Stearate-enriched plant sterol esters lower serum LDL cholesterol concentration in normo- and hypercholesterolemic adults

Biological and pharmacological effects and nutritional impact of phytosterols: A comprehensive review

Phytosterols (PSs), classified into plant sterols and stanols, are bioactive compounds found in foods of plant origin. PSs have been proposed to exert a wide number of pharmacological properties, including the potential to reduce total and low-density lipoprotein (LDL) cholesterol levels and thereby decreasing the risk of cardiovascular diseases. Other health-promoting effects of PSs include anti-obesity, anti-diabetic, anti-microbial, anti-inflammatory, and immunomodulatory effects. Also, anticancer effects have been strongly suggested, as phytosterol-rich diets may reduce the risk of cancer by 20%. The aim of this review is to provide a general overview of the available evidence regarding the beneficial physiological and pharmacological activities of PSs, with special emphasis on their therapeutic potential for human health and safety. Also, we will explore the factors that influence the physiologic response to PSs.

The effect of drying on the native tocopherol and phytosterol content of Sinapis alba L. seeds

BACKGROUND

Postharvest processing, including drying, has a significant effect on the processability of oil crop seeds. High drying air temperature may significantly affect the levels of bioactive compounds in plant raw materials. We decided to investigate the subject given the lack of data on the drying of mustard seeds. The aim was to determine the effect of drying temperature on free fatty acid, phytosterol and tocopherol levels in the oil obtained from white mustard seeds. Seeds were dried in a thin layer at 40, 60, 80, 100, 120 and 140 °C. Changes in phytosterol levels were assessed using gas chromatography-mass spectrometry and changes in tocopherol levels by high-performance liquid chromatography.

RESULTS

The analysis showed that, upon completion of air drying at 40-100 °C, losses of sterols did not exceed 5%, while upon completion of drying at 120 °C and 140 °C these losses amounted to 17-50%. Our investigation also showed that during drying of white mustard seed the total tocopherol levels increased, and the higher the drying temperature, the greater the increment. In seeds air-dried at 120 °C and 140 °C, the increase in tocopherol amounted to 7-9%.

CONCLUSION

We also showed that the temperature of the drying agent significantly affects the tocopherol and phytosterol levels. It was found that a maximum temperature of 100 °C provides optimal drying conditions for mustard seeds. Principal component analysis identified two subgroups of oils obtained from seeds dried at 120 °C and 140 °C, which differed considerably from the other samples in terms of their bioactive component contents. © 2019 Society of Chemical Industry.

Progress and perspectives in plant sterol and plant stanol research

Current evidence indicates that foods with added plant sterols or stanols can lower serum levels of low-density lipoprotein cholesterol. This review summarizes the recent findings and deliberations of 31 experts in the field who participated in a scientific meeting in Winnipeg, Canada, on the health effects of plant sterols and stanols. Participants discussed issues including, but not limited to, the health benefits of plant sterols and stanols beyond cholesterol lowering, the role of plant sterols and stanols as adjuncts to diet and drugs, and the challenges involved in measuring plant sterols and stanols in biological samples. Variations in interindividual responses to plant sterols and stanols, as well as the personalization of lipid-lowering therapies, were addressed. Finally, the clinical aspects and treatment of sitosterolemia were reviewed. Although plant sterols and stanols continue to offer an efficacious and convenient dietary approach to cholesterol management, long-term clinical trials investigating the endpoints of cardiovascular disease are still lacking.

LDL-Cholesterol Lowering of Plant Sterols and Stanols-Which Factors Influence Their Efficacy?

The LDL-cholesterol (LDL-C) lowering effect of plant sterols/stanols (PSS) is summarized in several meta-analyses showing a dose-response relationship with intakes of 1.5 to 3 g/day lowering LDL-C by 7.5% to 12%. This review summarizes evidence for the impact of various factors potentially influencing the LDL-C-lowering efficacy of PSS. PSS are efficacious in all food formats and in food supplements. Some factors related to food format, e.g., solid vs. liquid foods, seem to impact efficacy, while there is no difference between free PSS and esters. Compared to multiple daily intakes, once-a-day intake of PSS, especially in the morning with light breakfast, leads to a sub-optimal LDL-C lowering. However, intake frequency seems influenced by intake occasion, i.e., with or without a meal, and time of day. Meal intake is a critical factor for an optimal LDL-C lowering efficacy of PSS. While age has no impact, gender is suggested to influence the LDL-C lowering effect of PSS with greater reductions reported for men than women; but overall evidence is inconclusive and larger studies show no gender by treatment interaction. In conclusion, PSS are efficacious in all foods and food supplements; for optimal efficacy they should be consumed with a (main) meal and twice daily.

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.

CYP7A1-rs3808607 and APOE isoform associate with LDL cholesterol lowering after plant sterol consumption in a randomized clinical trial

BACKGROUND

The benefits of plant sterols (PSs) for cholesterol lowering are hampered by large heterogeneity across individuals, potentially because of genetic polymorphisms.

OBJECTIVE

We investigated the impact of candidate genetic variations on cholesterol response to PSs in a trial that recruited individuals with high or low endogenous cholesterol synthesis, estimated by lathosterol to cholesterol (L:C) ratio.

DESIGN

Mildly hypercholesterolemic adults preselected as possessing either high endogenous cholesterol synthesis (n = 24; mean ± SEM: L:C ratio = 2.03 ± 0.39 μmol/mmol) or low endogenous cholesterol synthesis (n = 39; mean ± SEM: L:C ratio = 0.99 ± 0.28 μmol/mmol) consumed 2 g PS/d or a placebo for 28 d by using a dual-center, single-blind, randomized crossover design. Cholesterol synthesis and change in cholesterol absorption were measured with stable isotopic tracers. Candidate single-nucleotide polymorphisms and apolipoprotein E (APOE) isoform were assessed by TaqMan genotyping assay.

RESULTS

The cholesterol fractional synthesis rate was higher (P < 0.001) in participants with high endogenous cholesterol synthesis (mean ± SEM: placebo: 9.16% ± 0.47%; PSs: 9.74% ± 0.47%) than in participants with low endogenous cholesterol synthesis (mean ± SEM placebo: 5.72% ± 0.43%; PS: 7.10% ± 0.43%). Low-density lipoprotein (LDL) cholesterol lowering in response to PSs was associated with individuals' genotypes. Cholesterol 7 alpha-hydroxylase (CYP7A1-rs3808607) T/T homozygotes showed no LDL cholesterol lowering (mean ± SEM: -0.05 ± 0.07 mmol/L, P = 0.9999, n = 20), whereas the presence of the G-allele associated with LDL cholesterol response in a dose-dependent fashion (mean ± SEM G/T: -0.22 ± 0.06 mmol/L, P = 0.0006, n = 35; G/G: -0.46 ± 0.12 mmol/L, P = 0.0009, n = 8). Similarly, APOE ɛ3 carriers (mean ± SEM: -0.13 ± 0.05 mmol/L, P = 0.0370, n = 40) responded less than APOE ɛ4 carriers (mean ± SEM: -0.31 ± 0.07 mmol/L, P < 0.0001, n = 23). Moreover, genoset CYP7A1-rs3808607 T/T/APOE ɛ3 was associated with nonresponsiveness (mean ± SEM: +0.09 ± 0.08 mmol/L, P = 0.9999, n = 14). rs5882 in cholesteryl ester transfer protein (CETP) and rs4148217 in ATP-binding cassette subfamily G member 8 (ABCG8) did not associate with LDL cholesterol lowering. Cholesterol absorption decreased as a result of PS consumption, but this decrease was not related to circulating LDL cholesterol concentrations, cholesterol synthesis phenotype, or genotypes.

CONCLUSION

CYP7A1-rs3808607 and APOE isoform are associated with the extent of reduction in circulating LDL cholesterol in response to PS consumption and could serve as potential predictive genetic markers to identify individuals who would derive maximum LDL cholesterol lowering with PS consumption. The trial was registered at clinicaltrials.gov as NCT01131832.

The effect of plant sterols and different low doses of omega-3 fatty acids from fish oil on lipoprotein subclasses

SCOPE

Consumption of a low-fat spread enriched with plant sterols (PS) and different low doses (<2 g/day) of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil reduces serum triglycerides (TGs) and low-density lipoprotein-cholesterol (LDL-Chol) and thus beneficially affects two blood lipid risk factors. Yet, their combined effects on TG and Chol in various lipoprotein subclasses have been investigated to a limited extent.

METHODS AND RESULTS

In a randomized, double-blind, placebo-controlled, parallel study, we determined TG and Chol in 13 LP subclasses in fasting serum of 282 hypercholesterolemic subjects, who consumed either a placebo spread or one of the four spreads containing PS (2.5 g/day) and EPA+DHA (0.0, 0.9, 1.3, and 1.8 g/day) for 4 weeks. After PS treatment, total LDL-Chol was reduced, which was not further changed by EPA+DHA. No shift in the LDL-Chol particle distribution was observed. The addition of EPA+DHA to PS dose-dependently reduced VLDL-Chol and VLDL-TG mainly in larger particles. Furthermore, the two highest doses of EPA+DHA increased Chol and TG in the larger HDL particles, while these concentrations were decreased in the smallest HDL particles.

CONCLUSION

The consumption of a low-fat spread enriched with both PS and EPA+DHA induced shifts in the lipoprotein distribution that may provide additional cardiovascular benefits over PS consumption alone.

Lathosterol-to-cholesterol ratio in serum predicts cholesterol-lowering response to plant sterol consumption in a dual-center, randomized, single-blind placebo-controlled trial

BACKGROUND

Benefits of plant sterols (PS) for cholesterol lowering are compromised by large variability in efficacy across individuals. High fractional cholesterol synthesis measured by deuterium incorporation has been associated with nonresponse to PS consumption; however, prospective studies that show this association have yet to be conducted.

OBJECTIVE

The goal was to test whether the lathosterol-to-cholesterol ratio (L:C ratio), a surrogate marker of endogenous cholesterol synthesis, serves as an a priori predictor of cholesterol lowering in response to PS consumption.

DESIGN

Sixty-three mildly hypercholesterolemic adults who were preselected as possessing either high endogenous cholesterol synthesis [HS; n = 24; L:C = 2.03 ± 0.39 μmol/mmol (mean ± SD)] or low endogenous cholesterol synthesis (LS; n = 39; L:C = 0.99 ± 0.28 μmol/mmol) on the basis of baseline L:C consumed 2 g PS/d or a placebo for 28 d with the use of a dual-center, single-blind, randomized crossover design. Plasma lipid and noncholesterol sterol concentrations were measured at the end of each phase.

RESULTS

PS consumption lowered total cholesterol (TC; -0.25 ± 0.05 mmol/L; P < 0.0001) and LDL cholesterol (-0.17 ± 0.04 mmol/L; P < 0.0001) overall. Specifically, LS individuals responded to PS treatment with a reduction in TC (-0.40 ± 0.07 mmol/L; P < 0.0001) and LDL cholesterol (-0.29 ± 0.05 mmol/L; P = 0.0002), whereas HS individuals failed to show cholesterol lowering (TC: -0.09 ± 0.09 mmol/L; P = 0.2843; LDL cholesterol: -0.05 ± 0.07 mmol/L; P = 0.4917). The odds of LS participants responding to PS consumption with cholesterol lowering better than the mean cholesterol lowering in all participants were 4.25 (95% CI: 1.242, 14.556; P = 0.0211) for TC and 3.36 (95% CI: 1.112, 10.161; P = 0.0317) for LDL cholesterol, which was higher than for HS participants.

CONCLUSIONS

The L:C ratio predicts the extent of reduction in circulating TC and LDL cholesterol in response to PS consumption. Cholesterol synthesis assessment may thus have a use in identifying responders and nonresponders to PS therapy.

Consumption of plant sterol-enriched foods and effects on plasma plant sterol concentrations--a meta-analysis of randomized controlled studies

OBJECTIVE

Intake of plant sterol (PS)-enriched foods effectively lowers plasma total- and LDL-cholesterol concentrations while increasing plasma PS concentrations. The magnitude of this increase has not been systematically assessed. This study aimed to investigate the effect of PS-enriched foods on plasma PS concentrations by performing a meta-analysis of randomized controlled studies.

METHODS

Published PS intervention studies reporting plasma PS concentrations were searched through June 2012. Studies were selected that fulfilled pre-defined in- and exclusion criteria. Data were extracted, particularly on campesterol, sitosterol, total- and LDL-cholesterol. Random-effects models were used to calculate net effects while weighing each study by the inverse of its variance. Potential sources of heterogeneity were investigated.

RESULTS

The meta-analysis included data from 41 studies (55 strata) with in total 2084 subjects. The average dose of PS from enriched foods was 1.6 g/d (range: 0.3-3.2 g/d). Plasma sitosterol and campesterol concentrations were increased by on average 2.24 μmol/L (31%) and 5.00 μmol/L (37%), respectively, compared to control. Total- and LDL-cholesterol were reduced by on average 0.36 mmol/L (5.9%) and 0.33 mmol/L (8.5%), respectively. The increase in sitosterol and campesterol was impacted by the dose of PS, the baseline PS concentration and the PS composition of the test products. In the highest PS dose category (2.0-3.2 g/d), increases in sitosterol and campesterol were on average 3.56 and 7.64 μmol/L, respectively.

CONCLUSION

Intake of PS-enriched foods increases plasma sitosterol and campesterol concentrations. However, total PS remain below 1% of total sterols circulating in the blood.

Effects of perilla oil on plasma concentrations of cardioprotective (n-3) fatty acids and lipid profiles in mice

The aim of this study was to examine the effects of perilla oil as well as several vegetable oils, including flaxseed oil, canola oil, and rice bran oil on plasma levels of cardioprotective (n-3) polyunsaturated fatty acids in mice by feeding each vegetable oil for a period of eight weeks. Concentrations of docosapentaenoic acid (DHA) and eicosapentaenoic acid (EPA), fish-based (n-3) polyunsaturated fatty acids, showed an increase in the plasma of mice fed perilla and flaxseed oils compared to those of mice in the control group (P < 0.05), whereas rice bran and canola oils did not alter plasma DPA and EPA concentrations. Arachidonic acid concentration was increased by feeding rice bran oil (P < 0.05), but not canola, flaxseed, or perilla oil. In addition, oleic acid, linoleic acid, and docosahexaenoic acid concentrations were altered by feeding dietary rice bran, canola, perilla, and flaxseed oils. Findings of this study showed that perilla oil, similar to flaxseed oil, is cardioprotective and could be used as an alternative to fish oil or even flaxseed oil in animal models.

A (1)H NMR-Based Metabonomic Investigation of Time-Related Metabolic Trajectories of the Plasma, Urine and Liver Extracts of Hyperlipidemic Hamsters

The hamster has been previously found to be a suitable model to study the changes associated with diet-induced hyperlipidemia in humans. Traditionally, studies of hyperlipidemia utilize serum- or plasma-based biochemical assays and histopathological evaluation. However, unbiased metabonomic technologies have the potential to identify novel biomarkers of disease. Thus, to obtain a better understanding of the progression of hyperlipidemia and discover potential biomarkers, we have used a proton nuclear magnetic resonance spectroscopy (¹H-NMR)-based metabonomics approach to study the metabolic changes occurring in the plasma, urine and liver extracts of hamsters fed a high-fat/high-cholesterol diet. Samples were collected at different time points during the progression of hyperlipidemia, and individual proton NMR spectra were visually and statistically assessed using two multivariate analyses (MVA): principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). Using the commercial software package Chenomx NMR suite, 40 endogenous metabolites in the plasma, 80 in the urine and 60 in the water-soluble fraction of liver extracts were quantified. NMR analysis of all samples showed a time-dependent transition from a physiological to a pathophysiological state during the progression of hyperlipidemia. Analysis of the identified biomarkers of hyperlipidemia suggests that significant perturbations of lipid and amino acid metabolism, as well as inflammation, oxidative stress and changes in gut microbiota metabolites, occurred following cholesterol overloading. The results of this study substantially broaden the metabonomic coverage of hyperlipidemia, enhance our understanding of the mechanism of hyperlipidemia and demonstrate the effectiveness of the NMR-based metabonomics approach to study a complex disease.

Bioavailability of vitamin E in humans: an update

Vitamin E is essential for human health and may play a role in the prevention of some degenerative diseases. Its bioavailability, however, is wide ranging and is affected by numerous factors. Recent findings showing that the intestinal absorption of vitamin E involves proteins have raised new relevant questions about factors that can affect bioavailability. It is, therefore, opportune to present a current overview of this topic. This review begins by exploring what is known, as well as what is unknown, about the metabolization of vitamin E in the human upper gastrointestinal tract and then presents a methodical evaluation of factors assumed to affect vitamin E bioavailability. Three main conclusions can be drawn. First, the proteins ABCA1, NPC1L1, and SR-BI are implicated in the absorption of vitamin E. Second, the efficiency of vitamin E absorption is widely variable, though not accurately known (i.e., between 10% and 79%), and is affected by several dietary factors (e.g., food matrix, fat, and fat-soluble micronutrients). Finally, numerous unanswered questions remain about the metabolization of vitamin E in the intestinal lumen and about the factors affecting the efficiency of vitamin E absorption.

Unsaturated fatty acids and phytosterols regulate cholesterol transporter genes in Caco-2 and HepG2 cell lines

Dietary consumption of phytosterols and certain fatty acids has been shown to reduce cholesterol absorption and plasma cholesterol concentrations. However, it has not been fully elucidated whether phytosterols or fatty acids can alter the expression of cholesterol transporters by functioning as signaling molecules. This study tested the hypothesis that various fatty acids and phytosterols commonly found in the food supply can modulate the expression of transporters including Niemann-Pick C1-like 1, low-density lipoprotein receptor, and scavenger receptor class B type I and 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the intestine and liver. Caco-2 cells were used as models of enterocytes, and HepG2 cells were used as a model of hepatocytes. The cells were treated for 18 hours with 100 μmol/L of a fatty acid, or for 24 hours with 10 μmol/L of 25α-hydroxycholesterol, or 100 μmol/L of cholesterol, sitosterol, and stigmasterol to measure expression of genes involved in cholesterol transport using quantitative real-time polymerase chain reaction. Polyunsaturated fatty acids in Caco-2 cells and sterols in HepG2 cells significantly reduced the messenger RNA expression levels of Niemann-Pick C1-like 1, scavenger receptor class B type I, low-density lipoprotein receptor, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Importantly, sitosterol and stigmasterol reduced the messenger RNA levels of genes to a similar extent as cholesterol. The data support the hypothesis that unsaturated fatty acid and phytosterols can act as signaling molecules and alter the expression of genes involved in cholesterol transport and metabolism.

Plasma noncholesterol sterols: current uses, potential and need for standardization

PURPOSE OF REVIEW

Noncholesterol sterols (NCSs) in plasma encompass endogenous cholesterol precursors and exogenous phytosterols and cholesterol metabolites, which are used as surrogate measures of cholesterol synthesis and cholesterol absorption, respectively. The ratios of cholesterol synthesis to cholesterol absorption surrogates are also utilized to assess the overall balance of cholesterol metabolism, with higher values representing more synthesis and lower values more absorption. The objective of this review is to focus on recent findings using plasma NCSs and their potential in customizing dietary and pharmacological hypolipidemic therapies.

RECENT FINDINGS

NCSs are often used to assess the impact of pharmacological and dietary interventions on cholesterol metabolism. Various forms of dyslipidemia have been characterized using NCSs, and NCSs may be a valuable tool in selecting appropriate treatment therapies. NCSs levels are affected by genetic, dietary and physiological factors and have been related to cardiovascular disease risk.

SUMMARY

The expanded use of plasma NCSs is currently limited by the lack of standardized methodology. However, noncholesterol sterols are still a valuable research tool for the overall assessment of cholesterol metabolism and may have clinical potential in the personalization of diet and medicine.

Analytical metabolomics: nutritional opportunities for personalized health

Nutrition is the cornerstone of health; survival depends on acquiring essential nutrients, and dietary components can both prevent and promote disease. Metabolomics, the study of all small molecule metabolic products in a system, has been shown to provide a detailed snapshot of the body's processes at any particular point in time, opening up the possibility of monitoring health and disease, prevention and treatment. Metabolomics has the potential to fundamentally change clinical chemistry and, by extension, the fields of nutrition, toxicology and medicine. Technological advances, combined with new knowledge of the human genome and gut microbiome, have made and will continue to make possible earlier, more accurate, less invasive diagnoses, all while enhancing our understanding of the root causes of disease and leading to a generation of dietary recommendations that enable optimal health. This article reviews the recent contributions of metabolomics to the fields of nutrition, toxicology and medicine. It is expected that these fields will eventually blend together through development of new technologies in metabolomics and genomics into a new area of clinical chemistry: personalized medicine.

Phytosterol stearate esters elicit similar responses on plasma lipids and cholesterol absorption but different responses on fecal neutral sterol excretion and hepatic free cholesterol in male Syrian hamsters

The dietary impact of specific phytosterols incorporated into phytosterol fatty acid esters has not been elucidated. Therefore, we tested the hypothesis that phytosterol esters containing different sterol moieties (sitosterol, sitostanol, or stigmasterol) but the same fatty acid moiety (stearic acid) produce different effects on cholesterol metabolism. Male Syrian hamsters were fed sitosterol, sitostanol, and stigmasterol stearate esters (25 g/kg diet) in an atherogenic diet containing cholesterol (1.2 g/kg) and coconut oil (80 g/kg). The phytosterol stearates produced no decrease in cholesterol absorption or plasma non-high-density lipoprotein cholesterol despite a reduction in liver free cholesterol in hamsters fed both sitosterol and sitostanol stearate diets. In addition, sitosterol stearate significantly increased fecal esterified and total neutral sterol excretion. Stigmasterol stearate did not differ from control in neutral sterol excretion, plasma lipids, or hepatic lipid concentration. Sitosterol stearate demonstrated the highest level of net intestinal hydrolysis, whereas sitostanol and stigmasterol stearate equivalently demonstrated the lowest. The cholesterol-lowering effect in liver-but not plasma-and the limited presence of fecal free sterols indicate that intact (unhydrolyzed) phytosterol stearates may impact cholesterol metabolism by mechanisms unrelated to the role of free phytosterols. The consumption of phytosterol esters at 2.5% of the diet elicited only modest impacts on cholesterol metabolism, although sitosterol stearate had a slightly greater therapeutic impact by lowering liver free cholesterol and increasing esterified and total neutral sterol fecal excretion, possibly due to a greater level of intestinal hydrolysis.

Lipid-altering effects of a dietary supplement tablet containing free plant sterols and stanols in men and women with primary hypercholesterolaemia: a randomized, placebo-controlled crossover trial

This randomized, placebo-controlled, crossover trial assessed the lipid-altering efficacy of a dietary supplement (tablet form) providing 1.8g/day free (non-esterified) plant sterols and stanols versus placebo for 6 weeks as part of a therapeutic lifestyle changes (TLC) diet in 32 men and women with primary hypercholesterolaemia. Mean ± SE baseline (end of a 5-week TLC diet lead-in) lipid concentrations (mmol/1) were total cholesterol (TC), 5.88 ± 0.08; non-high-density lipoprotein cholesterol (non-HDL-C), 4.71 ± 0.09; low-density lipoprotein cholesterol (LDL-C), 4.02 ± 0.08; HDL-C, 1.17 ± 0.06 and triglycerides (TGs), 1.51 ± 0.12. Differences from control in responses (plant sterol/stanol — control) were significant (p < 0.05) for LDL-C (− 4.9%), non-HDL-C (− 3.6%) and TC (− 2.8%). HDL-C and TG responses were not significantly different between treatment conditions. These results indicate that 1.8g/day free plant sterols/stanols administered in a tablet produced favourable lipoprotein lipid changes in men and women with hypercholesterolaemia.

Effects of plant sterol esters in skimmed milk and vegetable-fat-enriched milk on serum lipids and non-cholesterol sterols in hypercholesterolaemic subjects: a randomised, placebo-controlled, crossover study

Plant sterol (PS)-supplemented foods are recommended to help in lowering serum LDL-cholesterol (LDL-C). Few studies have examined the efficacy of PS-enriched skimmed milk (SM) or semi-SM enriched with vegetable fat (PS-VFM). There is also insufficient information on factors predictive of LDL-C responses to PS. We examined the effects of PS-SM (0·1 % dairy fat) and PS-VFM (0·1 % dairy fat plus 1·5 % vegetable fat) on serum lipids and non-cholesterol sterols in hypercholesterolaemic individuals. In a placebo-controlled, crossover study, forty-three subjects with LDL-C>1300 mg/l were randomly assigned to three 4-week treatment periods: control SM, PS-SM and PS-VFM, with 500 ml milk with or without 3·4 g PS esters (2 g free PS). Serum concentrations of lipids and non-cholesterol sterols were measured. Compared to control, LDL-C decreased by 8·0 and 7·4 % (P < 0·015, both) in the PS-SM and PS-VFM periods, respectively. Serum lathosterol:cholesterol (C) ratios increased by 11–25 %, while sitosterol:C and campesterol:C ratios increased by 70–120 % with both the PS-fortified milk. Adjusted LDL-C reductions were variably enhanced in participants with basal low serum lathosterol/C or conversely high sitosterol/C and campesterol/C. Subjects with post-treatment serum PS:C ratios above the median showed mean LDL-C changes of − 5·9 to − 10·4 %, compared with 1·7 to − 2·9 % below the median. In conclusion, consumption of 2 g/d of PS as PS-SM and PS-VFM lowered LDL-C in hypercholesterolaemic subjects to a similar extent. Basal and post-treatment changes in markers of cholesterol metabolism indicating low cholesterol synthesis and high cholesterol absorption predicted improved LDL-C responses to PS.

Synthesis of fatty acid sterol esters using cholesterol esterase from Trichoderma sp. AS59

We recently reported the characterization of novel cholesterol esterase (EC. 3.1.1.13) from Trichoderma sp. and preliminary work on sterol ester synthesis. In the present study, we further examined the enzyme ability to synthesize cholesterol esters from cholesterol and free fatty acids of various chain lengths, and compared the fatty acid specificity in synthesis with that in hydrolysis. The enzyme catalyzed the synthesis of medium- and long-chain fatty acid cholesterol esters, but failed to synthesize short-chain fatty acid esters. The fatty acid specificities in the synthesis and hydrolysis of cholesterol esters were entirely different from each other. Unlike other lipolytic enzymes, the enzyme was largely independent of water content in the synthesis of cholesterol oleate, and it achieved near-complete esterification in the presence of an equimolar excess of oleic acid. Of additional interest is the finding that the addition of n-hexane markedly enhanced the esterification activities on all the medium- and long-chain saturated fatty acids used. Based on these findings, we attempted to synthesize stigmasterol stearate as a food additive to lower cholesterol levels in blood plasma, and found that the enzyme catalyzed effective synthesis of the ester without the need of dehydration during the reaction, indicating the potential utility of the enzyme in the food industry.

High basal fractional cholesterol synthesis is associated with nonresponse of plasma LDL cholesterol to plant sterol therapy

BACKGROUND

The cholesterol-lowering effectiveness of plant sterol (PS) therapy is hindered by wide-ranging variability in LDL-cholesterol responsiveness across individuals. To capitalize on the LDL-cholesterol-lowering potential of PS in the clinical setting, it is paramount to characterize the metabolic factors that underlie this heterogeneity of responsiveness.

OBJECTIVE

The objective was to investigate the relation between cholesterol synthesis and plasma LDL-cholesterol reductions in response to PS consumption.

DESIGN

We evaluated previously conducted clinical PS interventions incorporating stable-isotope measures of cholesterol synthesis and conducted feeding studies in animal models of response (Syrian Golden hamsters) and nonresponse (C57BL/6J mice) to PS consumption.

RESULTS

From our clinical study population (n = 113), we identified 47 nonresponders (3.73 +/- 1.10% change in LDL cholesterol) and 66 responders (-15.16 +/- 1.04% change in LDL cholesterol) to PS therapy. The basal cholesterol fractional synthesis rate (FSR) as measured by direct deuterium incorporation was 23% higher (P = 0.003) in the nonresponder subgroup than in responders to PS therapy. The basal cholesterol FSR correlated (r = 0.22, P = 0.02) with the percentage change in LDL cholesterol after PS intervention. In support of our clinical observations, nonresponding mice showed a 77% higher (P = 0.001) basal cholesterol FSR than that of responding hamsters. Compared with control mice, PS-fed mice showed an increase in hepatic nuclear sterol regulatory element binding protein 2 abundance (1.3-fold of control, P = 0.04) and beta-hydroxy-beta-methylglutaryl coenzyme A reductase-mRNA expression (2.4-fold of control, P = 0.00).

CONCLUSION

The results suggest that subjects with high basal cholesterol synthesis are less responsive to PS treatment than are subjects with low basal cholesterol synthesis.