Effects of plant sterols and stanols on intestinal cholesterol metabolism: suggested mechanisms from past to present

Phytosterols on growth performance, antioxidant enzymes and intestinal morphology in weaned piglets

BACKGROUND

Plant extracts have been used widely to improve growth, lower cholesterol, and exert antioxidative defense and antimicrobial activities in animal production. The present study aimed to investigate the effects of dietary phytosterols (PS) on growth performance, antioxidant enzymes and intestinal morphology in weaned piglets.

RESULTS

A total of 120 crossbred piglets, weighing 9.58 ± 0.26 kg, were randomly allocated to three treatments: control, PS (0.2 g kg^-1 ) and polymyxin E (0.04 g kg^-1 , antibiotic control). Compared to the control, PS or polymyxin E supplementation decreased diarrhea rate, serum cholesterol and malondialdehyde (MDA) of the piglets (P < 0.05). Liver MDA was significantly decreased in PS-fed piglets compared to the control (P < 0.05), although there was no difference between the control and polymyxin E-fed piglets. PS increased the villous height/crypt depth ratio of the duodenum and jejunum compared to the control (P < 0.05). Polymyxin E supplementation in piglets did not alter the villous height/crypt depth ratio but raised the villous height and crypt depth of the duodenum compared to the control (P < 0.05).

CONCLUSION

The results of the present study indicated that PS could decrease diarrhea rate, lower serum cholesterol, reduce lipid peroxidation and ameliorate intestinal morphology in weaned piglets. In addition, PS exerted better amelioration on intestinal morphology than polymyxin E in piglets. © 2017 Society of Chemical Industry.

In Vitro Effects of Arthrocen, an Avocado/Soy Unsaponifiables Agent, on Inflammation and Global Gene Expression in Human Monocytes

Osteoarthritis (OA) is the most common form of arthritis. Symptomatically characterized by stiffness and pain, OA is a chronic degenerative disease of joints. Of note, there is growing interest in the potential use of plant-based compounds for symptomatic treatment of OA. Arthrocen is a plant-derived agent consisting of a one to two ratio of avocado and soy unsaponifiable extracts. In order to decipher the potential mechanisms of Arthrocen’s action at the molecular level, we employed an in vitro assay using cultured human THP-1 cells (a model cell line for monocytes) to study its effects. By pairing protein arrays enriched for inflammatory markers, transcriptomic pathway analysis using RNA-Sequencing, and eicosanoid specific lipidomics, we have begun to unravel its potential mechanism of action. Specifically, we found that Arthrocen can attenuate the inflammatory response at the transcript level while inducing significant changes in numerous cytokines. Furthermore, we discovered that while Arthrocen alone did not increase IL-8 or MCP-1 levels, its presence had a synergistic effect on the observed increase in response to LPS stimulation. Additionally, this synergistic effect of Arthrocen on LPS stimulation of IL-8 and MCP-1 protein levels was also observed at the mRNA level and suggests a regulatory mechanism at the transcriptional level. Interestingly, Arthrocen induced no changes in any of the eicosanoids studied. This multi-omics approach implies that Arthrocen functions at the level of gene transcription to dampen inflammation mediated by monocytes in OA.

Impact of thermooxidation of phytosteryl and phytostanyl fatty acid esters on cholesterol micellarization in vitro

The effects of thermooxidation of a phytosteryl/-stanyl and a phytostanyl fatty acid ester mixture on cholesterol micellarization were investigated using an in vitro digestion model simulating enzymatic hydrolysis by cholesterol esterase and subsequent competition of the liberated phytosterols/-stanols with cholesterol for incorporation into mixed micelles. As a first step, relationships between different doses of the ester mixtures and the resulting micellarized cholesterol were established. Subsequent subjection of the thermooxidized ester mixtures to the in vitro digestion model resulted in three principal observations: (i) thermal treatment of the ester mixtures led to substantial decreases of the intact esters, (ii) in vitro digestion of cholesterol in the presence of the thermooxidized ester mixtures resulted in significant increases of cholesterol micellarization, and (iii) the extents of the observed effects on cholesterol micellarization were strongly associated to the remaining contents of intact esters. The loss of efficacy to inhibit cholesterol micellarization due to thermally induced losses of intact esters corresponded to a loss of efficacy that would have been induced by an actual removal of these amounts of esters prior to the in vitro digestion. The obtained results suggest that in particular oxidative modifications of the fatty acid moieties might be responsible for the observed increases of cholesterol micellarization.

Bioactive compounds as an alternative for drug co-therapy: Overcoming challenges in cardiovascular disease prevention

Different pharmacological interventions have been applied with success to reduce the progression of atherosclerosis. However, many patients are not good responders or must interrupt treatment due to adverse effects. Bioactive compounds such as omega-3 fatty acids (n-3 FA), plant sterol esters (PSE) and phenolic compounds (PHC) are natural molecules with great potential to reduce the atherosclerosis burden by reducing inflammation, LDL cholesterol (LDL-C) and oxidative stress, respectively. Although their physiological effects on biomarkers are much lower than those expected by drugs used for the same purpose, bioactive compounds can easily be incorporated into the daily diet and present no adverse effects. However, little is known about the combination of n-3 FA, PSE, PHC, and drugs in atherosclerosis progression. This review article summarizes potential effects of co-therapies involving n-3 FA, PSE, and PHC combined with major hypolipidemic drugs on atherosclerosis biomarkers and clinical outcomes. Evidence of additive and/or complementary effects regarding drugs action reveals possible roles for bioactive compounds in disease management. Pharmaceutical companies, physicians, and food scientists should be prepared to better understand this type of interaction and its consequences in terms of efficacy and life quality.

Nutraceuticals in hypercholesterolaemia: an overview

Growing attention is now being given to the possible preventive/alternative ways to avoid illness onset. Changes in lifestyle and food habits are taking over from the conventional pharmaceutical-based approach, especially for chronic pathologies. Nutraceuticals have been proposed as key tools for the prevention and cure of some pathological conditions. This is leading research to develop new formulations based on these pharma-foods addressed in a specific way to prevent and cure health issues, which, in turn, will have an effect on therapy-related costs sustained by any National Health Organization. According to existing regulations, nutraceuticals cannot be categorized as either food or drugs but, by definition, often inhabit a grey area in between the two, being assimilated into food supplements, notwithstanding the beneficial properties that they can provide for some pathological conditions. A nutraceuticals-based approach for health management, in particular for some pathological conditions, has resulted in a worldwide growing 'nutraceutical' revolution. An outstanding example is the approach to the 'metabolic syndrome', which includes overweight, obesity and cardiovascular-related diseases, causing a sort of cascade of chronic health conditions, which is becoming a norm in modern life. Hypercholesterolaemia is one of these. It represents an example of a pathology that can be linked to both a poor lifestyle and dietary habits. The nutraceutical approach to hypercholesterolaemia is described in the present review as a possible alternative to the conventional drug-based therapy.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

A Randomized Open-Label Trial to Assess the Effect of Plant Sterols Associated with Ezetimibe in Low-Density Lipoprotein Levels in Patients with Coronary Artery Disease on Statin Therapy

Consumption of food products enriched with plant sterols and the use of ezetimibe reduce cholesterol absorption in the intestine and effectively reduce low-density lipoprotein (LDL) plasma levels. We evaluated the therapeutic effect of the ezetimibe+plant sterol association in patients with coronary artery disease still not reaching recommended lipid levels despite the use of statins. We performed a prospective open-label study with 41 patients with stable coronary disease and LDL >70 mg/dL. Patients were randomized into four groups for a 6-week treatment: the control (CT) group remained on the same statin therapy, the ezetimibe (EZ) group received 10 mg/day of ezetimibe, the plant sterol (PS) group received spread enriched with 2 g of plant sterols, and the ezetimibe+PS (EZ+PS) group received 10 mg/day EZ +2 g PS. Initial mean LDL level was 97.4 ± 31.1 mg/dL in control group, 105.1 ± 23.1 mg/dL in EZ group, 95.4 ± 27.7 mg/dL in PS group, and 97.0 ± 8.3 mg/dL in EZ+PS group (P > .05). After 6 weeks of treatment, LDL of patients slightly increased in the control group (+8.9%; P > .05) and dropped in EZ group (-19.1%; P = .06), PS group (-16.6%; P = .01), and EZ+PS group (-27.3%; P < .01). Mean LDL levels after treatment were 70.5 ± 17.9 mg/dL in EZ+PS group, lower than the other groups (control was 106.1 ± 34.9 mg/dL, EZ group was 85.0 ± 35.6 mg/dL, and PS was 79.6 ± 29.7 mg/dL) (P = .05 variance analysis factor [ANOVA]). Body weight, body-mass index, and glucose plasma levels did not change significantly after intervention. The combination of PS+ezetimibe was associated with lower LDL levels and suggests beneficial therapeutic effect against major cardiovascular events.

Pectin Penta-Oligogalacturonide Suppresses Intestinal Bile Acids Absorption and Downregulates the FXR-FGF15 Axis in High-Cholesterol Fed Mice

Haw pectin penta-oligogalacturonide (HPPS), purified from the hydrolysates of haw pectin, has important role in decreasing hepatic cholesterol accumulation and promoting bile acids (BA) excretion in the feces of mice fed a high-cholesterol diet (HCD). However, the mechanism is not clear. This study aims to investigate the effects of HPPS on BA reabsorption in ileum and biosynthesis in liver of mice. Results showed that HPPS increased fecal BA output by approximately 110%, but decreased ileal BA and the total BA pool size by approximately 47 and 36%, respectively, compared to HCD. Studies of molecular mechanism revealed that HPPS significantly decreased the mRNA and protein levels of farnesoid X receptor (FXR) in the small intestine of mice and inactivated the fibroblast growth factor 15 (FXR-FGF15) axis, which increased the mRNA and protein levels of CYP7A1 by approximately 204 and 104%, respectively, compared to HCD. Interestingly, the mRNA and protein levels of apical sodium-dependent bile acid transporter (ASBT) in the small intestine were approximately 128 and 73% higher in HPPS-fed mice than those in HCD-fed mice, respectively. However, no significant difference was detected for ASBT expression between HCD group and BA sequestrant cholestyramine group. These findings indicate that HPPS can suppress intestinal BA reabsorption and promoting hepatic BA biosynthesis. We speculated that HPPS could be ASBT competitive inhibitor rather than BA sequestrant in inhibiting BA reabsorption in ileum and improving cholesterol metabolism.

Cashew consumption reduces total and LDL cholesterol: a randomized, crossover, controlled-feeding trial

Background: Cashews are the third most-consumed tree nut in the United States and are abundant with monounsaturated fatty acids and polyunsaturated fatty acids, which are associated with reduced cardiovascular disease risk. Although a qualified Food and Drug Administration health claim exists for nuts and heart health, cashews have been exempt from its use because cashews exceed the disqualifying amount of saturated fatty acids. Approximately one-third of the saturated fat in cashews is stearic acid, which is relatively neutral on blood lipids, thereby suggesting that cashews could have effects that are similar to those of other nuts. However, clinical data on cashews and blood lipids have been limited.Objective: We investigated the effect of reasonable intakes of cashews on serum lipids in adults with or at risk of high LDL cholesterol.Design: In a randomized, crossover, isocaloric, controlled-feeding study, 51 men and women (aged 21-73 y) with a median LDL-cholesterol concentration of 159 mg/dL (95% CI: 146, 165 mg/dL) at screening consumed typical American diets with cashews (28-64 g/d; 50% of kilocalories from carbohydrate, 18% of kilocalories from protein, and 32% of kilocalories from total fat) or potato chips (control; 54% of kilocalories from carbohydrate, 18% of kilocalories from protein, and 29% of kilocalories from total fat) for 28 d with a ≥2-wk washout period.Results: Consumption of the cashew diet resulted in a significantly greater median change from baseline (compared with the control, all P < 0.05) in total cholesterol [-3.9% (95% CI: -9.3%, 1.7%) compared with 0.8% (95% CI: -1.5%, 4.5%), respectively], LDL cholesterol [-4.8% (95% CI: -12.6%, 3.1%) compared with 1.2% (95% CI: -2.3%, 7.8%), respectively], non-HDL cholesterol [-5.3% (95% CI: -8.6%, 2.1%) compared with 1.7% (95% CI: -0.9%, 5.6%), respectively], and the total-cholesterol:HDL-cholesterol ratio [-0.0% (95% CI: -4.3%, 4.8%) compared with 3.4% (95% CI: 0.6%, 5.2%), respectively]. There were no significant differences between diets for HDL cholesterol and triglyceride.Conclusions: In comparison with a control diet, the incorporation of cashews into typical American diets decreases total cholesterol and LDL cholesterol. Results from this study provide support that the daily consumption of cashews, when substituted for a high-carbohydrate snack, may be a simple dietary strategy to help manage total cholesterol and LDL cholesterol. This study was registered at clinicaltrials.gov as NCT02769741.

Microbial and endogenous metabolic conversions of rye phytochemicals

Rye is one of the main cereals produced and consumed in the hemiboreal climate region. Due to its use primarily as wholegrain products, rye provides a rich source of dietary fibre as well as several classes of phytochemicals, bioactive compounds with potentially positive health implications. Here, we review the current knowledge of the metabolic pathways of phytochemical classes abundant in rye, starting from the microbial transformations occurring during the sourdough process and colonic fermentation and continuing with the endogenous metabolism. Additionally, we discuss the detection of specific metabolites by MS in different phases of their journey from the cereal to the target organs and excretion.

Effect of dietary cholesterol and plant sterol consumption on plasma lipid responsiveness and cholesterol trafficking in healthy individuals

Dietary cholesterol and plant sterols differentially modulate cholesterol kinetics and circulating cholesterol. Understanding how healthy individuals with their inherent variabilities in cholesterol trafficking respond to such dietary sterols will aid in improving strategies for effective cholesterol lowering and alleviation of CVD risk. The objectives of this study were to assess plasma lipid responsiveness to dietary cholesterolv. plant sterol consumption, and to determine the response in rates of cholesterol absorption and synthesis to each sterol using stable isotope approaches in healthy individuals. A randomised, double-blinded, crossover, placebo-controlled clinical trial (n49) with three treatment phases of 4-week duration were conducted in a Manitoba Hutterite population. During each phase, participants consumed one of the three treatments as a milkshake containing 600 mg/d dietary cholesterol, 2 g/d plant sterols or a control after breakfast meal. Plasma lipid profile was determined and cholesterol absorption and synthesis were measured by oral administration of [3, 4-13C] cholesterol and2H-labelled water, respectively. Dietary cholesterol consumption increased total (0·16 (sem0·06) mmol/l,P=0·0179) and HDL-cholesterol (0·08 (sem0·03) mmol/l,P=0·0216) concentrations with no changes in cholesterol absorption or synthesis. Plant sterol consumption failed to reduce LDL-cholesterol concentrations despite showing a reduction (6 %,P=0·0004) in cholesterol absorption. An over-compensatory reciprocal increase in cholesterol synthesis (36 %,P=0·0026) corresponding to a small reduction in absorption was observed with plant sterol consumption, possibly resulting in reduced LDL-cholesterol lowering efficacy of plant sterols. These data suggest that inter-individual variability in cholesterol trafficking mechanisms may profoundly impact plasma lipid responses to dietary sterols in healthy individuals.

Effects of Arthrocen, an avocado/soy unsaponifiables agent, on inflammatory mediators and gene expression in human chondrocytes

Osteoarthritis (OA) is a chronic joint disease characterized by pain and stiffness. Recently, there has been great interest in the use of plant‐derived compounds and supplements in managing the symptoms of OA. Arthrocen is a plant‐based supplement consisting of avocado and soy unsaponifiable extracts in a 1 : 2 ratio. In an effort to unravel the potential mechanisms of its action on the cellular level, we utilized an in vitro assay to study its effects on cultured human chondrocytes. By pairing this assay with protein arrays on inflammatory markers, RNA‐Seq with downstream pathway analysis, and lipidomics on eicosanoids, we were able to further define its action at the molecular level. Specifically, we found a role for Arthrocen in attenuating the inflammatory response both at the protein and mRNA level. Furthermore, we discovered that Arthrocen diminished prostaglandin E2 (PGE2) levels in response to an inflammatory trigger. Additionally, unlike traditional COX‐2 inhibitors, this response rather specifically attenuated PGE2 levels in the presence of inflammation and without lowering levels of other eicosanoids. This implies that Arthrocen could potentially bring about the reduced pain produced by COX‐2 inhibitors without the known side effects of COX‐2 inhibition.

Food and plant bioactives for reducing cardiometabolic disease risk: an evidence based approach

Nutraceuticals active on the main cardiovascular disease risk factors.

Phytosterols and Dementia

As the aging of the world's population is becoming increasingly serious, dementia-related diseases have become a hot topic in public health research. In recent years, human epidemiological studies have focused on lipid metabolism disorders and dementia. The efficacy of phytosterol intake as a cholesterol-lowering agent has been demonstrated. Phytosterols directly serve as ligands of the nuclear receptors, peroxisome proliferator-activated receptors (PPARs), activating Sirtuin 1 (SIRT-1), which are involved in the regulation of lipid metabolism and the pathogenesis of dementia. Moreover, phytosterols mediate cell and membrane cholesterol efflux or beta amyloid (Aβ) metabolism, which have preventative and therapeutic effects on dementia. Additionally, incorporation of plant sterols in lipid rafts can effectively reduce dietary fat and alter the dietary composition of fiber, fat and cholesterol to regulate appetite and calories. Overall, the objectives of this review are to explore whether phytosterols are a potentially effective target for the prevention of dementia and to discuss a possible molecular mechanism by which phytosterols play a role in the pathogenesis of dementia via the PPARs-SIRT-1 pathway.

Effects of a Plant Sterol or Stanol Enriched Mixed Meal on Postprandial Lipid Metabolism in Healthy Subjects

Background

Evidence is increasing that plant sterols and stanols not only lower fasting serum low-density lipoprotein concentrations, but also those of triglycerides (TG). Insight into effects of these components on postprandial TG metabolism, an emerging risk factor for cardiovascular disease, is missing.

Objective

Our objective was to examine the 8-hour postprandial response after consuming plant sterol or stanol enriched margarine as part of a mixed meal.

Methods

This postprandial study was part of a randomized crossover study in which 42 subjects consumed plant sterol enriched (3 g/d plant sterols), plant stanol enriched (3 g/d plant stanols), and control margarines for 4 weeks. After each period, subjects consumed a shake enriched with 3g plant sterols (sterol period), 3g plant stanols (stanol period) or no addition (control period). Subjects received a second shake with no addition after 4 hours.

Results

TG and apoB48 incremental areas under the curves (iAUC) of the total (0-8h) and 1^st meal response (0-4h) were comparable between the meals and in all age categories (I:18-35y, II:36-52y, III:53-69y). In subjects aged 53-69y, TG iAUC after the 2^nd meal (4-8h) was higher in the stanol period as compared with the sterol (63.1±53.0 mmol/L/min; P < 0.01) and the control period (43.2±52.4 mmol/L/min; P < 0.05). ApoB48 iAUC after the 2^nd meal was higher after the stanol than after the sterol period (67.1±77.0 mg/L/min; P < 0.05) and tended to be higher than after the control period (43.1±64.5 mg/L/min; P = 0.08) in subjects aged 53-69y. These increased postprandial responses may be due to reduced lipoprotein lipase activity, since postprandial apoCIII/II ratios were increased after stanol consumption compared with the control meal.

Conclusion

Postprandial TG and apoB48 responses are age-dependently increased after plant stanol consumption, which might be related to a changed clearance of triglyceride-rich lipoproteins.

Trial Registration

ClinicalTrials.gov NCT01559428

Plasma fat-soluble vitamin and carotenoid concentrations after plant sterol and plant stanol consumption: a meta-analysis of randomized controlled trials

Purpose

Plant sterols and stanols interfere with intestinal cholesterol absorption, and it has been questioned whether absorption and plasma concentrations of fat-soluble vitamins and carotenoids are also affected. We conducted a meta-analysis to assess the effects of plant sterol and stanol consumption on plasma fat-soluble vitamin and carotenoid concentrations.

Methods

Forty-one randomized controlled trials involving 3306 subjects were included. Weighted absolute and relative changes of non-standardized and total cholesterol (TC)-standardized values (expressed as summary estimates and 95 % CIs) were calculated for three fat-soluble vitamins (α- and γ-tocopherol, retinol and vitamin D) and six carotenoids (β-carotene, α-carotene, lycopene, lutein, zeaxanthin and β-cryptoxanthin) using a random effects model. Heterogeneity was assessed using predefined subject and treatment characteristics.

Results

Average plant sterol or stanol intake was 2.5 g/d. Relative non-standardized and TC-standardized concentrations of β-carotene decreased by, respectively, −16.3 % (95 % CI −18.3; −14.3) and −10.1 % (−12.3; −8.0), α-carotene by −14.4 % (−17.5; 11.3) and −7.8 % (−11.3; −4.3), and lycopene by −12.3 % (−14.6; −10.1) and −6.3 % (−8.6; −4.0). Lutein concentrations decreased by −7.4 % (−10.1; −4.8), while TC-standardized concentrations were not changed. For zeaxanthin, these values were −12.9 % (−18.9; −6.8) and −7.7 % (−13.8; −1.7) and for β-cryptoxanthin −10.6 % (−14.3; −6.9) and −4.8 % (−8.7; −0.9). Non-standardized α-tocopherol concentrations decreased by −7.1 % (−8.0; −6.2) and γ-tocopherol by −6.9 % (−9.8; −3.9), while TC-standardized tocopherol concentrations were not changed. Non-standardized retinol and vitamin D concentrations were not affected. Results were not affected by baseline concentrations, dose, duration and type of plant sterols/stanols, except for significant effects of duration (≤4 vs. >4 weeks) on TC-standardized lutein concentrations (1.0 vs. −5.6 %) and type of plant sterol/stanol on TC-standardized β-carotene concentrations (−8.9 vs. −14.2 %).

Conclusions

Plant sterol and stanol intake lowers TC-standardized hydrocarbon carotenoid concentrations, differently affects TC-standardized oxygenated carotenoid concentrations, but does not affect TC-standardized tocopherol concentrations or absolute retinol and vitamin D concentrations. Observed concentrations remained within normal ranges.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-016-1289-7) contains supplementary material, which is available to authorized users.

Effect of Phytosterols on the Crystallization Behavior of Oil-in-Water Milk Fat Emulsions

Milk has been used commercially as a carrier for phytosterols, but there is limited knowledge on the effect of added plant sterols on the properties of the system. In this study, phytosterols dispersed in milk fat at a level of 0.3 or 0.6% were homogenized with an aqueous dispersion of whey protein isolate (WPI). The particle size, morphology, ζ-potential, and stability of the emulsions were investigated. Emulsion crystallization properties were examined through the use of differential scanning calorimetry (DSC) and Synchrotron X-ray scattering at both small and wide angles. Phytosterol enrichment influenced the particle size and physical appearance of the emulsion droplets, but did not affect the stability or charge of the dispersed particles. DSC data demonstrated that, at the higher level of phytosterol addition, crystallization of milk fat was delayed, whereas, at the lower level, phytosterol enrichment induced nucleation and emulsion crystallization. These differences were attributed to the formation of separate phytosterol crystals within the emulsions at the high phytosterol concentration, as characterized by Synchrotron X-ray measurements. X-ray scattering patterns demonstrated the ability of the phytosterol to integrate within the milk fat triacylglycerol matrix, with a concomitant increase in longitudinal packing and system disorder. Understanding the consequences of adding phytosterols, on the physical and crystalline behavior of emulsions may enable the functional food industry to design more physically and chemically stable products.

Quality of deli-style turkey enriched with plant sterols

Low-fat meat products could be excellent carriers for plant sterols, known for their cholesterol-lowering properties. In this study, we developed a protocol for the manufacture of a deli-style turkey enriched with plant sterols (S) at a level sufficient to deliver the maximum plant sterols amount recommended for cholesterol reduction by the European Food Safety Authority (3 g of plant sterols per day) in a 70 g portion. We investigated the stability of the plant sterols and the effects of their addition on the product quality. Plant sterols remained stable during the seven-day storage period. The addition of plant sterols significantly affected some texture parameters, shear force, lipid oxidation, L values and water-holding capacity compared with control (C). Sensory analysis was carried out by an untrained panel (32) using the difference-from-control test between C and S samples to evaluate first the extent of the overall sensory difference and then the extent of sensory difference on colour, texture and flavour. Results indicated that panellists considered the intensity of the difference between C and S samples to be ‘small’. Plant sterols could be used as a potential health-promoting meat ingredient with no effect on plant sterol stability but with some effects on texture and sensory characteristics.

Inhibition of cholesterol transport in an intestine cell model by pine-derived phytosterols

We have quantified the inhibition of intestinal cholesterol transport by pine-derived phytosterols using an HT29-MTX intestine cell model that forms a mucus layer similar to that in the intestine. An artificial intestinal fluid consisting of digested fat, bile salt, cholesterol, and phytosterols was formulated in order to mimic the conditions in the intestine. The apparent permeability coefficient (P_app) of the positive control, i.e., 0.1mM of cholesterol solubilized in the artificial intestine fluid, was found to be 0.33 (±0.17)×10^-6cm/s. When 0.1mM β-sitosterol was solubilized alongside, P_app was effectively zero, corresponding to a total inhibition of cholesterol transport. A similar strong inhibition was found when commercial pine-derived phytosterols, PinVita™ FSP DuPont, were co-solubilized with cholesterol in the dietary model micelles, leading to P_app=0.06 (±0.06)×10^-6cm/s, i.e., 5.5 times lower than the cholesterol positive control. Additionally, the effect of potential oral administration formulations generated by the pine-derived phytosterols was also characterized. The formulations were produced as a liquid formulation of the cholesterol-containing artificial intestine fluid. Six liquid formulations were tested of which four displayed a P_app in the range of 0-0.09×10^-6cm/s. The remaining two formulations did not show any inhibition effect on cholesterol transport and even enhanced cholesterol transport. It was furthermore observed that the phytosterols were found in the collected intestine cells but not transported to the basolateral region in the intestinal cell model system.

Lipid-modifying effects of nutraceuticals: An evidence-based approach

The present review provides an up-to-date summary of the findings on the lipid-lowering effects of the most important nutraceuticals and functional foods. Based on current knowledge, nutraceuticals might exert significant lipid-lowering, and their use has several advantages: A number of important questions remain to be addressed, including whether longer durations of therapy would result in a better response and the exact safety profile of nutraceuticals, especially at doses higher than those consumed in an average diet. Additionally, data regarding the effects of nutraceutical supplementation on the incidence of cardiovascular outcomes are lacking, and it is not clear whether additional lipid lowering by nutraceuticals can modify the residual cardiovascular risk that remains after statin therapy.

Quantification of Cholesterol Solubilized in Dietary Micelles: Dependence on Human Bile Salt Variability and the Presence of Dietary Food Ingredients

The solubility of cholesterol in bile salt (BS) micelles is important to understand the availability of cholesterol for absorption in the intestinal epithelium and to develop strategies to decrease cholesterol intake from the intestinal lumen. This has been the subject of intense investigation, due to the established relation between the development of diseases such as atherosclerosis and high levels of cholesterol in the blood. In this work we quantify the effect of BS variability on the amount of cholesterol solubilized. The effect of some known hypocholesterolemic agents usually found in the diet is also evaluated, as well as some insight regarding the mechanisms involved. The results show that, depending on the bile salt composition, the average value of sterol per micelle is equal to or lower than 1. The amount of cholesterol solubilized in the BS micelles is essentially equal to its total concentration until the solubility limit is reached. Altogether, this indicates that the maximum cholesterol solubility in the BS micellar solution is the result of saturation of the aqueous phase and depends on the partition coefficient of cholesterol between the aqueous phase and the micellar pseudophase. The effect on cholesterol maximum solubility for several food ingredients usually encountered in the diet was characterized using methodology developed recently by us. This method allows the simultaneous quantification of both cholesterol and food ingredient solubilized in the BS micelles even in the presence of larger aggregates, therefore avoiding their physical separation with possible impacts on the overall equilibrium. The phytosterols stigmasterol and stigmastanol significantly decreased cholesterol solubility with a concomitant reduction in the total amount of sterol solubilized, most pronounced for stigmasterol. Those results point toward coprecipitation being the major cause for the decrease in cholesterol solubilization by the BS micelles. The presence of tocopherol and oleic acid leads to a small decrease in the amount of cholesterol solubilized while palmitic acid slightly increases the solubility of cholesterol. Those dietary food ingredients are completely solubilized by the BS micelles, indicating that the effects on cholesterol solubility are due to changes in the properties of the mixed micelles.

Heating Two Types of Enriched Margarine: Complementary Analysis of Phytosteryl/Phytostanyl Fatty Acid Esters and Phytosterol/Phytostanol Oxidation Products

Two phytosteryl and/or phytostanyl fatty acid ester-enriched margarines were subjected to common heating procedures. UHPLC-APCI-MS analysis resulted for the first time in comprehensive quantitative data on the decreases of individual phytosteryl/-stanyl fatty acid esters upon heating of enriched foods. These data were complemented by determining the concurrently formed phytosterol/-stanol oxidation products (POPs) via online LC-GC. Microwave-heating led to the least decreases of esters of approximately 5% in both margarines. Oven-heating of the margarine in a casserole caused the greatest decreases, with 68 and 86% esters remaining, respectively; the impact on individual esters was more pronounced with increasing degree of unsaturation of the esterified fatty acids. In the phytosteryl/-stanyl ester-enriched margarine, approximately 20% of the ester losses could be explained by the formation of POPs; in the phytostanyl ester-enriched margarine, the POPs accounted for <1% of the observed ester decreases.

Increase of circulating cholesterol in vitamin D deficiency is linked to reduced vitamin D receptor activity via the Insig-2/SREBP-2 pathway

SCOPE

Individuals deficient in vitamin D are more likely to have higher circulating cholesterol levels and cardiovascular diseases. However, the underlying mechanisms are still unclear.

METHODS AND RESULTS

A cross-sectional survey, animal study, and in vitro experiments were conducted to investigate the effect and mechanisms of vitamin D deficiency on endogenous cholesterol metabolism. We demonstrated that vitamin D deficiency was positively associated with an increase of total serum cholesterol and low-density lipoprotein cholesterol levels in northern Chinese individuals. The vitamin D deficiency-induced increase of cholesterol concentration was mainly due to enhanced cholesterol biosynthesis rather than reduced catabolism. Under vitamin D deficiency, the transcriptional activity of vitamin D receptor (VDR) was decreased, leading to the downregulation of insulin-induced gene-2 (Insig-2) expression and thus its inhibitory role on sterol regulatory element-binding protein 2 activation; 3-hydroxy-3-methylglutaryl-coenzyme A reductase expression was accordingly increased. Vitamin D3 was protective against vitamin D deficiency-induced cholesterol increase by maintaining the transcriptional activity of VDR and Insig-2 expression.

CONCLUSION

Vitamin D deficiency is associated with the increase of circulating cholesterol in the people of northern China by enhancing hepatic cholesterol biosynthesis, which was linked to the reduction of transcriptional activity of VDR.

Metabolite Signatures of Metabolic Risk Factors and their Longitudinal Changes

CONTEXT

Metabolic dysregulation underlies key metabolic risk factors—obesity, dyslipidemia, and dysglycemia.

OBJECTIVE

To uncover mechanistic links between metabolomic dysregulation and metabolic risk by testing metabolite associations with risk factors cross-sectionally and with risk factor changes over time.

DESIGN

Cross-sectional—discovery samples (n = 650; age, 36–69 years) from the Framingham Heart Study (FHS) and replication samples (n = 670; age, 61–76 years) from the BioImage Study, both following a factorial design sampled from high vs low strata of body mass index, lipids, and glucose. Longitudinal—FHS participants (n = 554) with 5–7 years of follow-up for risk factor changes.

SETTING

Observational studies.

PARTICIPANTS

Cross-sectional samples with or without obesity, dysglycemia, and dyslipidemia, excluding prevalent cardiovascular disease and diabetes or dyslipidemia treatment. Age- and sex-matched by group.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Gas chromatography-mass spectrometry detected 119 plasma metabolites. Cross-sectional associations with obesity, dyslipidemia, and dysglycemia were tested in discovery, with external replication of 37 metabolites. Single- and multi-metabolite markers were tested for association with longitudinal changes in risk factors.

RESULTS

Cross-sectional metabolite associations were identified with obesity (n = 26), dyslipidemia (n = 21), and dysglycemia (n = 11) in discovery. Glutamic acid, lactic acid, and sitosterol associated with all three risk factors in meta-analysis (P < 4.5 × 10−4). Metabolites associated with longitudinal risk factor changes were enriched for bioactive lipids. Multi-metabolite panels explained 2.5–15.3% of longitudinal changes in metabolic traits.

CONCLUSIONS

Cross-sectional results implicated dysregulated glutamate cycling and amino acid metabolism in metabolic risk. Certain bioactive lipids were associated with risk factors cross-sectionally and over time, suggesting their upstream role in risk factor progression. Functional studies are needed to validate findings and facilitate translation into treatments or preventive measures.

Increases in plasma plant sterols stabilize within four weeks of plant sterol intake and are independent of cholesterol metabolism

BACKGROUND AND AIMS

Plant sterols (PS) lower plasma LDL-cholesterol through partial inhibition of intestinal cholesterol absorption. Although PS themselves are poorly absorbed, increased intakes of PS result in elevated plasma concentrations. In this paper, we report time curves of changes in plasma PS during 12 weeks of PS intake. Furthermore, the impact of cholesterol synthesis and absorption on changes in plasma PS is explored.

METHODS AND RESULTS

The study was a double-blind, randomized, placebo-controlled, parallel-group study with the main aim to investigate the effects of PS on vascular function (clinicaltrials.gov: NCT01803178). Hypercholesterolemic but otherwise healthy men and women (n = 240) consumed low-fat spreads without or with added PS (3 g/d) for 12 weeks after a 4-week run-in period. Blood sampling was performed at week 0, 4, 8 and 12. Basal cholesterol-standardized concentrations of lathosterol and sitosterol + campesterol were used as markers of cholesterol synthesis and absorption, respectively. In the PS group, plasma sitosterol and campesterol concentrations increased within the first 4 weeks of intervention by 69% (95%CI: 58; 82) starting at 7.2 μmol/L and by 28% (95%CI: 19; 39) starting at 11.4 μmol/L, respectively, and remained stable during the following 8 weeks. Placebo-corrected increases in plasma PS were not significantly different between high and low cholesterol synthesizers (P-values >0.05). Between high and low cholesterol absorbers, no significant differences were observed, except for the cholesterol-standardized sum of four major plasma PS (sitosterol, campesterol, brassicasterol and stigmasterol) showing larger increases in low absorbers (78.3% (95%CI: 51.7; 109.5)) compared to high absorbers (40.8% (95%CI: 19.9; 65.5)).

CONCLUSIONS

Increases in plasma PS stabilize within 4 weeks of PS intake and do not seem impacted by basal cholesterol synthesis or absorption efficiency. This study was registered at clinicaltrials.gov (NCT01803178).

Hypolipidemic Effect of the Autoclaved Extract Prepared from Pea (Pisum sativum L.) Pods In Vivo and In Vitro

By autoclaving, we obtained a polyphenol and dietary fiber from pea (Pisum sativum L.) pods in parallel without acid or alkali treatment or organic solvent extraction. Rats fed a high-sucrose (HS) diet containing 3% autoclaved extract (AE) for 4 wk exhibited significantly lower serum triglyceride and total cholesterol levels than rats fed a HS diet. AE and soluble dietary fiber (SDF) from AE exhibited pancreatic lipase inhibitory activity at 13.3 mg/mL in vitro. AE and insoluble dietary fiber (IDF) from AE adsorbed cholesterol. In total, 30% and 10% of a cholesterol micelle were significantly adsorbed by 2,000 mg of AE and 100 mg of IDF from AE in 7 mL, respectively. The amount of bifidobacteria in the cecum of the AE group was significantly increased compared with that in the HS group. These results suggest that AE has hypolipidemic, bifidogenic potential.

Bioaccessibility study of plant sterol-enriched fermented milks

The bioaccessibility (BA) of total and individual plant sterols (PS) of four commercial PS-enriched fermented milk beverages (designated as A to D) was evaluated using in vitro gastrointestinal digestion including the formation of mixed micelles.

Effects of Dietary Plant Sterols and Stanol Esters with Low- and High-Fat Diets in Chronic and Acute Models for Experimental Colitis

In this study, we evaluated the effects of dietary plant sterols and stanols as their fatty acid esters on the development of experimental colitis. The effects were studied both in high- and low-fat diet conditions in two models, one acute and another chronic model of experimental colitis that resembles gene expression in human inflammatory bowel disease (IBD). In the first experiments in the high fat diet (HFD), we did not observe a beneficial effect of the addition of plant sterols and stanols on the development of acute dextran sulphate sodium (DSS) colitis. In the chronic CD4CD45RB T cell transfer colitis model, we mainly observed an effect of the presence of high fat on the development of colitis. In this HFD condition, the presence of plant sterol or stanol did not result in any additional effect. In the second experiments with low fat, we could clearly observe a beneficial effect of the addition of plant sterols on colitis parameters in the T cell transfer model, but not in the DSS model. This positive effect was related to the gender of the mice and on Treg presence in the colon. This suggests that especially dietary plant sterol esters may improve intestinal inflammation in a T cell dependent manner.

Factors affecting intestinal absorption of cholesterol and plant sterols and stanols

Various factors affect intestinal absorption of cholesterol and plant sterols and stanols. Plant sterols and stanols are generally less absorptive than cholesterol. Differential absorption rates among various plant sterols and stanols have been also reported. Although it was suggested that differential absorption among cholesterol and various plant sterols was determined by difference in excretion rates of sterols and stanols through ATP-binding cassette transporter (ABC) G5/ABCG8 of intestinal cells, our study suggests that affinity for and solubility in bile salt micelles can be important determinants for differential absorption of plant sterols and stanols. It was also suggested that plant sterols were transiently incorporated into intestinal cells and then excreted to intestinal lumen through ABCG5/ABCG8. However, in a rat study, transient incorporation of sitosterol into intestinal cells was not observed, suggesting that sitosterol is differentiated from cholesterol at the incorporation site of intestinal cells. It is well established that plant sterols inhibit intestinal absorption of cholesterol and exert a hypocholesterolemic activity. Plant sterols are solubilized in bile salt micelles as cholesterol. Our study clearly showed that because the sterol-solubilizing capacity of bile salt micelles was limited, plant sterols solubilized in micelles reduced the solubility of cholesterol. This can be the major cause of inhibition of cholesterol absorption by plant sterols. Pancreatic cholesterol esterase accelerates intestinal absorption of unesterified cholesterol. Although it was suggested that cholesterol esterase accelerated esterification of cholesterol incorporated into intestinal cells and acted as a transporter at the surface of intestinal cells, our research revealed that the accelerated cholesterol absorption was caused by hydrolysis of phosphatidylcholine in bile salt micelles. It is thought that hydrolysis of phosphatidylcholine reduces the affinity of cholesterol for the micelles and accelerates the incorporation of cholesterol released from the micelles into intestinal cells.

Plasma cholesterol-lowering activity of dietary dihydrocholesterol in hypercholesterolemia hamsters

OBJECTIVE

Cholesterol analogs have been used to treat hypercholesterolemia. The present study was to examine the effect of dihydrocholesterol (DC) on plasma total cholesterol (TC) compared with that of β-sitosterol (SI) in hamsters fed a high cholesterol diet.

METHODS AND RESULTS

Forty-five male hamsters were randomly divided into 6 groups, fed either a non-cholesterol diet (NCD) or one of five high-cholesterol diets without addition of DC and SI (HCD) or with addition of 0.2% DC (DA), 0.3% DC (DB), 0.2% SI (SA), and 0.3% SI (SB), respectively, for 6 weeks. Results showed that DC added into diet at a dose of 0.2% could reduce plasma TC by 21%, comparable to that of SI (19%). At a higher dose of 0.3%, DC reduced plasma TC by 15%, less effective than SI (32%). Both DC and SI could increase the excretion of fecal sterols, however, DC was more effective in increasing the excretion of neutral sterols but it was less effective in increasing the excretion of acidic sterols compared with SI. Results on the incorporation of sterols in micellar solutions clearly demonstrated both DC and SI could displace the cholesterol from micelles with the former being more effective than the latter.

CONCLUSION

DC was equally effective in reducing plasma cholesterol as SI at a low dose. Plasma TC-lowering activity of DC was mediated by inhibiting the cholesterol absorption and increasing the fecal sterol excretion.

Triglyceride-Lowering Response to Plant Sterol and Stanol Consumption

Phytosterols (PS) have long been recognized for their cholesterol-lowering action, however, recent work has highlighted triglyceride (TG)-lowering responses to PS that may have been overlooked in previous human interventions and mechanistic animal model studies. This review assesses the current state of knowledge regarding the effect of dietary PS supplementation on blood TG concentrations by examining the average therapeutic response, potential mechanisms, and metabolic and genetic factors that may contribute to inter-individual variability. Data from human intervention trials demonstrates that, compared to baseline concentrations, PS supplementation results in a variable TG-lowering response ranging from 0.8 to 28%. It is evident that hypertriglyceridemic individuals (>1.7 mmol/L) have a greater TG-lowering response to PS (11-28%) than subjects with normal plasma TG concentrations (0.8-7%). Although a genetic basis for the variable TG-lowering effects of PS is probable, there are only limited studies to draw on. The available data suggest that polymorphisms in the apolipoprotein E (apoE) gene may affect responsiveness, with PS-induced reductions in TG more readily evident in apoE2 than apoE3 or E4 subjects. Although only a minimal number of animal model studies have been conducted to specifically examine the mechanisms whereby PS may reduce blood TG concentrations, it appears that there may be multiple mechanisms involved including interruption of intestinal fatty acid absorption and modulation of hepatic lipogenesis and very low density lipoprotein packaging and secretion. In summary, the available data suggest that PS may be an effective therapy to lower blood TG, particularly in hypertriglyceridemic individuals. However, before PS can be widely recommended as a TG-lowering therapy, studies that are specifically powered and designed to fully access therapeutic responses and the mechanisms involved are required.

Acute intake of plant stanol esters induces changes in lipid and lipoprotein metabolism-related gene expression in the liver and intestines of mice

The kinetics of plant stanol uptake and routing in 8-week-old C57BL/6J mice were determined after a plant stanol ester gavage. In addition, acute changes in intestinal and hepatic gene expression were investigated. Mice were fed a plant sterol/stanol poor diet from weaning. At the age of 8 weeks, they received an oral gavage consisting of 0.25 mg cholesterol + 50 mg plant stanol esters dissolved in olive oil. Animals were euthanized at different time points. In a second comparable set-up, mesenteric lymph-cannulated versus sham-operated mice received the same oral gavage, which was now deuterium labeled. Intestinal and hepatic sitostanol concentrations increased within 15 min post-gavage. This rapid hepatic appearance was absent in lymph-cannulated mice, suggesting a very fast lymph-mediated uptake. Hepatic mRNA expression of SREBP2 and its target genes rapidly decreased, whereas expression of LXR target genes increased. The intestinal SREBP2 pathway was increased, whereas the expression of LXR target genes hardly changed. The fivefold and sixfold increased expression of intestinal LDLr and PCSK9 is suggestive of TICE activation. We conclude that in C57BL/6J mice plant stanol kinetics are fast, and affect intestinal and hepatic gene expression within 15 min postprandial after lymph-mediated uptake.

Additive effects of plant sterols supplementation in addition to different lipid-lowering regimens

OBJECTIVE

Plant sterol (PS) supplementation has been widely used alone or combined with lipid-lowering therapies (LLTs) to reduce low-density lipoprotein (LDL) cholesterol. The effects of PS added to high-intensity LLT are less reported, especially regarding the effects on cholesterol synthesis and absorption.

METHODS

A prospective, randomized, open-label study, with parallel arms and blinded end points was designed to evaluate the effects of addition of PS to LLT on LDL cholesterol, markers of cholesterol synthesis, and absorption. Eighty-six patients of both genders were submitted to a 4-wk run-in period with atorvastatin 10 mg (baseline). Following, subjects received atorvastatin 40 mg, ezetimibe 10 mg, or combination of both drugs for another 4-wk period (phase I). In phase II, capsules containing 2.0 g of PSs were added to previous assigned treatments for 4 wk. Lipids, apolipoproteins, plasma campesterol, β-sitosterol, and desmosterol levels were assayed at all time points. Within and between-group analyses were performed.

RESULTS

Compared with baseline, atorvastatin 40 mg reduced total and LDL cholesterol (3% and 22%, respectively, P < .05), increased β-sitosterol, campesterol/cholesterol, and β-sitosterol/cholesterol ratios (39%, 47%, and 32%, respectively, P < .05); ezetimibe 10 mg reduced campesterol and campesterol/cholesterol ratio (67% and 70%, respectively, P < .05), and the combined therapy decreased total and LDL cholesterol (22% and 38%, respectively, P < .05), campesterol, β-sitosterol, and campesterol/cholesterol ratio (54%, 40%, and 27%, P < .05). Addition of PS further reduced total and LDL cholesterol by ∼ 7.7 and 6.5%, respectively, in the atorvastatin therapy group and 5.0 and 4.0% in the combined therapy group (P < .05, for all), with no further effects in absorption or synthesis markers.

CONCLUSIONS

PS added to LLT can further improve lipid profile, without additional effects on intestinal sterol absorption or synthesis.