The goal of this placebo controlled randomized double blind interventional study is to assess the effect of palmitoylethanolamide supplementation in patients with functional dyspepsia The main questions it aims to answer are:

• The efficacy of PEA on functional dyspepsia symptoms measured using the LPDS questionnaire
• The effect of PEA on duodenal mucosal permeability.

Participants will receive an 8-week during treatment with PEA 3x400 mg per day or placebo 3 times per day.

Inclusion Criteria:

• Patients with functional dyspepsia as diagnosed by the Rome IV criteria.
• Subjects must provide witnessed written informed consent prior to any study procedures being performed.
• Subjects aged 18-70 years old.
• Male or female subjects.
• Subjects who are capable to understand the study and the questionnaires, and to comply with the study requirements.
• Women of child-bearing potential agree to apply a highly effective method of birth control during the entire duration of the trial. Highly effective birth control is defined as those which result in a low failure rate (i.e., less than 1% per year) when used constantly and correctly such as implants, injectables, combined oral contraceptive method, or some intrauterine devices (IUDs), sexual abstinence, or vasectomized partner. Women of non-childbearing potential may be included if surgically sterile (tubal ligation or hysterectomy) or postmenopausal with at least 2 year without spontaneous menses.

Exclusion Criteria:

• Presence of a history of gastrointestinal surgery other than appendectomy and cholecystectomy.
• Organic gastro-intestinal disease
• Major psychiatric disorder such as major depression
• Presence of coeliac disease, lupus, scleroderma and other systemic auto-immune disease.
• Patients with eosinophilic esophagitis
• Presence of diabetes mellitus
• Active H. Pylori infection or < 6 months after eradication
• Predominant IBS (based on the Rome IV questionnaire)
• Predominant GERD (based on the Rome IV questionnaire)
• Patients taking prohibited medication
• Females who are pregnant or lactating
• Patients not capable to understand or be compliant with the study.