Therapeutic potential of plant sterols and stanols

Genome-wide meta-analysis of phytosterols reveals five novel loci and a detrimental effect on coronary atherosclerosis

Phytosterol serum concentrations are under tight genetic control. The relationship between phytosterols and coronary artery disease (CAD) is controversially discussed. We perform a genome-wide meta-analysis of 32 phytosterol traits reflecting resorption, cholesterol synthesis and esterification in six studies with up to 9758 subjects and detect ten independent genome-wide significant SNPs at seven genomic loci. We confirm previously established associations at ABCG5/8 and ABO and demonstrate an extended locus heterogeneity at ABCG5/8 with different functional mechanisms. New loci comprise HMGCR, NPC1L1, PNLIPRP2, SCARB1 and APOE. Based on these results, we perform Mendelian Randomization analyses (MR) revealing a risk-increasing causal relationship of sitosterol serum concentrations and CAD, which is partly mediated by cholesterol. Here we report that phytosterols are polygenic traits. MR add evidence of both, direct and indirect causal effects of sitosterol on CAD.

Highly efficient synthesis of 4,4-dimethylsterol oleates using acyl chloride method through esterification

In this study, the 4,4-dimethylsterol oleates were efficiently synthesized through esterification of 4,4-dimethylsterols and oleoyl chloride. The impact of reaction parameters on the 4,4-dimethylsterol conversion were investigated. The 4,4-dimethylsterol conversion increased with pyridine dosage, molar ratio of oleoyl chloride to 4,4-dimethylsterols, and temperature. The highest conversion of 99.27% was obtained with molar ratio of 1.1:1 at 313 K for 60 min. A second-order kinetic model describing acyl chloride esterification featuring high correlation coefficients was established. Arrhenius-Van't Hoff plot suggested activation energy and pre-exponential factor were 15.54 kJ mol^-1 and 1.78 × 10³ L mol^-1 min^-1, respectively. The molecular structure of 4,4-dimethylsterol oleates were finally identified by attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR), ultra-performance liquid chromatography system coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS), and nuclear magnetic resonance (NMR).

The protective effects of fucosterol against skin damage in UVB-irradiated human dermal fibroblasts

Exposure to ultraviolet (UV) light causes matrix metalloproteinase (MMP) overexpression and extracellular matrix depletion, leading to skin photoaging. The activation of MMP is related to increased interlukin-6 (IL-6) and type I procollagen production, which is regulated by transforming growth factor-β1 (TGF-β1). Activator protein-1 (AP-1) activation induces MMP-1 production and reduces type I procollagen secretion. Fucosterol, which is extracted and purified from the brown algae Hizikia fusiformis, is a phytosterol. We assessed the effects of fucosterol on photodamage and investigated its molecular mechanism of action in UVB-irradiated normal human dermal fibroblasts by using enzyme-linked immunosorbent assay, Western blot analysis, and reverse transcription-polymerase chain reaction. Our results showed that fucosterol significantly decreased the UVB-induced expression of MMP-1, IL-6, p-c-Jun, and p-c-Fos. Additionally, fucosterol markedly increased the UVB-induced production of type I procollagen and TGF-β1. Our results indicate that fucosterol regulates MMP-1 and type I procollagen expression by modulating AP-1 and TGF-β1 signaling and that MMP-1 activation is correlated with IL-6. These data suggest that fucosterol is a promising botanical agent to protect against skin photodamage.

Marine and semi-synthetic hydroxysteroids as new scaffolds for pregnane X receptor modulation

In recent years many sterols with unusual structures and promising biological profiles have been identified from marine sources. Here we report the isolation of a series of 24-alkylated-hydroxysteroids from the soft coral Sinularia kavarattiensis, acting as pregnane X receptor (PXR) modulators. Starting from this scaffold a number of derivatives were prepared and evaluated for their ability to activate the PXR by assessing transactivation and quantifying gene expression. Our study reveals that ergost-5-en-3β-ol (4) induces PXR transactivation in HepG2 cells and stimulates the expression of the PXR target gene CYP3A4. To shed light on the molecular basis of the interaction between these ligands and PXR, we investigated, through docking simulations, the binding mechanism of the most potent compound of the series, 4, to the PXR. Our findings provide useful functional and structural information to guide further investigations and drug design.

Fucosterol is a selective liver X receptor modulator that regulates the expression of key genes in cholesterol homeostasis in macrophages, hepatocytes, and intestinal cells

Fucosterol, a sterol that is abundant in marine algae, has hypocholesterolemic activity, but the mechanism underlying its effect is not clearly understood. Because data suggest that fucosterol can increase plasma high-density lipoprotein concentrations, we investigated whether it could activate liver X receptors (LXRs), critical transcription factors in reverse cholesterol transport. Fucosterol dose-dependently stimulated the transcriptional activity of both LXR-α and -β in a reporter gene assay, responses that were attenuated by the LXR antagonist As(2)O(3). Fucosterol also activated co-activator recruitment in cell-free time-resolved fluorescence resonance energy transfer analysis. In THP-1-derived macrophages, it induced the transcriptional activation of ABCA1, ABCG1, and ApoE, key genes in reverse cholesterol transport, and thereby significantly increased the efflux of cholesterol. Fucosterol also regulated intestinal NPC1L1 and ABCA1 in Caco-2 cells. Notably, fucosterol did not induce cellular triglyceride accumulation in HepG2 cells, primarily because of its upregulation of Insig-2a, which delays nuclear translocation of SREBP-1c, a key hepatic lipogenic transcription factor. These results suggest that fucosterol is a dual-LXR agonist that regulates the expression of key genes in cholesterol homeostasis in multiple cell lines without inducing hepatic triglyceride accumulation.

Current and new insights on phytosterol oxides in plant sterol-enriched food

Over the past 15 years, plant sterol-enriched foods have faced a great increase in the market, due to the asserted cholesterol-lowering effect of plant sterols. However, owing to their chemical structures, plant sterols can oxidize and produce a wide variety of oxidation products with controversial biological effects. Although oxyphytosterols can derive from dietary sources and endogenous formation, their single contribution should be better defined. The following review provides an overall and critical picture on the current knowledge and future perspectives of plant sterols-enriched food, particularly focused on occurrence of plant sterol oxidation products and their biological effects. The final objective of this overview is to evince the different aspects of plant sterols-enriched food that require further research, for a better understanding of the influence of plant sterols and their oxides on consumers' health.

GC-based analysis of plant stanyl fatty acid esters in enriched foods

Approaches for the capillary gas chromatographic (GC) based analysis of intact plant stanyl esters in enriched foods were developed. Reference compounds were synthesized by enzyme-catalyzed transesterifications. Their identities were confirmed by means of mass spectrometry. Using a medium polar trifluoropropylmethyl polysiloxane stationary phase, long-chain plant stanyl esters could be separated according to their stanol moieties and their fatty acid chains. Thermal degradation during GC analysis was compensated by determining response factors; calibrations were performed for ten individual plant stanyl esters. For the analysis of low-fat products (skimmed milk drinking yogurts), the GC separation was combined with a "fast extraction" under acidic conditions. For fat-based foods (margarines), online coupled LC-GC offered an elegant and efficient way to avoid time-consuming sample preparation steps. The robust and rapid methods allow conclusions on both, the stanol profiles and the fatty acid moieties, and thus provide a basis for the authentication of this type of functional food ingredients.

Plant stanols dose-dependently decrease LDL-cholesterol concentrations, but not cholesterol-standardized fat-soluble antioxidant concentrations, at intakes up to 9 g/d

BACKGROUND

It is unclear whether plant stanols lower serum LDL-cholesterol concentrations and cholesterol-standardized fat-soluble antioxidant concentrations dose-dependently when consumption exceeds the recommended daily intakes of 2.0-3.0 g.

OBJECTIVE

The objective was to study the relation between plant stanols provided as plant stanol esters on changes in serum concentrations of LDL cholesterol and fat-soluble antioxidants.

DESIGN

Healthy subjects (n = 93) with slightly elevated serum total cholesterol concentrations (5.0-8.0 mmol/L) received, after a 3-wk run-in period, control products (n = 22) or products (margarine and soy-based yogurt) providing 3 g (n = 24), 6 g (n = 22), or 9 g (n = 25) plant stanols provided as fatty acid esters for 4 wk.

RESULTS

Serum LDL cholesterol decreased dose-dependently. Compared with control, decreases in the 3-g group were 0.32 mmol/L (7.4%; P = 0.005 after adjustment for multiple comparisons). An intake of 6 g plant stanols caused an additional decrease of 0.18 mmol/L (4.5%; P = 0.100 compared with the 3-g group). In the 9-g group, a further decrease of 0.22 mmol/L (5.4%) was observed (P = 0.048 compared with the 6-g group). Serum LDL-cholesterol concentrations were lowered by 17.4% in the 9-g group compared with the control group. No effects on cholesterol-standardized beta-carotene concentrations were observed. Even the change of -0.01 mumol/mmol cholesterol (or -9.2%; P = 0.341) in the 3-g group compared with the control group was not statistically significant because of the large variation in response. Serum HDL-cholesterol and triacylglycerol concentrations, cholesterol-standardized alpha-tocopherol and lutein concentrations, and plasma markers reflecting liver and renal function were not affected.

CONCLUSIONS

Daily consumption of plant stanols up to 9 g reduces serum LDL-cholesterol concentrations linearly up to 17.4%. For cholesterol-standardized fat-soluble antioxidant concentrations, such a relation could not be ascertained.

Disodium ascorbyl phytostanol phosphate (FM-VP4), a modified phytostanol, is a highly active hypocholesterolaemic agent that affects the enterohepatic circulation of both cholesterol and bile acids in mice

Disodium ascorbyl phytostanol phosphate (FM-VP4) is a synthetic compound derived from sitostanol and campestanol that has proved to be efficient as a cholesterol-lowering therapy in mice and human subjects. However, the mechanism of action of FM-VP4 remains unknown. The present study tests the ability of FM-VP4 to alter intestinal and liver cholesterol homeostasis in mice. Female C57BL/6J mice were fed either a control chow or a 2 % FM-VP4-enriched diet for 4 weeks. FM-VP4 reduced the in vivo net intestinal cholesterol absorption and plasma and liver cholesterol concentrations by 2.2-, 1.5- and 1.6-fold, respectively, compared with control mice. Furthermore, FM-VP4 also showed an impact on bile acid homeostasis. In FM-VP4 mice, liver and intestinal bile acid content was increased by 1.3- and 2.3-fold, respectively, whereas faecal bile acid output was 3.3-fold lower. FM-VP4 also increased the intestinal absorption of orally administered [3H]taurocholic acid to small intestine in vivo. Inhibition of intestinal cholesterol absorption by FM-VP4 was not mediated via transcriptional increases in intestine liver X receptor (LXR)-alpha, adenosine triphosphate-binding cassette transporter (ABC)-A1, ABCG5/G8 nor to decreases in intestinal Niemann-Pick C1-like 1 (NPC1L1) expression. In contrast, FM-VP4 up-regulated liver LXRalpha, ABCA1, ABCG5, scavenger receptor class BI (SR-BI) and hydroxymethylglutaryl coenzyme A reductase (HMGCoA-R) gene expression, whereas it down-regulated several farnesoid X receptor (FXR)-target genes such as cytochrome P450 family 7 subfamily A polypeptide 1 (CYP7A1) and Na+/taurocholate co-transporter polypeptide (NTCP). In conclusion, FM-VP4 reduced intestinal cholesterol absorption, plasma and liver cholesterol and affected bile acid homeostasis by inducing bile acid intestinal reabsorption and changed the liver expression of genes that play an essential role in cholesterol homeostasis. This is the first phytosterol or stanol that affects bile acid metabolism and lowers plasma cholesterol levels in normocholesterolaemic mice.

Consuming functional foods enriched with plant sterol or stanol esters for 85 weeks does not affect neurocognitive functioning or mood in statin-treated hypercholesterolemic individuals

Recent animal and human studies have shown that plant sterols and stanols, which are used as functional food ingredients to lower increased LDL cholesterol concentrations, pass the blood-brain barrier. Whether this affects neurocognitive functioning and mental well-being in humans has, to our knowledge, never been investigated. The aim of the present study was therefore to examine the effects of long-term plant sterol or stanol consumption on neurocognitive functioning and mood in a randomized, double-blind, placebo-controlled dietary intervention trial. To this end, hypercholesterolemic individuals, aged 43-69 y, receiving stable statin treatment were randomly assigned to an 85-wk supplementation with margarines enriched with plant sterol esters (2.5 g/d), plant stanol esters (2.5 g/d), or placebo. At baseline and at the end of the intervention period, all participants underwent a cognitive assessment. In addition, subjective cognitive functioning and mood were assessed by means of questionnaires (Cognitive Failure Questionnaire and depression subscale of the Symptom Checklist 90, respectively). Long-term supplementation with plant sterol or stanol esters did not affect cognitive performance (memory, simple information processing speed, complex information processing speed, Letter-Digit Substitution test performance), subjective cognitive functioning, or mood. In conclusion, the present results indicate that long-term use of plant sterols or stanols at recommended intakes of 2.5 g/d does not affect neurocognitive functioning or mood in hypercholesterolemic individuals receiving statin treatment.

Current and future pharmacologic options for the management of patients unable to achieve low-density lipoprotein-cholesterol goals with statins

Low-density lipoprotein-cholesterol (LDL-C) lowering is the mainstay of the current treatment guidelines in the management of cardiovascular risk. HMG-CoA reductase inhibitors (statins) are currently the most effective LDL-C-lowering drugs. However, a substantial number of patients do not reach treatment targets with statins. Therefore, an unmet medical need exists for lipid-lowering drugs with novel mechanisms of action to reach the recommended cholesterol target levels, either by monotherapy or combination therapy. Upregulation of the LDL receptor with squalene synthase inhibitors has shown promising results in animal studies but the clinical development of the lead compound lapaquistat (TAK-475) has recently been discontinued. Ezetimibe combined with statins allowed significantly more patients to reach their LDL-C targets. Other inhibitors of intestinal cholesterol absorption such as disodium ascorbyl phytostanol phosphate (FM-VP4) and bile acid transport inhibitors have shown positive results in early development trials, whereas the prospect of acyl coenzyme A: cholesterol acyltransferase inhibition in cardiovascular prevention is dire. Selective inhibition of messenger RNA (mRNA) by antisense oligonucleotides is a new approach to modify cholesterol levels. The inhibition of apolipoprotein B mRNA is in advanced development and mipomersen sodium (ISIS 301012) has shown striking results in phase II studies both as monotherapy as well as in combination with statins.

Serum lipid and antioxidant responses in hypercholesterolemic men and women receiving plant sterol esters vary by apolipoprotein E genotype

Plant sterol esters reduce serum total cholesterol (TC) and LDL cholesterol (LDL-C), but with striking interindividual variability. In this randomized, double-blind, controlled study, serum lipid, plant sterol, fat-soluble vitamin, and carotenoid responses to plant sterols were studied according to the apolipoprotein E (ApoE) genotype in 217 hypercholesterolemic adults. Subjects received a reduced saturated fat and cholesterol diet for 4 wk, followed by a 5-wk intervention during which they consumed a control spread (n = 87) or a spread with plant sterol esters (1.1 g/d or 2.2 g/d plant sterols; n = 120). Twenty-six subjects carried the E2 allele (E2E2 and E2E3), 51 had the E4 allele (E3E4+E4E4), and 130 were E3 homozygotes. Ten E2E4 carriers were not studied. At baseline, the serum triacylglycerol (TAG) concentration was lower in E4 subjects than in E3 subjects, alpha-tocopherol was lower in E4 subjects than in E2 individuals, and LDL-C was lower in E2 carriers than in E3 and E4 carriers (P < 0.05 for all). During sterol consumption, TC, LDL-C, and ApoB concentrations and the TC:LDL-C and LDL-C:HDL-C ratios decreased in only E2 and E3 subjects and TAG decreased in only E2 subjects (all P < 0.05 vs. control). Significant reductions in serum carotenoids (P < 0.05 vs. control) were demonstrated for some alleles: beta-carotene and lycopene in E2 and E4; alpha-carotene in E3; cryptoxanthin in E3 and E4; zeaxanthin in E4; lycopene in E2 and E4; and lutein in E2 carriers. Thus, responses to plant sterols vary by ApoE genotype and may be of little value in ApoE4 carriers, who had reductions in serum carotenoid concentrations but not in TC, LDL-C, or ApoB.

Phytosterols do not change susceptibility to obesity, insulin resistance, and diabetes induced by a high-fat diet in mice

Most studies have focused on the cholesterol-lowering activity of phytosterols; however, other biological actions have also been attributed to these plant compounds. In this study, we investigated whether phytosterols could delay (progression phase) and/or reverse (regression phase) insulin resistance or type 2 diabetes mellitus in an experimental mouse model of diet-induced obesity, insulin resistance, and diabetes. Body mass, plasma lipid levels, insulin resistance, and hyperglycemia were determined. Phytosterol intake did not improve these metabolic parameters. Therefore, we were unable to substantiate any protective effect of phytosterol intake on diabetes development or regression in the mouse model used.

New insights into the molecular actions of plant sterols and stanols in cholesterol metabolism

Plant sterols and stanols (phytosterols/phytostanols) are known to reduce serum low-density lipoprotein (LDL)-cholesterol level, and food products containing these plant compounds are widely used as a therapeutic dietary option to reduce plasma cholesterol and atherosclerotic risk. The cholesterol-lowering action of phytosterols/phytostanols is thought to occur, at least in part, through competition with dietary and biliary cholesterol for intestinal absorption in mixed micelles. However, recent evidence suggests that phytosterols/phytostanols may regulate proteins implicated in cholesterol metabolism both in enterocytes and hepatocytes. Important advances in the understanding of intestinal sterol absorption have provided potential molecular targets of phytosterols. An increased activity of ATP-binding cassette transporter A1 (ABCA1) and ABCG5/G8 heterodimer has been proposed as a mechanism underlying the hypocholesterolaemic effect of phytosterols. Conclusive studies using ABCA1 and ABCG5/G8-deficient mice have demonstrated that the phytosterol-mediated inhibition of intestinal cholesterol absorption is independent of these ATP-binding cassette (ABC) transporters. Other reports have proposed a phytosterol/phytostanol action on cholesterol esterification and lipoprotein assembly, cholesterol synthesis and apolipoprotein (apo) B100-containing lipoprotein removal. The accumulation of phytosterols in ABCG5/G8-deficient mice, which develop features of human sitosterolaemia, disrupts cholesterol homeostasis by affecting sterol regulatory element-binding protein (SREBP)-2 processing and liver X receptor (LXR) regulatory pathways. This article reviews the progress to date in studying these effects of phytosterols/phytostanols and the molecular mechanisms involved.

Long-term phytosterol treatment alters gene expression in the liver of apo E-deficient mice

Dietary phytosterols significantly reduce plasma cholesterol concentrations and atherosclerosis in apolipoprotein E-knockout (apo E-KO) mice. We investigated the long-term effects of phytosterol treatment on gene expression in the liver of these mice. Male apo E-KO mice were fed an atherogenic diet supplemented with (n=6) or without (n=6) 2% (wt/wt) phytosterol mixtures for 14 weeks. Liver specimens were collected and stored in RNAlater immediately. mRNA was extracted and subjected to microarray analyses and real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay for confirmation. Oligonuleotide microarray analysis of pooled samples (n=3) revealed that the expression of 132 genes/transcripts was significantly altered in treated animals, considering the false discovery rate (FDR) of 0.23. Real-time RT-PCR techniques confirmed these alterations in the expression of several of these genes, including Hmgcr (2.16-fold; P=.0002), Hmgcs1 (1.79-fold; P=.001), Hsd17b7 (2.11-fold; P=.028), Sqle (2.03-fold; P=.01), Cyp51 (1.8-fold; P=.001), Fads1 (1.55-fold; P=.031), Fads2 (2.17-fold; P=.047), Lpin1 (3.67-fold; P=.001), Ppargc1b (PGC-1beta; a coactivator of sterol-regulatory element-binding proteins; 1.66-fold; P=.007) and Cyp7B1 (1.81-fold; P=.025). In summary, our data suggest that long-term dietary phytosterols can alter the expression of a number of hepatic genes that regulate sterol metabolism in apo E-KO mice. It is possible that these changes are due to inhibition of cholesterol absorption, but are not a direct effect of plant sterols. Further multivariate correlation or association analysis is needed to establish the relations between changes in the expression of these genes and prevention of atherosclerosis by phytosterols.

A high-saturated fat diet enriched with phytosterol and pectin affects the fatty acid profile in guinea pigs

This paper presents the results of a study whose aim was to test the effects of several doses of pectin and phytosterols on the body weight gain and the FA content in female guinea pigs. The treatments resulted from supplementing with pectin and plant sterol a guinea pig diet (rich in saturated FA), following a 3 x 3 factorial design, with three levels of pectin (0, 3.67 and 6.93%) and three levels of phytosterols (0, 1.37, and 2.45%). Seventy-two female Dunkin Hartley guinea pigs were randomly assigned to the treatment groups (8 animals/group), the duration of the treatment being 4 wk. Pectin dietary intake led to a significant increase in body weight (P < 0.001), food consumption (P = 0.025), and feed efficiency (P < 0.001), but no influence of phytosterols on weight gain or food consumption was detected. We found a significant negative effect of the addition of phytosterols on lauric, myristic, and palmitic acid contents in feces, and a positive effect on their concentration in plasma and liver, but no significant effect on stearic acid content. Apparent FA absorption was assessed by calculating the ratio of FA in feces and diets that the absorption of the different FA could be compared, and the negative effect of phytosterol supplementation on these ratios, especially for lauric and myristic acids, was established.

Ezetimibe: rationale and role in the management of hypercholesterolemia

Elevated low-density lipoprotein (LDL) cholesterol plays an important role in the development of atherosclerosis. In part, plasma LDL levels are dependent on cholesterol absorption in the intestine and the rate of intrinsic cholesterol synthesis. Therapy with 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors has often proven to be successful in reducing plasma LDL levels. However, a significant number of patients do not reach their target LDL levels despite statin therapy. As is reviewed, drugs that inhibit cholesterol absorption are a useful adjunct to lipid-lowering therapy by statins. This review discusses the mechanisms involved in intestinal absorption of cholesterol and its transport as potential targets of newer agents that affect cholesterol absorption. The use of bile acid sequestrants and esters of plant stanols, as well as other intestinally active agents for reducing plasma LDL levels, has been limited by side effects and difficulties in patient compliance. In contrast, the new selective cholesterol transporter inhibitor ezetimibe has been demonstrated to reduce plasma LDL alone or in combination with statins without significant adverse effects. In spite of the robust lipid-lowering data with ezetimibe, questions about clinical outcomes, safety, and efficacy in various combinations remain.

Effects of calcium and plant sterols on serum lipids in obese Zucker rats on a low-fat diet

Ca may interfere with fat and cholesterol metabolism through formation of insoluble soaps with fatty and bile acids in the intestine. In the present study, we examined the effects of different dietary Ca levels on the serum lipid profile and cholesterol metabolism in obese Zucker rats fed a low-fat diet. We also tested whether dietary Ca interfered with the lipid-lowering effects of a pine oil-derived plant sterol mixture. Increase in dietary Ca intake from 0·2 to 0·8 %, and further to 2·1 % (w/w) dose-dependently decreased serum total cholesterol (r -0·565,P=0·002,n27), LDL-cholesterol (r -0·538,P=0·006,n25), and triacylglycerol (r -0·484,P=0·014,n25) concentrations, and increased HDL-cholesterol (r 0·478,P=0·016,n25) and HDL : LDL cholesterol (r 0·672,P<0·001,n25) in rats fed a 1 % cholesterol diet. Analysis of serum campesterol : cholesterol and sitosterol : cholesterol suggested that Ca dose-dependently increased intestinal cholesterol absorption (r 0·913,P<0·001,n18), whereas serum desmosterol : cholesterol and lathosterol : cholesterol indicated that Ca dose-dependently increased endogenous cholesterol synthesis (r 0·691,P=0·003,n18). Therefore, the decrease of serum LDL-cholesterol appeared to be due to Ca-induced increase in the conversion of cholesterol to bile acids. The increase in Ca intake did not interfere with the beneficial effects of plant sterols on serum total cholesterol, LDL-cholesterol and HDL-cholesterol concentrations. The high-Ca diet with plant sterol supplementation further increased the HDL-cholesterol concentration and HDL : LDL cholesterol. The present findings indicate that the beneficial effects of dietary Ca on the serum lipid profile during a low-fat diet are dose-dependent, and resemble those of bile acid sequestrants. Increased dietary Ca did not impede the lipid-lowering effects of natural plant sterols.

Simultaneous intake of beta-glucan and plant stanol esters affects lipid metabolism in slightly hypercholesterolemic subjects

Intake of food products rich in water-soluble fiber beta-glucan and products enriched with plant stanol esters lower serum cholesterol. Combining 2 functional food ingredients into one food product may achieve additional reductions of serum cholesterol. Our objective was to investigate the effects of a simultaneous intake of beta-glucan plus plant stanol esters on lipid metabolism in mildly hypercholesterolemic volunteers. In a randomized, controlled, 3-period crossover study, 40 mildly hypercholesterolemic men and women received muesli in random order twice a day for 4 wk, which provided, in total, 5 g control fiber from wheat (control muesli), 5 g oat beta-glucan (beta-glucan muesli), or 5 g oat beta-glucan plus 1.5 g plant stanols (combination muesli). beta-Glucan muesli decreased serum LDL cholesterol by 5.0% compared with control muesli (P = 0.013). Combination muesli reduced LDL cholesterol by 9.6% compared with control muesli (P < 0.001), and by 4.4% compared with beta-glucan muesli (P = 0.036). Serum HDL cholesterol and triacylglycerol concentrations did not differ after the 3 treatments. Compared with control muesli, beta-glucan muesli increased bile acid synthesis (P = 0.043) and decreased cholesterol absorption (P = 0.011). Addition of plant stanols did not influence bile acid synthesis but decreased cholesterol absorption (P < 0.001) and raised cholesterol synthesis (P = 0.016) compared with control muesli, and the plant stanols decreased cholesterol absorption compared with beta-glucan muesli (P = 0.004). The combination muesli decreased serum concentrations of sitostanol compared with control muesli (P = 0.010). Plasma concentrations of lipid-soluble antioxidants did not differ after the 3 treatments. beta-Glucan muesli effectively lowered serum LDL cholesterol concentrations. The addition of plant stanol esters to beta-glucan-enriched muesli further lowered serum LDL cholesterol, although effects were slightly less than predicted.

Consistency of use of plant stanol ester margarine in Finland

Objective:

The aims of this study were to investigate the consistency of use of plant stanol ester margarine and to characterise consistent and inconsistent users.

Design:

A cohort of plant stanol ester margarine users was established based on 14 national surveys conducted by the National Public Health Institute in Finland between 1996 and 1999. A follow-up study questionnaire was developed and sent to 1294 users in 2000.

Setting:

Subjects who reported using plant stanol ester margarine in both the original survey and the follow-up study were classified as consistent users, and the rest as inconsistent users.

Subjects:

The study population consisted of 1094 subjects aged 18–87 years, 590 men and 504 women.

Results:

There were 357 (33%) consistent and 737 (67%) inconsistent users of plant stanol ester margarine in the study population. Consistent users were more likely to be men and to have a higher household income than inconsistent users. Both consistent and inconsistent users were predominantly middle-aged persons with a healthy lifestyle and diet as well as a history of cardiovascular disease. Healthfulness was the main factor affecting bread spread choice among 94% of the consistent users and 59% of the inconsistent users.

Conclusions:

The use of plant stanol ester margarine is more often inconsistent than consistent. There is nevertheless a relatively large subgroup of long-term users of plant stanol ester margarine. It is important to examine the health effects especially among these regular users.

Cholesterol absorption inhibitors as a therapeutic option for hypercholesterolaemia

The development of cholesterol-lowering drugs (including a variety of statins, bile acid-binding resins and recently discovered inhibitors of cholesterol absorption) has expanded the options for cardiovascular prevention. Recent treatment guidelines emphasise that individuals at substantial risk for atherosclerotic coronary heart disease should meet defined targets for LDL cholesterol concentrations. Combination therapy with drugs that have different or complementary mechanisms of action is often needed to achieve lipid goals. Existing approaches to the treatment of hypercholesterolaemia are still ineffective in halting the progression of coronary artery disease in some patients despite combination therapies. Other patients are resistant to conventional drug treatment and remain at high risk for the development and progression of atherosclerotic cardiovascular disease and alternative approaches are needed. The discovery and development of ezetimibe (a novel, selective and potent cholesterol absorption inhibitor) has advanced the treatment of hypercholesterolaemia. New agents including the phytostanol preparation FM-VP4 and inhibitors of acyl coenzyme A:cholesterol acyltransferase, the apical Na(+)-dependent bile acid transporter and microsomal triglyceride transfer protein may also play a future role in combination therapy. This review focuses on the recent progress in the molecular mechanisms of intestinal cholesterol absorption and transport, and novel therapeutic approaches to inhibit the cholesterol absorption process.

Serum Retinol, α-Tocopherol, and β-Carotene Levels Are Not Altered by Excess Ingestion of Diacylglycerol-Containing Plant Sterol Esters

BACKGROUND

Diacylglycerol (DAG) suppresses the postprandial increase in serum triglycerides, and has antiobesity effects. On the other hand, plant sterol esters (PSE) lower serum cholesterol levels in hypercholesterolemia. Thus, DAG-containing PSE (PSE/DAG) would be expected to maintain an appropriate serum cholesterol level and decrease the risk of arteriosclerotic disorders. Several recent studies, however, report negative effects of PSE on serum fat-soluble (pro)vitamin levels. The objective of this study was to investigate the effect of PSE/DAG on serum retinol, beta-carotene, and alpha-tocopherol levels using a threefold excess of the effective dose obtained in our previous study.

METHODS

A randomized placebo-controlled double-blind parallel study was performed in healthy and mildly hypercholesterolemic subjects, in which the subjects ingested 1.2 g PSE/30 g DAG for 2 weeks in the form of mayonnaise-type products. Triacylglycerol (TAG) mayonnaise was used as a control.

RESULT

There were no subjective adverse effects or changes in serum retinol, alpha-tocopherol, and beta-carotene levels, abdominal symptoms, hematologic values, or blood biochemical values.

CONCLUSION

Ingestion of a threefold excess of PSE/DAG for 2 weeks had no adverse effects compared to ingestion of conventional TAG mayonnaise.

Blood lipid responses to plant stanol ester supplementation and aerobic exercise training

The purpose of this study was to determine the independent and combined effects of plant stanol ester (PSE) margarine and aerobic exercise on blood lipid concentrations and related intravascular enzymes in 26 healthy sedentary, middle-aged men and postmenopausal women (age, 53 +/- 8 years; body mass index, 27 +/- 1.0, % fat, 28.5 +/- 2). In a stratified double-blind manner, participants were randomly assigned to either a PSE (n = 17) or a placebo (CON, n = 9) margarine group. Participants supplemented their daily diets with 42 g of margarine spread (PSE = 3 g; CON, PSE = 0 g, of approximately equal energy content) for 9 weeks. During the last 4 weeks of margarine supplementation (MS), participants expended 400 kcal on a treadmill 5 d/wk at 65% of VO(2) reserve (2000 kcal/wk). Fasting blood samples were obtained before initiating and after 4 weeks of MS and after exercise training. All blood samples were analyzed for total cholesterol, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), hepatic lipase, lipoprotein lipase, and cholesterol ester transfer protein activities. Total cholesterol (-10%), low-density lipoprotein cholesterol (-13%), and triglyceride (-18%) concentrations decreased after 4 weeks of MS in the PSE group, but not in the CON group (P < .05 for all). Four weeks of aerobic exercise increased HDL-C by 21% in the CON group (P < .05) and by 4% in the PSE group (P > .05). Total cholesterol-HDL-C ratio decreased significantly (P < .05) in the PSE group, but not in the CON group. No other significant alterations were observed with either PSE or exercise. Our findings suggest that PSE is effective in reducing blood cholesterol concentrations and that exercise can increase HDL-C in middle-aged men and postmenopausal women. Our findings also suggest that PSE supplementation may attenuate the exercise-induced increase in HDL-C.

Different apoptotic mechanisms are involved in the antiproliferative effects of 7beta-hydroxysitosterol and 7beta-hydroxycholesterol in human colon cancer cells

Plant sterols are found in fruits and vegetables. Their cholesterol-lowering effect is well documented. Our study aimed at comparing antiproliferative effects of 7beta-hydroxysitosterol (7beta-OHsito) versus 7beta-hydroxycholesterol (7beta-OHchol) on the human colon cancer cell line Caco-2. When cells were exposed for 32 h to 60 microM 7beta-OHsito or to 30 microM 7beta-OHchol, both compounds caused 50% growth inhibition. Cells treated with 7beta-OHsito showed enhanced caspase-9 and -3 activities followed by DNA fragmentation. In contrast, 7beta-OHchol did not activate caspase-3 and activation of caspase-9 and DNA fragmentation were delayed. The treatment of cells with the caspase inhibitor Z-VAD.fmk retarded the 7beta-OHsito-induced apoptotic process but not that triggered by 7beta-OHchol. Our data suggest that the two compounds in spite of their structural similarities target different cellular pathways, which lead to cell death.

Plant sterols and stanols: effects on mixed micellar composition and LXR (target gene) activation

Plant stanols and sterols of the 4-desmethyl family (e.g., sitostanol and sitosterol) effectively decrease LDL cholesterol concentrations, whereas 4,4-dimethylsterols (alpha-amyrin and lupeol) do not. Serum carotenoid concentrations, however, are decreased by both plant sterol families. The exact mechanisms underlying these effects are not known, although effects on micellar composition have been suggested. With a liver X receptor (LXR) coactivator peptide recruitment assay, we showed that plant sterols and stanols from the 4-desmethylsterol family activated both LXRalpha and LXRbeta, whereas 4,4-dimethyl plant sterols did not. In fully differentiated Caco-2 cells, the functionality of this effect was shown by the increased expression of ABCA1, one of the known LXR target genes expressed by Caco-2 cells in measurable amounts. The LXR-activating potential of the various plant sterols/stanols correlated positively with ABCA1 mRNA expression. Reductions in serum hydrocarbon carotenoids could be explained by the effects of the 4-desmethyl family and 4,4-dimethylsterols on micellar carotenoid incorporation. Our findings indicate that the decreased intestinal absorption of cholesterol and carotenoids by plant sterols and stanols is caused by two distinct mechanisms.

Plant stanol and sterol esters in the control of blood cholesterol levels: mechanism and safety aspects

Incorporation of plant stanol esters into margarine is among the first examples of a functional food with proven low-density lipoprotein (LDL) cholesterol-lowering effectiveness. Recently, there have been many studies on the effects of plant stanols/sterols on cholesterol metabolism. It has been found that the serum LDL cholesterol-lowering effect of plant stanols/sterols originates from reduced intestinal cholesterol absorption, a process in which changes in micellar composition are thought to play a major role. However, recent findings suggest that there is an additional process in which plant stanols/sterols actively influence cellular cholesterol metabolism within intestinal enterocytes. Furthermore, in response to the reduced supply of exogenous cholesterol, receptor-mediated lipoprotein cholesterol uptake is probably enhanced, as shown by increased LDL receptor expression. At recommended intakes of about 2 to 2.5 g/day, products enriched with plant stanol/sterol esters lower plasma LDL cholesterol levels by 10% to 14% without any reported side effects. Thus, plant stanols/sterols can be considered to be effective and safe cholesterol-lowering functional food ingredients.

Use of plant stanol ester margarine among persons with and without cardiovascular disease: early phases of the adoption of a functional food in Finland

BACKGROUND

The plant stanol ester margarine Benecol is a functional food that has been shown to lower effectively serum total and LDL-cholesterol. The purpose of this post-marketing study is to characterize users of plant stanol ester margarine with and without cardiovascular disease.

METHODS

A cohort of plant stanol ester margarine users was established based on a compilation of 15 surveys conducted by the National Public Health Institute in Finland between 1996-2000. There were 29,772 subjects aged 35-84 years in the cohort. The users of plant stanol ester margarine were identified by the type of bread spread used.

RESULTS

The plant stanol ester margarine was used as bread spread by 1332 (4.5%) subjects. Almost half (46%) of the users reported a history of cardiovascular disease. Persons with cardiovascular disease were more likely to use plant stanol ester margarine (8%) than persons without cardiovascular disease (3%). Users with and without cardiovascular disease seemed to share similar characteristics. In particular, they were elderly people with otherwise healthy life-styles and diet. They were less likely smokers, more likely physically active and less likely obese than nonusers. The users reported being in good or average health in general and having used cholesterol-lowering drugs.

CONCLUSION

Plant stanol ester margarine seems to be used by persons for whom it was designed and in a way it was meant: as part of efforts for cardiovascular disease risk reduction.

Free phytosterols facilitate excretion of endogenous cholesterol in gerbils

To determine whether phytosterols (PST) facilitate excretion of whole body cholesterol and whether dietary fat or enhancing gallbladder contraction with curcumin might influence this process, four experiments were conducted in gerbils. In Experiment 1, naive gerbils received cholesterol-free purified diets with 30% energy from fat and 0% or 0.75% free PST from tall oil for 4 weeks. In Experiment 2, body cholesterol pools were expanded by feeding a diet containing 0.3% cholesterol for 3 weeks. Subsequently, PST was provided in either fat-free or normal-fat diets without cholesterol for only 2 h each morning, followed by a low-fat diet for the rest of the day and food restriction overnight. In Experiment 3, gerbils were preloaded with cholesterol, followed by either PST alone or PST+curcumin to enhance gallbladder contraction. In Experiment 4, curcumin or curcumin+PST were fed with 30% as fat and 0.15% cholesterol throughout the study. Because of the small whole body cholesterol pool in Experiment 1, the impact of PST was limited. When whole body cholesterol was expanded in Experiments 2 and 3, subsequent reductions of liver esterified cholesterol by PST were significant. In the presence of dietary fat, PST caused a greater reduction (23%) than in a fat-free diet (8%) compared to respective controls. Curcumin (Experiments 3 and 4) proved ineffective in reducing liver or plasma cholesterol pools, and the 3:1 ratio between PST/diet cholesterol was less effective at blocking cholesterol absorption than a 5:1 ratio previously employed. Thus, free PST removed whole body cholesterol, which was enhanced by concomitant fat intake, but was unaffected by a gallbladder contracting agent.

Changes in intestinal and liver global gene expression in response to a phytosterol-enriched diet

BACKGROUND

Dietary phytosterols are a recommended therapeutic option for decreasing plasma cholesterol. The increased activity of ATP-binding cassette (ABC) transporters ABCA1, ABCG5 and ABCG8, or, alternatively, a decrease in Niemann-Pick C1 Like 1 (NPC1L1) could mediate the reduction in intestinal cholesterol absorption caused by phytosterols. Other biological properties such as a direct immune modulatory activity have recently been ascribed to these plant compounds.

METHODS

To gain insight into the molecular effects of phytosterols, global genome-wide gene profiling and real-time RT-PCR studies were conducted in small intestines and livers of phytosterol-treated apolipoprotein E-deficient (apoE(-/-)) mice. Re-testing of the main results was performed in C57BL/6J and LDL receptor-deficient (LDLR(-/-)) mice.

RESULTS

Intestinal cholesterol absorption was decreased in all mouse models but plasma cholesterol was only decreased in apoE(-/-) and LDLR(-/-) mice. ABCA1, ABCG5, ABCG8 and NPC1L1 mRNA levels were slightly reduced in the intestine of phytosterol-treated apoE(-/-) and LDLR(-/-) mice, but increased in C57BL/6J-treated mice. Phytosterols changed genes involved in immune regulation in apoE(-/-) mice. However, these changes were less extensive in LDLR(-/-) mice and were not found in C57BL/6J mice.

CONCLUSIONS

Inhibition of intestinal cholesterol absorption by phytosterols is not mediated via transcriptional changes in ABCA1, ABCG5, ABCG8 or NPC1L1. Changes suggestive of immunomodulation are associated with the hypocholesterolemic effect of phytosterols and with apoE deficiency.

Phytosterols in the prevention of human pathologies

Coronary heart disease is a major health problem in developed countries. Many studies have shown that elevated serum concentrations of total or low-density-lipoprotein cholesterol (LDL cholesterol) are high risk factors, whereas high concentrations of high-density-lipoprotein cholesterol (HDL cholesterol) or a low LDL to HDL cholesterol ratio may protect against coronary heart disease. Plant sterols and stanols derived from vegetable oils or wood pulp have been shown to lower total and LDL cholesterol levels in humans by inhibiting cholesterol absorption from the intestine. These findings may lead to new therapeutic options to treat hypercholesterolemia. In addition, phytosterols may influence cell growth and apoptosis of tumor cells. However, they can interfere with the absorption of fat soluble vitamins and carotenoids.

Gas chromatographic separation and mass spectrometric identification of mixtures of oxyphytosterol and oxycholesterol derivatives

Pure individual phytosterols were prepared using reversed-phase HPLC in order to obtain the oxidized compounds of sitosterol, campesterol, stigmasterol and brassicasterol. 7-Hydroxy-, 7-keto-, 5,6-epoxy-, 4beta-hydroxy-, 4-ene-6-hydroxy-, 6-keto- and 5alpha,6beta-dihydroxyphytosterols were obtained as well as analogous compounds of cholesterol. The gas chromatographic properties as well as the electronic impact mass spectra of these compounds (as trimethylsilyl ether derivatives) were studied. These data were used to identify oxyphytosterols in a spread enriched in phytosterols: the oxyphytosterols represented no more than 68 microg/g of spread (about 0.08% of phytosterols were oxidised).

Nonesterified phytosterols dissolved and recrystallized in oil reduce plasma cholesterol in gerbils and humans

When free phytosterols are adequately heated and then cooled in fat, they recrystallize and are rendered bioavailable for blocking cholesterol absorption. To extend the application of phytosterols to fried foods, the activity of these modified crystals was assessed in 2 experiments with 26 male gerbils fed purified diets containing 0.15 g/100 g cholesterol with or without 0.75 g/100 g free phytosterols. The heat-modified soybean sterols were added directly to the diet (Expt. 1) or as phytosterol-enriched potato chips (Expt. 2). In the gerbil experiments, only the diet containing phytosterols significantly reduced plasma cholesterol (35-48%) and the total cholesterol/HDL cholesterol (HDL-C) ratio (40%), as well as hepatic cholesterol esters (80%). In a subsequent human study, subjects (n = 7) consumed two 28-g servings of tortilla chips fried in oil with or without phytosterols that provided 0 or 1.5 g/d for 4-wk periods in a crossover design (Expt. 3). During consumption of the phytosterol-enriched chips, significant reductions in plasma cholesterol (10%) and LDL cholesterol (15%) were achieved without affecting HDL-C. This novel means of delivering free phytosterols proved to be both functionally efficient and effective.

Unesterified plant sterols and stanols do not affect LDL electrophoretic characteristics in hypercholesterolemic subjects

The extent to which sterols and stanols modulate LDL particle size is unknown. We examined the effects of supplementation with unesterified plant sterols and stanols on several LDL electrophoretic characteristics. Healthy hypercholesterolemic subjects (n = 14) consumed each of four experimental diets contained plant sterols (S), plant stanols (SN), a 50:50 mixture of sterols and stanols (SSN), or cornstarch (control) in a randomized crossover design. The butter component of the diet was blended with unesterified sterols and stanols at a dose of 1.8 g/d. The LDL particles were characterized by polyacrylamide gradient gel electrophoresis of whole plasma. LDL cholesterol (LDL-C) concentrations decreased by 8.8, 13.6, and 13.1% in the S, SN, and SSN groups, respectively (P < 0.01) with a significant increase of 4.3% in the control group. None of the treatments with sterols and stanols induced significant changes in LDL peak particle diameter or in the cholesterol levels of the small LDL subfraction (<25.5 nm). The reduction in plasma LDL-C levels with SN consumption was due mainly to a decrease (P < 0.05) in the concentration of cholesterol in the large subfraction (>26.0 nm). The significant reduction in plasma LDL-C concentrations by sterol and stanol consumption in subjects was not paralleled by any beneficial changes in LDL electrophoretic characteristics.

Analysis of plant sterol and stanol esters in cholesterol-lowering spreads and beverages using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectroscopy

Plant sterol and stanol esters were separated on a Luna hexyl-phenyl column using a gradient of acetonitrile (90-100%) in water. The eluted compounds were detected by atmospheric pressure chemical ionization (APCI)-mass spectroscopy (MS) in the positive mode. Sterol and stanol esters produced [M + H - HOOCR](+) ions. Application of the hyphenated technique-LC-MS-allowed differentiation between a number of esters of sitosterol, campesterol, stigmasterol, and (tentatively) avenasterol, as well as sitostanol and campestanol esters. With cholesteryl decanoate used as the internal standard, the method showed good linearity, precision, and reproducibility. The method required minimal sample pretreatment and can be applied to samples with high water content (juices) as well as samples with high oil content (margarine spreads). The method could be useful for the analysis of sterol and stanol esters in fortified food products.

Effects of a new soy/beta-sitosterol supplement on plasma lipids in moderately hypercholesterolemic subjects

Our aim was to test the hypocholesterolemic effect of a low-dose formulation of soy proteins supplemented with isolated b-sitosterol in a ratio of 4:1 in 20 moderately hypercholesterolemic subjects. The study has been divided in three different periods of forty days each: a stabilization diet period, then a treatment period during which all subjects assumed 10 g one time a day of the tested product and, finally, a wash out period. From the end of the stabilization diet period to the end of the soy protein added in b-sitosterol supplementation we observed a 0.45 +/- 0.30 mmol/L, 0.09 +/- 0.31 mmol/L and 0.17 +/- 0.22 mmol/L mean +/- SE decrease in respectively LDL-C, TG and apoB levels, associated with a 0.12 +/- 0.25 and 0.03 +/- 0.51 mg/dL mean increase respectively in HDL-C and apoA plasma concentrations. According to this recommends, low doses of soy protein added in b-sitosterol seems to be a practical and safe alternative for patients seeking modest reductions in LDL-C (< 15%).

Phytosterols, phytostanols, and their conjugates in foods: structural diversity, quantitative analysis, and health-promoting uses

Phytosterols (plant sterols) are triterpenes that are important structural components of plant membranes, and free phytosterols serve to stabilize phospholipid bilayers in plant cell membranes just as cholesterol does in animal cell membranes. Most phytosterols contain 28 or 29 carbons and one or two carbon-carbon double bonds, typically one in the sterol nucleus and sometimes a second in the alkyl side chain. Phytostanols are a fully-saturated subgroup of phytosterols (contain no double bonds). Phytostanols occur in trace levels in many plant species and they occur in high levels in tissues of only in a few cereal species. Phytosterols can be converted to phytostanols by chemical hydrogenation. More than 200 different types of phytosterols have been reported in plant species. In addition to the free form, phytosterols occur as four types of "conjugates," in which the 3beta-OH group is esterified to a fatty acid or a hydroxycinnamic acid, or glycosylated with a hexose (usually glucose) or a 6-fatty-acyl hexose. The most popular methods for phytosterol analysis involve hydrolysis of the esters (and sometimes the glycosides) and capillary GLC of the total phytosterols, either in the free form or as TMS or acetylated derivatives. Several alternative methods have been reported for analysis of free phytosterols and intact phytosteryl conjugates. Phytosterols and phytostanols have received much attention in the last five years because of their cholesterol-lowering properties. Early phytosterol-enriched products contained free phytosterols and relatively large dosages were required to significantly lower serum cholesterol. In the last several years two spreads, one containing phytostanyl fatty-acid esters and the other phytosteryl fatty-acid esters, have been commercialized and were shown to significantly lower serum cholesterol at dosages of 1-3 g per day. The popularity of these products has caused the medical and biochemical community to focus much attention on phytosterols and consequently research activity on phytosterols has increased dramatically.

Additive effect of plant sterol-ester margarine and cerivastatin in lowering low-density lipoprotein cholesterol in primary hypercholesterolemia

The objective of this study was to evaluate whether plant sterol-ester margarine has an additive or interactive effect on low-density lipoprotein (LDL) cholesterol reduction when ingested in combination with a statin drug. This was a multicenter, randomized, double-blind study with 4 parallel treatment arms in a balanced 2 x 2 factorial design. The 4 daily treatment options were: (1) placebo plus regular margarine 25 g (n = 38); (2) placebo plus sterol-ester margarine 25 g (2 g of plant sterol) (n = 39); (3) cerivastatin 400 microg plus regular margarine 25 g (n = 38); and (4) cerivastatin 400 microg plus sterol-ester margarine 25 g (n = 37). The study was conducted in men and women with primary hypercholesterolemia with baseline LDL cholesterol >/=97 mg/dl (mean 206). The primary efficacy parameter was the percent change in LDL cholesterol between baseline and at the end of 4 weeks' treatment. Cerivastatin (vs placebo) reduced LDL cholesterol by 32% (95% confidence intervals 28% to 36%, p <0.0001) and sterol-ester margarine (vs regular margarine) by 8% (95% confidence interval 4% to 12%, p <0.0001). The effect of sterol-ester margarine and cerivastatin together was additive (39% reduction in LDL cholesterol), but there was no significant interactive effect between sterol-ester margarine and cerivastatin (p = 0.29). The treatments were generally well tolerated with no major differences in adverse events between groups. In subjects with primary hypercholesterolemia, statin and sterol-ester margarine used together produce a purely additive effect on LDL cholesterol reduction. The addition of sterol-ester margarine to statin therapy offers LDL cholesterol reduction equivalent to doubling the dose of statin.

Effects on the human serum lipoprotein profile of beta-glucan, soy protein and isoflavones, plant sterols and stanols, garlic and tocotrienols

The effects of beta-glucan, soy protein, isoflavones, plant sterols and stanols, garlic and tocotrienols on serum lipoproteins have been of great interest the last decade. From a critical review of the literature, it appeared that recent studies found positive as well as no effects of beta-glucan from oats on serum LDL cholesterol concentrations. These conflicting results may suggest that the cholesterol-lowering activity of products rich in oat beta-glucan depends on factors, such as its viscosity in the gastrointestinal tract, the food matrix and/or food processing. The effects of beta-glucan from barley or yeast on the lipoprotein profile are promising, but more human trials are needed to further substantiate these effects. It is still not clear whether the claimed hypocholesterolemic effects of soy can be attributed solely to the isoflavones. Several studies found no changes in serum LDL cholesterol concentrations after consumption of isolated soy isoflavones (without soy protein), indicating that a combination of soy protein and isoflavones may be needed for eliciting a cholesterol-lowering effect of soy. Therefore, the exact (combination of) active ingredients in soy products need to be identified. The daily consumption of 2-3 g of plant sterols or stanols reduces LDL cholesterol concentrations by 9-14%. It has been demonstrated that functional foods enriched with plant sterols and stanols are effective in various population groups, and in combination with cholesterol-lowering diets or drugs. Whether garlic or garlic preparations can be used as a lipid-lowering agent is still uncertain. It is important to characterize the active components in garlic and their bioavailability after ingestion. It is not very likely that tocotrienols from palm oil or rice bran oil have favorable effects on the human serum lipoprotein profile.

Free phytosterols effectively reduce plasma and liver cholesterol in gerbils fed cholesterol

The potential of free phytosterols (including 20% stanols) to lower plasma and liver lipids was assessed in three experiments with gerbils fed diets containing cholesterol. The first explored the ability of phytosterols (0.5%) to block absorption of 0.05, 0.10, and 0.5% cholesterol. The second assessed the importance of consuming phytosterols (0.75%) simultaneously with cholesterol (0.15%). The third compared free phytosterols (0.75%) with similar levels of esterified sterols or stanols using diets containing 0.15% cholesterol. A 5:1 ratio of phytosterols:cholesterol effectively blocked cholesterol absorption when the dietary cholesterol load was moderate. Consuming a 5:1 ratio with every meal was more effective than receiving equal phytosterols in a 10:1 ratio every other day. Finally, free phytosterols dissolved in fat were as effective as esterified sterols and stanols in lowering plasma and liver cholesterol, and all were equally effective at blocking cholesterol absorption as shown by increased fecal cholesterol output. Plant sterol accumulation in the liver was minimal for all test groups.

HOE 402 lowers serum cholesterol levels by reducing VLDL-lipid production, and not by induction of the LDL receptor, and reduces atherosclerosis in wild-type and LDL receptor-deficient mice

Previous rodent studies suggested that the potent hypolipidemic agent 4-amino-2-(4,4-dimethyl-2-oxo-1-imidazolidinyl)pyrimidine-5-N-(trifluoromethyl-phenyl) carboxamide monohydrochloride (HOE 402) is an inducer of the LDL receptor (LDLR). Using wild-type and heterozygous and homozygous LDLR-deficient (LDLR+/0 and LDLR0/0) mice, fed a low or high cholesterol diet, we investigated whether HOE 402 specifically induces the LDLR and whether other pathways are affected. Upon treatment with 0.05% (w/w) HOE 402, the serum cholesterol levels of wild-type, LDLR+/0 and LDLR0/0 mice, were maximally reduced by 53, 56, and 73%, respectively (P<0.05), by reducing levels in very low density-lipoprotein (VLDL), intermediate density-lipoprotein (IDL), and low density-lipoprotein (LDL) cholesterol, whereas high density-lipoprotein (HDL) cholesterol levels were increased. The observations that HOE 402 exhibited no effect on in vivo clearance of 125I-labeled LDL in wild-type mice, and clearly reduced serum cholesterol levels in LDLR0/0 mice, indicate that the LDLR is not the main target for the compound. In wild-type mice, production of VLDL-TG, and cholesterol were reduced by more than 50% by HOE 402 (P<0.05), whereas VLDL apolipoprotein B (ApoB) secretion was unaffected, indicating that HOE 402 treatment changes the size, rather than the number of the secreted VLDL particles. The reduced VLDL production was accompanied by a 22% decreased hepatic cholesterol ester concentration (P<0.05). Additionally, HOE 402 treatment strongly reduced the aortic content of atherosclerotic lesions by 90 and 72% in LDLR+/0 and LDLR0/0 mice, respectively (P<0.01). In conclusion, HOE 402 is a potent cholesterol-lowering compound, which inhibits VLDL production, and consequently attenuates atherosclerosis development.

Plant sterols and blood lipid levels

Plant sterols have recently been recommended by the National Cholesterol Education Panel for use with the more traditional approaches of limiting saturated fat and cholesterol intakes, maintaining a healthy body weight and engaging in regular exercise, as a non-pharmacological approach to reduce low-density lipoprotein cholesterol levels. Recent data confirm the original observation that approximately 1.6 g of plant sterol esters per day results in a maximal low-density lipoprotein cholesterol lowering of approximately 10%. Few side-effects of plant sterols have been reported, with the exception of decreased levels of circulating carotenoids.

Effects of plant stanol esters supplied in low-fat yoghurt on serum lipids and lipoproteins, non-cholesterol sterols and fat soluble antioxidant concentrations

Oil-based products enriched with plant stanol esters can lower low-density lipoprotein (LDL) cholesterol concentrations by 10-14%. Effectiveness of low-fat products, however, has never been evaluated, although such products fit into a healthy diet. We therefore examined the effects of plant stanol esters emulsified into low-fat yoghurt (0.7% fat) on fasting concentrations of plasma lipids and lipid-soluble antioxidants, which may also change by plant stanol consumption. Sixty non-hypercholesterolemic subjects first consumed daily three cups (3 x 150 ml) of placebo yoghurt for 3 weeks. For the next 4 weeks, 30 subjects continued with the placebo yoghurt, while the other 30 subjects received three cups of experimental yoghurt. Each cup provided 1 g of plant stanols (0.71 g sitostanol plus 0.29 g campestanol) as its fatty acid ester. LDL cholesterol (mean+/-S.D.) increased by 0.06+/-0.21 mmol/l in the placebo group, but decreased by -0.34+/-0.30 mmol/l in the experimental group. The difference in changes between the two groups of 0.40 mmol or 13.7% was highly significant (P<0.001; 95% confidence interval for the difference, (-)0.26 -(-)0.53 mmol/l). Effects were already maximal after 1 week. HDL cholesterol and triacylglycerol concentrations did not change. Total tocopherol levels increased by 1.43 micromol/mmol LDL cholesterol (14.0%, P=0.015). beta-carotene levels, however, decreased by -0.02 micromol/mmol LDL cholesterol (-14.4%, P=0.038). Decreases in absolute beta-carotene concentrations were found in all apoB-containing lipoproteins. LDL-cholesterol standardised phytofluene levels decreased by 21.4+/-25.7% (P<0.001), while other plasma carotenoid (lutein/zeaxanthin, beta-cryptoxanthin, lycopene and alpha-carotene) levels did not change significantly. We conclude that low-fat yoghurt enriched with plant stanol esters lowers within 1 week LDL cholesterol to the same extent as oil-based products. LDL-cholesterol standardised concentrations of tocopherol increased. The observed decrease in beta-carotene levels, as found in many other studies, appears not to be limited to the LDL fraction.