IngredientsErgostanol is a naturally occurring saturated sterol belonging to the ergostane family of steroids. Its recognized systematic and common names include: Ergostan-3-ol, (3β,5α)-; 5α-Ergostan-3β-ol; (3β,5α)-Ergostan-3-ol; Epiergostanol; and 24S-Methyl-5α-cholestan-3β-ol. Additional synonyms documented in chemical databases include 5(H)-Campestanol; (24S)-Campestanol; 5α(H)-Campestanol; Hexahydroergosterol; and (24S)-5α-Ergostan-3β-ol. Its CAS Registry Number is 6538-02-9, and it is registered in PubChem under Compound ID 5283641 with the molecular formula C₂₈H₅₀O, molecular weight 402.707 g/mol.
According to the Chemical Entities of Biological Interest (ChEBI) database, 5α-ergostan-3β-ol is classified as an ergostanoid. The compound is a fully saturated (stanol) form of the C28 ergostane sterol family, distinguished by a hydroxyl group at the 3β position of the sterol ring and complete saturation across the ring system. Ergostanol is specifically the 24S-epimer at carbon C-24: catalytic hydrogenation of the unsaturated C28 phytosterols can yield two 24-methyl epimers — campestanol (24α = 24R) or ergostanol (24β = 24S) — both recognized as markers of sterol absorption.
It is essential to clearly distinguish ergostanol from the structurally related but different compound ergosterol. Ergosterol (ergosta-5,7,22-trien-3β-ol) is a mycosterol found in cell membranes of fungi and protozoa, serving many of the same functions that cholesterol serves in animal cells. Ergosterol carries three double bonds and is unsaturated, while ergostanol is the fully saturated derivative bearing none. The synonym "Hexahydroergosterol" reflects the fact that ergostanol can be conceptually derived from ergosterol by complete hydrogenation of all three double bonds, yielding the fully saturated ergostane skeleton. Chemically, removing carbon 242 and hydrogenating the double bond between carbons 5 and 6 of campesterol yields campestanol — the 24R epimer directly related to ergostanol's 24S configuration.
Ergostanol occupies a defined position within the broader phytostanol class. The main sterols found in eukaryotes are three predominant forms: cholesterol in vertebrates, phytosterols (sitosterol, stigmasterol, campesterol) in plants, and ergosterol in fungi. Stanols — including ergostanol — are the saturated counterparts of these sterols. Stanols such as sitostanol and campestanol are saturated sterols and are less common in nature than sterols.
Ergostanol is encountered in nature as a minor constituent of fungal and plant material. Because ergosterol is the dominant sterol of fungi, and ergostanol is its fully saturated equivalent, fungi are a relevant biological matrix. Sterols in fungi typically exist as a mixture of several sterols, with one comprising more than 50% of the total sterol composition; ergosterol is the predominant sterol of many fungi (ascomycetes and basidiomycetes). Ergostanol is also documented by Wikidata's PubChem-linked database as being found in the plant species Carthamus tinctorius (safflower) and Simarouba versicolor.
In the context of commercial phytostanol preparations derived from plant sources, ergostanol arises as a stereospecific byproduct of industrial hydrogenation. Catalytic hydrogenation — the method currently used in the production of commercial stanol ester products — of the unsaturated C28 phytosterols can yield the two 24-methyl epimers, campestanol (24α = 24R) or ergostanol (24β = 24S). The 24R epimer (campestanol) is the predominant commercial product; ergostanol (24S) appears as a minor stereoisomeric companion in processed phytostanol mixtures.
The most commonly occurring phytosterols in the human diet are β-sitosterol, campesterol and stigmasterol, accounting for about 65%, 30% and 3% of diet contents respectively. The most common plant stanols in the human diet are sitostanol and campestanol, which combined make up about 5% of dietary phytosterol. Ergostanol, as a minor 24S-epimer of campestanol, represents a still smaller fraction of total dietary stanol intake.
Ergostanol is available commercially as an isolated research compound for laboratory use. It is supplied in pure crystalline powder form for in vitro and analytical work. In industrial and consumer contexts, ergostanol is not typically sold as a stand-alone supplement; rather, it is encountered as a minor constituent within mixed phytostanol preparations derived from vegetable oil processing. Authorized novel food phytosterol/phytostanol preparations concern phytosterols extracted from plants, which may be presented as free sterols and stanols or esterified with food grade fatty acids. Esterification with fatty acids is a common preparation technique used to improve solubility and bioavailability in functional food matrices such as margarines and spreads.
No specific ethnobotanical or traditional medical tradition has been documented in the peer-reviewed literature as using ergostanol as an isolated, identified substance. However, humans have consumed phytosterols and phytostanols, including ergostanol as a trace constituent, throughout history simply by eating plant-based foods. The intake of naturally occurring phytosterols ranges between approximately 200–300 mg/day depending on eating habits. Traditional plant-rich diets — such as those characteristic of East Asian, Mediterranean, and rural agrarian populations — would have provided higher phytostanol exposure through grains, legumes, vegetable oils, and fungi.
The therapeutic use of phytosterols, the class to which ergostanol belongs, has a documented mid-twentieth century history. Phytosterols have a long history of safe use in humans; the drug Cytellin® was marketed in the United States between 1954 and 1982. This product contained sitosterol as a cholesterol-lowering agent and was used clinically for hypercholesterolemia, establishing the earliest formal medical application of phytosterols. In the 1980s it was demonstrated that sitostanol, a 5α-saturated sitosterol derivative, reduced the intestinal absorption of cholesterol and serum cholesterol more effectively than sitosterol and at doses below those of sitosterol. This discovery helped establish the stanol class — of which ergostanol is a member — as therapeutically relevant.
The use of ergosterol (the unsaturated precursor in the ergostane family) has its own documented historical lineage. Ergosterol is converted by ultraviolet irradiation into ergocalciferol (vitamin D2), a nutritional factor that promotes proper bone development in humans and other mammals; its relationship to vitamin D was established in 1927, when it was shown that an irradiated sample of ergosterol could be used to alleviate rickets, a deficiency disease of bone caused by lack of vitamin D in the diet. While this history pertains to ergosterol rather than ergostanol, it established the broader importance of fungal-derived ergostane-type sterols in nutrition and medicine.
Ergostanol possesses the classic steroid nucleus — a cyclopentanoperhydrophenanthrene ring system — with the ergostane-type side chain at C-17. Its molecular formula is C₂₈H₅₀O, consistent with a fully saturated 28-carbon sterol with a single hydroxyl group at C-3β. The 5α stereochemistry at the A/B ring junction confers a planar, rigid molecular geometry. The key stereochemical feature distinguishing ergostanol from its close epimer campestanol is the configuration at C-24: ergostanol is the 24S isomer while campestanol is the 24R isomer. Both campestanol (24α = 24R) and ergostanol (24β = 24S) are recognized as markers of sterol absorption in the phytostanol literature.
The most common phytosterols and phytostanols are sitosterol (CAS Number 83-46-5), sitostanol (CAS Number 83-45-4), campesterol (CAS Number 474-62-4), campestanol (CAS Number 474-60-2), stigmasterol (CAS Number 83-48-7), and brassicasterol (CAS Number 474-67-9). Ergostanol, as the 24S-epimer of campestanol, shares the same molecular formula and carbon count but differs in stereochemistry. Phytosterols are chemically classified as triterpenes, a class of terpenes composed of six isoprene units; these natural products include more than 200 different phytosterols and more than 400 other triterpenes.
As a fully saturated stanol, ergostanol shares the key physicochemical characteristic of all phytostanols: markedly reduced intestinal absorption compared to unsaturated phytosterols and cholesterol. Less than 5% of dietary plant sterols and less than 0.5% of dietary plant stanols are systemically absorbed, in contrast to about 50–60% of dietary cholesterol. This low systemic absorption is of considerable functional importance because it means ergostanol exerts its primary effects at the intestinal lumen level, with minimal systemic accumulation. The absorption of campestanol (the 24R epimer of ergostanol) from 600 mg of soy stanols was found to be 0.155 ± 0.017%; reduction of the double bond at position 5 decreased absorption by 90% relative to the unsaturated campesterol, underlining the structural basis for poor stanol bioavailability.
While 50% of cholesterol is absorbed in the intestinal tract, the intestinal absorption of stanols and sterols is much lower: 10–15% for campesterol and campestanol, 4–7% for sitosterol, and 1% for sitostanol. Stanols and sterols are hydrolyzed in the upper small intestine.
The principal mechanism by which ergostanol and related phytostanols lower serum cholesterol is through competitive inhibition of intestinal cholesterol absorption. Like cholesterol, phytosterols must be incorporated into mixed micelles before they are taken up by enterocytes. Phytostanols compete with cholesterol for incorporation into these mixed micelles within the intestinal lumen, physically displacing cholesterol and reducing the amount available for uptake.
Once inside the enterocyte, systemic absorption of phytosterols is inhibited by the activity of an efflux transporter consisting of a pair of ATP-binding cassette (ABC) proteins known as ABCG5 and ABCG8. These proteins each form one half of a transporter that secretes phytosterols and unesterified cholesterol from the enterocyte back into the intestinal lumen. This mechanism is central to why phytostanols — including ergostanol — have such low systemic absorption and yet can substantially reduce cholesterol uptake. Loss-of-function mutations in ABCG5 and/or ABCG8 increase intestinal absorption of phytosterols from a normal value of less than 5% to as high as 60% in patients with homozygous mutations.
The molecular basis of the inhibition of cholesterol absorption by phytostanols is not fully elucidated, but suggested mechanisms include displacing cholesterol from mixed micelles, increased expression of genes encoding sterol transporter proteins (NPC1L1, ABCG5, and ABCG8) that promote cholesterol efflux from enterocytes into the intestinal lumen, decreased cholesterol reesterification rate in enterocytes, and increased cholesterol removal from the body via transintestinal cholesterol efflux.
It has been questioned whether plant sterols and stanols interact with intracellular cholesterol sensors such as LXR (liver X receptor), leading to increased expression of ABCG5/ABCG8 and ABCA1. ABCA1 transports sterols to nascent HDL particles, whereas ABCG5/ABCG8 promotes the efflux of sterols back into the intestinal lumen, resulting in decreased cholesterol absorption. Additionally, transintestinal cholesterol excretion (TICE) has been suggested as a possible further target for the plant sterol/stanol-mediated cholesterol-lowering effect.
Notably, plant sterols and stanols are poor substrates for ACAT-2 (acyl-CoA:cholesterol acyltransferase-2) and remain in their free form inside the enterocyte, in contrast to cholesterol which is efficiently esterified and incorporated into chylomicrons. This biochemical difference contributes to differential processing and the preferential efflux of stanols back into the gut lumen.
Because phytostanols including ergostanol are absorbed at low but measurable rates that correlate with general sterol absorption efficiency, circulating phytostanol concentrations serve as clinical biomarkers. Oxysterols and phytosterols are sterol compounds present at markedly low levels in tissues and serum of healthy individuals; a wealth of evidence suggests that they could be employed as biomarkers for human diseases or for cholesterol absorption; an increasing number of reports suggest circulating or tissue oxysterols as putative biomarkers for cardiovascular and neurodegenerative diseases or cancers.
Because phytosterols and stanols cannot be synthesized in the body and have significantly reduced absorption capability compared with cholesterol, the plasma measurement of noncholesterol sterols/stanols can establish whether elevated cholesterol levels are due in part to hyperabsorption, hypersynthesis, or a combination of both or neither.
The most robustly investigated effect of phytostanols as a class — directly relevant to ergostanol as a constituent of commercial phytostanol preparations — is their ability to reduce LDL cholesterol. A meta-analysis of 41 trials showed that intake of 2 g/day of stanols or sterols reduced low-density lipoprotein (LDL) by 10%; higher intakes added little.
The European Food Safety Authority (EFSA) concluded that blood cholesterol can be reduced on average by 7 to 10.5% if a person consumes 1.5 to 2.4 grams of plant sterols and stanols per day, an effect usually established within 2–3 weeks. Longer-term studies extending up to 85 weeks showed that the cholesterol-lowering effect could be sustained.
A randomized, placebo-controlled, double-blind crossover study in 32 healthy adults assessed a phytosterol emulsion delivering 1.5 g/day phytosterol equivalents. Phytosterol supplementation significantly lowered LDL cholesterol 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).
Research specifically examining phytostanol esters in humans demonstrated that phytostanol esters reduced LDL cholesterol by 10–13% in both high- and low-absorber groups, and directly measured cholesterol absorption efficiency by 41 ± 7% in low-absorbers and 47 ± 5% in high-absorbers (p < 0.001 for all), without side effects, when participants consumed mayonnaise or margarine with phytostanol esters for six to nine weeks.
A large meta-analysis of 124 randomized controlled trials in humans found that the LDL-cholesterol-lowering effect of plant sterols and plant stanols continues to increase up to intakes of approximately 3 g/day to an average effect of 12%, and doses higher than 3 g/day appear to be well tolerated.
Despite the well-documented LDL-lowering effect, evidence for reduction in clinical cardiovascular events remains indirect. Despite well-documented LDL cholesterol-lowering effects from long-term consumption of phytosterols, typically in the range of about 5–10%, there is no conclusive evidence from long-term outcome trials that phytosterols themselves reduce the incidence of cardiovascular diseases, improve fasting blood sugar, or glycated hemoglobin levels, or overall mortality rate. Expert reviews have therefore emphasized that phytosterol-enriched products can be considered a dietary option for LDL-cholesterol reduction, but that their impact on 'hard' cardiovascular endpoints and mortality remains to be established.
The rationale for an expected cardiovascular benefit is nonetheless stated by leading bodies: although such absence of clinical trials showing that phytosterol intake can reduce the incidence of clinical endpoints such as myocardial infarction or coronary deaths needs to be acknowledged, it is also necessary to remember that the accrued evidence clearly shows that lowering cholesterol concentrations by any means is always accompanied by a proportional reduction in cardiovascular risk. Hence, both the European Atherosclerosis Society (EAS) and EFSA state that the plasma LDL cholesterol-reducing effects of phytosterols will proportionally reduce cardiovascular risk and related coronary events.
Plant sterols and stanols, when compared head-to-head in clinical trials, have been shown to equally reduce cholesterol levels. This implies that ergostanol-containing phytostanol preparations have comparable cholesterol-lowering efficacy to phytosterol preparations when used at equivalent doses.
Ergostanol is specifically described in chemical reference databases as a phytosterol content in plant food which showed hypocholesterolemic and hypotriglyceridemic effects in hypercholesterolemic overweight volunteers. This characterization positions ergostanol — within mixed phytostanol contexts — as having potential utility in metabolic conditions marked by elevated triglycerides and cholesterol. However, it must be noted that no peer-reviewed clinical trial isolating ergostanol as the sole active agent was identified in the available literature; this attribution is derived from its participation in mixed phytostanol preparations studied in such populations.
A separate and well-supported application of ergostanol is its use as a serum biomarker of sterol absorption. Both campestanol (24α = 24R) and ergostanol (24β = 24S) are recognized markers of sterol absorption. Measurement of circulating non-cholesterol sterols including phytostanols enables clinicians and researchers to phenotype individuals as cholesterol hypersynthesizers or hyperabsorbers, which has implications for selecting lipid-lowering therapy and predicting response. Serum concentrations of certain noncholesterol sterols/stanols have been validated in clinical trials as tools for the diagnosis of genetic noncholesterol sterol disorders, the evaluation of cholesterol homeostasis and cardiovascular risk, and clinical trial assessment of lipid-lowering therapies.
A cross-sectional analysis measuring serum levels of six phytosterols including campestanol, campesterol, stigmasterol, sitosterol, sitostanol, and brassicasterol together with cholesterol synthesis markers and inflammatory markers (CRP, IL-6, and TNF-α) in two cross-sectional surveys of a population-based, prospective study found modest inverse associations between phytostanol levels and inflammatory markers, though these were not uniformly statistically significant.
The evidence for ergostanol-containing phytostanol preparations reducing LDL cholesterol is strong and consistent, supported by multiple meta-analyses of randomized controlled trials. The evidence for cardiovascular event reduction remains indirect and inferential. Although phytosterols decrease LDL cholesterol levels, there is no evidence that they reduce the risk of cardiovascular diseases; on the contrary, some studies suggest an increased risk of atherosclerosis with increasing serum levels of phytosterols. Ergostanol-specific human clinical trial evidence, as distinct from phytostanol class evidence, has not been identified in the peer-reviewed literature; the compound has been studied almost exclusively as a component of mixed phytostanol preparations.
Ergostanol exerts its primary physiological action within the gastrointestinal tract. Stanol (and presumably sterol) esters are hydrolyzed in the upper small gut. Free stanols and sterols presumably displace cholesterol from mixed micelles and thereby reduce intestinal cholesterol absorption. The enterocyte ABCG5/ABCG8 efflux system is the primary determinant of whether absorbed stanols re-enter the gut lumen.
Through its LDL-lowering mechanism, ergostanol-containing phytostanol preparations are associated with cardiovascular health. Numerous intervention studies have indicated that as little as a 10% reduction in LDL cholesterol concentrations can decrease an individual's risk of CVD by as much as 20%; if 2 g of phytosterols and stanols lowers LDL by 10–15%, this could lead to a reduction in CVD risk of 10–30%.
Ergostanol influences the broader landscape of whole-body cholesterol homeostasis. Its measurement in serum reflects absorption phenotype. Reports have proposed a phytostanol action on cholesterol esterification and lipoprotein assembly, cholesterol synthesis, and apolipoprotein (apo) B100-containing lipoprotein removal, though these mechanisms are less conclusively established than the micellar displacement effect.
Sitosterolemia, also known as phytosterolemia, is a very rare hereditary disease that results from inheriting a mutation in both copies of the ABCG5 or ABCG8 gene. Individuals who are homozygous for a mutation in either transporter protein have dramatically elevated serum phytosterol concentrations due to increased intestinal absorption and decreased biliary excretion of phytosterols. In this rare condition, ergostanol and its relatives accumulate in the bloodstream and tissues. Measurement of ergostanol and related stanols is part of the diagnostic workup for this disorder. Measurement of noncholesterol sterols is required to diagnose most of the rare lipidoses such as phytosterolemia, cerebrotendinous xanthomatosis, Smith-Lemli-Opitz syndrome, desmosterolosis, and lathosterolosis.
Ergostanol is not commercially sold as a standalone supplement in dosage units. In the context of mixed phytostanol or phytosterol/phytostanol preparations studied in clinical and regulatory contexts, the following dosages have been reported:
In research use, ergostanol is available as a pure analytical or reference compound in milligram-scale quantities. For authorized phytosterol/phytostanol novel food preparations, regulatory specifications include limits such as less than 15% campestanol, illustrating the proportion of C28 stanols (closely related to ergostanol) in commercial preparations.
The class-level safety record of phytostanols is well established. The EFSA Panel notes the history of multiple safety assessments of phytosterols performed by Member States and EFSA, in addition to the group ADI (acceptable daily intake) established by JECFA. The EFSA NDA Panel concluded that the authorized novel food phytosterol/phytostanol preparation is safe under its proposed specifications.
According to an expert consensus statement from the European Atherosclerosis Society, at the recommended daily intake of two grams of plant sterols per day, the available evidence does not suggest any adverse effect associated with long-term intake.
An important and source-documented safety consideration for all phytosterols and phytostanols, including ergostanol-containing preparations, is their potential to reduce plasma concentrations of fat-soluble vitamins and carotenoids. This occurs because stanols interfere with the same micellar solubilization system used by fat-soluble vitamins and carotenoids. Based on 49 human interventional and 3 bioavailability studies, regular consumption of foods fortified with phytostanols/phytosterols as recommended in labeling does not significantly impact plasma vitamins A, D, and K concentrations; however, a 10% significant median reduction was observed for α-tocopherol (vitamin E).
Carotenoid reductions are of particular documented concern. A meta-analysis of randomized controlled studies reported about 5 to 20% reductions in plasma hydrocarbon carotenoids after consumption of plant sterol- or stanol-enriched foods for one month to one year. Even when standardized to serum total cholesterol concentrations, decreases in α-carotene, β-carotene, and lycopene may persist, suggesting that phytosterols could inhibit the absorption of these carotenoids. Total cholesterol-standardized concentrations of xanthophyll carotenoids, zeaxanthin and β-cryptoxanthin, but not lutein, were also found to be significantly reduced by 5 to 15%.
Analog to cholesterol, plant sterols and stanols, fat-soluble vitamins and carotenoids are lipophilic compounds that require solubilization into mixed micelles for intestinal absorption. Plant sterols and plant stanols interfere with micellar sterol composition and probably also interact with incorporation of fat-soluble vitamins and carotenoids in the micelles. This seems particularly evident for the more lipophilic hydrocarbon carotenoids for which the largest reductions in serum concentrations were found after plant sterol or plant stanol intake.
Mutations in intestinal ABCG5 and ABCG8 transporters are responsible for at least some forms of phytosterolemia. In individuals with this rare hereditary condition, phytostanol-containing preparations are contraindicated, as impaired efflux transport leads to abnormal accumulation of plant stanols including ergostanol in plasma and tissues. Under normal circumstances, any small amounts of noncholesterol sterols that are absorbed are rapidly taken up by the liver and preferentially excreted into bile. ABCG5 and ABCG8 serve specifically to exclude noncholesterol sterol entry at the intestinal level and are involved in sterol excretion at the hepatobiliary level.
The addition of phytosterols to industrialized food as an ingredient to reduce cholesterol has already been approved by several regulatory agencies around the world, including Health Canada, the U.S. Food and Drug Administration (FDA), EFSA, Food Standards Australia New Zealand (FSANZ), and the National Health Surveillance Agency (ANVISA) in Brazil. Phytostanol preparations are frequently used concomitantly with statin drugs in clinical practice. While the combination is generally considered to provide complementary benefit, monitoring blood levels of vitamin A, vitamin E, as well as α- and β-carotene is warranted with combination phytostanol and statin therapy, as reductions of serum levels of all vitamins and provitamins ranging from 10 to 50% have been reported.
The use of phytosterols (or plant sterols) for the control of plasma cholesterol concentrations has recently gained traction because their efficacy is acknowledged by scientific authorities and leading guidelines. Phytosterols, marketed as supplements or functional foods, are formally classified as food in the European Union, are freely available for purchase, and are frequently used without any health professional advice. Ergostanol, as a component of authorized phytostanol mixtures, falls within this regulatory framework. No specific regulatory maximum intake limit for isolated ergostanol has been identified in the sources reviewed; regulatory specifications govern the overall phytostanol mixture rather than each individual epimer.
Health conditions that Ergostanol may help support.
Body systems that Ergostanol may help support.
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