delta-5-avenasterol

Delta‑5‑avenasterol is a plant sterol — a type of phytosterol — that occurs naturally in many plant tissues and oils. Phytosterols are structurally similar to cholesterol, the primary sterol found in animals, but differ in their side chains and double bond positions. Specifically, delta‑5‑avenasterol, also known as isofucosterol or Δ5‑avenasterol, has the chemical formula C29H48O and is a member of the stigmastane series of sterols characterized by a 3β‑hydroxy‑Δ5‑steroid backbone with an ethylidene substitution at carbon 24. In plants, sterols like delta‑5‑avenasterol play important roles in maintaining membrane integrity and fluidity, analogous to cholesterol's functions in animal cells. While cholesterol is essential for human cellular function, phytosterols such as delta‑5‑avenasterol are not considered essential nutrients for humans and do not have established dietary reference intakes. Instead, they contribute to the spectrum of bioactive non‑nutrient compounds that can exert physiological effects when consumed. Delta‑5‑avenasterol is found particularly in the unsaponifiable fraction of vegetable oils obtained through mechanical pressing or solvent extraction. Research chemical suppliers and food metabolomics databases report its presence in corn oil, peanut oil, sunflower oil, and other plant oils, as well as in cereal grains like oats and in tree nuts such as walnuts. It is practically insoluble in water and exists as a white to off‑white solid in pure form. Phytosterols, including delta‑5‑avenasterol, have drawn research interest because of their structural resemblance to cholesterol and their influence on cholesterol metabolism in experimental settings. However, unlike well‑studied phytosterols such as beta‑sitosterol and campesterol, delta‑5‑avenasterol has not been the subject of large clinical trials assessing specific health outcomes. Its identification in food analysis often arises within broader profiling of lipid concomitants in plant oils, rather than targeted nutritional studies. The compound also appears in some cosmetic and pharmaceutical preparations for its antioxidant and anti‑inflammatory properties, although these applications remain distinct from dietary recommendations.

Delta‑5‑avenasterol functions primarily as a structural sterol in plants, contributing to cell membrane stability and organization. In humans, it is a dietary phytosterol, consumed as part of plant oils and other plant foods. Phytosterols in general have been studied for their potential to influence cholesterol metabolism because they can compete with dietary cholesterol for absorption in the intestinal lumen; however, the majority of research focuses on specific phytosterols like beta‑sitosterol and campesterol. While delta‑5‑avenasterol is structurally similar, evidence for its independent biological effects in humans is limited and largely inferred from phytosterol research. Laboratory studies and food chemistry analyses suggest that delta‑5‑avenasterol possesses antioxidant activity, meaning it can neutralize free radicals and reduce oxidative stress in cell models. For example, analyses of unsaponifiable matter from oat grains and wheat germ oil — which include delta‑5‑avenasterol among other sterols — demonstrated antioxidant potential in Food Chemistry research. Such antioxidant properties imply that delta‑5‑avenasterol could contribute to reducing oxidative damage in foods and possibly biological systems when present at sufficient levels, although direct clinical benefits in humans remain unproven. In experimental settings, phytosterols including delta‑5‑avenasterol have been associated with anti‑inflammatory effects, as indicated by reductions in inflammatory mediator production in certain cell and animal studies. Research chemicals providers note these attributes when describing delta‑5‑avenasterol, but these findings are preliminary and derived from models rather than controlled human trials. Some studies point to antibacterial activities in vitro, yet such effects require further validation and are not part of established health guidance. Regarding cardiovascular health, the broader class of phytosterols has been studied for its capacity to lower LDL cholesterol by inhibiting intestinal absorption of cholesterol. While dietary phytosterols at higher intakes have shown modest LDL‑lowering effects in adults, specific data on delta‑5‑avenasterol’s contribution separate from other phytosterols are lacking. Regulatory bodies have recognized that consuming 2–3 grams per day of phytosterols (as a group) can modestly reduce LDL cholesterol, but delta‑5‑avenasterol’s individual role within that effect has not been isolated in large human trials. In summary, delta‑5‑avenasterol may contribute to the known functions of phytosterols — such as competing with cholesterol absorption and providing antioxidant potential — but direct evidence for specific health benefits in humans remains limited. Its inclusion in plant oils contributes to the overall phytosterol content of these foods, which are part of dietary patterns associated with better cardiovascular profiles when replacing saturated fats. Until further research clarifies its unique effects, delta‑5‑avenasterol is best understood as a component of plant sterol mixtures that contribute collectively to health outcomes.

Delta‑5‑avenasterol does not have an established recommended dietary allowance (RDA), adequate intake (AI), or tolerable upper intake level (UL) because it is not considered an essential nutrient for human health. There are no authoritative intake recommendations from the NIH Office of Dietary Supplements or other major nutrition authorities specifying how much delta‑5‑avenasterol individuals should consume daily, for any age group. Phytosterols in general are recognized for their potential to influence cholesterol metabolism, and health organizations sometimes provide guidance on total phytosterol intake (e.g., 2–3 grams per day for LDL cholesterol lowering). However, such guidance pertains to the total phytosterol mix, not specifically to delta‑5‑avenasterol. In the absence of formal dietary reference intakes, scientists and health professionals consider delta‑5‑avenasterol as part of overall phytosterol consumption obtained through plant oils, nuts, seeds, legumes, whole grains, and other plant foods. The typical intake of phytosterols in Western diets ranges from 200 mg to 400 mg per day, largely from foods such as vegetable oils, nuts, seeds, and whole grains. Within that total, the contribution from delta‑5‑avenasterol is comparatively small and variable depending on food choices. Although no deficiency syndrome is associated with low delta‑5‑avenasterol intake, consuming a diverse array of plant foods ensures exposure to a broad spectrum of phytosterols, including delta‑5‑avenasterol, beta‑sitosterol, and campesterol. Diets rich in vegetable oils (such as olive, sunflower, and corn oils) and whole plant foods naturally provide these compounds. Observational studies suggest that diets high in plant sterols correlate with favorable lipid profiles and a reduced risk of cardiovascular disease, but causality and the specific contribution of delta‑5‑avenasterol remain undefined. Special considerations may arise for individuals using phytosterol‑enriched products, such as fortified margarines or supplements designed to provide 2–3 grams of phytosterols daily for cholesterol management. In such contexts, delta‑5‑avenasterol may be one of several phytosterols included, but its proportion varies by product formulation. Until research defines specific needs, intake recommendations focus on overall phytosterol consumption rather than individual sterols. Healthcare professionals may advise increased consumption of phytosterol‑rich foods as part of a heart‑healthy diet, emphasizing vegetable oils, nuts, seeds, and whole grains rather than targeting delta‑5‑avenasterol specifically.

Delta‑5‑avenasterol is not an essential nutrient for humans, and there is no recognized deficiency state associated with low intake. Unlike essential vitamins and minerals that have well‑defined roles in metabolism and structural functions, and whose absence leads to clinical deficiency diseases (such as scurvy for vitamin C or rickets for vitamin D), delta‑5‑avenasterol does not have an established biological requirement in human physiology. Consequently, there are no specific clinical signs, symptoms, or syndromes linked to inadequate intake of delta‑5‑avenasterol. Phytosterols in general — including delta‑5‑avenasterol, beta‑sitosterol, and campesterol — are components of plant cell membranes that humans consume as part of a plant‑based diet. They are absorbed at low efficiency in the gut and are largely excreted or metabolized. Their contribution to human metabolism is primarily of interest for potential effects on cholesterol absorption and metabolism, rather than fulfilling a fundamental metabolic requirement. As a result, low levels of delta‑5‑avenasterol in the diet do not produce overt symptoms and are not considered a health concern. While some research suggests that diets high in phytosterols may be associated with lower LDL cholesterol levels, this effect is seen as a potential health benefit rather than correction of an insufficiency. There is no clinical testing recommended to assess delta‑5‑avenasterol levels in humans, and blood biomarkers are not used to diagnose any deficiency related to this compound. In metabolomics studies, delta‑5‑avenasterol can sometimes serve as a biomarker of plant food consumption — for example, indicating intake of certain nuts, seeds, or oils — but this is distinct from deficiency diagnostics. At‑risk populations for low phytosterol intake are simply those with very low consumption of plant foods, such as individuals who consume minimal fruits, vegetables, whole grains, nuts, and seeds. Even in these cases, there is no evidence that low intake of delta‑5‑avenasterol per se leads to health problems. Rather, low intake of the broader array of nutrients found in plant foods — including fiber, vitamins, minerals, and diverse phytochemicals — is of greater concern. Healthcare providers focus on encouraging balanced diets with ample plant food intake to support overall health, rather than monitoring specific phytosterol levels. Clinical signs of poor diet quality are more likely related to deficiencies of essential nutrients rather than a lack of delta‑5‑avenasterol.

Delta‑5‑avenasterol is found predominantly in plant‑derived foods, particularly in the unsaponifiable fraction of vegetable oils. The best quantified sources are various cooking oils where analytical food composition databases indicate measurable amounts of delta‑5‑avenasterol per 100 grams of oil. For example, corn oil provides approximately 25.9 mg per 100 g, canola oil has about 24.7 mg per 100 g, and extra virgin olive oil contains around 23.1 mg per 100 g. Other oils such as peanut, safflower, sunflower, and soybean oils also contain delta‑5‑avenasterol in the range of approximately 10–16 mg per 100 g depending on processing and cultivar. These amounts reflect analytical nutrient profiling of the sterol fraction isolated from the oils. Vegetable oils are the most concentrated dietary sources because sterols are concentrated in the lipid fraction of plants. Cold‑pressed, unrefined oils may retain higher levels of phytosterols compared to highly refined oils, where processing can reduce sterol content. Including a variety of plant oils in the diet — such as olive oil for salads, corn oil for cooking, or canola oil for baking — contributes to phytosterol intake, including delta‑5‑avenasterol. Oils from seeds such as sunflower or safflower also provide supplementary contributions. In addition to oils, delta‑5‑avenasterol has been identified in other plant foods through phytochemical databases, though quantified amounts are often not reported in standard nutrient composition tables. Phytochemical profiling indicates that compounds like delta‑5‑avenasterol can occur in lettuce, walnuts, carob, and other plant tissues, making these foods part of a broader spectrum of sterol intake when consumed. However, specific amounts in these foods are not standardized in food composition tables, and their contributions are generally much lower than those from concentrated plant oils. Whole grains and cereal products, particularly those derived from oats or wheat germ, contain a variety of sterols including delta‑5‑avenasterol in the unsaponifiable lipid fraction, contributing small amounts of this compound. Nuts and seeds — such as walnuts and pecans — also contain phytosterols as part of their lipid profiles, though the proportions of delta‑5‑avenasterol relative to other phytosterols vary by species and are not always reported. Because delta‑5‑avenasterol is part of the broader phytosterol category, a diet rich in plant‑based foods — including oils, nuts, seeds, legumes, and whole grains — ensures a diverse intake of sterols. These foods offer numerous additional nutritional benefits beyond phytosterols, including essential fatty acids, fiber, vitamins, and minerals. Choosing unrefined and minimally processed plant foods maximizes the retention of phytosterols and other bioactive compounds, supporting overall diet quality.

Delta‑5‑avenasterol, like other phytosterols, is absorbed in the human gastrointestinal tract at low efficiency compared to cholesterol. Phytosterols are structurally similar to cholesterol, differing primarily in their side chain composition, which affects their interaction with intestinal transporters. In the intestinal lumen, phytosterols compete with cholesterol for incorporation into micelles, which are necessary for absorption by enterocytes. Because phytosterols are less soluble in micelles than cholesterol, they displace cholesterol and thus reduce cholesterol absorption, leading to increased fecal excretion of cholesterol. This mechanism underlies the LDL‑lowering effect attributed to high intakes of phytosterol mixtures, though delta‑5‑avenasterol’s individual contribution has not been isolated in human trials. Once absorbed, delta‑5‑avenasterol is transported in the bloodstream within lipoproteins, primarily in LDL and HDL fractions. However, the overall absorption rate of phytosterols is very low — typically less than 5% of intake — and the body preferentially excretes phytosterols through biliary secretion and transintestinal cholesterol efflux pathways. Because of this limited absorption, circulating levels of delta‑5‑avenasterol in plasma are much lower than those of cholesterol, and significant bioaccumulation in tissues is uncommon in normal dietary patterns. Factors that influence phytosterol absorption include the presence of dietary fat, the food matrix, and individual genetic variations in transporter proteins such as NPC1L1 (Niemann‑Pick C1‑like 1), which facilitate sterol uptake into enterocytes. Diets with higher total fat content and sufficient bile acids enhance micelle formation, potentially increasing the incorporation of both cholesterol and phytosterols into micelles. However, because phytosterols outcompete cholesterol for micellar incorporation, the net effect can still favor reduced cholesterol absorption. Other dietary components can modify absorption. For example, soluble fiber binds bile acids and sterols in the gut, further reducing cholesterol absorption and promoting excretion. Conversely, highly processed foods with low phytosterol content provide minimal competition for cholesterol absorption. The bioavailability of delta‑5‑avenasterol from whole foods versus oils may differ due to the food matrix and the presence of other lipids that affect micelle formation. Timing and food combinations also play a role. Consuming phytosterol‑rich foods with meals that contain dietary fat enhances micelle formation, which is necessary for sterol uptake. Taking phytosterol‑enriched products between meals may reduce their efficacy because micelle formation is diminished in the absence of dietary fat. Thus, integrating phytosterol‑containing foods into balanced meals may optimize their functional impact on cholesterol metabolism.

Delta‑5‑avenasterol is not an essential nutrient with established intake recommendations, and supplements specifically marketed as delta‑5‑avenasterol are uncommon. Unlike vitamins or minerals that may be recommended in supplemental form to correct deficiencies or support specific health conditions, phytosterol supplementation focuses on blends of sterols designed to modestly lower LDL cholesterol when consumed at higher doses (e.g., 2–3 grams per day). Products intended for this purpose typically provide a mixture of phytosterols, including beta‑sitosterol, campesterol, and stigmasterol, with delta‑5‑avenasterol present as one of several components depending on the formulation. For individuals seeking to improve lipid profiles, particularly to lower LDL cholesterol, phytosterol‑enriched foods or supplements may offer a modest benefit as part of an overall heart‑healthy diet. The evidence suggests that consuming 2–3 grams per day of phytosterols can reduce LDL cholesterol by about 5–15%. However, this effect is attributed to the total phytosterol intake rather than to delta‑5‑avenasterol alone. Before starting any supplement regimen, individuals should discuss their cardiovascular risk factors and medications with a healthcare provider, especially since phytosterols can interact with cholesterol‑lowering drugs like ezetimibe. Because delta‑5‑avenasterol is not an essential nutrient, there is no clinical indication for supplementation in otherwise healthy individuals who consume a balanced diet that includes plant oils, nuts, seeds, and whole grains. Dietary intake through whole foods provides a range of phytosterols along with other nutrients that contribute to overall health. Supplements claiming to provide delta‑5‑avenasterol alone may lack evidence for specific benefits and could be unnecessary or expensive without clear clinical utility. Certain populations — such as those with genetic disorders affecting sterol metabolism (e.g., sitosterolemia) — need to avoid high phytosterol intake, as elevated circulating phytosterols may exacerbate disease. In such cases, specialized medical guidance is essential. For the general population, focusing on dietary patterns that emphasize plant‑based foods rather than isolated compounds aligns with evidence‑based nutrition practice. A diet rich in vegetables, fruits, whole grains, legumes, and healthy oils inherently supplies phytosterols, fiber, and essential nutrients, supporting cardiovascular and metabolic health without the need for targeted supplementation of delta‑5‑avenasterol.

Delta‑5‑avenasterol does not have an established tolerable upper intake level (UL) because it is not classified as an essential nutrient and has not been associated with toxicity in human studies. Phytosterols as a group are generally recognized as safe for consumption at typical dietary levels found in plant‑based foods, including oils, nuts, seeds, and whole grains. Reports from chemical and food composition research indicate that no toxicity or carcinogenicity of delta‑5‑avenasterol itself has been documented, although individuals may have idiosyncratic sensitivities or allergic responses to plant sterols in some contexts. When phytosterols are consumed at higher supplemental doses (e.g., >2–3 grams per day) to achieve cholesterol‑lowering effects, clinical trials have not reported major safety concerns in the short to medium term, though long‑term safety data are limited. Some individuals may experience gastrointestinal discomfort when consuming high levels of phytosterol‑enriched products. Elevated plasma phytosterol levels have been observed with high intakes, but the clinical significance of these elevations remains an area of investigation. A rare genetic condition called sitosterolemia involves impaired elimination of phytosterols, leading to accumulation of phytosterols — including beta‑sitosterol and potentially delta‑5‑avenasterol — in plasma and tissues. People with sitosterolemia can develop premature atherosclerosis and xanthomas because of abnormal sterol deposition. For this reason, individuals with this condition must strictly limit phytosterol intake under medical supervision. However, sitosterolemia is a distinct metabolic disorder, not a general toxicity concern for the broader population. Overall, there is no evidence to suggest that delta‑5‑avenasterol is toxic at levels obtained through normal dietary patterns. Because it is part of the unsaponifiable fraction of plant oils, its intake is tied to consumption of foods that also provide beneficial nutrients. As with all dietary components, moderation and balance within a diverse diet are advisable. Individuals with specific medical conditions affecting sterol metabolism should consult healthcare providers for tailored guidance on phytosterol intake.

There are no well‑documented direct drug interactions specific to delta‑5‑avenasterol, because it is not a drug and is not widely studied in clinical pharmacology. However, as a member of the phytosterol class, it may influence cholesterol metabolism in ways that could interact with medications affecting lipid absorption and transport. For example, ezetimibe, a cholesterol‑lowering medication, inhibits the Niemann‑Pick C1‑like 1 (NPC1L1) transporter in the intestinal lumen, reducing absorption of both cholesterol and phytosterols. Individuals taking ezetimibe may experience altered phytosterol absorption, though this is generally not clinically problematic. Bile acid sequestrants (such as cholestyramine and colesevelam) bind bile acids in the gut and reduce cholesterol absorption, which can also affect the absorption dynamics of dietary sterols. These medications may increase fecal excretion of both cholesterol and phytosterols, potentially enhancing the lipid‑lowering effects of phytosterol‑rich foods. However, because delta‑5‑avenasterol contributes only a small portion of total phytosterol intake, such interactions are of theoretical interest rather than clinical concern. Statins, which inhibit HMG‑CoA reductase to reduce endogenous cholesterol synthesis, do not directly interfere with phytosterol absorption, but the combined effect of statins and high phytosterol intake can produce additive reductions in LDL cholesterol. Patients combining statin therapy with phytosterol‑enriched diets should do so under medical guidance to monitor lipid levels and overall cardiovascular risk management. There is no evidence that delta‑5‑avenasterol affects the metabolism of unrelated drug classes such as antihypertensives, anticoagulants, or antidiabetic medications. As a dietary phytosterol, its influence on drug metabolism enzymes and transporters is minimal compared to more potent bioactive compounds. Individuals on complex medication regimens should consult healthcare professionals about their overall diet and supplement use to avoid unintended interactions and ensure coordinated care.

Common Forms: Phytosterol blends containing delta‑5‑avenasterol, Plant sterol extracts

Typical Doses: Not established

When to Take: With meals containing dietary fat for functional cholesterol effects

Best Form: Not established

⚠️ Interactions: Ezetimibe (affects sterol absorption), Bile acid sequestrants