Palmitoylethanolamide in Ulcerative Colitis

Ulcerative colitis (UC) is a chronic immune-mediated inflammatory bowel disease (IBD) of the large intestine characterized by a continuous pattern of mucosal and submucosal inflammation and ulceration involving the distal, the proximal or even the entire colon. It is reported to commonly affect people aged 15-30 years with a slight male predominance. The global prevalence rate of UC is estimated to be about 120 per 100,000 as of 2025 with a rapidly rising incidence especially in industrialized regions. It follows a relapsing-remitting course and commonly presents with abdominal pain, bloody diarrhea, urgency, and tenesmus. Although its etiology is poorly understood, multiple factors are thought to be implicated in its pathogenesis including genetic susceptibility, environmental factors such as diet, infections, medications…etc. and changes in intestinal microbiome composition which trigger an overreactive immune response damaging the mucosal barrier, and genetic susceptibility.

Multiple modalities are utilized in the pharmacological management of UC targeting the local and systemic chemical mediators of inflammation like 5-aminosalicylates, corticosteroids, immunomodulators and biologics. Molecular targets like: TNF-α, IL-6, IL-12, IL-17, IL-23, leukotrienes and integrins have been extensively studied which led to the development of therapeutic ligands. Interestingly, peroxisome proliferator-activated receptor- α (PPAR-α), a member of nuclear hormone receptor superfamily of ligand-activated transcription factors, is a promising target investigated in animal models for its anti-inflammatory and protective effects. Activation of such receptor is thought to reduce NO production, neutrophil influx, and decrease the expression of proinflammatory proteins, such as inducible NO synthase (iNOS), cyclo-oxygenase-2 (COX-2) and TNF- α.

The currently approved interventions can only calm down the underlying abnormal immune response and the associated inflammation successfully achieving remission. However, they cannot completely eradicate the cause of autoimmunity or restore the regular immune balance. Their use, especially biologics, is associated with loss of efficacy over time due to possible immunogenicity, high risk of infection and allergic reactions. Multisystem side effects are also commonly seen with corticosteroids' use particularly in the long term. Therefore, the focus has shifted in recent years towards complementary and alternative medicine in order to provide safe and reliably effective options.

Palmitoylethanolamide (PEA) is an endocannabinoid-like bioactive lipid mediator which belongs to the family of N-acylethanolamine (NAE) fatty acid amides. It exerts anti-inflammatory, antioxidant, antimicrobial, analgesic, immunomodulatory and neuroprotective actions through acting at different sites like: PPAR-α, G-protein coupled receptor 55 (GPR55), cannabinoid receptors 1 and 2 (CB1 and CB2) and transient receptor potential vanilloid receptor 1 (TRPVR1) channels. PEA is a commercially available supplement mainly used to alleviate chronic neuropathic pain and persistent musculoskeletal pain. PEA has proven to be safe and tolerable across multiple studies with very rare cases reporting mild side effects like: intermittent headache, nausea, constipation, urticaria and fatigue.

PEA has demonstrated broad analgesic and anti-inflammatory effects across multiple conditions. It effectively reduces diabetic peripheral neuropathic pain, chronic pain in knee osteoarthritis, and cutaneous adverse effects related to interferon-β therapy in multiple sclerosis in previous clinical trials, while also lowering circulating pro-inflammatory cytokines. PEA has further shown the ability to attenuate inflammatory, oxidative stress, and serological biomarkers in early COVID-19. In gastrointestinal disorders, particularly irritable bowel syndrome (IBS), PEA -especially when combined with polydatin- significantly alleviates abdominal pain in pediatrics. Experimental evidence from murine colitis models and ex-vivo human and animal colonic tissues suggests a potential therapeutic role for PEA in UC. Its anti-inflammatory action is mainly mediated through selective activation of PPAR-α, leading to suppression of enteroglial S100B release, inhibition of toll-like receptor signaling, and downstream inflammatory pathways. Additionally, PEA may exert anti-angiogenic effects and provide protection against colonic carcinogenesis by reducing VEGF release via modulation of the AKT/mTOR pathway.