IngredientsOleoylethanolamide (OEA), an endogenous fatty acid amide, is a bioactive mono-unsaturated lipid mediator that is part of the acylglycerol and N-acylethanolamine families, sharing structural similarities with endocannabinoids. Its systematic IUPAC name is N-(2-hydroxyethyl)-(9Z)-octadecenamide. Its molecular formula is C₂₀H₃₉NO₂, and it carries the CAS number 111-58-0. Oleoylethanolamide is an N-(long-chain-acyl)ethanolamine that is the ethanolamide of oleic acid and is the monounsaturated analogue of the endocannabinoid anandamide. Other names used in the literature include N-oleoylethanolamine, oleic monoethanolamide, N-oleoyl ethanolamine, and OEA.
OEA is a major N-acylethanolamine and an endogenous ethanolamide fatty acid. Although it is an endocannabinoid-like compound, it does not bind to cannabinoid receptors. OEA is a shorter, monounsaturated analogue of the endocannabinoid anandamide, but unlike anandamide it acts independently of the cannabinoid pathway, regulating PPAR-α activity to stimulate lipolysis.
It has a role as a geroprotector, a PPAR-alpha agonist and an EC 3.5.1.23 (ceramidase) inhibitor. N-acylethanolamines (NAEs) are lipid-signaling molecules that are widely distributed in plant, invertebrate, and mammalian tissues.
OEA is produced from oleic acid and is synthesized in the gastrointestinal tract, fat tissues, neurons, and astrocytes. The fatty acid ethanolamide OEA is an endogenous lipid mediator derived from the monounsaturated fatty acid, oleic acid. OEA is synthesized from membrane glycerophospholipids and is a high-affinity agonist of the nuclear transcription factor peroxisome proliferator-activated receptor α (PPAR-α).
Oatmeal, nuts, and cocoa powder are dietary sources of OEA; however, their OEA content is low (less than 2 μg/g). Dietary intake of oleic acid elevates circulating levels of OEA in humans by increasing substrate availability for OEA biosynthesis. This fatty acid is mostly found in sources such as olives and sesame.
OEA is commercially available primarily as an encapsulated oral supplement. The preparation of OEA for biomedical studies can be performed by N-acylation of oleic acid/esters or using oleoyl chloride. Human clinical trials have administered OEA in capsule form, with oral doses of 125 mg to 250 mg per day being the most commonly reported in published research.
OEA does not have a documented history of isolated traditional use in any specific herbal or indigenous medical tradition, as it was not identified as a discrete bioactive compound until the twentieth century. Fatty acid ethanolamides (FAEs) are a family of naturally occurring lipids that are present in both plant and animal tissues. Their physiological significance was first recognized nearly 50 years ago, with the discovery of the antiallergic effects of palmitoylethanolamide (PEA), the amide of palmitic acid and ethanolamine.
Functional roles of OEA remained hidden for decades, until a study published in 2001 by RodrÃguez de Fonseca et al. finally identified it as an anorexic lipid mediator regulated by feeding. The discovery of OEA's specific appetite-suppressing and lipid-modulating functions thus belongs entirely to the modern era of molecular pharmacology, not to traditional ethnobotanical or herbal medicinal use.
What can be stated, however, is that OEA is an intrinsic product of oleic acid metabolism. Cultures throughout history that consumed olive oil, nuts, and other oleic acid-rich foods would have produced OEA endogenously; the health effects historically attributed to Mediterranean diets may in part reflect the downstream signaling of OEA. Dietary intake of oleic acid elevates circulating levels of OEA in humans by increasing substrate availability for OEA biosynthesis. Numerous clinical studies demonstrate a beneficial relationship between high-oleic acid diets and body composition, with emerging evidence to suggest OEA may mediate this response through modulation of lipid metabolism and energy intake.
OEA is produced by the small intestine following feeding in two steps. First, an N-acyl transferase (NAT) activity joins the free amino terminus of phosphatidylethanolamine (PE) to the oleoyl group derived from sn-1-oleoyl-phosphatidylcholine, which contains the fatty acid oleic acid at the sn-1 position. This produces an N-acylphosphatidylethanolamine, which is then split (hydrolyzed) by N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) into phosphatidic acid and OEA.
Biochemical studies have demonstrated that dietary oleic acid, but not plasma-derived oleic acid, serves as a metabolic precursor for OEA biosynthesis. Fat digestion in the small intestine triggers the release of free oleic acid, which is internalized by the enterocytes lining the lumen of the proximal gut and is directed to produce either chylomicrons or OEA. Duodenal infusion of individual nutrients revealed that fat, in particular oleic acid, is a potent stimulator of OEA synthesis, whereas proteins and sugar are not.
Other key elements that bind OEA are the membrane glycoprotein fatty-acid transporter CD36, which plays an obligatory role in food-stimulated OEA production, and the Gαs-coupled receptor GPR119. CD36 binds long-chain fatty acids and translocates them through cell membranes; presumably it acts as a biosensor for food-derived oleic acid, as its deletion abrogates food-stimulated production of OEA. Targeted disruption of CD36 or PPAR-α abrogates the satiety response induced by fat. The results suggest that activation of small-intestinal OEA mobilization, enabled by CD36-mediated uptake of dietary oleic acid, serves as a molecular sensor linking fat ingestion to satiety.
Nutrient availability may control OEA signaling in duodenal and jejunal mucosa by reciprocally regulating OEA biosynthesis — through activation of the NAT/NAPE-PLD pathway — and OEA hydrolysis — through downregulation of FAAH and, possibly, other as-yet-uncharacterized amidases. Feeding-induced OEA mobilization is accompanied by enhanced accumulation of OEA-generating N-acyl phosphatidylethanolamines (NAPEs), increased activity and expression of the OEA-synthesizing enzyme NAPE-phospholipase D (NAPE-PLD), and decreased activity and expression of the OEA-degrading enzyme fatty-acid amide hydrolase (FAAH).
OEA is hydrolyzed into oleic acid and ethanolamine, the primary mechanism through which its biological actions are terminated. The structurally unrelated enzymes involved in this transformation are the fatty acid amide hydrolase (FAAH) and N-acylethanolamine acid amidase (NAAA).
OEA is a natural fatty acid amide that mainly modulates feeding and energy homeostasis by binding to peroxisome proliferator-activated receptor-alpha (PPAR-alpha). OEA activates the PPAR-alpha receptor, generating an input that induces several transcriptional changes leading to an increase of fatty-acid catabolism, a reduction of blood lipid levels, and a decrease of body-weight gain. Several lines of evidence indicate that OEA is a high-affinity agonist of the nuclear PPAR-alpha, the molecular target of the antihyperlipidemic drugs fibrates, whereas it does not engage PPAR-gamma or retinoid-X receptor.
OEA is a more potent activator of PPAR-alpha (EC50 = 120 nM) compared to other natural ligands, such as oleic acid (EC50 = 10 μM). Saturation binding experiments show that OEA binds to the purified ligand-binding domain of PPAR-alpha with a KD of approximately 40 nM.
Experiments in genetically modified mice show that OEA does not reduce feeding in animals lacking a functional PPAR-alpha gene, suggesting that PPAR-alpha activation crucially contributes to the hypophagic actions of OEA.
Besides the PPAR-alpha receptor, other molecular targets have been proposed to mediate OEA's actions in vivo. These include the transient receptor potential cation channel vanilloid-1 (TRPV1) and the "orphan" G-coupled receptor, GPR119.
GPR119 activation is thought to mediate OEA regulation of glucose homeostasis. Several targets, such as transient receptor potential vanilloid 1 (TRPV1), peroxisome proliferator-activated receptor-α (PPARα), and GPR119, have been investigated for the anorectic action of OEA.
This lipid sensor is an agonist at peroxisome proliferator-activated receptor-α (PPAR-α) while also being an inhibitor of ceramidase and thereby the sphingolipid signaling pathway.
OEA (1–20 μM) stimulated glycerol and fatty acid release from freshly dissociated rat adipocytes in a concentration-dependent and structurally selective manner. Under the same conditions, OEA had no effect on glucose uptake or oxidation. OEA enhanced fatty acid oxidation in skeletal muscle strips, dissociated hepatocytes, and primary cardiomyocyte cultures.
Administration of OEA in vivo (5 mg/kg, intraperitoneally) produced lipolysis in both rats and wild-type mice, but not in mice in which PPAR-α had been deleted by homologous recombination. Likewise, OEA was unable to enhance lipolysis in adipocytes or stimulate fatty acid oxidation in skeletal muscle strips isolated from PPAR-α mice.
The satiety function of OEA is known to involve peroxisome proliferator-activated receptor type-α (PPAR-α). OEA stimulates afferent sensory fibers (possibly those of the vagus nerve) and provokes the recruitment of feeding-controlling circuits in the brain that use oxytocin and histamine as neurotransmitters for regulating satiety.
OEA delays meal initiation and causes reduction in meal size and meal frequency. However, it did not influence food intake when injected into cerebral ventricles; its anorexic action was inhibited by blockage of peripheral sensory fibers upon treatment with capsaicin, implying peripheral regulation on feeding.
Activating PPAR-α receptors after exposure to OEA enhances the expression of genes related to fatty acid oxidation and lipolysis in white adipose tissue. Furthermore, OEA acts as a ligand for PPAR-α, binding to its receptors and decreasing the production of pro-inflammatory cytokines and reactive oxygen species (ROS).
OEA can cross the blood-brain barrier after systemic administration and mediate antioxidant and anti-inflammatory effects in the brain through activation of the nuclear receptor PPARα, which induces changes in inflammation-related genes by repressing the nuclear factors NF-κB and activator protein-1.
It has been demonstrated that OEA has beneficial effects on health by inducing food intake control, lipid β-oxidation, body weight loss, and analgesic effects. Subchronic treatment with OEA reduced body weight gain and triacylglycerol content in liver and adipose tissue of diet-induced obese rats and wild-type mice, but not in obese PPAR-α−/− mice. In obese rodent models, OEA decreased hyperphagia and body weight gain, increased lipolysis, and decreased hypertriglyceridemia, hypercholesterolemia, and liver steatosis, when chronically administered, thus demonstrating a significant effect not only on the acute, short-term but also on the long-term appetite and energy regulation.
In an RCT conducted by Laleh et al., it was reported that supplementation with two 125 mg OEA capsules daily for 8 weeks in a group of 60 healthy obese individuals enhanced the expression of the PPAR-α gene and improved various anthropometric measurements, including weight, BMI, waist circumference, fat mass, and appetite sensations. In contrast, another study did not demonstrate any significant weight loss following the OEA intervention.
These biological effects contribute to clinically observed outcomes in randomized controlled trials (RCTs), including reductions in body weight, BMI, waist circumference (WC), fat mass, fasting blood glucose (FBG), insulin, and HOMA-IR, along with an increase in total antioxidant capacity (TAC).
Evidence strength: The evidence in humans consists of a small number of single-center RCTs with modest sample sizes (typically 60–76 participants), conducted primarily in Iranian cohorts of obese individuals. Effect sizes are generally moderate and results on weight endpoints are not consistently significant across studies. The 2025 systematic review and meta-analysis representing the most comprehensive pooling of this evidence is described below under cardiometabolic outcomes.
OEA is a gut-endocrine fat-derived lipid and endogenous ligand of PPAR-α. Administration of OEA as a pharmacologic compound can cause stimulation of lipolysis, induction of β-oxidation, and increase of fatty acid uptake through the activation of PPAR-α signaling pathway.
In a randomized, double-blind, placebo-controlled clinical trial carried out in Tabriz, Iran, 60 obese people were enrolled. The intervention group consumed 125 mg of OEA capsules, and the placebo group received the same amount of starch twice for 8 weeks. The results showed that OEA decreased TG and TC significantly at the end of the intervention period.
In a triple-blinded, randomized, placebo-controlled clinical trial, 76 obese patients with NAFLD confirmed by ultra-sonographic findings were randomly assigned to receive a weight reduction diet plus either 250 mg OEA (n=38) or placebo (n=38) for 12 weeks. Atherogenic factors including total cholesterol/HDL-C, LDL-C/HDL-C, TG/HDL-C, non-HDL-C/HDL-C ratios and non-HDL-C level, as well as hematological parameters, were assessed before and after intervention.
Evidence strength: Several small RCTs (60–76 participants, 8–12 weeks duration) report statistically significant improvements in TG and total cholesterol with doses of 125–250 mg/day of OEA. These findings are consistent but limited by small populations, short durations, and a concentration in a single geographic research cluster. Independent replication in larger populations is needed.
OEA is an endogenous lipid mediator capable of exerting multiple hypolipidemic, anti-inflammatory, and hepatoprotective effects mediated by agonism with receptors of the peroxisome proliferator-activated receptor (PPAR) family (PPAR-α and PPAR-γ). It has been demonstrated that OEA can decrease lipid synthesis and lipoprotein secretion in the liver and improve liver steatosis in rats and humans. OEA attenuated liver fibrosis through a PPAR-α dependent mechanism.
The objective of one triple-blind placebo-controlled randomized clinical trial was to examine the effects of OEA supplementation along with weight loss intervention on the expression of PPAR-α, uncoupling proteins 1 and 2 (UCP1 and UCP2) genes in peripheral blood mononuclear cells, metabolic parameters, and anthropometric indices among obese patients with NAFLD. In this trial, 76 obese patients newly diagnosed with NAFLD were randomly allocated into either OEA or placebo group along with calorie-restricted diets for 12 weeks.
A 2023 randomized controlled trial was conducted on 60 obese patients with NAFLD. The patients were treated with OEA (250 mg/day) or placebo along with a low-calorie diet for 12 weeks.
One study investigated the effects of OEA supplementation on the expression levels of SIRT1, AMPK, PGC-1α, PPAR-γ, CEBP-α and CEBP-β genes and serum neuregulin 4 (NRG4) levels in patients with NAFLD. Sixty obese patients with NAFLD were equally allocated into either OEA or placebo group for 12 weeks. The mRNA expression levels of genes were determined using the RT-PCR technique. Serum NRG4 level was also assessed using ELISA. At the endpoint, mRNA expression levels of SIRT1 (p = 0.001), PGC-1α (p = 0.011) and AMPK (p = 0.019) were significantly higher in the OEA group compared to placebo group.
At the molecular level, OEA increased the expression of PPAR-α and uncoupling proteins (UCP1 and UCP2) in peripheral blood mononuclear cells, suggesting enhanced systemic fatty acid oxidation and energy dissipation. Additional clinical trials in obese patients with NAFLD reported that OEA supplementation improves atherogenic indices, lipid profiles, and inflammatory biomarkers, when administered alongside dietary interventions.
Evidence strength: Multiple small RCTs in NAFLD populations consistently show molecular and biochemical improvements, but all trials are from a single research group in Iran, populations are small, and all co-administered a dietary (calorie-restricted) intervention. These findings are preliminary and require independent multicenter replication before clinical conclusions can be drawn.
One study aimed to investigate the effects of OEA supplementation on inflammatory biomarkers and oxidative stress in obese people. This randomized, double-blind, placebo-controlled clinical trial was carried out on 60 healthy obese people in 2016 in Tabriz, Iran. Eligible subjects were randomly divided into intervention (received daily, two 125 mg OEA capsules) and control groups (the same amounts of starch) and were treated for 8 weeks.
OEA supplementation activates PPAR-α receptors in the liver, muscle, and adipose tissue. This activation enhances fatty acid oxidation and lipolysis, while reducing inflammation (CRP, TNF-α) and oxidative stress (MDA, ROS).
Through comprehensive meta-analysis published in 2025, researchers aimed to clarify the potential benefits of OEA in improving inflammation, oxidative stress, and metabolic parameters. A comprehensive search was conducted using Google Scholar and four databases: PubMed, Embase, Scopus, and Web of Science, up to November 2024. Ten trials (with 11 treatment arms) were eligible for inclusion in this review. Meta-analysis revealed that OEA supplementation led to a significant improvement in C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and total antioxidant capacity.
Evidence strength: Moderate. The 2025 meta-analysis pooling 10 RCTs represents the highest level of available human evidence and demonstrates consistent directional improvements in inflammatory markers. However, the trials underlying the meta-analysis share methodological limitations including small sample sizes, short durations, and limited geographic diversity.
Certain randomized controlled trials indicated a relationship between OEA levels and enhanced glycemic control, as well as lower blood glucose, insulin levels, and HOMA-IR in individuals with metabolic disorders. The 2025 meta-analysis documented that clinically observed outcomes across RCTs included reductions in fasting blood glucose (FBG), insulin, and HOMA-IR.
Earlier cell studies showed that OEA inhibits insulin-stimulated glucose uptake in isolated adipocytes and produces glucose intolerance in rats. This preclinical finding stands in contrast to the general direction seen in human trials and warrants attention in future larger studies.
Evidence strength: Preliminary in humans. The glycemic improvements reported in human RCTs are promising but must be considered alongside conflicting mechanistic findings from preclinical models. Larger, adequately powered trials are required.
There is a growing body of evidence for the efficacy of OEA in patients with inflammatory disorders. One randomized double-blind placebo-controlled study evaluated the efficacy of OEA add-on treatment in patients with acute ischemic stroke (AIS). In within-group analysis, patients who received a moderate dose of OEA, 300 mg/day, showed statistically significant decrease in IL-6 and CRP levels.
Evidence strength: Very preliminary. A single small RCT in a specific clinical population (acute ischemic stroke) has been reported. This represents an area for future investigation and does not constitute sufficient evidence for clinical use in this indication.
Sub-chronic OEA administration to mice fed a normal chow diet changed the faecal microbiota profile, shifting the Firmicutes:Bacteroidetes ratio in favour of Bacteroidetes (in particular Bacteroides genus) and decreasing Firmicutes (Lactobacillus), and reduced intestinal cytokines expression by immune cells isolated from Peyer's patches. The results suggest that sub-chronic OEA treatment modulates gut microbiota composition towards a "lean-like phenotype" and polarises gut-specific immune responses mimicking the effect of a diet low in fat and high in polysaccharides.
When administered exogenously, OEA has beneficial effects in several cognitive paradigms; therefore, in all respects, OEA can be considered a hormone of the gut-brain axis.
Evidence strength: Preclinical only (rodent studies). No human clinical data on gut microbiota modulation by exogenous OEA supplementation had been published as of the literature searched. This area is considered exploratory.
Exogenous administration of OEA blocks the alcohol-induced TLR4-mediated proinflammatory cascade, thereby reducing proinflammatory cytokines and chemokines, oxidative and nitrosative stress, and ultimately preventing neural damage.
In preclinical research, pharmacological boosting of endocannabinoid system signaling can improve depressive-like and anxious behavior. Systemic administration of OEA has been proven to have antidepressant activity using models of physical and social stress.
Evidence strength: Preclinical only. Human RCT data specifically targeting depression, anxiety, or neuroprotective outcomes with OEA supplementation were not identified in the peer-reviewed literature at the time of this writing. All neuroprotective findings are from animal models.
OEA has been evaluated for its effect in two types of nociceptive responses evoked by visceral and inflammatory pain in rodents. Results suggest that OEA has analgesic properties reducing the nociceptive responses produced by administration of acetic acid and formalin in two experimental animal models.
Evidence strength: Preclinical only. No human clinical trials specifically targeting pain outcomes with exogenous OEA supplementation were identified. All pain-related findings are from in vitro and rodent studies.
The most comprehensive synthesis of human clinical evidence for OEA supplementation is a systematic review and meta-analysis published in Frontiers in Nutrition in 2025. A comprehensive search was conducted using Google Scholar and four databases: PubMed, Embase, Scopus, and Web of Science, up to November 2024. Pooled effect sizes were calculated using meta-analyses and expressed as standard mean difference (SMD) with a 95% confidence interval (CI).
OEA supplementation activates PPAR-α receptors in the liver, muscle, and adipose tissue. This activation enhances fatty acid oxidation and lipolysis, while reducing inflammation (CRP, TNF-α) and oxidative stress (MDA, ROS). These biological effects contribute to clinically observed outcomes in randomized controlled trials (RCTs), including reductions in body weight, BMI, waist circumference (WC), fat mass, fasting blood glucose (FBG), insulin, and HOMA-IR, along with an increase in total antioxidant capacity (TAC).
Two prior systematic reviews investigating the effects of OEA on risk factors for non-alcoholic fatty liver disease and obesity management showed that OEA regulates pathophysiological pathways involved in NAFLD, including lipid metabolism, inflammation, oxidative stress, and energy homeostasis.
All human clinical trials to date have administered OEA in oral capsule form. The following doses and schedules have been specifically reported in published RCTs:
Preclinical studies in rodents typically employed intraperitoneal administration. Administration of OEA in vivo (5 mg/kg, intraperitoneally) produced lipolysis in both rats and wild-type mice. These parenteral animal doses are not directly comparable to oral human supplementation doses due to differences in route, bioavailability, and species.
Based on the totality of published evidence, OEA has been investigated in connection with the following physiological systems:
In the acute ischemic stroke RCT, adverse effects were recorded. Nausea, vomiting, dyspepsia, and headache were the most frequently reported adverse effects among the participants regardless of their treatment group. Because these adverse effects were observed across both placebo and treatment groups, it is difficult to attribute them solely to OEA at the doses studied.
The use of OEA as a complementary pharmacotherapy agent could be effective in improving inflammation and oxidative stress in obese people. Future studies are needed to confirm the obtained results.
The initial pharmaceutical interest for the endocannabinoid system as a target for antiobesity therapies was restricted by the severe adverse effects of the CB1 antagonist rimonabant. This pointed to OEA — a monounsaturated analogue and functional antagonist of anandamide — as a potential and safer antiobesity alternative to CB1 antagonism. OEA is a mediator of satiety that exerts anorectic effects mainly through peripheral mechanisms. This property is essential to avoid central effects and minimize the risk of adverse reactions that may limit its use.
OEA treatment decreased eating activity within the first 30 min and caused a temporary increase of resting time that was not accompanied by any decline of horizontal, vertical, and total motor activity. In contrast, rimonabant caused a marked increase of the time spent grooming and decreased horizontal motor activity, alterations indicative of aversive non-motivational effects on feeding.
Earlier in vitro and animal research has shown that OEA inhibits insulin-stimulated glucose uptake in isolated adipocytes and produces glucose intolerance in rats, and OEA dose-dependently activates JNK and p38 MAPK, and inhibits insulin receptor phosphorylation. This preclinical observation has not been consistently replicated in human trials, but remains a consideration for populations with insulin-dependent diabetes or those on insulin-sensitizing medications.
No long-term human safety studies of OEA as an oral supplement (beyond 12 weeks) have been identified in the peer-reviewed literature. More comprehensive clinical studies must be conducted to confirm therapeutic effects, define optimal dosing regimens, and evaluate long-term safety. The existing trial durations of 8–12 weeks do not permit conclusions about long-term safety.
The Cosmetic Ingredient Review (CIR) Expert Panel concluded that ethanolamides, including oleic monoethanolamide, are safe in the present practices of use and concentration described when formulated to be non-irritating. The Expert Panel cautioned that these ingredients should not be used in cosmetic products in which N-nitroso compounds may be formed. This assessment pertains to topical cosmetic use only and is not directly applicable to oral supplementation.
Health conditions that Oleoylethanolamide may help support.
Body systems that Oleoylethanolamide may help support.
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