Benefits
Appetite, fullness and food intake
In a small trial of 60 adults with obesity, 250 mg a day for 8 weeks lowered hunger, desire to eat and sweet cravings and raised fullness within the OEA group, and food records showed lower energy and carbohydrate intake. A 76-person trial with a calorie-restricted diet also reported better appetite ratings than placebo. Both trials come from the same research team.
Body weight, waist size and body fat
In the 60-person trial, weight, waist and body fat fell within the OEA group; in the 76-person diet trial, body measurements and fat mass fell more than on placebo. One pooled analysis found a small weight reduction that was no longer significant when either of two trials was removed; another found no clear effect on weight or BMI but a smaller waist. Effects were measured over 8 to 12 weeks, mostly alongside a diet.
Blood sugar and insulin markers
In 46 adults with prediabetes, 125 mg a day for 8 weeks lowered fasting glucose, insulin, insulin resistance and HbA1c, while placebo did not change; a 90-woman trial in polycystic ovary syndrome reported similar marker changes. These are lab markers from small Iranian trials, and pooled results varied widely between trials. Blood sugar concerns need medical care.
Triglycerides and cholesterol ratios
In a small trial of 60 adults with obesity, triglycerides fell more with OEA than placebo after 8 weeks, while total and HDL cholesterol and fasting glucose did not change. In the 76-person diet trial, triglycerides and the TG/HDL and LDL/HDL ratios were lower than on placebo. A meta-analysis found lower triglycerides but no change in total or LDL cholesterol.
Oxidative stress markers
In 60 adults with fatty liver on a low-calorie diet, 250 mg a day for 12 weeks raised total antioxidant capacity and SOD and lowered MDA and oxidized LDL versus placebo. An earlier 8-week trial found no significant change in MDA or antioxidant status. A meta-analysis rated the certainty of these marker results as very low.
Inflammatory markers in blood
Results are inconsistent. One 8-week trial in adults with obesity reported lower IL-6 and TNF-alpha in the OEA group, but a separate 12-week trial found no change in CRP, IL-1 beta, IL-6, IL-10 or TNF-alpha, and a US trial found no difference in blood cytokines. These are lab markers, not symptoms.
Fatigue and mood scores in a veterans trial
In an exploratory US trial, 52 veterans with Gulf War Illness took 200 mg twice daily or placebo for 10 weeks. Fatigue and mood disturbance scores improved more with OEA, along with self-rated energy and emotional well-being; memory, thinking and pain did not change. It is a single small trial in one specific group, and it needs confirming.
Mechanism of action
PPAR-alpha activation
OEA binds PPAR-alpha, a nuclear receptor that switches on genes for fat breakdown. In mice, OEA reduced food intake and weight gain, but not in mice lacking PPAR-alpha. In two Iranian trials, PPAR-alpha gene expression rose with OEA, which shows the pathway was engaged but not that it caused the other results.
A gut signal of fat intake
In rodents, fat reaching the small intestine raises local OEA production from dietary oleic acid, using the fat transporter CD36, and this OEA signal contributes to the feeling of fullness after fatty meals. This pathway has not been measured directly in people taking OEA capsules.
GPR119 receptor signaling
Laboratory work identified OEA as a natural activator of GPR119, a receptor found mainly in the pancreas and gut. The authors suggested part of OEA's effect on food intake may run through it; their rat feeding tests used synthetic GPR119 activators, not OEA. Its role in people taking OEA has not been tested.
Clinical trials
Randomized, double-blind, placebo-controlled trial of 125 mg OEA twice daily versus starch placebo for 60 days in Tabriz, Iran; the same trial was also reported in separate papers on food intake, inflammation and blood lipids (Laleh et al. 2018, Appetite).
60 otherwise healthy adults with obesity; 56 analyzed.
PPAR-alpha gene expression rose in the OEA group. Weight, BMI, waist and body fat percentage fell and hunger, desire to eat and sweet cravings fell, with fullness rising, all reported as changes within the OEA group. A companion report of the same trial found triglycerides lower than placebo after adjustment, with no change in fasting glucose or cholesterol.
Triple-blind, randomized, placebo-controlled trial of OEA (250 mg a day) or placebo for 12 weeks, both groups on a calorie-restricted diet; further reports of the same trial covered body composition and blood lipid ratios (Tutunchi et al. 2020, Pharmacol Res).
76 adults with obesity and newly diagnosed non-alcoholic fatty liver disease.
Versus placebo, OEA produced larger falls in body measurements, energy and carbohydrate intake, triglycerides, liver enzymes and glycemic markers other than HbA1c, a rise in HDL cholesterol and better appetite ratings. Liver fat severity improved in both groups, and the difference between groups was not significant (P = 0.061). PPAR-alpha, UCP1 and UCP2 gene expression in blood cells rose with OEA. The authors note that the triglyceride, HDL, liver enzyme and appetite improvements were influenced by changes in BMI.
Randomized, placebo-controlled trial of OEA 250 mg a day or placebo with a low-calorie diet for 12 weeks, registered as IRCT20090609002017N32 (Tutunchi et al. 2023, Front Pharmacol).
60 adults with obesity and non-alcoholic fatty liver disease.
No inflammatory marker changed: hs-CRP, IL-1 beta, IL-6, IL-10 and TNF-alpha did not differ between or within groups. Total antioxidant capacity and SOD rose and MDA and oxidized LDL fell versus placebo; glutathione peroxidase and catalase did not differ.
Double-blind randomized trial of one 125 mg OEA capsule a day versus wheat-flour placebo for 8 weeks at Qazvin University of Medical Sciences, Iran (Pouryousefi et al. 2022, Diabetol Metab Syndr).
46 adults with prediabetes, 23 per group.
The abstract reports lower blood glucose, insulin, insulin resistance, HbA1c and CRP after OEA, with no change in the placebo group. Body measurements, food intake and physical activity did not differ between the groups at the start or the end of the trial.
Exploratory randomized, double-blind, placebo-controlled trial (NCT05252949) of OEA 200 mg twice daily for 10 weeks, followed by 5 weeks of open-label OEA, funded by a US Department of Defense research program (Abdullah et al. 2026, Sci Rep).
52 US veterans with Gulf War Illness, mean age 59, 94% men.
OEA improved fatigue and total mood disturbance scores, with higher self-rated energy, emotional well-being and social functioning. Cognitive performance and pain did not change, and blood cytokines, LDL and triglycerides did not differ from placebo. All symptom outcomes were declared exploratory and no power calculation was made for them. Digestive complaints were similar on OEA and placebo, with no serious adverse events.
Systematic review and meta-analysis of randomized controlled trials of OEA at 125 to 600 mg a day, searched to November 2024 (Bahari et al. 2025, Front Nutr).
10 small trials (11 treatment arms), all conducted in Iran, in adults with obesity, fatty liver, prediabetes, polycystic ovary syndrome and other conditions.
Body weight was lower with OEA (SMD -0.26 across 4 effect sizes), but the result lost significance when either of two trials was removed. Triglycerides, waist, fat mass, glucose, insulin, HOMA-IR, CRP and TNF-alpha also favored OEA; IL-6, fat-free mass, cholesterol and HbA1c did not change. Glycemic results were highly inconsistent, and the authors flag that all trials came from one country.