Symptoms associated with histamine intolerance due to DAO deficiency Nutritional, Metabolic, Endocrine
Conditions
Interventions
Current interventions as of 27/04/2026:
A total of 300 patients divided into eight treatment groups (50 individuals per group) will be assigned randomly using a computer-generated random number table
Sponsors
DR Healthcare España, S.L.U
Eligibility
Sex/Gender
All
Age
18 Years to 80 Years
Inclusion criteria
Inclusion criteria: 1. Adults over 18 years of age 2. Recent history of two or more symptoms associated with histamine intolerance (headache, dermatological, respiratory, and digestive) 3. Present altered plasma DAO enzyme activity and/or have any of the genetic variants of DAO deficiency: 3.1. SNP-type variants associated with reduced levels of DAO activity (oral mucosal smear or blood) 3.2. rs10156191 3.3. rs1049742 3.4. rs1049793 3.5. rs2052129 4. Not having started dietary treatment (low histamine diet/DAO enzyme supplementation) before starting the study
Exclusion criteria
Exclusion criteria: 1. Food and/or environmental allergies 2. Have taken pharmacological treatment with antibiotics or probiotic supplements in the last month before the start of the study 3. Being pregnant
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| 1. Plasma DAO enzyme activity measured using radioimmune assay (REA-HIT test) at the recruitment visit and 3 months 2. SNP-type variants associated with reduced levels of DAO activity measured using multiplex PCR at recruitment visit 3. Symptoms and quality of life measured using validated questionnaires at baseline, 1, 2 and 3 months: 3.1. Gastrointestinal symptoms (Criteris Roma IV, Bristol Stool Scale, Gastrointestinal Quality of Life Index [GIQLI]) 3.2. Headaches (quality of life questionnaire: Migraine Disability Assessment [MIDAS] and Headache Impact Test [HIT-6] scale) 3.3. Respiratory symptoms (SNTO-22 or PNIF, Quality of Life Questionnaire for patients with rhinoconjunctivitis [RQLQ]) 3.4. Dermatological symptoms (Index SCORing Atopic Dermatitis [SCORAD], Itch Severity Scale [ISS], Quality of Life Questionnaire Dermatology Life Quality Index [DLQI]/Quality of Life Index for Atopic Dermatitis [QoLIAD]) 3.5. Quality of life (SF-36) 4. Effectiveness of the low histamine diet assessed using weekly record at baseline, 1, 2 and 3 months 5. Low-histamine diet assessed using a 151-item consumption frequency questionnaire (FFQ) at baseline and 3 months | — |
Secondary
| Measure | Time frame |
|---|---|
| 1. Metabolomic markers in urine (histamine, methylhistamine, imidazole acetic acid, methyl-imidazole acetic acid) measured using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) (untargeted) at baseline, 1, 2 and 3 months 2. Intestinal microbiota assessed using mass sequencing of bacterial 16S rRNA genes, v3-v4 regions at baseline and 3 months 3. Biochemical parameters of the study: 3.1. Serum tryptase levels (marker that measures the total level of tryptase released by mast cells into circulation) determined by immunoassay using the UniCAP Thermofisher method (which includes alpha and beta-tryptase) at baseline, 1, 2 and 3 months 3.2. Eosinophils, basophils, TSH, copper, zinc measured using the standardized methods of the CORE laboratory of the Hospital Clínic of Barcelona at baseline, 1, 2 and 3 months 4. Safety study parameters: blood count, blood biochemistry (glycemia, HbA1c, kidney and liver function, ionogram, lipid profile, nutritional assessment, C-reactive protein and interleukin 6) and urine (basic examination) – proteinuria and sediment) measured using the standardized methods of the CORE laboratory of the Hospital Clínic of Barcelona at baseline, 1, 2 and 3 months | — |
Countries
Spain
Outcome results
None listed