The metabolism of plant sterols is disturbed in postmenopausal women with coronary artery disease

High cholesterol absorption: A risk factor of atherosclerotic cardiovascular diseases?

Lowering elevated low-density lipoprotein cholesterol (LDL-C) concentrations reduces the risk of atherosclerotic cardiovascular diseases (ASCVDs). However, increasing evidence suggests that cholesterol metabolism may also be involved in the risk reduction of ASCVD events. In this review, we discuss if the different profiles of cholesterol metabolism, with a focus on high cholesterol absorption, are atherogenic, and what could be the possible mechanisms. The potential associations of cholesterol metabolism and the risk of ASCVDs are evaluated from genetic, metabolic, and population-based studies and lipid-lowering interventions. According to these studies, loss-of-function genetic variations in the small intestinal sterol transporters ABCG5 and ABCG8 result in high cholesterol absorption associated with low cholesterol synthesis, low cholesterol elimination from the body, and a high risk of ASCVDs. In contrast, loss-of-function genetic variations in another intestinal sterol transporter, NPC1L1 result in low cholesterol absorption associated with high cholesterol synthesis, elevated cholesterol elimination from the body, and low risk of ASCVDs. Statin monotherapy is not sufficient to reduce the ASCVD risk in cases of high cholesterol absorption, and these individuals need combination therapy of statin with cholesterol absorption inhibition. High cholesterol absorption, i.e., >60%, is estimated to occur in approximately one third of a population, so taking it into consideration is important to optimise lipid-lowering therapy to prevent atherosclerosis and reduce the risk of ASCVD events.

The effects of phytosterol and phytostanol supplementation on the lipid profile in postmenopausal women: A systematic review and meta-analysis of randomized controlled trials

Various studies have proven that phytosterols and phytostanols (PS) are lipid-lowering agents. These compounds play a role in regulating high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG) metabolism. Although various drugs are available and are currently used to treat dyslipidemia, the management of lipid abnormalities during the postmenopausal period remains a challenge. Thus, scientists are trying to develop new strategies to reduce serum lipids concentrations using natural products. However, the impact of PS administration on serum lipids in postmenopausal women remains unclear. Hence, the purpose of this study was to assess the effect of PS supplementation on the lipid profile in postmenopausal women based on a systematic review of the literature and a meta-analysis of randomized controlled trials. PubMed/Medline, Scopus, Embase, and Web of Science were searched to identify suitable papers published until January 18, 2022. We combined the effect sizes with the DerSimonian and Laird method using a random effects model. PS supplementation resulted in a significant decrease in TC (weighted mean difference [WMD]: -16.73 mg/dl) and LDL-C (WMD: -10.06 mg/dl) levels. No effect of PS supplementation on TG (WMD: -1.14 mg/dl) or HDL-C (WMD: -0.29 mg/dl) concentrations was detected. In the stratified analysis, there was a notable reduction in TC and LDL-C levels when the PS dose was ≥2 g/day (TC: -22.22 mg/dl and LDL-C: -10.14 mg/dl) and when PS were administered to participants with a body mass index ≥25 kg/m² (TC: -20.22 mg/dl and LDL-C: -14.85 mg/dl). PS administration can decrease TC and LDL-C, particularly if the dose of administration is ≥2 g/day and if the participants are overweight or obese. Further high-quality studies are needed to firmly establish the clinical efficacy of PS usage in postmenopausal females.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Serum Metabolomic Analysis of Coronary Heart Disease Patients with Stable Angina Pectoris Subtyped by Traditional Chinese Medicine Diagnostics Reveals Biomarkers Relevant to Personalized Treatments

To improve the treatment of patients with coronary heart disease (CHD), personalized treatments based on potential biomarkers could make a difference. To investigate if such potential biomarkers could be found for CHD inhomogeneous, we combined traditional Chinese medicine based diagnosis with untargeted and targeted metabolomics analyses. Shi and Xu patient subtype groups of CHD with angina pectoris were identified. Different metabolites including lipids, fatty acids and amino acids were further analyzed with targeted metabolomics and mapped to disease-related pathways. The long-chain unsaturated lipids ceramides metabolism, bile acid metabolism were differentially affected in the Xu subtype groups. While, Shi-subtype patients seemed to show inflammation, anomalous levels of bioactive phospholipids and antioxidant molecules. Furthermore, variations in the endothelial damage response and energy metabolism found based on ELISA analysis are the key divergence points between different CHD subtypes. The results showed Xu subtype patients might benefit from long-chain unsaturated lipids ceramides as therapeutic targets. Shi subtype patients might benefit more from levels of polyunsaturated fatty acid consumption and treatments that help in restoring energy balance. Metabolic differences can be essential for treatment protocols. Thus, patient group specific differences can serve as important information to refine current treatment approaches in a personalized manner.

Overview of bile acid signaling in the cardiovascular system

Bile acids (BAs) are classically known to play a vital role in the metabolism of lipids and in absorption. It is now well established that BAs act as signaling molecules, activating different receptors (such as farnesoid X receptor, vitamin D receptor, Takeda G-protein-coupled receptor 5, sphingosine-1-phosphate, muscarinic receptors, and big potassium channels) and participating in the regulation of energy homeostasis and lipid and glucose metabolism. In addition, increased BAs can impair cardiovascular function in liver cirrhosis. Approximately 50% of patients with cirrhosis develop cirrhotic cardiomyopathy. Exposure to high concentrations of hydrophobic BAs has been shown to be related to adverse effects with respect to vascular tension, endothelial function, arrhythmias, coronary atherosclerotic heart disease, and heart failure. The BAs in the serum BA pool have relevant through their hydrophobicity, and the lipophilic BAs are more harmful to the heart. Interestingly, ursodeoxycholic acid is a hydrophilic BA, and it is used as a therapeutic drug to reverse and protect the harmful cardiac effects caused by hydrophobic elevated BAs. In order to elucidate the mechanism of BAs and cardiovascular function, abundant experiments have been conducted in vitro and in vivo. The aim of this review was to explore the mechanism of BAs in the cardiovascular system.

Plasma Non-cholesterol Sterols as Markers of Cholesterol Synthesis and Intestinal Absorption: A Critical Review

Plasma concentrations of phytosterols and non-cholesterol sterol precursors of cholesterol synthesis have been used as markers of intestinal cholesterol absorption and synthesis in inherited and secondary dyslipidemias and in population-based investigations to evaluate the risk for cardiovascular disease, respectively. The method aims at replacing initial research procedures such as the use of stable isotopes associated with fecal steroid balance, which are limited by the high cost and tedious procedures. However, we show in this review that numerous results obtained with serum sterol measurements are contradictory. In this regard, the following points are discussed: 1) how phytosterols relate to atherosclerosis considering that defects in biliary output or in the transport of phytosterols from the intestinal mucosa back into the intestinal lumen provide increased content of phytosterols and other sterols in plasma and tissues, thus not allowing to conclude that their presence in arteries and atheromas represents the etiology of atherosclerosis; 2) serum non-cholesterol sterols as markers of cholesterol synthesis and absorption, such as cholestanol, present discrepant results, rendering them often inadequate to identify cases of coronary artery disease as well as alterations in the whole body cholesterol metabolism; 3) such methods of measurement of cholesterol metabolism are confounded by factors like diabetes mellitus, body weight and other pathologies including considerable hereditary hyperlipidemias biological variabilities that influence the efficiency of synthesis and intestinal absorption of cholesterol.

Squalene: More than a Step toward Sterols

Squalene (SQ) is a natural triterpene widely distributed in nature. It is a metabolic intermediate of the sterol biosynthetic pathway and represents a possible target in different metabolic and oxidative stress-related disorders. Growing interest has been focused on SQ’s antioxidant properties, derived from its chemical structure. Strong evidence provided by ex vivo models underline its scavenging activity towards free radicals, whereas only a few studies have highlighted its effect in cellular models of oxidative stress. Given the role of unbalanced free radicals in both the onset and progression of several cardiovascular diseases, an in depth evaluation of SQ’s contribution to antioxidant defense mechanisms could represent a strategic approach in dealing with these pathological conditions. At present experimental results overall show a double-edged sword role of squalene in cardiovascular diseases and its function has to be better elucidated in order to establish intervention lines focused on its features. This review aims to summarize current knowledge about endogenous and exogenous sources of SQ and to point out the controversial role of SQ in cardiovascular physiology.

Activation of GLP-1 and Glucagon Receptors Regulates Bile Homeostasis Independent of Thyroid Hormone

BACKGROUND

Balanced coagonists of glucagon-like peptide-1 (GLP-1) and glucagon receptors are emerging therapies for the treatment of obesity and diabetes. Such coagonists also regulate lipid metabolism, independent of their body weight lowering effects. Many actions of the coagonists are partly mediated by fibroblast growth factor 21 (FGF21) signaling, with the major exception of bile homeostasis. Since thyroid hormone is an important regulator of bile homeostasis, we studied the involvement of thyroid hormone in coagonist-induced changes in lipid and bile metabolism.

METHODS

We evaluated the effect of a single dose of coagonist Aib2 C24 chimera2 at 150 to 10000 µg/kg on tetraiodothyronine (T4) and triiodothyronine (T3) in high-fat diet-induced obese (DIO) mice and chow-fed mice. Repeated dose treatment of coagonist (150 µg/kg, subcutaneously) was assessed in four mice models namely, on lipid and bile homeostasis in DIO mice, propylthiouracil (PTU)-treated DIO mice, methimazole (MTM)-treated DIO mice and choline-deficient, L-amino acid-defined, highfat diet (CDAHFD)-induced nonalcoholic steatohepatitis (NASH).

RESULTS

Single dose treatment of coagonist did not alter serum T3 and T4 in chow-fed mice and DIO mice. Coagonist treatment improved lipid metabolism and biliary cholesterol excretion. Chronic treatment of GLP-1 and glucagon coagonist did not alter serum T3 in hypothyroid DIO mice and CDAHFDinduced NASH. Coagonist increased serum T4 in DIO mice after 4 and 40 weeks of treatment, though no change in T4 levels was observed in hypothyroid mice or mice with NASH.

CONCLUSION

Our data demonstrate that coagonist of GLP-1 and glucagon receptors does not modulate bile homeostasis via thyroid signaling.

Taxonomic profiling and populational patterns of bacterial bile salt hydrolase (BSH) genes based on worldwide human gut microbiome

BACKGROUND

Bile salt hydrolase plays an important role in bile acid-mediated signaling pathways, which regulate lipid absorption, glucose metabolism, and energy homeostasis. Several reports suggest that changes in the composition of bile acids are found in many diseases caused by dysbacteriosis.

RESULTS

Here, we present the taxonomic identification of bile salt hydrolase (BSH) in human microbiota and elucidate the abundance and activity differences of various bacterial BSH among 11 different populations from six continents. For the first time, we revealed that bile salt hydrolase protein sequences (BSHs) are distributed in 591 intestinal bacterial strains within 117 genera in human microbiota, and 27.52% of these bacterial strains containing BSH paralogs. Significant variations are observed in BSH distribution patterns among different populations. Based on phylogenetic analysis, we reclassified these BSHs into eight phylotypes and investigated the abundance patterns of these phylotypes among different populations. From the inspection of enzyme activity among different BSH phylotypes, BSH-T3 showed the highest enzyme activity and is only found in Lactobaclillus. The phylotypes of BSH-T5 and BSH-T6 mainly from Bacteroides with high percentage of paralogs exhibit different enzyme activity and deconjugation activity. Furthermore, we found that there were significant differences between healthy individuals and patients with atherosclerosis and diabetes in some phylotypes of BSHs though the correlations were pleiotropic.

CONCLUSION

This study revealed the taxonomic and abundance profiling of BSH in human gut microbiome and provided a phylogenetic-based system to assess BSHs activity by classifying the target sequence into specific phylotype. Furthermore, the present work disclosed the variation patterns of BSHs among different populations of geographical regions and health/disease cohorts, which is essential to understand the role of BSH in the development and progression of related diseases.

Non-Cholesterol Sterol Concentrations as Biomarkers for Cholesterol Absorption and Synthesis in Different Metabolic Disorders: A Systematic Review

Non-cholesterol sterols are validated biomarkers for intestinal cholesterol absorption and endogenous cholesterol synthesis. However, their use in metabolic disturbances has not been systematically explored. Therefore, we conducted a systematic review to provide an overview of non-cholesterol sterols as markers for cholesterol metabolism in different metabolic disorders. Potentially relevant studies were retrieved by a systematic search of three databases in July 2018 and ninety-four human studies were included. Cholesterol-standardized levels of campesterol, sitosterol and cholestanol were collected to reflect cholesterol absorption and those of lathosterol and desmosterol to reflect cholesterol synthesis. Their use as biomarkers was examined in the following metabolic disorders: overweight/obesity (n = 16), diabetes mellitus (n = 15), metabolic syndrome (n = 5), hyperlipidemia (n = 11), cardiovascular disease (n = 17), and diseases related to intestine (n = 16), liver (n = 22) or kidney (n = 2). In general, markers for cholesterol absorption and synthesis displayed reciprocal patterns, showing that cholesterol metabolism is tightly regulated by the interplay of intestinal absorption and endogenous synthesis. Distinctive patterns for cholesterol absorption or cholesterol synthesis could be identified, suggesting that metabolic disorders can be classified as 'cholesterol absorbers or cholesterol synthesizers'. Future studies should be performed to confirm or refute these findings and to examine whether this information can be used for targeted (dietary) interventions.

Diminished bile acids excretion is a risk factor for coronary artery disease: 20-year follow up and long-term outcome

BACKGROUND

Patients with coronary artery disease (CAD) had significantly lower bile acid excretion (BAE) compared with non-CAD patients, leading to the hypothesis that the inability to efficiently excrete bile acids leads to coronary atherosclerosis development. We investigated the long-term role of BAE in CAD development and related mortality in 50 patients with proven CAD compared with that of 50 patients with chest pain and no CAD (controls) matched for clinical and laboratory characteristics.

METHODS

All subjects received a 4-day standard diet that included ~500 mg of cholesterol. Fecal bile acids from 24-h stool collections were measured by gas liquid chromatography.

RESULTS

CAD patients excreted lower amounts of total bile acids than controls (p < 0.001), less deoxycholic acid (p < 0.0001) and less lithocholic acid (p < 0.01). BAE was the best significant independent laboratory factor that predicted CAD (p < 0.05). Mortality and CAD development rates were significantly lower for the controls at the 20-year follow up.

CONCLUSIONS

These results showed that CAD patients had markedly decreased BAE levels compared with non-CAD controls. BAE <415 mg/day was associated with increased CAD long-term mortality. Impaired ability to excrete cholesterol might be considered an additional independent risk factor for CAD development.

Plant sterols, cholesterol precursors and oxysterols: Minute concentrations-Major physiological effects

Non-cholesterol sterols are present in our body at very low concentrations as compared to cholesterol. Small changes in the structure of sterol molecules confer them highly distinct biological activities. The best-known example are steroid hormones derived from cholesterol. During the past decade, our knowledge of also other biomolecules related to or derived from cholesterol, particularly plant sterols, biosynthetic precursors of cholesterol, and oxysterols, has expanded rapidly. In this review article we recapitulate the latest insights into the properties and physiological activities of these non-cholesterol sterols, as well as their importance in disease processes and potential as diagnostic biomarkers.

Potential risks associated with increased plasma plant-sterol levels

The consumption of plant sterols is associated with a decrease in LDL cholesterol. However, it is also associated with an increase in plasma plant-sterol (sitosterol, campesterol) levels that may be detrimental. Indeed, the genetic disease sitosterolaemia, which is characterized by elevated plasma levels of plant sterol, is associated with premature atherosclerosis. Yet, although plasma plant-sterol levels are recognized markers of cholesterol absorption, the relationship between such levels and atherosclerosis is not clear. Several studies have analysed the association between plasma plant-sterol levels and cardiovascular disease (CVD), but have found conflicting results. Although the largest prospective trials and genome-wide association studies suggest that high plasma levels of plant sterols are associated with increased CV risk, other studies have reported no such association and even an inverse relationship. Thus, the available data cannot confirm an increased CV risk with plant sterols, but cannot rule it out either. Only a prospective interventional trial to analyse the effects of plant-sterol-enriched food on the occurrence of CV events can exclude a potential CV risk linked with their consumption.

Genomics of post-prandial lipidomic phenotypes in the Genetics of Lipid lowering Drugs and Diet Network (GOLDN) study

BACKGROUND

Increased postprandial lipid (PPL) response to dietary fat intake is a heritable risk factor for cardiovascular disease (CVD). Variability in postprandial lipids results from the complex interplay of dietary and genetic factors. We hypothesized that detailed lipid profiles (eg, sterols and fatty acids) may help elucidate specific genetic and dietary pathways contributing to the PPL response.

METHODS AND RESULTS

We used gas chromatography mass spectrometry to quantify the change in plasma concentration of 35 fatty acids and 11 sterols between fasting and 3.5 hours after the consumption of a high-fat meal (PPL challenge) among 40 participants from the GOLDN study. Correlations between sterols, fatty acids and clinical measures were calculated. Mixed linear regression was used to evaluate associations between lipidomic profiles and genomic markers including single nucleotide polymorphisms (SNPs) and methylation markers derived from the Affymetrix 6.0 array and the Illumina Methyl450 array, respectively. After the PPL challenge, fatty acids increased as well as sterols associated with cholesterol absorption, while sterols associated with cholesterol synthesis decreased. PPL saturated fatty acids strongly correlated with triglycerides, very low-density lipoprotein, and chylomicrons. Two SNPs (rs12247017 and rs12240292) in the sorbin and SH3 domain containing 1 (SORBS1) gene were associated with b-Sitosterol after correction for multiple testing (P≤4.5*10(-10)). SORBS1 has been linked to obesity and insulin signaling. No other markers reached the genome-wide significance threshold, yet several other biologically relevant loci are highlighted (eg, PRIC285, a co-activator of PPARa).

CONCLUSIONS

Integration of lipidomic and genomic data has the potential to identify new biomarkers of CVD risk.

Clinical utility of serum markers of cholesterol absorption and synthesis

PURPOSE OF REVIEW

The serum noncholesterol sterols are widely used today in clinical lipid research as surrogate markers of cholesterol absorption and synthesis. Their applicability and some aspects related to their analysis, use, and interpretations are discussed.

RECENT FINDINGS

The serum markers of cholesterol metabolism have been carefully validated in several populations and during different interventions. If the homeostasis between cholesterol absorption and synthesis is lost, the markers cannot be used as surrogates. The markers have been applied in large population and cohort studies to find out how cholesterol metabolism is related to coronary artery disease. Most of the large studies suggested that increased levels of the markers of cholesterol absorption may conceivably be a risk factor for coronary artery disease.

SUMMARY

Results even from large population studies vary from population to population. The large number of factors, which interfere with cholesterol metabolism, such as age, sex, BMI, diet, health status, medication, and genetic background, and differences in the analysis methods of the serum markers should be taken into consideration when interpreting the data.

ABCG5/8 variants are associated with susceptibility to coronary heart disease

ATP-binding cassette sub-family G member 5 (ABCG5) and ABCG8 are members of an ATP-binding cassette transporter superfamily. ABCG5 and ABCG8 variants affected serum levels of cholesterol and were considered as risk factors for coronary heart disease (CHD). The present control study analyzed ABCG5 and ABCG8 variants in a population for association with the risk of CHD. A total of 417 CHD patients and 267 controls were recruited for genotyping of four single nucleotide polymorphisms (SNPs; i.e. i7892T>C in ABCG5 and Tyr54CysA>G, Thr400LysC>A and 5U145A>C in ABCG8) using quantitative PCR high-resolution melting (qPCR-HRM). Serum lipid levels were measured using an automatic biochemical analyzer. The association of ABCG5/8 variants with lipid levels was analyzed using a Chi-square test. The impact of candidate ABCG5/8 SNPs on CHD was evaluated in a dominant genetic model with stepwise multiple regression analysis. Subgroup analyses were performed with regard to these SNPs, tobacco smoking status, alcohol consumption and gender. Genotypic and allelic frequencies of ABCG8 Thr400LysC>A were significantly different (P<0.05) between CHD patients and controls. CC homozygotes of the ABCG8 Thr400LysC>A SNP had greater triglyceride levels than CA/AA carriers with CHD. Logistic analysis revealed CHD risk was significantly higher in CC homozygotes of ABCG8 Thr400LysC>A than in carriers of the A allele (adjusted P=0.048; OR=2.034; 95% CI=0.983-4.207). Furthermore, there was a significant gene-tobacco smoking interaction. CC homozygotes of ABCG8 Thr400LysC>A SNP had significantly higher triglyceride concentrations (P=0.012) and an increased risk of CHD than tobacco smoking carriers of the A allele. The data from the current study suggested that ABCG8 Thr400LysC>A SNP genetic variants modulated plasma triglyceride levels and thereby affected CHD risk in the population studied. The genetic variant of ABCG8 also contributed to CHD risk through interaction with tobacco smoking.

Sex-specific differences in the predictive value of cholesterol homeostasis markers and 10-year cardiovascular disease event rate in Framingham Offspring Study participants

BACKGROUND

Available data are inconsistent regarding factors influencing plasma cholesterol homeostasis marker concentrations and their value in predicting subsequent cardiovascular disease (CVD) events.

METHODS AND RESULTS

To address this issue, the relationship between markers of cholesterol absorption (campesterol, sitosterol, cholestanol) and synthesis (squalene, desmosterol, lathosterol) and 10-year CVD incidence was assessed in Framingham Offspring Study participants (cycle 6) who were without CVD at baseline and not taking lipid-lowering medications (N=2616). The primary end point was "hard" coronary heart disease (HCHD; coronary death and myocardial infarction), and the secondary end point was full CVD (HCHD plus stroke, coronary insufficiency, angina pectoris, peripheral artery disease, and congestive heart failure). In cross-sectional analysis, significant differences by sex, age, body mass index, blood pressure, and smoking status were observed. In both women and men, lower cholesterol absorption was associated with higher triglyceride and lower high-density lipoprotein (HDL) cholesterol concentrations, whereas lower cholesterol synthesis was associated with higher low-density lipoprotein (LDL) cholesterol concentrations (P for trend <0.05). In women only, lower cholesterol synthesis and absorption were associated with higher non-HDL cholesterol concentrations. Using Cox proportional hazards model adjusting for standard CVD risk factors, squalene concentrations were associated with lower HCHD in women (hazard ratio=0.70 [0.5 to 0.9]). In contrast, squalene (hazard ratio=1.40 [1.1 to 1.8]) concentrations were associated with higher HCHD in men (P<0.0001 for interaction). The cholesterol absorption markers were not predictive of HCHD or full CVD in either women or men.

CONCLUSIONS

These data suggest significant sex differences in the 10-year prognostic value of cholesterol synthesis markers and HCHD, specifically coronary death and incidence of myocardial infarction.

CLINICAL TRIAL REGISTRATION

URL:http://ClinicalTrials.gov. Unique identifier: NCT00074464.

Plasma plant sterols serve as poor markers of cholesterol absorption in man

The validation of the use of plasma plant sterols as a marker of cholesterol absorption is frail. Nevertheless, plant sterol concentrations are routinely used to describe treatment-induced changes in cholesterol absorption. Their use has also been advocated as a clinical tool to tailor cholesterol-lowering therapy. Prior to wider implementation, however, the validity of plant sterols as absorption markers needs solid evaluation. Therefore, we compared plasma plant sterol concentrations to gold-standard stable isotope-determined cholesterol absorption. Plasma campesterol/TC concentrations (camp/TC) were measured in a population of 175 mildly hypercholesterolemic individuals (age: 59.7 ± 5.6 years; BMI: 25.5 ± 2.9 kg/m(2); LDL-C: 4.01 ± 0.56 mmol/l). We compared cholesterol absorption according to the plasma dual-isotope method in subjects with the highest camp/TC concentrations (N = 41, camp/TC: 2.14 ± 0.68 μg/mg) and the lowest camp/TC concentrations (N = 39, camp/TC: 0.97 ± 0.22 μg/mg). Fractional cholesterol absorption did not differ between the groups (24 ± 12% versus 25 ± 16%, P = 0.60), nor was it associated with plasma camp/TC concentrations in the total population of 80 individuals (β = 0.13; P = 0.30, adjusted for BMI and plasma triglycerides). Our findings do not support a relation between plasma plant sterol concentrations and true cholesterol absorption and, therefore, do not favor the use of these sterols as markers of cholesterol absorption. This bears direct consequences for the interpretation of earlier studies, as well as for future studies targeting intestinal regulation of cholesterol metabolism.

Plant sterols and cardiovascular disease: a systematic review and meta-analysis

The impact of increased serum concentrations of plant sterols on cardiovascular risk is unclear. We conducted a systematic review and meta-analysis aimed to investigate whether there is an association between serum concentrations of two common plant sterols (sitosterol, campesterol) and cardiovascular disease (CVD). We systematically searched the databases MEDLINE, EMBASE, and COCHRANE for studies published between January 1950 and April 2010 that reported either risk ratios (RR) of CVD in relation to serum sterol concentrations (either absolute or expressed as ratios relative to total cholesterol) or serum sterol concentrations in CVD cases and controls separately. We conducted two meta-analyses, one based on RR of CVD contrasting the upper vs. the lower third of the sterol distribution, and another based on standardized mean differences between CVD cases and controls. Summary estimates were derived by fixed and random effects meta-analysis techniques. We identified 17 studies using different designs (four case–control, five nested case–control, three cohort, five cross-sectional) involving 11 182 participants. Eight studies reported RR of CVD and 15 studies reported serum concentrations in CVD cases and controls. Funnel plots showed evidence for publication bias indicating small unpublished studies with non-significant findings. Neither of our meta-analyses suggested any relationship between serum concentrations of sitosterol and campesterol (both absolute concentrations and ratios to cholesterol) and risk of CVD. Our systematic review and meta-analysis did not reveal any evidence of an association between serum concentrations of plant sterols and risk of CVD.

Credibility engineering in the food industry: linking science, regulation, and marketing in a corporate context

We expand upon the notion of the "credibility cycle" through a study of credibility engineering by the food industry. Research and development (R&D) as well as marketing contribute to the credibility of the food company Unilever and its claims. Innovation encompasses the development, marketing, and sales of products. These are directed towards three distinct audiences: scientific peers, regulators, and consumers. R&D uses scientific articles to create credit for itself amongst peers and regulators. These articles are used to support health claims on products. However, R&D, regulation, and marketing are not separate realms. A single strategy of credibility engineering connects health claims to a specific public through linking that public to a health issue and a food product.

The role of bile Acid excretion in atherosclerotic coronary artery disease

The impact of cholesterol and different classes of lipoproteins on the development of coronary artery disease (CAD) has been investigated in extensively during the past 50 years. The cholesterol metabolism is dependent on numerous factors, including dietary fat, fractional absorption of dietary cholesterol, tissue stores of cholesterol, endogenous cholesterol synthesis, and fecal bile excretion. Several studies showed significantly lower amounts of bile acid secretion in adult patients with CAD compared to non-CAD patients. Could it be that the inability to efficiently excrete bile acids may lead to CAD development?

The association of bile acid excretion and atherosclerotic coronary artery disease

BACKGROUND

Excess cholesterol is usually eliminated from the body by conversion to bile acids excreted in feces as bile salts. The excretion of large amounts of bile protects against atherosclerosis, while diminished excretion may lead to coronary artery disease (CAD).

OBJECTIVE

To investigate a relationship between CAD and bile acid excretion.

METHODS

Bile acid excretion was compared between 36 patients with proven CAD and 37 CAD-free individuals (controls). The groups were comparable for demographics and selected risk factors. All subjects received a 4-day standard diet that included ∼500 mg of cholesterol. Fecal bile acids from 24-hour stool collections were measured by gas liquid chromatography.

RESULTS

CAD patients excreted lower amounts of total bile acids (358 ± 156 mg) than controls (617 ± 293 mg; p < 0.01) and less deoxycholic acid (188.29 ± 98.12 mg versus 325.96 ± 198.57 mg; p < 0.0001) and less lithocholic acid (115.43 ± 71.89 mg versus 197.27 ± 126.87 mg; p < 0.01). Advanced age, male gender, left ventricular ejection fraction and total bile acid levels were significant independent factors that predicted CAD (p < 0.05). Mortality, CAD and cerebrovascular accident development rates were significantly lower for the controls at the 13-year follow up.

CONCLUSION

CAD patients have significantly decreased bile acid excretion levels than non-CAD patients. An impaired ability to excrete cholesterol may be an additional risk factor for CAD development.

Consumption of plant sterols reduces plasma and hepatic triglycerides and modulates the expression of lipid regulatory genes and de novo lipogenesis in C57BL/6J mice

To investigate emerging clinical data suggesting a triglyceride (TAG)-lowering response to plant sterol (PS) therapy, we characterized changes in TAG metabolism in 16 C57BL/6J mice fed a basal control diet (CON) or the CON diet supplemented with 2% PS for 6 wk. PS consumption reduced (p<0.05) plasma (-28%) and hepatic (-30%) TAG concentrations compared with CON mice. PS consumption increased (p<0.05) hepatic lipogenic gene expression (sterol-regulatory-element-binding protein 1c, 2.4-fold of CON; fatty acid synthase, 6.5-fold of CON) and de novo lipogenesis (4.51+/-0.72 versus 2.82+/-0.61%/day) compared with CON. PS consumption increased (p<0.05) fecal palmitate and stearate excretion and reduced body weight gain compared with CON mice. Although no change in the transcription of intestinal fatty acid absorptive genes was observed, peroxisome proliferator-activated receptor alpha mRNA was reduced (p<0.05, 2.0-fold of CON) in the PS-fed mice. In conclusion, PS-fed C57BL/6J mice showed pronounced reductions in plasma and hepatic TAG concentrations despite increases in hepatic lipogenic gene expression and de novo lipogenesis. Interference with intestinal fatty acid/TAG metabolism as suggested by increased fecal fatty acid loss and reduced weight gain may be associated with the TAG-lowering response to PS consumption.

ABCG5/G8 polymorphisms and markers of cholesterol metabolism: systematic review and meta-analysis

Genetic variation at the ABCG5/G8 locus has been associated with markers of cholesterol homeostasis. As data originate from small-scale studies, we performed a meta-analysis to study these associations in a large dataset. We first investigated associations between five common ABCG5/G8 polymorphisms (p.Q604E, p.D19H, p.Y54C, p.T400K, and p.A632V) and plasma sterol levels in 245 hypercholesterolaemic individuals. No significant associations were found. Subsequently, our data were pooled into a meta-analysis that comprised 3,364 subjects from 16 studies (weighted mean age, 46.7 ± 10.5 years; BMI, 23.9 ± 3.5 kg/m(2)). Presence of the minor 632V allele correlated with reduced LDL-C concentrations (n = 367) compared with homozygosity for the 632A variant [n = 614; -0.11 mmol/l (95% CI, range: -0.20 to -0.02 mmol/l); P = 0.01]. The remaining polymorphisms were not associated with plasma lipid levels. Carriers of the 19H allele exhibited lower campesterol/TC (n = 83; P < 0.001), sitosterol/TC (P < 0.00001), and cholestanol/TC (P < 0.00001), and increased lathosterol/TC ratios (P = 0.001) compared with homozygous 19D allele carriers (n = 591). The ABCG8 632V variant was associated with a clinically irrelevant LDL-C reduction, whereas the 19H allele correlated with decreased cholesterol absorption and increased synthesis without affecting the lipid profile. Hence, associations between frequently studied missense ABCG5/G8 polymorphisms and markers of cholesterol homeostasis are modest at best.