Dietary Phytosterols Research Articles

PWE-010 Dietary campesterol is inversely associated with the risk of developing oesophageal adenocarcinoma: a UK prospective study in the EPIC-Norfolk cohort, using information from 7-day food diaries

IntroductionDietary phytosterols (PS), including campesterol, the most bioavailable of this group, are structurally similar to cholesterol, and are present in grain legumes, cereals, nuts and vegetable oils. Experimental studies have...

Mo1605 Dietary Docosahexaenoic Acid is Inversely Associated With the Risk of Developing Esophageal Adenocarcinoma: A UK Prospective Study in the EPIC-Norfolk Cohort, Using Information From 7-Day Food Diaries

Introduction Dietary phytosterols (PS), including campesterol, the most bioavailable of this group, are structurally similar to cholesterol, and are present in grain legumes, cereals, nuts and vegetable oils. Experimental studies have shown PS have several anticarcinogenic effects, including inducing apoptosis and inhibiting both angiogenesis and cell proliferation. The aim of this study was to conduct the first epidemiological investigation to determine if an inverse association exists between PS intake and the risk of both Barrett9s oesophagus (BO) and oesophageal adenocarcinoma (OAC). Methods A total of 25 639 men and women aged 40–75 years, were recruited between the years 1993 and 1997 into the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort Study. At baseline, participants completed detailed 7-day food diaries which were coded by nutritionists. Subjects were followed-up over subsequent years for the development of BO and OAC. A review of case notes confirmed these diagnoses. Dietary intakes were compared between cases and a random sample of 3 797 controls in a case-cohort analysis. Cox regression estimated the HR for both campesterol and total PS. Results During follow-up, 104 patients were diagnosed with BO (80% men, median age 67.0 yrs [IQR 61.1–73.1] at diagnosis) after a median follow-up of 6.2 yrs (IQR 4.1–8.1). A further 63 patients developed OAC (83% men, median age 73.0 yrs [IQR 67.0–78.0] at diagnosis) after a median follow-up of 6.4 yrs (IQR 4.4–8.9). For BO, no significant associations were found with campesterol (HR 1.47, 95% CI 0.77 to 2.79) or total dietary PS (HR 1.28, 95% CI 0.70 to 2.33), in either sex. For OAC, in men, there were inverse associations with campesterol (HR 0.43, 95% CI 0.22 to 0.83, p=0.01), in a threshold manner, comparing the lowest with a summation of the top four quintiles of intake. In women, for OAC, there were no such associations with campesterol (HR 2.13, 95% CI 0.44 to 10.15, p=0.34). Total PS intake (HR 0.71, 95% CI 0.38 to 1.35) was not significantly associated with OAC in either sex. Conclusion Campesterol intake was associated with an approximate 55% risk reduction for OAC in men, although there were no significant effects in BO or for either condition in women. The data support a role for dietary campesterol, in preventing the malignant transformation of BO to OAC, and therefore these micronutrients should be measured in future aetiological studies of OAC. Competing interests None declared.

ABCG5/G8 deficiency results in reduced intestinal cholesterol and fatty acid transport

Adenosine triphosphate‐binding cassette (ABC) half transporters G5 and G8 are critical in protecting the body from the accumulation of dietary phytosterols, which is associated with an elevated risk of coronary heart disease. Expressed in the liver and intestines, they are proposed to promote phytosterol excretion and to limit phytosterol absorption. However, the role of G5/G8 in cholesterol and fatty acid (FA) absorption is unclear. The aim of this study was to investigate the effects of G5/G8 deficiency on intestinal lipid transport in chow‐fed mice. We employed the conscious lymph fistula model to examine radiolabeled dietary cholesterol and FA transport into the lymph using wild‐type (WT) and G5/G8 knockout (KO) mice. Since it has been thought that G5/G8 promote sterol excretion, we were surprised to find that G5/G8 KO mice displayed a ~53% reduction in dietary cholesterol transport into the lymph compared to WT controls. In addition, G5/G8 KO mice also displayed a ~45% reduction in FA transport into the lymph. This reduction in cholesterol and FA transport was also accompanied by an accumulation of cholesterol and FAs in the intestinal lumen, suggesting that the loss of G5/G8 inhibit transport across the enterocyte. We conclude that G5/G8 deficiency results in reduced intestinal cholesterol and FA absorption in mice, and therefore may play a previously unknown role in intestinal lipid absorption.Grant Funding Source: University of Cincinnati

Combined effects of ezetimibe and phytosterols on cholesterol metabolism: a randomized, controlled feeding study in humans.

Both ezetimibe and phytosterols inhibit cholesterol absorption. We tested the hypothesis that the combination of ezetimibe and phytosterols is more effective than ezetimibe alone in altering cholesterol metabolism. Twenty-one mildly hypercholesterolemic subjects completed a randomized, double-blind, placebo-controlled, triple-crossover study. Each subject received a phytosterol-controlled diet plus (1) ezetimibe placebo+phytosterol placebo, (2) 10 mg/d ezetimibe+phytosterol placebo, and (3) 10 mg/d ezetimibe+2.5 g phytosterols for 3 weeks each. All meals were prepared in a metabolic kitchen. Primary outcomes were intestinal cholesterol absorption, fecal cholesterol excretion, and low-density lipoprotein cholesterol levels. The combined treatment resulted in significantly lower intestinal cholesterol absorption (598 mg/d; 95% confidence interval [CI], 368 to 828) relative to control (2161 mg/d; 95% CI, 1112 to 3209) and ezetimibe alone (1054 mg/d; 95% CI, 546 to 1561; both P<0.0001). Fecal cholesterol excretion was significantly greater (P<0.0001) with combined treatment (962 mg/d; 95% CI, 757 to 1168) relative to control (505 mg/d; 95% CI, 386 to 625) and ezetimibe alone (794 mg/d; 95% CI, 615 to 973). Plasma low-density lipoprotein cholesterol values during treatment with control, ezetimibe alone, and ezetimibe+phytosterols averaged 129 mg/dL (95% CI, 116 to 142), 108 mg/dL (95% CI, 97 to 119), and 101 mg/dL (95% CI, 90 to 112; (P<0.0001 relative to control). The addition of phytosterols to ezetimibe significantly enhanced the effects of ezetimibe on whole-body cholesterol metabolism and plasma low-density lipoprotein cholesterol. The large cumulative action of combined dietary and pharmacological treatment on cholesterol metabolism emphasizes the potential importance of dietary phytosterols as adjunctive therapy for the treatment of hypercholesterolemia. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00863265.

Beyond cholesterol-lowering effects of plant sterols: clinical and experimental evidence of anti-inflammatory properties

Inflammation is a strong risk factor for cardiovascular disease. Dietary plant sterols are known to reduce plasma cholesterol levels and thereby reduce cardiovascular risk. Recent observations from animal and human studies have demonstrated anti-inflammatory effects of phytosterols. For example, several animal and human studies report reductions in the levels of proinflammatory cytokines, including C-reactive protein, after consumption of dietary plant sterols. Although the cholesterol-lowering effects of phytosterols in humans are well documented, studies on the effects of phytosterols on inflammatory markers have produced inconsistent results. This review summarizes and discusses findings from recent animal and human studies with regard to the potential anti-inflammatory effects of dietary phytosterols. Findings on the effects of plant sterols on inflammation remain limited and confounding. Future research using better-designed and well-controlled laboratory studies and clinical trials are needed to fully understand the mechanisms through which phytosterols influence inflammation. Additional well-designed placebo-controlled studies are needed to better understand how and to what extent dietary plant sterols may modify the immune system and the production of inflammatory markers.

Sterol Composition in Larvae of the Silkworm,Bombyx mori

Sterols in silkworm larvae were analyzed. Cholesterol was predominantly detected in all tissues examined. Dietary phytosterols and desmosterol, a putative biosynthetic intermediate from phytosterols to cholesterol, were also detected, indicating that imperfect intestinal conversion from phytosterols to cholesterol influences the sterol composition in larval tissues.

Dietary phytosterol esters must be hydrolyzed for optimal reduction in cholesterol absorption

Consumption of phytosterol esters (PSE) is a well accepted therapy for reducing LDL cholesterol, a primary atherosclerosis risk factor. The mechanism by which PSE lower LDL cholesterol has yet to b...

Pro‐atherogenic effects of probucol may be mediated through alterations in the coagulation system in apo E‐KO mice

We have previously shown that probucol paradoxically increases atherogenesis in apo E‐KO mice, while dietary phytosterol significantly reduce the disease in this animal model. Male apo E‐KO mice were fed with an atherogenic diet containing 9% (w/w) fat and 0.2% (w/w) cholesterol in the presence of either 2% (w/w) dietary phytosterol mixture (phytosterol‐treated group, n=8), or 1% (w/w) probucol (probucol‐treated group, n=8) or nothing (control group, n=8) for 18 weeks. Plasma total cholesterol levels were significantly decreased in both treated groups as compared to controls. Aortic atherosclerotic lesion size was significantly lower in the phytosterol‐treated and significantly higher in the probucol‐treated mice as compared to controls. Plasma and aortic PAI‐1 levels were significantly higher in the probucol‐treated animals as compared to controls, while these values were comparable between the phytosterol‐treated and control mice. Both DNA microarray and RT‐PCR tests showed a significant increase in the expression of F13a1 in the liver of probucol treated mice as compared to controls. These observations suggest that pro‐atherogenic effects of probucol maybe mediated through alterations in the coagulation system in this animal model.

Dietary phytosterols and phytostanols decrease cholesterol levels but increase blood pressure in WKY inbred rats in the absence of salt-loading

BackgroundThere are safety concerns regarding widespread consumption of phytosterol and phytostanol supplemented food products. The aim of this study was to determine, in the absence of excess dietary salt, the individual effects of excess accumulation of dietary phytosterols and phytostanols on blood pressure in Wistar Kyoto (WKY) inbred rats that have a mutation in the Abcg5 gene and thus over absorb phytosterols and phytostanols.MethodsThirty 35-day old male WKY inbred rats (10/group) were fed a control diet or a diet containing phytosterols or phytostanols (2.0 g/kg diet) for 5 weeks. The sterol composition of the diets, plasma and tissues were analysed by gas chromatography. Blood pressure was measured by the tail cuff method. mRNA levels of several renal blood pressure regulatory genes were measured by real-time quantitative PCR.ResultsCompared to the control diet, the phytosterol diet resulted in 3- to 4-fold increases in the levels of phytosterols in plasma, red blood cells, liver, aorta and kidney of WKY inbred rats (P < 0.05). The phytostanol diet dramatically increased (> 9-fold) the levels of phytostanols in plasma, red blood cells, liver, aorta and kidney of these rats (P < 0.05). The phytosterol diet decreased cholesterol levels by 40%, 31%, and 19% in liver, aorta and kidney, respectively (P < 0.05). The phytostanol diet decreased cholesterol levels by 15%, 16%, 20% and 14% in plasma, liver, aorta and kidney, respectively (P < 0.05). The phytostanol diet also decreased phytosterol levels by 29% to 54% in plasma and tissues (P < 0.05). Both the phytosterol and phytostanol diets produced significant decreases in the ratios of cholesterol to phytosterols and phytostanols in plasma, red blood cells, liver, aorta and kidney. Rats that consumed the phytosterol or phytostanol diets displayed significant increases in systolic and diastolic blood pressure compared to rats that consumed the control diet (P < 0.05). The phytosterol diet increased renal angiotensinogen mRNA levels of these rats.ConclusionThese data suggest that excessive accumulation of dietary phytosterols and phytostanols in plasma and tissues may contribute to the increased blood pressure in WKY inbred rats in the absence of excess dietary salt. Therefore, even though phytosterols and phytostanols lower cholesterol levels, prospective clinical studies testing the net beneficial effects of dietary phytosterols and phytostanols on cardiovascular events for subgroups of individuals that have an increased incorporation of these substances are needed.

The mouse mutation “thrombocytopenia and cardiomyopathy” (trac) disrupts Abcg5: a spontaneous single gene model for human hereditary phytosterolemia/sitosterolemia

AbstractThe spontaneous mouse mutation “thrombocytopenia and cardiomyopathy” (trac) causes macrothrombocytopenia, prolonged bleeding times, anemia, leukopenia, infertility, cardiomyopathy, and shortened life span. Homozygotes show a 20-fold decrease in platelet numbers and a 3-fold increase in platelet size with structural alterations and functional impairments in activation and aggregation. Megakaryocytes in trac/trac mice are present in increased numbers, have poorly developed demarcation membrane systems, and have decreased polyploidy. The thrombocytopenia is not intrinsic to defects at the level of hematopoietic progenitor cells but is associated with a microenvironmental abnormality. The trac mutation maps to mouse chromosome 17, syntenic with human chromosome 2p21-22. A G to A mutation in exon 10 of the adenosine triphosphate (ATP)–binding cassette subfamily G, member 5 (Abcg5) gene, alters a tryptophan codon (UGG) to a premature stop codon (UAG). Crosses with mice doubly transgenic for the human ABCG5 and ABCG8 genes rescued platelet counts and volumes. ABCG5 and ABCG8 form a functional complex that limits dietary phytosterol accumulation. Phytosterolemia in trac/trac mice confirmed a functional defect in the ABCG5/ABCG8 transport system. The trac mutation provides a new clinically significant animal model for human phytosterolemia and provides a new means for studying the role of phytosterols in hematologic diseases and testing therapeutic interventions.

Dose effects of dietary phytosterols on cholesterol metabolism: a controlled feeding study

Phytosterol supplementation of 2 g/d is recommended by the National Cholesterol Education Program to reduce LDL cholesterol. However, the effects of different intakes of phytosterol on cholesterol metabolism are uncertain. We evaluated the effects of 3 phytosterol intakes on whole-body cholesterol metabolism. In this placebo-controlled, crossover feeding trial, 18 adults received a phytosterol-deficient diet (50 mg phytosterols/2000 kcal) plus beverages supplemented with 0, 400, or 2000 mg phytosterols/d for 4 wk each, in random order. All meals were prepared in a metabolic kitchen; breakfast and dinner on weekdays were eaten on site. Primary outcomes were fecal cholesterol excretion and intestinal cholesterol absorption measured with stable-isotope tracers and serum lipoprotein concentrations. Phytosterol intakes (diet plus supplements) averaged 59, 459, and 2059 mg/d during the 3 diet periods. Relative to the 59-mg diet, the 459- and 2059-mg phytosterol intakes significantly (P < 0.01) increased total fecal cholesterol excretion (36 +/- 6% and 74 +/- 10%, respectively) and biliary cholesterol excretion (38 +/- 7% and 77 +/- 12%, respectively) and reduced percentage intestinal cholesterol absorption (-10 +/- 1% and -25 +/- 3%, respectively). Serum LDL cholesterol declined significantly only with the highest phytosterol dose (-8.9 +/- 2.3%); a trend was observed with the 459-mg/d dose (-5.0 +/- 2.1%; P = 0.077). Dietary phytosterols in moderate and high doses favorably alter whole-body cholesterol metabolism in a dose-dependent manner. A moderate phytosterol intake (459 mg/d) can be obtained in a healthy diet without supplementation. This trial was registered at clinicaltrials.gov as NCT00860054.

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.

Dietary Phytosterols and Phytostanols Alter the Expression of Sterol-Regulatory Genes in SHRSP and WKY inbred Rats

Background/Aims: We elucidated the molecular mechanism(s) underlying sterol trafficking by investigating alterations in gene expression in response to increased retention of dietary phytosterols and phytostanols in stroke-prone spontaneously hypertensive (SHRSP) and normotensive Wistar Kyoto (WKY) inbred rats. Methods: SHRSP and WKY inbred rats were fed a control diet or a diet supplemented with phytosterols or phytostanols (2 g/kg diet). Results: Intake of phytosterols and phytostanols increased their incorporation in plasma, red blood cells, liver, aorta and kidney, but decreased cholesterol levels in liver and aorta in both rat strains. Phytosterol intake up-regulated mRNA expression of intestinal Npc1l1 and Abcg8, and hepatic Abcg5, Abca1, Cyp27a1 and Hmgcr. Phytostanol intake up-regulated Npc1l1 and Srebp2, but down-regulated Abcg5 mRNA expression in small intestine. Phytostanols also up-regulated Abca1 expression in SHRSP rats, but down-regulated Abca1 expression in WKY inbred rats. Compared to phytosterols, dietary phytostanols reduced phytosterol levels in plasma, red blood cells, and kidney, as well as altered mRNA levels of hepatic Abca1,Cyp27a1, and Hmgcr and intestinal Abcg5/8, Hmgcr and Srebp2. Conclusions: Altered expression of multiple sterol-regulatory genes may contribute to the incorporation and cholesterol-lowering actions of phytosterols and phytostanols. Phytosterols and phytostanols may act through different mechanism(s) on cholesterol and phytosterol/phytostanol trafficking.

Effect of phytosterols on copper lipid peroxidation of human low-density lipoproteins

Objective Phytosterols and stanols have received much attention in the past several years because of their cholesterol-lowering properties, and several studies have shown a protective effect against cardiovascular disease and colon and breast cancer development. A significant decrease of plasma low-density lipoprotein (LDL) cholesterol and apolipoprotein B has been demonstrated in subjects whose diet was supplemented with 2 g/d of plant sterols. Changes in plasma lipoprotein levels were associated with a decrease of oxidized LDL, suggesting that plant sterols could exert an antioxidant effect. The aim of the present study was to further investigate the interaction between the major dietary phytosterols and plasma lipoproteins. Moreover, their antioxidant effect against in vitro–induced lipid peroxidation of human LDL was investigated. Methods Susceptibility to copper-induced lipid peroxidation was investigated in LDLs isolated from plasma of normolipemic subjects. Concentrations of β-sitosterol, campesterol, and stigmasterol ranging from 5 to 50 μM were studied. Analyses of the emission fluorescence spectra of tryptophan and of the probe 6-dodecanoyl-2-dimethyl-aminoaphthalene were used to investigate the effect of phytosterols on apoprotein structure and physicochemical properties of LDL. Results Our results demonstrated that phytosterols exert an inhibitory effect against copper-induced lipid peroxidation of LDLs, as shown by the lowered levels of conjugated dienes in oxidized lipoproteins incubated with different concentrations of plant sterols (5–50 μM). Moreover, analysis of fluorescence emission spectra of tryptophan and 6-dodecanoyl-2-dimethyl-aminoaphthalene demonstrated that phytosterols prevent the alterations of apoprotein structure and physicochemical properties associated with copper-triggered lipid peroxidation of lipoproteins. Conclusion We suggest that the effect exerted by β-sitosterol, stigmasterol, and campesterol against lipid peroxidation of LDL possibly related to phytosterol–lipoprotein interactions could be of physiologic relevance.

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.

Phytosterols as functional food ingredients: linkages to cardiovascular disease and cancer

To examine experimental evidence that has examined association of phytosterols and the reduction of the risk of cardiovascular disease and cancer. Phytosterols exist as naturally occurring plant sterols that are present in the nonsaponifiable fraction of plant oils. Phytosterols are plant components that have a chemical structure similar to cholesterol except for the addition of an extra methyl or ethyl group; however, phytosterol absorption in humans is considerably less than that of cholesterol. In fact, phytosterols reduce cholesterol absorption, although the exact mechanism is not known, and thus reduce circulating levels of cholesterol. The efficacy of phytosterols as cholesterol-lowering agents have been shown when incorporated into fat spreads as well as other food matrices. In addition, phytosterols have been combined with other beneficial dietary components including fish and olive oils, psyllium and beta-glucan to enhance their effect on risk factors of cardiovascular disease. Phytosterols appear not only to play an important role in the regulation of cardiovascular disease but also to exhibit anticancer properties. A side effect associated with the consumption of phytosterols is that they reduce the blood levels of carotenoid. Nevertheless, it has been suggested that compensation for this impact on serum carotenoid levels can occur either by increasing the intake of carotenoid-rich foods or by taking supplements containing these carotenoids. Dietary phytosterols appear to play an important role in the regulation of serum cholesterol and to exhibit anticancer properties.

Phytosterol glycosides reduce cholesterol absorption in humans

Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received approximately 300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4-5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6+/-4.8% (P<0.0001) and phytosterol esters 30.6+/-3.9% (P=0.0001). These results suggest that natural phytosterol glycosides purified from lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content.

Feeding laying hens a bioavailable soy sterol mixture fails to enrich their eggs with phytosterols or elicit egg yolk compositional changes

Coronary heart disease (CHD) is the leading cause of death in the United States. Elevated levels of plasma total cholesterol (TC), and particularly plasma low density lipoprotein-cholesterol (LDLC), are primary contributing factors to CHD. Dietary plant sterols (phytosterols) have been shown to significantly reduce plasma TC and LDLC in humans, primarily through inhibition of intestinal cholesterol absorption, and are potentially effective agents for reduction of CHD risk. Although a variety of phytosterol-containing foods are currently available, phytosterol-enriched eggs, which represent a potential value-added product, are conspicuously absent from the marketplace. Therefore, the objectives of this study were 1) to enrich shell eggs with phytosterols; and 2) to determine if feeding phytosterols to hens elicits egg compositional changes, particularly that of yolk cholesterol content. Sixteen 32-wk-old White Leghorn hens were fed a corn-soy-based layer diet without (n = 8) or with (n = 8) 1 g of supplemental soy sterols/100 g of diet for 28 d.. Hen performance was determined on an individual basis, and 1 egg/hen per week was collected, processed, and analyzed for yolk cholesterol, CP, crude fat (CF), and phytosterol content. There was no effect (P > 0.05) of supplemental dietary phytosterols on 28-d weight gain, feed consumption, feed efficiency, plasma TC, hen-day egg production, egg weights, egg component weights, and yolk cholesterol, CP, and CF contents. Small amounts of campesterol were present in most of the eggs (average of 0.29 and 1.02 mg/yolk for control vs. soy sterol-fed hens, respectively; P < or = 0.05), whereas only 3 of the 80 analyzed eggs contained trace amounts of beta-sitosterol and none contained any detectable stigmasterol. It was concluded that phytosterols are either poorly absorbed from the chicken intestine or, if they are absorbed, they are efficiently secreted back into the intestinal lumen, most likely via as yet uncharacterized adenosine triphosphate-binding cassette transporters.

Contents of Phytosterols in Vegetables and Fruits Commonly consumed in China

To quantify five specific dietary phytosterols and phytostanols in vegetables and fruits commonly consumed in China. A total of 34 different kinds of vegetables and 33 kinds of fruits were chosen according to the consuming habit of Chinese people. All the samples were purchased from two shops in Beijing. The contents of phytosterols (beta-sitosterol, campesterol, stigmasterol, beta-sitostanol, and campestanol) were analyzed by GLC method which was established by our laboratory, and the total phytosterols were calculated. The total phytosterol content in vegetables ranged 1.1-53.7 mg/100 g edible portion. The highest concentration was found in pea, cauliflower, broccoli, and romaine lettuce. The phytosterol contents in fruits ranged 1.6-32.6 mg/100 g, the highest concentration was found in navel orange, tangerine, and mango. The phytosterol contents in vegetables and fruits are not as high as those in edible oils, but because of the large amount of consumption, they also play an important role in increasing the people's phytosterols intake, indicating that increased intake of vegetables and fruits with higher phytosterol contents helps increase the phytosterol intake in China.