This article was written by Adriana Duelo, clinical nutritionist specialized in digestive pathologies and DAO deficiency, and published in the Mazorca magazine nº74 (magazine of The Spanish Federation of Coeliac Associations).

If you are celiac or you have a non-celiac gluten sensibility (NCGS) and you have not yet started a gluten-free diet or you have only recently been on it, your intestinal villi may still be damaged. This means that you have a reduced part of the intestinal surface to absorb nutrients and synthesize digestive enzymes due to the few epithelial cells there are. Hence, a common characteristic among patients is the deficiency of certain minerals such as calcium or iron, vitamins such as D or group B and/or digestive enzymes, such as lactase or diamine oxidase (DAO).

In 1986, Dr. Forget, a pediatrician at Bavière Hospital (Belgium), linked the DAO enzyme deficiency with celiac disease. His research focused on finding a less aggressive alternative to intestinal biopsy to diagnose celiac disease. Forget found that patients with celiac disease had the DAO activity enzyme reduced, both in the intestinal mucosa and at the serum level. This result made him think that it could be a reflection of the low quality of the enterocytes (villus cells), a characteristic feature of a celiac intestine. This result gave rise to other researchers such as W.J. Schnedl, D. Enko and K. Griauzdaitė, among others, will seek more answers to the possibility that the DAO enzyme could be used as a biomarker to evaluate the intestinal status of people with celiac disease or NCGS.

But, how could this DAO deficiency affect us? Let’s first see what the DAO is and what its functions are:

DiAmino Oxidase or DAO is a digestive enzyme located in the small intestine, synthesized by enterocytes and is responsible for metabolizing a molecule that we ingest through the diet, histamine. The primary function of DAO is to prevent histamine from entering the bloodstream. If histamine manages to enter, this inflammatory molecule can build up and lead to various symptoms.

To suspect a possible DAO deficiency, it must be present two symptoms from different systems at least:

• Nervous system: migraine, vascular headaches, vertigo and/or ADHD.
• Digestive system: abdominal bloating, intestinal irregularities, functional dyspepsia and/or cyclic vomiting syndrome.
• Dermal system: itching, redness and/or edema.
• Respiratory sistem: non-allergic rhinitis, sneezing and/or asthma.
• Locomotor system: muscle and/or joint pain.
• Constitutional system: chronic fatigue and/or sleep irregularities.
• Cardiovascular system: hypotension and/or tachycardia.

All mammals have DAO enzyme to a greater or lesser extent. But it is estimated that 15% of the population suffer from a deficiency, according to the International Society of DAO Deficiency. Although it is true that the main origin is genetic (AOC1 gene), as with lactose intolerance, an acquired DAO deficiency could develop if there is some type of impairment in the small intestine. This fact is common in inflammatory bowel diseases such as ulcerative colitis, Crohn’s disease, celiac disease or non-celiac gluten sensitivity (NCGS).

After following a gluten-free diet, it is common for the intestinal villi to recover within a few weeks and, with it, also the enzyme production such as lactase or DAO. But sometimes it does not happen and the patient continues to have specific discomfort or symptoms, usually extradigestive. In these cases, it is essential to investigate a little more and check if there is lactose intolerance and/or DAO deficiency. In this possible situation, the gluten-free diet would be accompanied by a lactose-free diet that is also low-histamine. On the other hand, it would be advisable to accompany the diet with DAO enzyme until the intestinal villi regenerate and part or all of the enzymatic activity is recovered.

Below I share some gluten-free, lactose-free and low-histamine breakfasts and dishes:

1. 1. Buckwheat toast with sesame or tahini cream and blueberry compote on top.
   2. Coconut or soy yogurt with chia seeds and raspberries.
   3. Scrambled egg yolks with arugula and rice drink.
   4. Carrot cream with potato, turmeric, ginger and pepper.
   5. Lentil salad with red pepper, broccoli, olives and lactose-free fresh cheese.
   6. Beef with reduced onion and apple sauce, rice and wild asparagus.
   7. Hake with sweet potato and bitter leaf salad with mushrooms.

Bibliography

Forget, P., Grandfils, C., Van Cutsem, J. L., & Dandrifosse, G. (1986). Diamine oxidase in serum and small intestinal biopsy tissue in childhood celiac disease.

Journal of pediatric gastroenterology and nutrition, 5(3), 379-383. https://doi.org/10.1097/00005176-198605000-00007

Griauzdaitė, K., Maselis, K., Žvirblienė, A., Vaitkus, A., Jančiauskas, D., Banaitytė-Baleišienė, I., Kupčinskas, L., & Rastenytė, D. (2020). Associations between migra- ine, celiac disease, non-celiac gluten sensitivity and activity of diamine oxidase. Medical hypotheses, 142, 109738. https://doi.org/10.1016/j.mehy.2020.109738

Schnedl, W. J., Lackner, S., Enko, D., Schenk, M., Mangge, H., & Holasek, S. J. (2018). Non-celiac gluten sensitivity: people without celiac disease avoiding gluten-is it due to histamine intolerance?. Inflammation research: official journal of the European Histamine Research Society … [et al.], 67(4), 279-284. https://doi. org/10.1007/s00011-017-1117-4

Schnedl, W. J., Mangge, H., Schenk, M., & Enko, D. (2021). Non-responsive celiac disease may coincide with additional food intolerance/malabsorption, including histamine intolerance. Medical hypotheses, 146, 110404. https://doi.org/10.1016/j.mehy.2020.110404

Schnedl, W. J., Schenk, M., Michaelis, S., Enko, D., & Mangge, H. (2023). Functional Abdominal Pain Disorders in Children May Be Associated with Food Intolerance/Malabsorption. Children (Basel, Switzerland), 10(9), 1444. https://doi.org/10.3390/children10091444

Honzawa, Y., Nakase, H., Matsuura, M., & Chiba, T. (2011). Clinical significance of serum diamine oxidase activity in inflammatory bowel disease: Importance of evaluation of small intestinal permeability. Inflammatory bowel diseases, 17(2), E23-E25. https://doi.org/10.1002/ibd.21588