并测定实验开始时、10d及20d后,血脂、血糖、肝功能指标以及血清脂肪酸组成的变化。结果显示：每日摄入100g鱿鱼,可明显降低受试者血清甘油三酯(TG)浓度(降低18%,P＜0.004),但对血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、血糖浓度及肝功能标志酶活性均无显著影响。摄食鱿鱼后血清总脂肪酸组成发生明显变化,血清中二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)显著增加。提示每日100g鱿鱼的摄入不会影响健康人群血清胆固醇浓度,对动脉粥样硬化不具危险性。     

大米蛋白调控胆固醇代谢的研究进展

由于胆固醇代谢紊乱已成为威胁人类健康的第一杀手,胆固醇与许多疾病如冠心病及动脉粥样硬化等疾病密切相关,所以开发一种降低胆固醇的保健食品已经成为世界范围研究的热点。大米蛋白具有高营养价值,是一种优质的植物蛋白。介绍了大米蛋白的营养价值和大米蛋白的结构组成,并对国内外大米蛋白的降低胆固醇水平及调控胆固醇代谢机制进行了综述。研究表明,大米蛋白能够降低血液和肝脏的胆固醇水平,促进粪便和类固醇的排泄,降低LDL的水平。     

Has the association between saturated fatty acids,serum cholesterol and coronary heart disease been over emphasized?

Despite 50 years of research and public health messages, coronary heart disease is still the major cause of death in developed countries. This review outlines the elaboration of risk factors for coronary heart disease with emphasis on total and LDL cholesterol levels and discusses the dynamic and heterogeneous nature of serum lipoproteins. The role of saturated fatty acids in hypercholesterolemia is examined and it is concluded that those acids that increase levels concomitantly increase antiatherogenic HDL cholesterol and decrease proatherogenic lipoprotein[a] and small dense LDL particles such that they could be atherogenically neutral. Evidence from epidemiological studies does not supply convincing evidence for an association between saturated fatty acids and coronary heart disease. The surprisingly few randomised controlled trials that examined isocaloric substitution of saturated fatty acids for vegetable-derived fats mostly fail to show a benefit for reduction in saturated fatty acid intake on coronary heart disease risk. The contention that the benefits accruing from the potent hypocholesterolemic action of statin drugs ends the cholesterol controversy is disputed.     

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized,Controlled Study

A randomized, double‐blinded, placebo‐controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4‐wk daily exposure to plant sterols‐enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m²) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (β‐sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope‐labeled gas chromatography‐mass spectrometry. L‐arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 μmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 μmol/L) were significantly elevated after 4‐wk plant sterols supplementation Placebo and 3‐h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L‐arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, β‐Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4‐wk treatments compared to the placebo and 3‐h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo.     

Functional Foods: Their Role in Health Promotion and Disease Prevention

ABSTRACT: The effect of food factors on health status has been recognized since antiquity. More recently, epide-miological studies have led to fundamental research for unraveling the chemistry and mechanism of action of dietary phytochemicals and bioactives. Functional foods and natural health products encompass a wide range of food and ingredients, with a variety of bioactives responsible for their efficacy in health promotion and disease prevention. Phenolic and polyphenolic compounds constitute an important class of secondary plant metabolites that act as free radical scavengers and inhibitors of LDL cholesterol oxidation and DNA breakage, among others. Thus, the role of food phenolics and polyphenolics in the prevention of cardiovascular disease and certain types of cancer is well recognized. In addition, certain marine foods have often been considered as "heart food" because of their omega-3 constituents which are known to lower blood triacylglycerol and, possibly, cholesterol levels. Thus, food factors from both plants and animals may be participating in human health promotion.     

Sterols heating: degradation and formation of their ring-structure polar oxidation products

Cholesterol and phytosterols can be oxidised under heating conditions to give sterol oxidation products (SOPs), known by their toxic effects. This paper studied the degradation of cholesterol and three plant sterols during a 360 min heating treatment (180 °C). The formation and further degradation of SOPs was also analysed by GC-MS. Results revealed a sterol susceptibility to degradation according to the following decreasing order: campesterol≈β-sitosterol≥stigmasterol>cholesterol. The degradation curve fit (R(2)=0.907-0.979) a logarithmic model. SOPs increased their concentration during the first 5-10 min and thereafter, their degradation rate was higher than their formation rate, resulting in a decrease over time. Irrespective of the sterol from which they had derived, 7-keto derivatives presented the highest levels throughout the entire process, and also SOPs with the same type of oxidation followed a similar degradation pattern (R=0.90-0.99).     

Plant sterols in vegetables,fruits and berries

The plant sterol contents of the most important vegetables, fruits and berries available in Finland were determined by capillary gas chromatography. The sample preparation procedure included both acid and alkaline hydrolysis to liberate sterols from their conjugates. The plant sterol contents of fresh vegetables ranged from 51 to 370 mg kg^?1 fresh weight (fw) in samples obtained from retail sale. The highest contents (>300 mg kg^?1) were measured in broccoli, Brussels sprouts, cauliflower and dill and the lowest (51 mg kg^?1) in potato. The range of sterol contents on a dry weight (dw) basis was high, 246–4100 mg kg^?1 dw. Considerable variation was also observed when individual samples of some vegetables were compared. Sitosterol was the main sterol (proportion 43–86%) in all vegetables except cucumber and spinach, in which Δ⁷‐sterols dominated. The total sterol contents were in the range 116–228 mg kg^?1 fw in all fresh fruits except avocado, which contained more sterols, 752 mg kg^?1 fw. In fresh berries the corresponding range was 60–279 m kg^?1 fw. The wild berries lingonberry and blueberry were better plant sterol sources than the cultivated berries blackcurrant, redcurrant and strawberry. In fruits and berries the proportion of sitosterol ranged from 61–93% total sterols. On the basis of the results, the contribution of vegetables, fruits and berries to the total average daily plant sterol intake was estimated to be ca 60 mg. © 2003 Society of Chemical Industry     

Influence of rosemary (Rosmarinus officinalis, L.) on plant sterol oxidation in extra virgin olive oil

The objective of this study was to investigate the potential role of rosemary compounds in inhibiting the plant sterol oxidation in extra virgin olive oil during heating. The stability of plant sterols was measured by quantification of plant sterol and sterol oxide formation upon 6 h of heating in both the extra virgin olive oil and its respective oil at 10% rosemary concentration (ROE). The total sterol and sitosterol oxide contents were determined by GC-flame ionization detection (GC-FID) and GC-MS techniques, respectively. Heating experiments were carried out at 180 degrees C for 0, 1, 3 and 6 h. The total sterol content in the extra virgin olive oil was 255 mg/100 g and that in the ROE 270 mg/100 g. Sitosterol was the most abundant sterol in both samples (50% of total sterol). The ROE showed a lower content of sitosterol oxides with respect to the extra virgin olive oil during heating: after 6 h of heating only 6.1% of sitosterol oxides were formed, while up to 11.5% of sitosterol oxidized in the extra virgin olive oil. Our findings suggested that rosemary compounds were able to counteract the oxidation of plant sterols in the extra virgin olive oil during heating, preventing formation of potentially harmful compounds to human health.