Research
Our work
Our research focuses on the biological foundations, clinical manifestations, and therapeutic implications of DAO Deficiency. We investigate the enzymatic, genetic, metabolic, and nutritional factors that contribute to impaired histamine degradation, and we evaluate their impact on conditions such as functional gastrointestinal disorders, headache and migraine, urticaria, and other systemic symptoms associated with histamine excess.
This multidisciplinary approach integrates laboratory research, clinical observational studies, interventional trials, and the development of diagnostic
and therapeutic tools to ensure that scientific advances translate into meaningful benefits for patients worldwide.
Scientific Publications
This section compiles scientific publications co-authored by Duelo, A. and other members of the Institute, covering key topics such as DAO biochemistry, histamine metabolism, clinical phenotypes of DAO Deficiency, its underlying etiology, nutritional therapy, diagnostic methodologies, and the outcomes of enzymatic supplementation.
These publications contribute to the global body of evidence and support the Institute’s mission to advance rigorous, high-quality research in the field:
2025 | Duelo, A; Sánchez-Pérez, S.; Pellicer-Roca, S.; Sánchez-Buxens, S.; Comas-Basté, O.; Latorre-Moratalla, M.L.; Vidal-Carou, M.C.
Improvement of Histamine Intolerance Symptoms in Pregnant Women with Diamine Oxidase Deficiency: An Exploratory Study.
J. Clin. Med. 2025, 14, 4573.
2024 | Duelo, A; Sánchez-Pérez, S.; Ruiz-Leon, A.M.; Casanovas-Garriga, F.; Pellicer-Roca, S.; Iduriaga-Platero, I.; Costa-Catala, J.; Veciana-Nogués, M.T.; Fernández-Solà, J.; Muñoz-Cano, R.M.; et al.
Study Protocol for a Prospective, Unicentric, Double-Blind, Randomized, and Placebo-Controlled Trial on the Efficacy of a Low-Histamine Diet and DAO Enzyme Supplementation in Patients with Histamine Intolerance.
Nutrients 2025, 17, 29.
2024 | Duelo, A; Comas-Basté, O.; Sánchez-Pérez, S.; Veciana-Nogués, M.T.; Ruiz-Casares, E.; Vidal-Carou, M.C.; Latorre-Moratalla, M.L.
Pilot Study on the Prevalence of Diamine Oxidase Gene Variants in Patients with Symptoms of Histamine Intolerance.
Nutrients 2024, 16, 1142.
2023 | Okutan, G.; Perucho Alcalde, T.; Ruiz Casares, E.; Penadés, B. F.; Sánchez Niño, G. M.; Terrén Lora, A.; López Oliva, S.; Torrente Estríngana, L.; Duelo, A.; San Mauro Martín, I.
Cumulative effect of AOC1 gene variants on symptoms and pathological conditions in adult women with fibromyalgia: a pilot study.
Frontiers in genetics 2023, 14, 1180777.
2022 | Sánchez-Pérez, S.; Comas-Basté, O.; Duelo, A.; Veciana-Nogués, M. T.; Berlanga, M.; Vidal-Carou, M. C.; Latorre-Moratalla, M. L.
The dietary treatment of histamine intolerance reduces the abundance of some histamine-secreting bacteria of the gut microbiota in histamine intolerant women.
Frontiers in genetics 2023, 14, 1180777.
2022 | Sánchez-Pérez, S., Comas-Basté, O., Duelo, A., Veciana-Nogués, M. T., Berlanga, M., Latorre-Moratalla, M. L., & Vidal-Carou, M. C.
Intestinal Dysbiosis in Patients with Histamine Intolerance.
Nutrients, 14(9), 1774.
2022 | Blasco, H.; Wang, P.; Li, C.; Duelo, A.; Ruiz, E.; Perucho, T.
Prevalencia y perfil clínico de la deficiencia de diamino oxidasa (DAO) en pacientes con trastorno por déficit de atención e hiperactividad (TDAH).
Revista de Psoquiatría, Infanto-Juvenil. Vol. 39, Supl. 1.
2019 | Duelo, A.
Low-histamine diet treatment to two patients with migraine and diamine oxidase deficiency.
Journal or negative & no positive results. 2019.
2018 | Izquierdo-Casas, J.; Comas-Basté, O.; Latorre-Moratalla, M.L.; Lorente-Gascón, M.; Duelo, A.; Soler-Singla, L.; Vidal-Carou, M.C.
Diamine Oxidase (DAO) supplement reduces headache in episodic migraine patients with DAO deficiency: a randomized double-blind trial.
Clinical Nutrition. 2018.
2018 | Duelo, A., Berbel, M., Mantecon-Laviguerie, H., Comas-Basté, O., Latorre-Moratalla, M.L., Veciana-Nogués, M.T., Vidal-Carou, M.C.
Low-histamine diet supplemented with exogenous diamine oxidase enzyme is useful for treating migraine in patients with DAO deficiency.
Ann Nutr Metab.
2018-2017 | Izquierdo-Casas, J., Comas-Basté, O., Latorre-Moratalla, M.L., Lorente-Gascón, M., Duelo, A., Vidal-Carou, M.C. Soler-Singla, L.,
Low serum diamine oxidase (DAO) activity levels in patients with migraine.
Journal of Physiology and Biochemistry. 2017.
Innovation
Juanjo Duelo, chair of the board of the DAO Institute is widely recognized as one of the early pioneers in advancing scientific research on the enzyme Diamine Oxidase (DAO) and its clinical implications. In 2007, he founded DR Healthcare, a medical research company specifically created to generate scientific evidence, develop innovative DAO-based technologies, and help establish a regulatory framework in a field that at the time was still emerging.
Under his leadership, the company built a substantial portfolio of intellectual property and contributed to shaping international standards for DAO-related products. Duelo is the inventor of several foundational patents covering novel therapeutic and functional applications of DAO, work that demonstrated unprecedented innovation in this domain. After more than a decade of scientific and technological development, DR Healthcare was acquired in 2021 by the British group AB Foods.
Ongoing projects
Our ongoing projects include clinical studies, laboratory investigations, and technological developments designed to improve the detection, characterization, and management of DAO Deficiency.
Current lines of work involve:
- Evaluating clinical outcomes of DAO supplementation in specific patient populations
- Developing advanced diagnostic biomarkers and digital assessment tools
- Studying genotype–phenotype correlations
- Investigating dietary, microbiome-related, and metabolic contributors to histamine imbalance
- Building global research networks to standardize diagnostic and therapeutic protocols
- Analyses assessing the quality and enzymatic activity of DAO-based supplements
These projects are conducted in collaboration with international experts, healthcare institutions, and industry partners.
Future projects
Future research initiatives aim to deepen our understanding of DAO Deficiency and expand the scientific and clinical resources available to both professionals and patients. Upcoming projects include:
- Large-scale multicenter clinical trials
- Longitudinal cohort studies to assess long-term outcomes
- New therapeutic formulations and medical nutrition innovations
- Implementation of AI-supported diagnostic tools through our technological platform
- Creation of new educational tools for patients
- Expansion of global data registries to support epidemiological and translational research
These forward-looking projects embody the Institute’s commitment to advancing scientific innovation and improving patient care on a global scale. As with all cutting-edge research, their realization requires dedicated resources. To support this effort, the Institute has established a Partnership Program, enabling collaborations with pharmaceutical and food-industry companies that share an interest in DAO Deficiency and its growing clinical and scientific relevance.