Dietary Intake Of Phytosterols Research Articles

A targeted GC-MS/MS approach for the determination of eight sterols in microgreen and mature plant material

Over the past decades, a remarkable number of scientific studies supported the correlation between an adequate dietary intake of phytosterols (PS) and the reduced risk of cardiovascular diseases. PS are known to inhibit the intestinal absorption of cholesterol, thus promoting the reduction of the low-density lipoproteins (LDL) amount in the bloodstream. Despite the fact that a non-negligible atherogenicity was recognized to PS, thus requiring a careful risk-benefits assessment for plant sterol supplementation, the potential role of PS as cholesterol-lowering agents has been contributing to the spreading awareness of the health benefits associated with the consumption of plant-based foods. In recent years, this has been fueling the market of innovative vegetable products, such as microgreens. Surprisingly, the recent literature concerning microgreens exhibited the lack of studies focusing on the characterization of PS. To fill this gap, a validated analytical method based on the hyphenation of gas chromatography and tandem mass spectrometry is proposed here for the quantitative analysis of eight phytosterols, namely β-sitosterol, campesterol, stigmasterol, brassicasterol, isofucosterol, and cholesterol, lathosterol and lanosterol. The method was exploited for the characterization of the PS content in 10 microgreen crops, i.e., chia, flax, soybean, sunflower, rapeseed, garden cress, catalogna chicory, endive, kale and broccoli raab. Finally, these results were compared to the PS content of mature forms of kale and broccoli raab. A remarkable amount of PS was detected in chia, flax, rapeseed, garden cress, kale, and broccoli raab microgreens. 100 g (wet weight) of these microgreen crops were found to contain from 20 to 30 mg of the investigated PS. Interestingly, in the case of kale and broccoli raab microgreens, the overall PS content was higher than the one measured in the edible parts of the corresponding mature forms. Additionally, a symmetric change of the PS inner profile was observed between the two growth stages of the latter two crops. Here, the overall decrease of the PS sterol content in the mature forms was associated with the increase of the relative amount of β-sitosterol and campesterol at the expense of minor PS species, such as brassicasterol.

Abstract P521: Association Between Dietary Phytosterols and Risk of Cardiovascular Disease Mortality in US Adults: Findings From the Third National Health and Nutrition Examination Survey (NHANES III), 1988-1994

Introduction: Phytosterols (plant sterols) are naturally occurring components of plant food sources, including vegetable oils, nuts, cereals and legumes. Their chemical structure impedes intestinal cholesterol absorption and regular consumption has been related to lower serum low-density cholesterol (LDL-C), a causal risk factor for cardiovascular disease (CVD). The association between dietary plant sterol intake and CVD has yet to be determined. Objective: We aimed to examine the association of phytosterol consumption in the diet with cardiovascular mortality in US adults the National Health & Nutrition Examination Survey III (NHANES III), 1988-1994. Methods: We conducted a prospective cohort analysis on National Health and Nutrition Examination Survey (NHANES, 1988-1994 [III]), linked with the National Death Index mortality data (2015) to associate dietary phytosterol intake from 24h dietary recall data with CVD mortality. We included 13,004 adults aged ≥20 years who were non-pregnant, free of CVD at baseline and completed ≥1 24h dietary recall with plausible caloric intake data. We excluded individuals with death occurring within 1 year of baseline. We created a database quantifying the phytosterol content of foods in the 24h dietary recall data and estimated usual intake by quintiles using the NCI method. We determined the risk function by regression calibration and estimated CVD mortality risk between the 10 th (Q1) and 90 th (Q5) percentiles of usual intake. Data was adjusted for sex, age, smoking status and ethnicity. Results: Over a mean±SD follow-up period of 21.2±5.1y, 949 CVD deaths occurred in a population with a mean±SD age of 44.2±14.3y, BMI 26.7±4.7 kg/m 2 and mean dietary plant sterol usual intake of 272.3 mg/day. The top sources of dietary phytosterols were from potatoes 23%), wheat and other grains (21%) and beans, legumes and nuts (13%). Mean usual intake plant intake in the 10 th (Q1) and 90 th (Q5) percentiles of the population was 150.1 and 414.0 mg/day. The estimated relative risk for CVD mortality between Q1 (ref) and Q5 was 0.972 (p<0.05). Conclusions: Preliminary analyses suggest a CVD death risk reduction of 2.8% in the highest versus lowest intakes of dietary plant sterols in the US population. We plan to expand the multivariable model to include the Healthy Eating Index (diet quality) and assess stratification by healthful and unhealthful sources of phytosterols and linear and non-linear dose response analyses to determine the robustness of the association. OSF Registration: osf.io/da4sg Funding: Amgen Scholars Program, Canadian Institutes of Health Research (CIHR), Banting and Best Diabetes Centre (BBDC), Toronto 3D Knowledge Synthesis and Clinical Trials foundation

225Association between phytosterol consumption esophageal cancer risk

Abstract Background Phytosterols have anticancer effects and have been shown to inhibit various forms of cancer. However, epidemiological studies on the relationship between phytosterols and esophageal cancer risk are quite limited. The aim of this study was to investigate dietary phytosterol intake in relation to esophageal squamous cell carcinoma (ESCC) in the Chinese population. Methods A case–control study was conducted from July 2011 to June 2013, recruiting 856 eligible ESCC cases plus 856 controls. Dietary information was collected by using a validated food frequency questionnaire. The OR and 95% CI of ESCC risk were assessed by multivariable logistic regression models. Results The total phytosterols was found to be associated with a 56% (95% CI: 0.32- 0.61) reduction in ESCC risk when comparing the highest with the lowest tertiles, after adjusting for various confounders. An inverse association was also found between the consumption of β-sitostanol, β-sitosterol, campesterol and ESCC risk. No statistically significant association was found between rapesanol and ESCC risk. Conclusions These data indicated that the consumption of total phytosterols, β-sitostanol, β-sitosterol, campesterol is inversely associated with ESCC risk in a Chinese population Key messages Phytosterols consumption may contribute to the prevention of esophageal squamous cell carcinoma

Economic outcomes of nutritional interventions with functional bioactive compounds

The aim of this short review is to present and discuss the available evidence regarding the effects of consumption of compounds with functional properties on economic aspects. Medline (PubMed), EMBASE, and Scielo were used to search intervention studies published between 2000 and 2018 on the effects of functional bioactive compounds ingestion (via diet or supplement use) and economic outcomes, such as productivity and cost savings. The fatty acids omega-3 is the one with most studies published and through simulations developed in several countries, like the USA, Canada, and Italy, the supplementation of omega-3 has proven to be a cost-effective strategy for the reduction of cardiovascular diseases (considering only direct costs, not including costs of work absence and productivity losses). Also, it is reported that the increase of 1 g/day in consumption of dietary fibers can generate an important economy through the reduction of direct and indirect costs with diabetes mellitus, cardiovascular diseases, and intestinal constipation. Lastly, estimates point to the fact that regular dietary intake of phytosterols can reduce the incidence of cardiovascular diseases and the costs associated. Interventions involving functional bioactive compounds, such as n-3, dietary fibers, and phytosterols, are strategies that promote favorable health outcomes with viable costs. It is important to discuss the need for the development of models for economic evaluation in nutrition, to better estimate the absolute and relative monetary impact of nutritional interventions.

Phytosterol Profiles of Common Foods and Estimated Natural Intake of Different Structures and Forms in China.

Phytosterols are well-known for their cholesterol-lowering effects, and the structures and forms of phytosterols affect their bioactivity. We aimed to illustrate the phytosterol profiles in common foods and estimate their natural intake in five geographical regions and among different age groups in China. In total, 12 phytosterols in free and esterified forms of 119 foods from five regions across China were examined using gas chromatography-mass spectrometry. Then, the dietary intake of phytosterols was calculated combined with the dietary foods intake data of Chinese people. The total phytosterol content was highest in vegetable oils (150.4-1230.9 mg/100 g), followed by legumes (129.6-275.6 mg/100 g), nuts (18.9-255.2 mg/100 g), and cereals (11.9-93.8 mg/100 g). Vegetables and fruits contained lower contents of total phytosterols. Phytosterols were mainly esterified in most common foods except in nuts. The predominant phytosterols were β-sitosterol, campesterol, and stigmasterol, all of which belonged to plant sterols and 4-desmethylsterols. Total phytosterol intake varied across different regions, ranging between 257.7 and 473.7 mg/standard-person (sp)/day, with the highest intake in Beijing, followed by Hangzhou, Wuhan, Chongqing, and Guangzhou. However, phytosterol proportion was similar across regions, with β-sitosterol accounting for 46.5-50.3% of the natural intake. Phytosterol intake was mainly constituted by plant sterols and 4-desmethylsterols in esterified form (61.9-74.6%). At the age of 2-70 years, phytosterol intake ranged from 154.3 mg/day to 348.0 mg/day in the national scale.

Association between phytosterol intake and colorectal cancer risk: a case-control study.

A study in rodent models showed that phytosterols protected against colon carcinogenesis, probably by inhibiting dysregulated cell cycle progression and inducing cellular apoptosis. However, epidemiological studies on the relationship between phytosterols and colorectal cancer risk are quite limited. The aim of this study was to investigate dietary phytosterol intake in relation to colorectal cancer risk in the Chinese population. A case-control study was conducted from July 2010 to June 2016, recruiting 1802 eligible colorectal cancer cases plus 1813 age (5-year interval) and sex frequency-matched controls. Dietary information was collected by using a validated FFQ. The OR and 95 % CI of colorectal cancer risk were assessed by multivariable logistic regression models. A higher total intake of phytosterols was found to be associated with a 50 % reduction in colorectal cancer risk. After adjusting for various confounders, the OR of the highest quartile intake compared with the lowest quartile intake was 0·50 (95 % CI 0·41, 0·61, P trend<0·01) for total phytosterols. An inverse association was also found between the consumption of β-sitosterol, campesterol, campestanol and colorectal cancer risk. However, stigmasterol intake was related to an increased risk of colorectal cancer. No statistically significant association was found between β-sitostanol and colorectal cancer risk. Stratified analysis by sex showed that the positive association of stigmasterol intake with colorectal cancer risk was found only in women. These data indicated that the consumption of total phytosterols, β-sitosterol, campesterol and campestanol is inversely associated with colorectal cancer risk in a Chinese population.

Plasma biomarker of dietary phytosterol intake.

BackgroundDietary phytosterols, plant sterols structurally similar to cholesterol, reduce intestinal cholesterol absorption and have many other potentially beneficial biological effects in humans. Due to limited information on phytosterol levels in foods, however, it is difficult to quantify habitual dietary phytosterol intake (DPI). Therefore, we sought to identify a plasma biomarker of DPI.Methods and FindingsData were analyzed from two feeding studies with a total of 38 subjects during 94 dietary periods. DPI was carefully controlled at low, intermediate, and high levels. Plasma levels of phytosterols and cholesterol metabolites were assessed at the end of each diet period. Based on simple ordinary least squares regression analysis, the best biomarker for DPI was the ratio of plasma campesterol to the endogenous cholesterol metabolite 5-α-cholestanol (R2 = 0.785, P < 0.0001). Plasma campesterol and 5-α-cholestanol levels varied greatly among subjects at the same DPI level, but were positively correlated at each DPI level in both studies (r > 0.600; P < 0.01).ConclusionThe ratio of plasma campesterol to the coordinately regulated endogenous cholesterol metabolite 5-α-cholestanol is a biomarker of dietary phytosterol intake. Conversely, plasma phytosterol levels alone are not ideal biomarkers of DPI because they are confounded by large inter-individual variation in absorption and turnover of non-cholesterol sterols. Further work is needed to assess the relation between non-cholesterol sterol metabolism and associated cholesterol transport in the genesis of coronary heart disease.

Common sources and composition of phytosterols and their estimated intake by the population in the city of São Paulo, Brazil

ObjectivePhytosterols have been used alone, or combined with lipid-altering drugs, to reduce cholesterol levels and the burden of cardiovascular disease. Considerable variation in the composition of phytosterols exists and its consumption, in a regular diet, by the Brazilian population is still unknown. Thus, the aim of the present study was to determine the phytosterols content of the most consumed plant foods and to estimate the phytosterols intake by this population. MethodsIntake of plant foods of a representative population of the city of São Paulo (n = 1609), randomly selected on the basis of the Brazilian Institute for Geography and Statistics census data (2010), was obtained by a food frequency questionnaire (FFQ). Foods were chosen on the basis of the Consume Expenditure Survey (2002–2003) and from answers to the FFQ. Phytosterols composition of most consumed greens, legumes, cereals, and seeds, fruits, and vegetable oils was determined by gas chromatography (flame ionization detection). Daily phytosterols intake was estimated in terms of mg per 100 g (mg/100 g−1) of edible portion. Underreporters and overreporters were excluded. ResultsMean (SE) daily phytosterols intake in the diet of the study population was 100.6 (1.2) mg, with β-sitosterol as the largest sterol component (65.4%), followed by campesterol (23.2%), and stigmasterol (10%). No significant changes in daily phytosterols intake were observed after exclusion of underreporters and overreporters. Considerable variation was observed in phytosterols content among the most consumed plant foods. ConclusionsAnalysis of phytosterols composition in most consumed plant foods has shown that phytosterols content varied among food groups. Dietary intake of phytosterols in a large population of the city of São Paulo is in the same range of some countries.

Comparison of the dietary phytosterols intake and serum lipids content in elderly women from three cities of China

To investigate the dietary phytosterol intake of elderly women in three different cities of China, and to compare the main dietary sources, so that to discuss the relationship of dietary phytosterol intake and serum lipids. Based on the dietary pattern, women more than 50 years old from Beijing, Hefei and Urumchi were chosen as testers, 80 - 100 people for each city respectively. The dietary survey was done by continues 24 hours review of two days, the plant food were collected and the phytosterol content (include beta-sitosterol, campesterol, stigmasterol, sitostanol) were analyzed by GC methods, the total phytosterols content were calculated. The dietary phytosterol intake were calculated and serum lipids were also analyzed in all the testers. Testers from Beijing, Hefei and Urumchi were 100, 101 and 84 respectively. The average dietary phytosterol intake of people in Beijing and Hefei were 340.3 mg/d and 313.5 mg/d, the main sources were plant oil and cereals, while the average dietary phytosterol intake of people in Urumchi were 550.4 mg/d, higher than the other two cities (t values were 9.369, 10.420, respectively, both P values < 0.01), the main source in Urumchi was cereal (provide 53.1% of the total phytosterol intake). The laboratory results showed, testers in Urumchi had significantly lower serum TC content ((4.04 +/- 0.78) mmol/L) than that in Beijing ((4.89 +/- 0.91) mmol/L) and Hefei ((4.71 +/- 0.83) mmol/L) (t value were 6.766 and 5.401 respectively, both P values < 0.01); serum TG content in Urumchi((1.01 +/- 0.48) mmol/L) was also lower than that in Beijing ((1.31 +/- 0.53) mmol/L) and Hefei ((1.66 +/- 0.75) mmol/L) (t values were 3.343 and 7.293 respectively, both P values < 0.01); the serum glucose is also lower in testers in Urumchi ((5.02 +/- 2.18) mmol/L) compared with testers in Beijing ((5.69 +/- 1.53) mmol/L, t = 2.561, P < 0.05) and Hefei ((5.78 +/- 1.53) mmol/L, t = 2.934, P < 0.01). Different dietary pattern result in significantly different dietary phytosterol intake in elder women in three cities, higher, phytosterol intake seemed to contribute to lower serum lipids.

A moderate intake of phytosterols from habitual diet affects cholesterol metabolism

Cholesterol metabolism homeostasis is the result of a balance between synthesis, degradation and intestinal absorption. It is well established that intestinal cholesterol absorption efficiency can be modified by the intake of phytosterol-enriched food and, therefore, have a serum cholesterol-lowering effect. Recent epidemiological and clinical studies have shown that presence of phytosterols at normal diet levels could also be effective on lowering total and LDL serum cholesterol since they affect whole-body cholesterol metabolism even at those moderate doses. The aim of this study was to analyze the effect of the levels of the naturally-occurring phytosterols in the diet on cholesterol metabolism parameters. In order to do that a group of 99 healthy volunteers was studied for their dietary habits and surrogate markers of cholesterol synthesis and absorption. The mean daily dietary intake of phytosterols, measured by a food semiquantitative frequency questionnaire, was found to be 494 mg being beta-sitosterol the major contributor to it. Subjects were classified into tertiles according to their total phytosterol intake and comparisons were done between subgroups. No statistical differences were observed for surrogate markers of intestinal cholesterol absorption, but a significant increase in the cholesterol synthesis surrogate marker lathosterol-to-cholesterol ratio associated to highest dietary phytosterol intake was observed. Regardless of this, only a non significant trend toward a less atherogenic lipid profile was observed in the upper tertile. In conclusion, the intake of moderate amounts of phytosterols naturally present in habitual diet may affect cholesterol metabolism and specially the rate of cholesterol synthesis as estimated by the surrogate marker lathosterol-to-cholesterol ratio in serum.

Phytosterol-enriched foods: Role in lowering serum cholesterol level, community authorising and conditions of marketing

Phytosterols are isoprene compounds that may be found in a great variety of different food products. Most important phytosterol compounds are β-sitosterol, campesterol and stigmasterol. Plant sources of phytosterols are oily seeds, nuts, plant oils, grains, and pulses. Many controlled clinical studies have demonstrated their ability to reduce blood cholesterol levels in hyper- and normocholesterolaemic subjects. Investigators report that phytosterol intakes of 2 to 3 g/day reduce low-density lipoprotein (LDL) cholesterol levels by about 7 to 11% in human subjects, while LDL and TG levels show no change. Phytosterol intake higher than 3 g daily results in no greater decrease of LDL level, but even the consumption of 8.6 g/day has no detrimental effect on human health. Documented side effect of elevated phytosterol intake is the reduced level of certain carotenoids in sera but this effect can be balanced by increased consumption of fruits and vegetables rich in carotenoids. Subjects having hereditary sitosterolaemia are highly advised to refrain from consuming foods supplemented with phytosterols. As dietary intake of phytosterols is too low to achieve a significant reduction of cholesterol level, based on the Community legislation of 258/97/EC regulation related to novel foods and novel food ingredients the European Union authorized to use phytosterols in certain food products at a concentration which resulted in a daily phytosterol intake less than 3 g. European survey of European Food Safety Authority (EFSA) shows that only 10 to 15% of the population consume foods supplemented with phytosterols, and phytosterol intake is less than the effective dose. Based on this survey it is supposed that the risk of phytosterol overdose is low. EFSA also stated that — based on the relevant scientific information — regular intake of foods supplemented with phytosterols/phytostanols is in significant correlation with reduced serum cholesterol level. Based on this statement authorized foods enriched with phytosterols will be the first food group legally having health claim for reduced risk of disease since the new Community legislation on nutritional and health claim on foods 1924/2006/EC exists. Consumers will have a scientifically substantiated health claim on the label of these foods: “Plant sterols/stanols have been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of coronary heart disease”.

Serum sterol responses to increasing plant sterol intake from natural foods in the Mediterranean diet

Phytosterols in natural foods are thought to inhibit cholesterol absorption. The Mediterranean diet is rich in phytosterol-containing plant foods. To assess whether increasing phytosterol intake from natural foods was associated with a cholesterol-lowering effect in a substudy of a randomized trial of nutritional intervention with Mediterranean diets for primary cardiovascular prevention (PREDIMED study). One hundred and six high cardiovascular risk subjects assigned to two Mediterranean diets supplemented with virgin olive oil (VOO) or nuts, which are phytosterol-rich foods, or advice on a low-fat diet. Outcomes were 1-year changes in nutrient intake and serum levels of lipids and non-cholesterol sterols. Average phytosterol intake increased by 76, 158 and 15 mg/day in participants assigned VOO, nuts and low-fat diets, respectively. Compared to participants in the low-fat diet group, changes in outcome variables were observed only in those in the Mediterranean diet with nuts group, with increases in intake of fibre, polyunsaturated fatty acids and phytosterols (P < 0.020, all) and significant (P < 0.05) reductions of LDL-cholesterol (0.27 mmol/l or 8.3%) and the LDL/HDL-cholesterol ratio (0.29 mmol/l or 11.5%). Variations in saturated fat, cholesterol or fibre intake were unrelated to LDL-cholesterol changes. In the whole group, changes in serum sitosterol-to-cholesterol, which reflect those of dietary phytosterol intake and absorption, correlated inversely to LDL-cholesterol changes (r = -0.256; P = 0.008). In multivariate analyses, baseline LDL-cholesterol, increases in serum sitosterol ratios and statin use were independently associated with LDL-cholesterol reductions. Small amounts of phytosterols in natural foods appear to be bioactive in cholesterol lowering.

Foods fortified with phytosterins: their role in decreasing the cholesterol level in serum, their Community authorization and requirements for placing them to the market

Phytosterols are isoprene compounds that may be found in a great variety of different food products. The most important phytosterol compounds are β-sitosterol, campesterol and stigmasterol. Plant sources of phytosterols are oily seeds, nuts, plant oils, grains, and pulses. Many controlled clinical studies have demonstrated their ability to reduce blood cholesterol levels in hyper- and normocholesterolaemic subjects. Investigators report that phytosterol intakes of 2 to 3 g/d reduce low-density lipoprotein (LDL) cholesterol levels by about 7–11% in human subjects, while LDL and TG levels do not change. Phytosterol intake higher than 3 g daily does not result in higher decrease of LDL level, but about consumption of 8.6 g per day does not have any detrimental effect on human health. A documented side effect of elevated phytosterol intake is the reduced level of certain carotenoids in sera but this effect can be balanced by increased consumption of fruits and vegetables rich in carotenoids. Subjects having hereditary sitosterolemia are highly advised to refrain from consuming foods supplemented with phytosterols. While dietary intake of phytosterols is too low to achieve significant reduce of cholesterol level, based on the Community legislation of 258/97/EC regulation related to novel foods and novel food ingredients, the European Union authorized to use phytosterols in certain food products at a concentration which resulted in a daily phytosterol intake less than 3 g. A European survey of the European Food Safety Authority (EFSA) shows that only 10-15% of the population consume foods supplemented with phytosterols, and phytosterol intake is less than the effective dose. Based on this survey it is supposed that the risk of phytosterols overdose is low. EFSA also stated that – based on the relevant scientific information – regular intake of foods supplemented with phytosterols/phytostanols is in significant correlation with reduced serum cholesterol level. Based on this statement, authorized foods supplemented with phytosterols will be the first food group legally having health claim for reduced risk of disease since the new Community legislation on nutritional and health claim on foods 1924/2006/EC exists. Consumers will have a scientifically substantiated health claim on the label of these foods: “Plant sterols/stanols have been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of coronary heart disease.”

Association of plasma phytosterol concentrations with incident coronary heart disease: Data from the CORA study, a case–control study of coronary artery disease in women

AimsPhytosterols have been proposed to be atherogenic. This research investigates whether plasma concentrations of phytosterols correlate with the manifestation of coronary heart disease. Methods and resultsThe CORA study compares clinical, biochemical, and lifestyle factors in consecutive pre- and postmenopausal women with incident coronary heart disease to those in age-matched population-based controls. Controls (n=231) had significantly higher plasma concentrations of the major phytosterol species than cases (n=186) (4.649mg/l vs. 4.092mg/l; p<0.001). Cases had a higher dietary intake of phytosterols, but the ratio of lathosterol over sitosterol did not significantly differ. Phytosterols correlated with cholesterol concentrations of LDL and HDL, the phytosterol-carrying lipoproteins. The age-adjusted odds ratio for the association of total phytosterols and risk of coronary heart disease was 0.69 per 5mg/dl (95% CI 0.46–0.99). After adjustment for LDL- and HDL-cholesterol the odds ratio approached 1 (0.89; 95% CI 0.61–1.30), which was reached after additional adjustment for major risk factors, particularly those reflecting the metabolic syndrome (1.05; 95% CI 0.64–1.97). ConclusionsHealthy controls had higher unadjusted concentrations of plasma phytosterols, but the adjusted odds ratio for coronary heart disease did not point to an impact of plasma phytosterols on coronary heart disease.

Preferential Efflux of Phytosterols over Cholesterol from Macrophages

Phytosterols are structurally similar to cholesterol. Increased dietary intake of phytosterols effectively lowers LDL-cholesterol. Since phytosterols are incorporated in a growing number of foods and some of the ingested phytosterols reach the circulation, accumulation of phytosterols in foam-cell-prone cells such as macrophages might occur. Therefore we examined the influx and efflux of phytosterols by human THP-1 macrophages. The influx rates of methyl-beta-cyclodextrin delivered phytosterols did not significantly differ from that of cholesterol (approximately 3.8 pmol/min per mg cellular protein), neither did the total influx of oxidised LDL delivered phytosterols differ from that of cholesterol. The efflux of beta-sitosterol and sitostanol from preloaded THP-1 cells to HDL was more efficient than the efflux of campesterol and cholesterol (rate constants of 0.41 +/- 0.04/h, 0.62 +/- 0.08/h, 0.23 +/- 0.05/h and 0.29 +/- 0.03/h, respectively). The efflux of beta-sitosterol was not associated with a dominant transfer to ApoA-I, nor did ABCA1 induction-promoted cholesterol efflux to the level observed for beta-sitosterol. Our data show that THP-1 macrophages take up phytosterols, but have efficient mechanisms to remove phytosterols from their cellular compartments. Consequently, it is less likely that macrophages preferentially accumulate phytosterols over cholesterol and hence promote foam-cell formation in vivo.

Enhancement of seed phytosterol levels by expression of an N‐terminal truncated Hevea brasiliensis (rubber tree) 3‐hydroxy‐3‐methylglutaryl‐CoA reductase

Dietary intake of phytosterols (plant sterols) has been shown to be effective in reducing blood cholesterol levels, thereby reducing the risk of cardiovascular disease. Phytosterols are most commonly sourced from vegetable oils, where they are present as minor components. We report here the generation of transgenic tobacco seeds substantially enhanced in phytosterol content by the expression of a modified form of one of the key sterol biosynthetic enzymes, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR). The constitutive expression of an N-terminal truncated Hevea brasiliensis HMGR (t-HMGR), lacking the membrane binding domain, enhanced seed HMGR activities by 11-fold, leading to increases in total seed sterol of 2.4-fold. Seed-specific expression of t-HMGR enhanced total seed sterol levels by 3.2-fold, to 1.36% dry weight or 3.25% of oil. 4-desmethylsterols were increased by 2.2-fold, whilst certain sterol biosynthetic intermediates, in particular cycloartenol and 24-ethylidene lophenol, also accumulated. The additional sterol in seed tissue was present in the form of fatty acid esters. Constitutive expression of t-HMGR increased leaf phytosterol sterol levels by 10-fold, representing 1.8% dry weight, and the sterol was sequestered, in acyl ester form, as cytoplasmic 'oil droplets'. These studies establish HMGR as a key enzyme controlling overall flux into the sterol biosynthesis pathway in seed tissue, but the accumulation of certain intermediates suggests additional slow steps in the pathway. The expression of an N-truncated HMGR activity has generated novel phytosterol-enriched raw materials that may provide the basis of new sourcing opportunities for this important class of cholesterol-lowering actives.

The role of phytosterols and phytosterolins in immune modulation: a review of the past 10 years.

Although plant sterols (phytosterols) were chemically described in 1922, their biological role in human and animal health has been underestimated. Their ability to control cholesterol plasma levels in hypercholesterolimic patients was first described in 1983 when the structure of phytosterols implied that they could, by steric hindrance, inhibit the absorption of cholesterol from our diets. This has led to the development of functional foods containing high contents of these plant molecules or their esters as cholesterol controlling foods. Over the last 15 years, however, several reports have appeared in the literature indicating that phytosterols have some immunological activity as highlighted in animal models of inflammation or even in in-vitro and in-vivo models of cancer (colorectal and breast cancer). These findings were paralleled by epidemiological studies correlating the reduced risk of numerous diseases and the dietary intake of phytosterols. It is only in the last 10 years, however, that their direct immune modulatory activity on human lymphocytes has been proven and the mechanism of action in cancer cells has been elucidated. The use of phytosterols as supportive therapies in certain chronic conditions has been tested under clinical trial conditions. This review presents a summary of the in-vitro and in-vivo studies published to date.

Selective Solubilization of Sterols by Bile Salt Micelles in Water: A Thermodynamic Study

To study thermodynamically the so-called lowering effect of the plasma cholesterol level caused by dietary intake of phytosterols (plant sterols) or phytostanols, solubilization was investigated for the respective single systems of cholesterol (Ch), cholestanol (Chsta), and stigmasterol (Stig) and for their 1:1 mixed systems with two kinds of free bile salts (BS), sodium cholate (NaC) and sodium deoxycholate (NaDC), in pH 10 Kolthoff buffer solution at 37 °C. For the sterol/stanol solubilizates examined, compared with NaC, NaDC is stronger in solubilizing power, Sp, which is defined as the derivative of the solubilized amount, W, in mM by the total BS concentration, Ct (dW/dCt), as expected in terms of hydrophobicity and aggregation number. The following findings were made: (i) the amount solubilized by both BS micelles follows the order Ch > Chsta > Stig among the three single solubilizates; (ii) Chsta is much stronger in lowering ability than Stig in regard to Ch solubilization; (iii) from the 1:1 mixt...

Dose-dependent effects of dietary phytosterol on epithelial cell proliferation of the murine colon

Phytosterols are a group of compounds in plants that have been found to inhibit tumour development and decrease enhanced colonic epithelial cell proliferation in carcinogen-treated rats. The mechanism by which phytosterols may inhibit tumour development and alter cell proliferation is unknown. However, studies have shown that dietary phytosterol intake may alter levels of certain promoters in the colonic lumen, leading to altered levels of colonic epithelial cell proliferation. In this study, the effect of dietary phytosterol on the proliferative status of the intestinal epithelium was investigated in mice. Inbred C57BI/6J mice were fed semi-synthetic diet (control); 0.1% cholic acid, 0% phytosterol (cholic acid control); and cholic acid plus 0.3, 1.0 or 2.0% phytosterol. Dietary cholic acid significantly increased colonic epithelial cell proliferation and the highest labelled cell position by 92 and 35%, respectively. Phytosterol significantly reduced the enhanced labelling index and the position of the highest labelled cell in a dose-dependent manner. Mitotic index was also reduced significantly by phytosterol but not in a dose-dependent manner. The results of this study indicate that phytosterol influences the colonic epithelial cell morphometrics, that are important preneoplastic events in colon carcinogenesis, and may thus contribute to a reduced risk of cancer.