Plant sterol ester diet supplementation increases serum plant sterols and markers of cholesterol synthesis, but has no effect on total cholesterol levels

Effects of phytosterols on cardiovascular risk factors: A systematic review and meta-analysis of randomized controlled trials

Cardiovascular diseases are the major cause of death globally. The primary risk factors are high blood lipid levels, hypertension, diabetes, and obesity. Phytosterols are naturally occurring plant bioactive substances. Short-term clinical trials have demonstrated phytosterols' cholesterol-lowering potential, but their effects on cardiovascular risk factors remain controversial, and relevant meta-analyses are limited and incomplete. We conducted a systematic and comprehensive search of PubMed, Web of Science, Embase and Cochrane Library up to December 22, 2023. A total of 109 randomized controlled trials (RCTS) of phytosterols (PS) intervention on cardiovascular risk factor outcomes were included in a preliminary screening of the retrieved literature by Endnote 20. We assessed the quality of all included randomized controlled trials using the Cochrane Collaboration's Risk of Bias tool. Cochrane data conversion tool was used for data conversion, and finally Stata was used for meta-analysis, egger test and sensitivity analysis of the included studies. The results indicated that dietary phytosterols intake could significantly decrease total cholesterol (TC) level (mean difference = -13.41; 95% confidence interval [CI]: -15.19, -11.63, p < 0.001), low density lipoprotein cholesterol (LDL-C) level (mean difference = -12.57; 95% CI: -13.87, -11.26, p < 0.001), triglycerides (TG) level (mean difference = -6.34; 95% CI: -9.43, -3.25, p < 0.001), C-reactive protein (CRP) level (mean difference = -0.05; 95% CI: -0.08, -0.01, p = 0.671), systolic blood pressure (SBP) level (mean difference = -2.10; 95% CI: -3.27, -0.9, p < 0.001), diastolic blood pressure (DBP) level (mean difference = -0.83; 95% CI: -0.58, -0.07, p = 0.032), increased high-density lipoprotein cholesterol (HDL-C) level (mean difference = 0.46; 95% CI: 0.13, 0.78, p = 0.005), but did not alter the levels of blood glucose (GLU) (mean difference = -0.44; 95% CI: -1.64, 0.76, p = 0.471), glycosylated hemoglobin, Type A1C (HbA1c) (mean difference = -0.28; 95% CI: -0.75, 0.20, p = 0.251), interleukin-6 (IL-6) (mean difference = 0.00; 95% CI: -0.02, 0.02, p = 0.980), tumor necrosis factor (TNF-α) (mean difference = 0.08; 95% CI: -0.08, 0.24, p = 0.335), oxidized low-density lipoprotein cholesterol (OXLDL-C) (standard mean difference = 0.16; 95% CI: -0.38, 0.06, p = 0.154), body mass index (BMI) (mean difference = 0.01; 95% CI: -0.07, 0.09, p = 0.886), waist circumference (WC) (mean difference = -0.10; 95% CI: -0.50, 0.30, p = 0.625) and body weight (mean difference = 0.03; 95% CI: -0.18, 0.24, p = 0.787). Our results suggest that phytosterols may be beneficial in reducing the levels of TC, LDL-C, TG, CRP, SBP, and DBP, but have no significant effect on GLU, HbA1c, TNF-α, IL-6, OXLDL-C, BMI, WC, and Weight. However, there were a small number of RCTS included in this study and their small population size may have reduced the quality of the study. And most of the included studies were short-term intervention trials. Therefore, higher quality studies need to be designed in future studies to establish more accurate conclusions.

Blood Phytosterol Concentration and Genetic Variant Associations in a Sample Population

The main objective of this study was to determine plasma levels of PS and to study SNVs rs41360247, rs4245791, rs4148217, and rs11887534 of ABCG8 and the r657152 SNV at the ABO blood group locus in a sample of a population treated at our hospital, and to determine whether these SNVs are related to plasma PS concentrations. The secondary objective was to establish the variables associated with plasma PS concentrations in adults. Participants completed a dietary habit questionnaire and a blood sample was collected to obtain the following variables: campesterol, sitosterol, sitostanol, lanosterol, stigmasterol, biochemical parameters, and the SNVs. In addition, biometric and demographic variables were also recorded. In the generalized linear model, cholesterol and age were positively associated with total PS levels, while BMI was negatively related. For rs4245791, homozygous T allele individuals showed a significantly lower campesterol concentration compared with C homozygotes, and the GG alleles of rs657152 had the lowest levels of campesterol compared with the other alleles of the SNV. Conclusions: The screening of certain SNVs could help prevent the increase in plasma PS and maybe PNALD in some patients. However, further studies on the determinants of plasma phytosterol concentrations are needed.

Effects of phytosterols' intake on systemic and tissue-specific lipid metabolism in C57BL/6J mice

This study aimed to investigate the long-term effects of phytosterols (PS) intake on systemic and tissue-specific lipid metabolism in C57BL/6J mice. Healthy male C57BL/6J mice were randomly divided into control diet group (CS) and PS diet group (2% PS). After 28 weeks of continuous feeding, serums, livers, and lungs were collected for targeted free sterols quantification, biochemical tests, lipid profile detection, and RNA-seq analysis. Compared with the CS group, 2% PS supplementation significantly increased campesterol concentrations and its ratio to cholesterol in the serum, liver, and lung of mice, with cholestanol concentrations and its ratio to cholesterol decreased. Total cholesterol (TC) levels were reduced in the serum of the PS group (p < 0.05), with the triglyceride (TG) levels unchanged. In response to the decreased circulating cholesterol concentration, the expression of endogenous cholesterol synthesis genes was upregulated in the liver, but caused no obvious lipid accumulation and inflammatory cell infiltration. However, for peripheral tissues, long-term PS-fed mice exhibited diminished cholesterol synthesis, fatty acid transport, and oxidation in the lung. The results provided clear indication that 2% PS diet effectively reduced circulating TC levels in the healthy mice, with tissue-specific lipid metabolic regulation in the liver and the lung.

Serum Phytosterols Are Not Associated with Inflammatory Markers in Two Cross-Sectional, Swiss Population-Based Studies (The CoLaus|PsyCoLaus Study)

Background: The association between inflammation and dietary sterols remains poorly assessed at the population level. Aims: To assess the possible association between serum levels of various phytosterols (PS) and inflammatory markers. Methods: Serum levels of six PS (campesterol, campestanol, stigmasterol, sitosterol, sitostanol, brassicasterol), four cholesterol synthesis markers (lathosterol, lanosterol, desmosterol, dihydroxylanosterol) and one cholesterol absorption marker (cholestanol) were measured together with levels of CRP, IL-6 and TNF-α in two cross-sectional surveys of a population-based, prospective study. Results: CRP levels were negatively associated with levels of cholestanol and of sterols of plant origin, although some associations were not statistically significant. CRP levels were positively associated with cholesterol synthesis markers in the first but not in the second follow-up. IL-6 levels were negatively associated with cholestanol in both follow-ups. No associations between IL-6 levels and PS were found in the first follow-up, while significant negative associations with campesterol, sitosterol, brassicasterol, sitostanol and campesterol:TC ratio were found in the second follow-up. TNF-α levels were negatively associated with cholestanol in both follow-ups. These associations did not withstand adjusting for sex, age, BMI and statin administration. Conclusions: In a population-based study, PS serum levels were not significantly associated with inflammatory markers.

Phytosterols and Cardiovascular Disease

Purpose of Review

Coronary heart disease is the leading cause of mortality worldwide. Elevated blood cholesterol levels are not only the major but also the best modifiable cardiovascular risk factor. Lifestyle modifications which include a healthy diet are the cornerstone of lipid-lowering therapy. So-called functional foods supplemented with plant sterols lower blood cholesterol levels by about 10–15%.

Recent Findings

In the recent revision of the ESC/EAS dyslipidemia guideline 2019, plant sterols are recommended for the first time as an adjunct to lifestyle modification to lower blood cholesterol levels. However, the German Cardiac Society (DGK) is more critical of food supplementation with plant sterols and calls for randomized controlled trials investigating hard cardiovascular outcomes. An increasing body of evidence suggests that plant sterols per se are atherogenic.

Summary

This review discusses this controversy based on findings from in vitro and in vivo studies, clinical trials, and genetic evidence.

Effect of dietary macronutrients on intestinal cholesterol absorption and endogenous cholesterol synthesis: a randomized crossover trial

BACKGROUND AND AIMS

Extensive research showed a diurnal rhythm of endogenous cholesterol synthesis, whereas recent research reported no diurnal rhythm of intestinal cholesterol absorption in males who consumed low-fat meals. Little is known about the acute effect of macronutrient consumption on cholesterol metabolism, and hence if meal composition may explain this absence of rhythmicity in cholesterol absorption. Therefore, we examined the effect of a high-fat, high-carbohydrate, and high-protein meal on postprandial intestinal cholesterol absorption and endogenous cholesterol synthesis in apparently healthy overweight and slightly obese males.

METHODS AND RESULTS

Eighteen males consumed in random order an isoenergetic high-fat, high-carbohydrate, and high-protein meal on three occasions. Serum total cholesterol concentrations, cholesterol absorption markers (campesterol, cholestanol, and sitosterol), and cholesterol synthesis intermediates (7-dehydrocholesterol, 7-dehydrodesmosterol, desmosterol, dihydrolanosterol, lanosterol, lathosterol, zymostenol, and zymosterol) were measured at baseline (T0) and 240 min postprandially (T240). Meal consumption did not significantly change total cholesterol concentrations and cholesterol absorption marker levels (all p > 0.05). Serum levels of 7-dehydrocholesterol, lanosterol, lathosterol, zymostenol, and zymosterol decreased significantly between T0 and T240 (all p < 0.05). These decreases were not significantly different between the three meals (all p > 0.05), except for a larger decrease in dihydrolanosterol levels after the high-fat versus the high-carbohydrate meal (p = 0.009).

CONCLUSION

The high-fat, high-carbohydrate, and high-protein meal did not significantly influence postprandial intestinal cholesterol absorption. Several cholesterol synthesis intermediates decreased postprandially, but the individual macronutrients did not differentially affect these intermediates, except for a possible effect on dihydrolanosterol.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03139890.

Utilizing network pharmacology and molecular docking to explore the underlying mechanism of Guizhi Fuling Wan in treating endometriosis

Background

Guizhi Fuling Wan (GZFLW) is a widely used classical Chinese herbal formulae prescribed for the treatment of endometriosis (EMs). This study aimed to predict the key targets and mechanisms of GZFLW in the treatment of EMs by network pharmacology and molecular docking.

Methods

Firstly, related compounds and targets of GZFLW were identified through the TCMSP, BATMAN-TCM and CASC database. Then, the EMs target database was built by GeneCards. The overlapping targets between GZFLW and EMs were screened out, and then data of the PPI network was obtained by the STRING Database to analyze the interrelationship of these targets. Furthermore, a topological analysis was performed to screen the hub targets. After that, molecular docking technology was used to confirm the binding degree of the main active compounds and hub targets. Finally, the DAVID database and Metascape database were used for GO and KEGG enrichment analysis.

Results

A total of 89 GZFLW compounds and 284 targets were collected. One hundred one matching targets were picked out as the correlative targets of GZFLW in treating EMs. Among these, 25 significant hub targets were recognized by the PPI network. Coincidently, molecular docking simulation indicated that the hub targets had a good bonding activity with most active compounds (69.71%). Furthermore, 116 items, including the inflammatory reaction, RNA polymerase, DNA transcription, growth factor activity, and steroid-binding, were selected by GO enrichment analysis. Moreover, the KEGG enrichment analysis results included 100 pathways focused on the AGE-RAGE pathway, HIF pathway, PI3K Akt pathway, MAPK pathway, and TP53 pathway, which exposed the potential mechanisms of GZFLW in treating EMs. Also, the MTT colorimetric assay indicated that the cell proliferation could be inhibited by GZFLW. Compared with the control group, the protein levels of P53, BAX, and caspase3 in the drug groups were all increased in Western blotting results. The results of flow cytometry showed that the percentage of apoptotic cells in the GZFLW group was significantly higher than that in the control group.

Conclusion

Through the exploration of network pharmacology and molecular docking technology, GZFLW has a therapeutic effect on EMs through multi-target mechanism. This study provided a good foundation for further experimental research.

Phytosterols: From Preclinical Evidence to Potential Clinical Applications

Phytosterols (PSs) are plant-originated steroids. Over 250 PSs have been isolated, and each plant species contains a characteristic phytosterol composition. A wide number of studies have reported remarkable pharmacological effects of PSs, acting as chemopreventive, anti-inflammatory, antioxidant, antidiabetic, and antiatherosclerotic agents. However, PS bioavailability is a key issue, as it can be influenced by several factors (type, source, processing, preparation, delivery method, food matrix, dose, time of administration into the body, and genetic factors), and the existence of a close relationship between their chemical structures (e.g., saturation degree and side-chain length) and low absorption rates has been stated. In this sense, the present review intends to provide in-depth data on PS therapeutic potential for human health, also emphasizing their preclinical effects and bioavailability-related issues.

A Randomized, Placebo-Controlled, Double-Blind Crossover Study to Assess a Unique Phytosterol Ester Formulation in Lowering LDL Cholesterol Utilizing a Novel Virtual Tracking Tool

Elevated blood concentration of low-density lipoprotein cholesterol (LDLc) is a primary risk factor for developing cardiovascular disease. Lifestyle interventions including an increase in dietary phytosterols as well as medications have proven effective in lowering LDLc. The primary objective of this randomized, placebo controlled, double blind, crossover study was to determine the impact of a new phytosterol emulsion for dietary supplements (1.5 g/day phytosterol equivalents) on LDLc concentrations. Thirty-two healthy adults were randomly assigned to receive placebo or treatment followed by a washout period, followed by placebo or treatment, each phase lasting one month. Secondary endpoints related to cardiovascular health were also assessed. Study management, including screening, recruitment, monitoring, compliance, and data collection, were done remotely (a siteless clinical trial) utilizing a novel virtual tool. Phytosterol supplementation significantly lowered LDLc concentrations by 10.2% (16.17 mg/dL or 0.419 mmol/L, p = 0.008 by paired t-test, p = 0.014 by Wilcoxon signed rank testing). No secondary biomarkers were found to change significantly. Supplementation with phytosterols in a new dietary supplement formulation efficiently and safely decreases LDLc within one month in a free-living setting.

Plant-based sterols and stanols in health & disease: "Consequences of human development in a plant-based environment?"

Dietary plant sterols and stanols as present in our diet and in functional foods are well-known for their inhibitory effects on intestinal cholesterol absorption, which translates into lower low-density lipoprotein cholesterol concentrations. However, emerging evidence suggests that plant sterols and stanols have numerous additional health effects, which are largely unnoticed in the current scientific literature. Therefore, in this review we pose the intriguing question "What would have occurred if plant sterols and stanols had been discovered and embraced by disciplines such as immunology, hepatology, pulmonology or gastroenterology before being positioned as cholesterol-lowering molecules?" What would then have been the main benefits and fields of application of plant sterols and stanols today? We here discuss potential effects ranging from its presence and function intrauterine and in breast milk towards a potential role in the development of non-alcoholic steatohepatitis (NASH), cardiovascular disease (CVD), inflammatory bowel diseases (IBD) and allergic asthma. Interestingly, effects clearly depend on the route of entrance as observed in intestinal-failure associated liver disease (IFALD) during parenteral nutrition regimens. It is only until recently that effects beyond lowering of cholesterol concentrations are being explored systematically. Thus, there is a clear need to understand the full health effects of plant sterols and stanols.

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.

Cholesterol metabolism in humans: a review of methods and comparison of results

PURPOSE OF REVIEW

Cholesterol metabolism has been the object of intense investigation for decades. This review focuses on classical and novel methods assessing in vivo cholesterol metabolism in humans. Two factors have fueled cholesterol metabolism studies in the last few years: the renewed interest in the study of reverse cholesterol transport (RCT) as an atheroprotective mechanism and the importance of the gut microbiome in affecting cholesterol metabolism.

RECENT FINDINGS

Recent applications of these methods have spanned from the assessment of the effect on cholesterol synthesis, absorption or excretion of drugs (such as ezetimibe, PCSK9 inhibitors and plant sterols) and the gut microbiome to the more complex assessment of transintestinal cholesterol excretion (TICE) and RCT.

SUMMARY

These methods continue to be a valuable tool to answer novel questions and investigate the complexity of in-vivo cholesterol metabolism.

Plant sterol enriched functional food and atherosclerosis

Hypercholesterolaemia is a major cardiovascular risk factor. A healthy diet and a healthy lifestyle reduces cardiovascular risk. 'Functional foods' supplemented with phytosterols are recommended for the management of hypercholesterolaemia and have become a widely used non-prescription approach to lower plasma cholesterol levels. Two billion euros are spent world-wide each year on various functional foods, which have regulator-approved health claims for the management of elevated cholesterol levels. While international societies, such as the European Atherosclerosis Society or the National Heart Foundation in Australia, still advise phytosterols as an additional dietary option in the management of hypercholesterolaemia, recently released guidelines such as those from the National Institute of Health and Clinical Excellence in the United Kingdom are more critical of food supplementation with phytosterols and draw attention to significant safety issues. This review challenges whether an intervention with phytosterol supplements is beneficial. We summarize the current evidence from genetic diseases, genetic association studies, clinical trial data and data from animal studies.

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.