Abstract
Targeted modulation of the gut microbiome represents a promising nutritional strategy to support metabolic and intestinal health in overweight and obese adults. Oleoylethanolamide (OEA) is an endogenous lipid mediator that regulates satiety, lipid metabolism, and inflammation, but its effects on the human microbiome are not well defined. In this randomized, double-blind, placebo-controlled trial, 57 adults with obesity (BMI 30–40 kg/m²) received either 300 mg of TRPTI, providing 250 mg/day of OEA (n = 28), or placebo (n = 29) for 12 weeks. Outcomes included shotgun metagenomics, microbiome profiling, intestinal barrier and inflammatory biomarkers, and safety measures. OEA was safe and well-tolerated with no adverse changes in clinical biomarkers. Although overall microbial diversity remained stable, OEA induced selective, health-relevant compositional shifts. Notably, Faecalibacterium prausnitzii and Akkermansia muciniphila were enriched. These changes coincided with functional host benefits, including increased occludin at Week 12 and interleukin-2 at Week 6, while reducing interleukin-1β, consistent with improved epithelial barrier dynamics and reduced inflammation. Functional pathway analysis suggested enhanced microbial metabolic and redox capacity. These findings indicate OEA supplementation selectively enriches beneficial gut bacteria – particularly A. muciniphila, while improving gut barrier biomarkers and immune function without disrupting microbiome stability. These findings position OEA as a safe, targeted microbiome-modulating ingredient with potential applications for supporting gut and metabolic health.
Introduction
Obesity represents one of the most pressing public health challenges of the 21 st century, affecting nearly 880 million adults worldwideCitation1 and driving an escalating burden of metabolic comorbidities, including insulin resistance,Citation2 nonalcoholic fatty liver disease (NAFLD),Citation3 and cardiovascular disease.Citation4 Beyond excessive adiposity, obesity is characterized by chronic low-grade inflammation.Citation5–7 This inflammation originates from adipocyte dysfunction, immune cell infiltration, and dysregulated secretion of cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).Citation7–9 These processes exacerbate insulin resistance and tissue injury.Citation8–10
Concurrently, the endocannabinoid system—an intricate network of lipid mediators, receptors, and metabolic enzymes—has emerged as a key regulator of appetite and metabolic homeostasis.Citation11 Oleoylethanolamide (OEA), an endogenous fatty acid ethanolamide synthesized in the proximal small intestine during dietary fat absorption through enzymatic conversion of oleic acid, is also produced in neurons and adipose tissue.Citation12–14 It influences gene expression related to fat absorption and fatty acid metabolismCitation15,Citation16 and it is present in small amounts (less than 2 µg/g) in foods like cocoa powder, oatmeal, and nuts.Citation17
While OEA levels rise postprandially and fall during fasting, exogenous administration of OEA restores its concentration in metabolic disorders where its synthesis is impaired, such as obesity and accelerated aging associated with high-fat diets.Citation18 OEA is primarily recognized for its capacity to induce satiety through high-affinity activation of the nuclear receptor peroxisome proliferator-activated receptor-α (PPAR-α), leading to reduced meal size, delayed meal initiation, and decreased meal frequency.Citation19 These effects occur without engagement of psychoactive cannabinoid receptors.Citation20
Beyond PPAR-α, OEA interacts with multiple targets, including the capsaicin receptor transient receptor potential vanilloid 1 (TrpV1) and orphan G protein-coupled receptors GPR55 and GPR119.Citation21,Citation22 Through these pathways, OEA enhances anandamide activity via competitive inhibition of fatty acid amide hydrolase (FAAH),Citation23 modulates gut–brain neural circuits,Citation24,Citation25 induces anorexigenic hormones such as glucagon-like peptide-1 (GLP-1,Citation26 suppresses hunger signals,Citation27 and promotes lipid transport proteins such as cluster of differentiation 36 (CD36) and fatty acid transport protein (FATP).Citation18,Citation28 In vitro and animal studies demonstrate OEA’s ability to enhance lipid metabolism,Citation18 improve insulin and cholesterol profiles,Citation29,Citation30 and activate feeding-related neural networks.Citation27,Citation31,Citation32
Importantly, OEA exhibits protective effects across a spectrum of metabolic, gastrointestinal, neurodegenerative, and inflammatory conditions.Citation13,Citation33,Citation34 It downregulates the NF-κB proinflammatory pathway,Citation35 reduces oxidative stress markers such as malondialdehyde (MDA), and attenuates nociceptive responses, underscoring its anti-inflammatory and antioxidant properties.Citation36 Exogenous OEA supplementation in obese patients with NAFLD (250 mg/day for 8 to 12 weeks) has yielded significant improvements in triglycerides, fasting blood glucose, C-reactive protein, IL-6, TNF-α, and HDL-C levels. These findings highlight its therapeutic potential in cardiometabolic disorders.Citation37
Emerging data link OEA’s systemic actions to modulation of the gut microbiome. Sub-chronic OEA treatment in rodents shifts fecal microbial communities toward a lean-like phenotype by decreasing the Firmicutes:Bacteroidetes ratio and reducing proinflammatory taxa.Citation38 In Caco-2 cell models, OEA restores epithelial barrier function by reducing hyperpermeability and inflammation.Citation39 In obese adults, OEA supplementation increases the abundance of Akkermansia muciniphila, a mucin-degrading bacterium associated with enhanced fat oxidation, strengthened gut barrier integrity, and immunomodulation, while decreasing carbohydrate intake.Citation40,Citation41 OEA may also modulate these effects by promoting the expansion of A. muciniphila levels in the body through the activation of GPR119 and PPAR-α receptors. These findings suggest that OEA’s metabolic and anti-inflammatory benefits may be mediated, in part, by shaping microbial communities.
In addition to human studies, a substantial body of preclinical evidence supports OEA’s metabolic and microbiota-related actions in obesity. Recent work by Cimmino et al. (2025) demonstrated that, in rodent models of diet-induced obesity, OEA does not broadly restructure gut microbial communities but selectively increases the relative abundance of A. muciniphila, aligning with human observations.Citation42 An earlier study by Izzo and colleagues further showed that peripheral OEA levels are dysregulated in obese rodents, with both intestinal and systemic concentrations reduced compared with lean controls.Citation43 These findings suggest that impaired endogenous OEA signaling may contribute to obesity-related metabolic dysfunction and highlight the relevance of restoring OEA tone through exogenous supplementation.
The global rise in obesity has led to widespread inflammatory and metabolic complications, highlighting an urgent need for novel, safe, and targeted interventions. Although preclinical and early clinical findings suggest that OEA may offer such benefits,Citation33,Citation44 no placebo-controlled trial has directly examined whether OEA supplementation can alter the gut microbiota in adults with obesity. Therefore, we designed a randomized, double-blind study to compare daily oral OEA versus placebo in obese participants, with the primary aim of assessing changes in microbial diversity and community structure. It was hypothesized that supplementation with OEA would modulate circulating biomarkers and the gut microbiome, leading to improvements in gut barrier function, reduced inflammation and enhanced quality of life compared with a placebo. Specifically, we evaluated whether OEA selectively enriches beneficial taxa, such as A. muciniphila, and whether these microbiome shifts coincide with reductions in systemic inflammation and improvements in metabolic markers.
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Batacan, R., Rao, A., Bajagai, Y. S., Stanley, D., & Briskey, D. (2026). Oleoylethanolamide supplementation enriches Akkermansia muciniphila and modulates intestinal barrier function in adults with obesity: A randomized, double-blind, placebo-controlled trial. Gut Microbes Reports, 3(1). https://doi.org/10.1080/29933935.2026.2622259
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The World Obesity Day 4th March 2026
