Comparison of intestinal absorption of cholesterol with different plant sterols in man

Additional mechanism for selective absorption of cholesterol and phytosterols

Phytosterols are structurally similar to cholesterol but they are much less absorbed (<2%) than cholesterol (>50%) in the intestine. We hypothesize that phytosterols are poor substrates of intestinal acyl-CoA: cholesterol acyltransferase 2 (ACAT2), and thus minimal phytosterol esters are formed and packed into chylomicrons, leading to their low absorption. Two isotope tracing models, including a radioactive hamster microsomal ACAT2 reaction model and a differentiated Caco-2 cell model, were established to examine the specificity of ACAT2 to various sterols, including cholesterol, sitosterol, stigmasterol, and campesterol. Both models consistently demonstrated that only cholesterol but not phytosterols could be efficiently esterified by ACAT2 in a time- and dose-dependent manner. Molecular docking further suggested that unfavorable interactions existed between ACAT2 and phytosterols. In conclusion, phytosterols are poor substrates of ACAT2 and thus minimally absorbed. This work provides a theoretical basis for the use of phytosterol-based supplements in treating dyslipidemia and preventing heart diseases.

Lipolysis and Sterol Stability and Bioaccessibility of Wholemeal Rye Bread Enriched with Plant Sterols Subjected to Adult and Elderly Digestion Conditions

This study evaluated the impact of different digestion conditions (adult and senior) on lipolysis and bioaccessibility of plant sterols (PS) and phytosterol oxidation products (POPs) in PS-enriched wholemeal rye bread. Under adult digestion conditions, the addition of gastric lipase (GL) reduced lipolysis products (by 6.1% for free fatty acids and 11.7% for monoacylglycerols) and the bioaccessibility of PS by 6.7%, compared to the control. In digestion with both GL and cholesterol esterase (CE), these reductions were 12.9, 20.1, and 11.3%, respectively. Both modifications (GL and GL + CE) increased the bioaccessibility of POPs by 4.5-4.0%. When simulating the elderly digestion, the modified gastric and intestinal phases did not alter PS bioaccessibility but decreased POPs bioaccessibility by 21.8% compared to control, along with reduced lipolysis. Incorporating GL and CE thus approached physiological conditions and influenced lipid digestion. Elderly simulated digestion conditions resulted in a positive outcome by maintaining PS bioaccessibility while reducing potentially harmful POPs.

Nuclear receptors behind the therapeutic effects of plant sterols on metabolism: A review

Plant sterols are known for their hypocholesterolemic action, and the molecular mechanisms behind this within the gut have been extensively discussed and demonstrated to the point that there is a degree of consensus. However, recent studies show that these molecules exert an additional umbrella of therapeutic effects in other tissues, which are related to immune function, lipid metabolism, and glucose metabolism. A strong hypothesis to explain these effects is the structural relationship between plant sterols and the ligands of a group of nuclear receptors. This review delves into the molecular aspects of therapeutic effects related with lipid and energy metabolism that have been observed and demonstrated for plant sterols, and turns the perspective to explore the involvement of nuclear receptors as part of these mechanisms.

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.

A Comprehensive Update on Phytochemistry, Analytical Aspects, Medicinal Attributes, Specifications and Stability of Stigmasterol

Phytosterols are bioactive substances naturally found in plant cell membranes, and their chemical structure is comparable to cholesterol found in mammalian cells. They are widely distributed in plant foods like olive oil, nuts, seeds, and legumes. Amongst the variety of phytosterols, stigmasterol is the vital compound found abundantly in plants. Numerous hormones, including estrogen, progesterone, corticoids and androgen, are synthesized by stigmasterol. Multiple in-vitro and in-vivo investigations have shown that stigmasterol has various biological effects, including antioxidant, anticancer, antidiabetic, respiratory diseases, and lipid-lowering effects. Experimental research on stigmasterol provides indisputable proof that this phytosterol has the potential to be employed in supplements used to treat the illnesses mentioned above. This substance has a high potential, making it a noteworthy medication in the future. Although several researchers have investigated this phytosterol to assess its prospective qualities, it has not yet attained therapeutic levels, necessitating additional clinical studies. This review offers a comprehensive update on stigmasterol, including chemical framework, biosynthesis, synthetic derivatives, extraction and isolation, analytical aspects, pharmacological profile, patent status, clinical trials, stability and specifications as per regulatory bodies.

Stigmasterol protects human brain microvessel endothelial cells against ischemia-reperfusion injury through suppressing EPHA2 phosphorylation

Stigmasterol is a plant sterol with anti-apoptotic, anti-oxidative and anti-inflammatory effect through multiple mechanisms. In this study, we further assessed whether it exerts protective effect on human brain microvessel endothelial cells (HBMECs) against ischemia-reperfusion injury and explored the underlying mechanisms. HBMECs were used to establish an in vitro oxygen and glucose deprivation/reperfusion (OGD/R) model, while a middle cerebral artery occlusion (MCAO) model of rats were constructed. The interaction between stigmasterol and EPHA2 was detected by surface plasmon resonance (SPR) and cellular thermal shift assay (CETSA). The results showed that 10 μmol·L^-1 stigmasterol significantly protected cell viability, alleviated the loss of tight junction proteins and attenuated the blood-brain barrier (BBB) damage induced by OGD/R in thein vitro model. Subsequent molecular docking showed that stigmasterol might interact with EPHA2 at multiple sites, including T692, a critical gatekeep residue of this receptor. Exogenous ephrin-A1 (an EPHA2 ligand) exacerbated OGD/R-induced EPHA2 phosphorylation at S897, facilitated ZO-1/claudin-5 loss, and promoted BBB leakage in vitro, which were significantly attenuated after stigmasterol treatment. The rat MCAO model confirmed these protective effects in vivo. In summary, these findings suggest that stigmasterol protects HBMECs against ischemia-reperfusion injury by maintaining cell viability, reducing the loss of tight junction proteins, and attenuating the BBB damage. These protective effects are at least meditated by its interaction with EPHA2 and inhibitory effect on EPHA2 phosphorylation.

Health Benefits and Pharmacological Properties of Stigmasterol

Stigmasterol is an unsaturated phytosterol belonging to the class of tetracyclic triterpenes. It is one of the most common plant sterols, found in a variety of natural sources, including vegetable fats or oils from many plants. Currently, stigmasterol has been examined via in vitro and in vivo assays and molecular docking for its various biological activities on different metabolic disorders. The findings indicate potent pharmacological effects such as anticancer, anti-osteoarthritis, anti-inflammatory, anti-diabetic, immunomodulatory, antiparasitic, antifungal, antibacterial, antioxidant, and neuroprotective properties. Indeed, stigmasterol from plants and algae is a promising molecule in the development of drugs for cancer therapy by triggering intracellular signaling pathways in numerous cancers. It acts on the Akt/mTOR and JAK/STAT pathways in ovarian and gastric cancers. In addition, stigmasterol markedly disrupted angiogenesis in human cholangiocarcinoma by tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor receptor-2 (VEGFR-2) signaling down-regulation. The association of stigmasterol and sorafenib promoted caspase-3 activity and down-regulated levels of the anti-apoptotic protein Bcl-2 in breast cancer. Antioxidant activities ensuring lipid peroxidation and DNA damage lowering conferred to stigmasterol chemoprotective activities in skin cancer. Reactive oxygen species (ROS) regulation also contributes to the neuroprotective effects of stigmasterol, as well as dopamine depletion and acetylcholinesterase inhibition. The anti-inflammatory properties of phytosterols involve the production of anti-inflammatory cytokines, the decrease in inflammatory mediator release, and the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Stigmasterol exerts anti-diabetic effects by reducing fasting glucose, serum insulin levels, and oral glucose tolerance. Other findings showed the antiparasitic activities of this molecule against certain strains of parasites such as Trypanosoma congolense (in vivo) and on promastigotes and amastigotes of the Leishmania major (in vitro). Some stigmasterol-rich plants were able to inhibit Candida albicans, virusei, and tropicalis at low doses. Accordingly, this review outlines key insights into the pharmacological abilities of stigmasterol and the specific mechanisms of action underlying some of these effects. Additionally, further investigation regarding pharmacodynamics, pharmacokinetics, and toxicology is recommended.

An evaluation of graded levels of beta-sitosterol supplementation on growth performance, antioxidant status, and intestinal permeability-related parameters and morphology in broiler chickens at an early age

This study was designed to examine the effects of different levels of beta-sitosterol (BS) supplementation on growth performance, serum biochemical indices, redox status, and intestinal permeability-related parameters and morphology of young broilers. Two hundred and forty male Arbor Acres broiler chicks were allocated into 5 groups of 6 replicates with 8 birds each, and fed a basal diet supplemented with 0, 25, 50, 75, and 100 mg/kg BS for 21-d, respectively. The BS quadratically decreased feed conversion ratio during 1 to 14 d and 1 to 21 d, with its effect being more prominent at 25 or 50 mg/kg (P < 0.05). The BS linearly and quadratically reduced 14-d plasma diamine oxidase activity and D-lactate level, and this effect was more pronounced when its supplemental level was 25 or 50 mg/kg (P < 0.05). The BS linearly increased duodenal villus height (VH) and quadratically increased jejunal VH and ratio of VH and crypt depth (CD) at 14 d, and these effects in 25 mg/kg group were more remarkable (P < 0.05). Similarly, BS linearly or quadratically increased VH and ratio of VH and CD, but decreased CD in the jejunum and ileum at 21 d, with these effects being more pronounced at 50 mg/kg (P < 0.05). The BS supplementation especially at 50 or 75 mg/kg linearly or quadratically reduced 14-d serum and 21-d hepatic malondialdehyde concentration, and increased serum glutathione peroxidase and catalase activities at 14 and 21 d (P < 0.05). Moreover, the BS administration linearly and/or quadratically increased glutathione peroxidase, catalase, and superoxide dismutase activities and glutathione level, and reduced malondialdehyde accumulation in the intestinal mucosa at 14 and/or 21 d, and these consequences were more significant in 50 to 100 mg/kg BS-supplemented groups (P < 0.05). The results demonstrated that BS administration could improve growth performance, intestinal barrier function, and antioxidant status of broilers at an early age, with these effects being more pronounced at a level of 50 mg/kg.

Sterol bioaccessibility in a plant sterol-enriched beverage using the INFOGEST digestion method: Influence of gastric lipase, bile salts and cholesterol esterase

This study evaluates the influence of increasing bile salts and the addition of key enzymes of the lipidic metabolism in the INFOGEST digestion method on sterol bioaccessibility from a plant sterol (PS)-enriched beverage. The assayed modifications were increasing concentration of bovine bile salts (10 vs. 17.5 mM), and addition of gastric lipase (GL) (60U/mL), cholesterol esterase (CE) (0.075 or 2U/mL) or both. Compared to the original method (10 mM bile salts without enzymes), the assayed conditions significantly reduced bioaccessibility of individual (from 11.3 to 19.7 to 5.1-16.6%) and total PS (13.7 to 6.9-8.0%), and cholesterol (52.8 to 20.9-26.1%), except only when CE is added not allowing cholesterol quantification. The bioaccessibility achieved when lipolytic enzymes were tested was similar for all sterols. For a more physiological approach to in vivo conditions, incorporation of bile salts (10 mM), GL (60U/mL) and CE (0.075U/mL) to the INFOGEST method is proposed, although it increases the cost compared to the established method.

From Dietary Cholesterol to Blood Cholesterol, Physiological Lipid Fluxes, and Cholesterol Homeostasis

Dietary cholesterol (C) is a major contributor to the endogenous C pool, and it affects the serum concentration of total C, particularly the low-density lipoprotein cholesterol (LDL-C). A high serum concentration of LDL-C is associated with an increased risk for atherosclerosis and cardiovascular diseases. This concentration is dependent on hepatic C metabolism creating a balance between C input (absorption and synthesis) and C elimination (conversion to bile acids and fecal excretion). The daily C absorption rate is determined by dietary C intake, biliary C secretion, direct trans-intestinal C excretion (TICE), and the fractional C absorption rate. Hepatic C metabolism coordinates C fluxes entering the liver via chylomicron remnants (CMR), LDL, high-density lipoproteins (HDL), hepatic C synthesis, and those leaving the liver via very low-density lipoproteins (VLDL), biliary secretion, and bile acid synthesis. The knowns and the unknowns of this C homeostasis are discussed.

Property of Phytosterols and Development of Its Containing Mayonnaise-Type Dressing

Phytosterols are functional ingredients with known efficacy and safety. Phytosterols are found as free sterols or as their esters with fatty acids. Although phytosterol esters are soluble in oil and have been used in many commercial foods, it has been difficult to similarly use free phytosterols since they are insoluble in water and practically insoluble in oil. We have developed mayonnaise-type dressing materials using free phytosterols since people who are conscious about cholesterol intake are likely to be conscious about oil. In this review article, we summarized pieces of evidence for the development of phytosterol-containing mayonnaise-type dressing materials.

Absorption, Pharmacokinetics, Tissue Distribution, and Excretion Profiles of Sea Cucumber-Derived Sulfated Sterols in Mice

Sea cucumber-derived sulfated sterols exhibited more significant bioactivities compared to plant sterols due to the distinctive structure of the sulfate group at the C-3 position; however, their absorption, pharmacokinetics, tissue distribution, and excretion profiles are unknown, which limits the analysis of molecular mechanisms related to their unique activities. In this study, the absorption characteristics of sea cucumber sterols were determined by oral gavage administration, and their pharmacokinetics, excretion, and tissue distribution were studied by tail vein injection. The results showed that SS1 and SS2 reached the peak at 3 h (20.14 ± 1.2 μg/mL) and 4 h (13.32 ± 0.9 μg/mL) in serum, respectively, after oral gavage administration, suggesting the faster absorption rate of SS1 than SS2 due to the difference in the side-chain groups. Besides, lipid-containing food media improved the digestion and absorption rates of sea cucumber sterols. Moreover, SS1 exhibited a relatively longer duration of efficacy than SS2, and they were almost completely excreted within 9 h through urine. Additionally, sea cucumber sterols were found to be mainly accumulated in the liver (P < 0.05), followed by the kidney and spleen. These findings might provide a theoretical basis for the research and development of functional foods and nutraceuticals associated with sea cucumber sterols.

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.

Linking phytosterols and oxyphytosterols from food to brain health: origins, effects, and underlying mechanisms

Phytosterols and their oxidation products, namely oxyphytosterols, are natural compounds present in plant foods. With increased intake of phytosterol-enriched functional food products, the exposure of both phytosterols and oxyphytosterols is rising. Over the past ten years, researches have been focused on their absorption and metabolism in human body, as well as their biological effects. More importantly, recent studies showed that phytosterols and oxyphytosterols can traverse the blood-brain barrier and accumulate in the brain. As brain health problems resulting from ageing being more serious, attenuating central nervous system (CNS) disorders with active compounds in food are becoming a hot topic. Phytosterols and oxyphytosterols have been shown to implicated in cognition altering and the pathologies of several CNS disorders, including Alzheimer's disease and multiple sclerosis. We will overview these findings with a focus on the contents of phytosterols and oxyphytosterols in food and their dietary intake, as well as their origins in the brain, and illustrate molecular pathways through which they affect brain health, in terms of inflammation, cholesterol homeostasis, oxidative stress, and mitochondria function. The existing scientific gaps of phytosterols and oxyphytosterols to brain health in knowledge are also discussed, highlighting research directions in the future.

Cholesterol metabolites and plant sterols in cerebrospinal fluid are associated with Alzheimer's cerebral pathology and clinical disease progression

BACKGROUND AND PURPOSE

Altered cholesterol metabolism is associated with increased risk of neurodegeneration and in particular with the development of Alzheimer's disease (AD). Here, we investigate whether non-cholesterol sterols and oxysterols in the central nervous system are associated with (i) the presence of cerebral AD pathology, (ii) distinct aspects of AD pathology, i.e. amyloid pathology, neuronal injury, and tau pathology, and (iii) cognitive decline over time.

EXPERIMENTAL APPROACH

One hundred forty-two elder subjects with normal cognition, mild cognitive impairment, or mild dementia participating in a cohort study on cognitive decline and AD were included. Clinical and neuropsychological assessments were performed at inclusion and repeated at follow-up visits at 18 and 36 months. Concentrations of cholesterol, non-cholesterol sterols, and cholesterol metabolites were measured in cerebrospinal fluid (CSF), along with CSF beta-amyloid (Aβ)_1-42; Aβ_1-42/Aβ_1-40 ratio, total-tau (tau), and tau phosphorylated at threonine 181 (p-tau) as markers of amyloid pathology, neuronal injury and tau pathology, respectively. Cognitive decline was assessed by changes in Mini-Mental State Examination and Clinical Dementia Rating sum of boxes at follow-up visits.

KEY RESULTS

CSF 24S-hydroxycholesterol (24S-OHC) and the 24S-OHC/27-OHC ratio were higher in subjects with AD pathology. CSF desmosterol correlated with Aβ_1-42 levels. The 24S-OHC levels, the 24S-OHC/27-OHC ratio and the plant sterols campesterol and sitosterol were associated with the tau and p-tau levels. Both plant sterol concentrations along with the 24S-OHC/27-OHC ratio at baseline predicted cognitive decline at follow-up visits.

CONCLUSIONS AND IMPLICATIONS

We show the importance of CSF levels of several non-cholesterol sterols and oxysterols to AD and core AD biomarkers. The plant sterols campesterol and sitosterol appear to be involved in tau pathology and neurodegeneration. CSF desmosterol level indicates CNS cholesterol synthesis and might be of relevance for clinical disease severity. Therefore these non-cholesterol sterols may represent intervention targets to slow down disease progression.

Effects of phytosterols supplementation on growth performance and intestinal microflora of yellow-feather broilers

This research investigated effects of dietary phytosterols supplementation on growth performance and cecal gut microflora in yellow-feather broilers. A total of 360 yellow-feather broilers (1-day-old) were randomly assigned to 3 treatment groups: control group (basal diet), antibiotic group (basal diet supplemented with 200 mg/kg oxytetracycline calcium and 250 mg/kg nosiheptide), and phytosterols groups (basal diet supplemented with 25 mg/kg phytosterols). Each treatment group had 6 replicates, and there were 20 broilers within each replicate. No treatment effects on average daily feed intake, average daily gain, and food conversion rate were observed. The antibiotic group had a lower liver index compared with control group and phytosterols group. Other visceral indexes including bursa of Fabricius, spleen, and heart were not different among the 3 treatment groups. In terms of alpha diversity, no treatment effects on Shannon and Simpson indexes were observed. Supplementation of phytosterols significantly decreased the Chao1 and Ace indexes, indicating lower community richness of the gut microflora. At phylum level, the phytosterols group had a higher abundance of Bacteroidetes compared with the control group. At genus level, no treatment effect was observed on the top 10 genera. Overall, supplementation of phytosterols at 25 mg/kg level did not affect the growth performance of yellow-feather broilers, and its effect on gut microflora was limited.

Safety of the extension of use of plant sterol esters as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of an extension of use of the novel food 'plant sterol esters' when added to vegetable fat spreads and to liquid vegetable fat-based emulsions for cooking and baking purposes pursuant to Regulation (EU) 2015/2283. Member States expressed concerns in relation to plant sterol oxidation products (POP) and consumption by non-target population groups. The median (0.5%) and P90 (2.28%) value of the oxidation rates of plant sterols determined by a wide range of cooking experiments were used together with exposure estimates for plant sterol when added and cooked with vegetable fat spreads and liquids. The no-observed adverse effect level (NOAEL) of a subchronic rat study and an applied default uncertainty factor of 200 served to derive levels (i.e. 0.64 mg POP/kg body weight (bw) per day) considered safe for humans. This safe level of exposure would be exceeded at the P95 by all age groups when considering the P90 oxidation rate and using EFSA's comprehensive food consumption database for assessing the potential exposure. When considering the median oxidation rate, the safe level of 0.64 mg POP/kg bw per day would be exceeded at the highest P95 intake estimates in children below 9 years of age. When considering an intake of the maximum authorised use level of 3 g plant sterols/person per day and oxidation rates of 0.5% and 2.28%, the resulting daily POP intakes per kg bw by an adult weighing 70 kg would be 0.21 and 0.98 mg/kg bw per day, respectively, the latter value exceeding 0.64 mg/kg bw per day. The Panel concludes that the safety of the intended extension of use of plant sterol esters under the proposed conditions of use has not been established.

Phytosterols in Cancer: From Molecular Mechanisms to Preventive and Therapeutic Potentials

Cancer is the second leading cause of death worldwide. Compelling evidence supports the hypothesis that the manipulation of dietary components, including plant compounds termed as phytochemicals, demonstrates certain important health benefits in humans, including those in cancer. In fact, beyond their well-known cardiovascular applications, phytosterols may also possess anticancer properties, as has been demonstrated by several studies. Although the mechanism of action by which phytosterols (and derivatives) may prevent cancer development is still under investigation, data from multiple experimental studies support the hypothesis that they may modulate proliferation and apoptosis of tumor cells. Phytosterols are generally considered safe for human consumption and may also be added to a broad spectrum of food matrices; further, they could be used in primary and secondary prevention. However, few interventional studies have evaluated the relationship between the efficacy of different types and forms of phytosterols in cancer prevention. In this context, the purpose of this review was to revisit and update the current knowledge on the molecular mechanisms involved in the anticancer action of phytosterols and their potential in cancer prevention or treatment.

Recent Advances in the Critical Role of the Sterol Efflux Transporters ABCG5/G8 in Health and Disease

Cardiovascular disease is characterized by lipid accumulation, inflammatory response, cell death, and fibrosis in the arterial wall and is the leading cause of morbidity and mortality worldwide. Cholesterol gallstone disease is caused by complex genetic and environmental factors and is one of the most prevalent and costly digestive diseases in the USA and Europe. Although sitosterolemia is a rare inherited lipid storage disease, its genetic studies led to identification of the sterol efflux transporters ABCG5/G8 that are located on chromosome 2p21 in humans and chromosome 17 in mice. Human and animal studies have clearly demonstrated that ABCG5/G8 play a critical role in regulating hepatic secretion and intestinal absorption of cholesterol and plant sterols. Sitosterolemia is caused by a mutation in either the ABCG5 or the ABCG8 gene alone, but not in both simultaneously. Polymorphisms in the ABCG5/G8 genes are associated with abnormal plasma cholesterol metabolism and may play a key role in the genetic determination of plasma cholesterol concentrations. Moreover, ABCG5/G8 is a new gallstone gene, LITH9. Gallstone-associated variants in ABCG5/G8 are involved in the pathogenesis of cholesterol gallstones in European, Asian, and South American populations. In this chapter, we summarize the latest advances in the critical role of the sterol efflux transporters ABCG5/G8 in regulating hepatic secretion of biliary cholesterol, intestinal absorption of cholesterol and plant sterols, the classical reverse cholesterol transport, and the newly established transintestinal cholesterol excretion, as well as in the pathogenesis and pathophysiology of ABCG5/G8-related metabolic diseases such as sitosterolemia, cardiovascular disease, and cholesterol gallstone disease.

Navy Beans Impact the Stool Metabolome and Metabolic Pathways for Colon Health in Cancer Survivors

Colorectal cancer (CRC) is the third leading cause of cancer-related death in the United States and emerging evidence supports that increased consumption of legumes, such as navy beans, can reduce risk. Navy bean consumption was previously shown to modulate host and microbiome metabolism, and this investigation was performed to assess the impact on the human stool metabolome, which includes the presence of navy bean metabolites. This 4-week, randomized-controlled trial with overweight and obese CRC survivors involved consumption of 1 meal and 1 snack daily. The intervention contained 35 g of cooked navy bean or macronutrient matched meals and snacks with 0 g of navy beans for the control group (n = 18). There were 30 statistically significant metabolite differences in the stool of participants that consumed navy bean at day 28 compared to the participants’ baseline (p ≤ 0.05) and 26 significantly different metabolites when compared to the control group. Of the 560 total metabolites identified from the cooked navy beans, there were 237 possible navy bean-derived metabolites that were identified in the stool of participants consuming navy beans, such as N-methylpipecolate, 2-aminoadipate, piperidine, and vanillate. The microbial metabolism of amino acids and fatty acids were also identified in stool after 4 weeks of navy bean intake including cadaverine, hydantoin-5 propionic acid, 4-hydroxyphenylacetate, and caprylate. The stool relative abundance of ophthalmate increased 5.25-fold for navy bean consumers that can indicate glutathione regulation, and involving cancer control mechanisms such as detoxification of xenobiotics, antioxidant defense, proliferation, and apoptosis. Metabolic pathways involving lysine, and phytochemicals were also modulated by navy bean intake in CRC survivors. These metabolites and metabolic pathways represent an acute response to increased navy bean intake, which merit further investigation for improving colonic health after long-term consumption.

Tamarindus indica seeds improve carbohydrate and lipid metabolism: An in vivo study

BACKGROUND

The tamarind seeds have a lot of nutrients that may be used to control cholesterol or glucose levels.

OBJECTIVE(S)

The effects of tamarind seeds (T) on lipid and carbohydrate metabolism in rats were studied. Rats were offered basal diet (BD) with T (2%, 4% or 8%) or without T.

MATERIALS AND METHODS

Feeding and growth performance in rats were measured and samples of liver and blood were analyzed for glycogen content and levels of cholesterol and glucose respectively.

RESULTS

The inclusion of T in the diet influences the feeding and growth performance in rats. The serum cholesterol level was reduced (p < 0.05) in Sprague Dawley (SD) rats fed on basal diet (BD) containing 4% and 8% T (0.24 ± 0.14 g/l and 0.31 ± 0.06 g/l respectively) compared to control (0.79 ± 0.04 g/l). The serum glucose levels in the spontaneous hypertensive rats (SHR) was lower (50.74 ± 2.50 mg/dl; p < 0.05) than control (93.52 ± 10.83 mg/dl) at 4% T. Incorporation of increasing doses of T resulted in linear increase of glycogen storage in livers of SD rats fed on BD and high sucrose diet.

CONCLUSION

Tamarind seeds can lower blood glucose and serum cholesterol and enhance storage of glycogen in rats.

Role of soybean-derived bioactive compounds in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, inflammatory condition of the gastrointestinal tract. Patients with IBD present with debilitating symptoms that alter the quality of life and can develop into severe complications requiring surgery. Epidemiological evidence indicates Westernized societies have an elevated IBD burden when compared with Asian societies. Considering the stark contrast between the typical Western and Eastern dietary patterns, it is postulated that differences in food and lifestyle contribute to lower IBD incidence in Asian countries. Soybeans (Glycine max), which are consumed in high quantities and as various preparations in Eastern societies, contain a wealth of natural, biologically active compounds that include isoflavones, bioactive peptides, protease inhibitors, and phytosterols, among many others. These compounds have been shown to improve human health, and preclinical evidence suggests they have potential to improve the prognosis of IBD. This review summarizes the current state of evidence regarding the effects and the mechanisms of action of these soybean-derived bioactive compounds in experimental models of IBD.

Low Childhood Cholesterol Absorption Predisposes to Gallstone Disease: The Cardiovascular Risk in Young Finns Study

OBJECTIVES

Unraveling pathogenesis of gallstones could help to diminish its enormous disease burden. We hypothesized that certain properties of childhood cholesterol metabolism predict gallstone disease in adulthood.

METHODS

Childhood serum cholestanol and plant sterols (surrogates for cholesterol absorption), cholesterol precursors (surrogates for cholesterol synthesis), lipids, demographics, and dietary habits were compared between individuals diagnosed with gallstone disease subsequently in adulthood (n = 95) and control subjects (n = 190) matched for age, sex, and body mass index in 1980. Subjects were participants of prospective Cardiovascular Risk in Young Finns Study.

RESULTS

In 1980, at mean age of 11.4 years gallstone cohort was characterized by 5.8% lower cholestanol (P = 0.038), and 11.2% to 12.2% (P range = 0.003-0.008) lower plant sterols campesterol, sitosterol, and avenasterol compared with controls. Mean lathosterol/sitosterol ratio was 16.3% higher in gallstone compared with control cohort (P = 0.028). Female gallstone group had 5.4% lower mean cholestanol compared with controls (P < 0.05), and, respectively, those of campesterol, sitosterol, and avenasterol were 12.7% to 14.0% lower (P < 0.05 for each). Body mass index was inversely related to cholestanol and sitosterol (r range = -0.161 to -0.208, P < 0.05 for each) in controls, but not among patients with gallstone. In whole study population, surrogates of cholesterol absorption (eg, campesterol, P = 0.018) and low dietary intake of vegetables (P = 0.009) were significant predictors of gallstones in logistic regression model.

CONCLUSIONS

Cholesterol metabolism trait characterized by low serum levels of surrogate markers of cholesterol absorption precedes adult gallstone disease already in childhood. Low serum cholestanol and plant sterol ratios during normal Western diet may have role as predictive biomarkers for gallstones.

Biomarkers of cholesterol homeostasis in a clinical laboratory database sample comprising 667,718 patients

BACKGROUND

Circulating noncholesterol sterols/stanols (NCS) are used in clinical lipidology as surrogate measures of cholesterol synthesis and absorption, where they can be valuable tools in assessing cholesterol metabolism and personalizing therapies in patients with dyslipidemia.

OBJECTIVES

To describe the distributions of plasma NCS concentrations and inter-NCS correlations in a large cohort of American patients constituting a clinical laboratory database, and to investigate the relationship between circulating NCS, age, sex, and apolipoprotein E (APOE) genotype.

METHODS

A total of 667,718 patient blood samples submitted for testing to Health Diagnostic Laboratory, Inc. (Richmond, VA) were analyzed for cholesterol absorption markers (sitosterol, campesterol, and cholestanol) and one cholesterol synthesis marker (desmosterol). NCS percentiles were determined, along with intermarker correlations (Pearson's R). Analysis of variance was used to assess the effect of age and sex on NCS level, and to evaluate the relationship between cholesterol synthesis/absorption status and APOE genotype in a subset of 336,866 patients.

RESULTS

Mean NCS concentrations were: sitosterol, 2.45 μg/mL; campesterol, 3.3 μg/mL; cholestanol, 2.92 μg/mL; and desmosterol 0.99 μg/mL. The correlations between each NCS and its ratio to total cholesterol ranged from 0.72 (cholestanol) to 0.94 (desmosterol). NCS levels were significantly affected by age and sex (P < .0001), and prevalence of cholesterol hyperabsorption was higher in APOE ε4 allele carriers compared with the other APOE genotypes.

CONCLUSIONS

We have described sample distributions of NCS biomarkers and characterized their relationship to age, sex, and APOE genotype. These data may facilitate research into altered cholesterol homeostasis and human disease, and help physicians optimize lipid-lowering therapies.

Assessment of hormone-like activities in Ginkgo biloba, Elettaria cardamomum and Plantago ovata extracts using in vitro receptor-specific bioassays

Medicinal plants are widely used for the treatment of diseases and for the development of new drugs. This study was designed to determine the presence of hormone-like activities dependent on the activation of human estrogen receptor alpha (hERa) and/or androgen receptor (hAR) in methanol extracts prepared from three medicinal plants historically and currently used for therapeutic purposes: Ginkgo biloba leaves (GBL), Elettaria cardamomum seeds (ECS) and Plantago ovata seeds (POS). After a solid-liquid extraction (SLE) step, their effects on hERa function were assessed in MCF-7 breast cancer cells using the E-Screen bioassay, and their ability to induce hAR-mediated reporter gene expression was evaluated using the androgen-sensitive stable prostatic PALM cell line. Unlike POS extracts, GBL and ECS extracts showed estrogenic (0.07 and 0.20 nM E2Eq mg(-1), respectively) and anti-estrogenic (0.01 and 0.02 μM ICI182780Eq mg(-1), respectively) activities. ECS extracts evidenced androgenic activity (0.30 nM R1881Eq mg(-1)) and POS extracts anti-androgenic activity (22.30 μM ProcEq mg(-1)). According to these findings, these plant extracts may interfere with the endocrine system via one or more hormonal receptors, and further investigation is warranted into their role as endocrine disrupters in humans.

Plant Sterols, Stanols, and Sitosterolemia

Phytosterolemia (sitosterolemia) is a rare autosomal recessive sterol storage disease caused by mutations in either of the adenosine triphosphate (ATP) binding cassette transporter genes; (ABC) G5 or ABCG8, leading to impaired elimination of plant sterols and stanols, with their increased accumulation in the blood and tissues. Thus the disease is characterized by substantially elevated serum plant sterols and stanols, with moderate to high plasma cholesterol levels, and increased risk of premature atherosclerosis. Hematologic abnormalities including macrothrombocytopenia, stomatocytosis and hemolysis are frequently observed in sitosterolemia patients. Currently, ezetimibe, a sterol absorption inhibitor, is used as the routine treatment for sitosterolemia, with reported improvement in plant sterol levels and hemolytic parameters. This review summarizes the research related to the health impact of plant sterols and stanols on sitosterolemia.

Structures of phytosterols and triterpenoids with potential anti-cancer activity in bran of black non-glutinous rice

Structures of some bioactive phytochemicals in bran extract of the black rice cv. Riceberry that had demonstrated anti-cancer activity in leukemic cell line were investigated. After saponification with potassium hydroxide, separation of the unsaponified fraction by reversed-phase high performance liquid chromatography (HPLC) resulted in four sub-fractions that had a certain degree of anti-proliferation against a mouse leukemic cell line (WEHI-3 cell), this being IC50 at 24 h ranging between 2.80-467.11 μg/mL. Further purification of the bioactive substances contained in these four sub-fractions was performed by normal-phase HPLC. Structural characterization by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR) resulted in, overall, the structures of seven phytosterols and four triterpenoids. Four phytosterols, 24-methylene-ergosta-5-en-3β-ol, 24-methylene-ergosta-7-en-3β-ol, fucosterol, and gramisterol, along with three triterpenoids, cycloeucalenol, lupenone, and lupeol, were found in the two sub-fractions that showed strong anti-leukemic cell proliferation (IC50 = 2.80 and 32.89 μg/mL). The other sterols and triterpenoids were campesterol, stigmasterol, β-sitosterol and 24-methylenecycloartanol. Together with the data from in vitro biological analysis, we suggest that gramisterol is a significant anti-cancer lead compound in Riceberry bran extract.

Cholesterol side chain analogs but not its ether analogs possess cholesterol-lowering activity

SI is hypocholesterolemic with little absorption, while CE and CM are well absorbed and have no effect on plasma cholesterol.

Nutraceuticals for the treatment of hypercholesterolemia

Hypercholesterolemia is a well-established modifiable cardiovascular risk factor and its treatment is an essential aim in preventing cardiovascular disease. Current guidelines highlight lifestyle intervention as a primary issue in the treatment of the patient with hypercholesterolemia. Therapeutic lifestyle changes are often insufficient to achieve desirable cholesterol levels. This is particularly true for high risk patients; however, also low risk patients, whose cholesterol levels are not necessarily far from recommended targets, have either sub-optimal or even significantly increased lipid levels. Nutraceuticals are borderline devices between nutrients and drugs providing a supplementation of particular nutrients with beneficial effects on health. Several nutraceuticals have been suggested to improve plasma lipid profile. The literature counted over 40 nutraceutical substances with a supposed beneficial effect on lipid metabolism; for some of them a number of clinical trials highlighted a cholesterol lowering effect and a possible positive influence on cardiovascular prognosis. The aim of this article is to review the main evidences supporting or denying the efficacy and safety of some of the most commonly used nutraceuticals with supposed cholesterol lowering activity.

Non-cholesterol sterols and cholesterol metabolism in sitosterolemia

Sitosterolemia (STSL) is a rare autosomal recessive disease, manifested by extremely elevated plant sterols (PS) in plasma and tissue, leading to xanthoma and premature atherosclerotic disease. Therapeutic approaches include limiting PS intake, interrupting enterohepatic circulation of bile acid using bile acid binding resins such as cholestyramine, and/or ileal bypass, and inhibiting intestinal sterol absorption by ezetimibe (EZE). The objective of this review is to evaluate sterol metabolism in STSL and the impact of the currently available treatments on sterol trafficking in this disease. The role of PS in initiation of xanthomas and premature atherosclerosis is also discussed. Blocking sterols absorption with EZE has revolutionized STSL patient treatment as it reduces circulating levels of non-cholesterol sterols in STSL. However, none of the available treatments including EZE have normalized plasma PS concentrations. Future studies are needed to: (i) explore where cholesterol and non-cholesterol sterols accumulate, (ii) assess to what extent these sterols in tissues can be mobilized after blocking their absorption, and (iii) define the factors governing sterol flux.