Understanding the Root Causes of Low DAO
When you are navigating the complexities of histamine intolerance, it is natural to focus on the foods you are eating. However, understanding why your body struggles to process histamine in the first place is an equally important part of the puzzle. For many people, the answer lies with a specific enzyme: diamine oxidase, or DAO.
As we explore in our guide, What is DAO?, this enzyme is your digestive system’s primary tool for breaking down histamine from your diet. A lack of this enzyme, known as DAO deficiency, is a key factor in a majority of histamine intolerance cases. But what causes this deficiency? While genetics can play a role, several other factors can reduce your DAO enzyme’s production or block its activity.
1. The Health of Your Gut Lining
Your DAO enzyme is produced primarily in the lining of your small intestine. It follows, then, that the health of your gut is directly linked to your body’s ability to produce an adequate supply of DAO. When the intestinal lining (or mucosa) is damaged or inflamed, it can compromise the production of the enzyme.
Research has shown a connection between reduced DAO activity and certain gastrointestinal conditions, including:
- Inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis
- Coeliac disease
- Small intestinal bacterial overgrowth (SIBO)
It is important to remember that this is a correlation, and having one of these conditions does not automatically mean you will have DAO deficiency. However, it highlights the importance of working with a healthcare professional to address any underlying gut health issues, as supporting your digestive system is a foundational part of managing histamine intolerance.
2. The Impact of Certain Medications
Some commonly prescribed medications can interfere with the function of your DAO enzyme. They can act as “DAO inhibitors,” which means they block the enzyme from doing its job effectively. This can lead to a temporary, medication-induced form of DAO deficiency.
The list is extensive and includes certain types of:
- Painkillers (non-steroidal anti-inflammatory drugs, or NSAIDs)
- Antidepressants
- Diuretics
- Antibiotics
- Muscle relaxants
We want to be very clear: this is not a reason to stop taking any prescribed medication. If you are taking regular medication and suspect you have histamine intolerance, it is a valuable topic to discuss with your GP or specialist. They can help you understand if your medication might be playing a role and discuss the best path forward for your specific situation.
3. Alcohol's Dual Role
If you have ever experienced a near-instant headache or flushing after a glass of red wine, you have felt the potent connection between alcohol and histamine. This reaction is often twofold.
Firstly, many alcoholic drinks, especially fermented ones like wine and beer, are naturally high in histamine, directly adding to your histamine bucket. You can learn more in our article about why wine affects people with histamine intolerance.
Secondly, alcohol (specifically the compound ethanol) acts as a competitive inhibitor of the DAO enzyme. In simple terms, your DAO enzyme becomes busy trying to process the alcohol, which means there is less of it available to break down the histamine from your food and drink. This double impact, adding histamine while simultaneously blocking its breakdown, is why alcohol can be such a significant trigger for many people.
4. A Lack of Essential Cofactors
For your DAO enzyme to work correctly, it needs a team of nutritional helpers called cofactors. These are vitamins and minerals that activate the enzyme and allow it to perform its function. Even if your body is producing enough DAO, it cannot work effectively without these essential building blocks.
The key cofactors for DAO activity include:
- Vitamin C: An essential vitamin that plays a direct role in the breakdown of histamine
- Vitamin B6: Crucial for the function of many enzymes, including DAO.
- Copper: A mineral that is a central component of the DAO enzyme itself
- Zinc: Another vital mineral that helps DAO to function correctly
Ensuring your diet is rich in these nutrients is a foundational way to support your body's natural processes. We explore this topic in more detail in our guide to supporting natural DAO production.
The Role That Genetics Plays
As we explored in our article on how your genes influence histamine processing, some people have a natural predisposition towards lower DAO production. Everyone has a gene called their AOC1 gene, which contains the instructions for the creation of DAO in your body. If you have a variation in that gene (known as a SNP) then your body may naturally struggle to produce DAO, which in turn could lead to a DAO deficiency and a histamine bucket that overflows more easily.
Putting This Knowledge Into Practice
We understand that this information might feel overwhelming, but we want you to see it as empowering. It provides you with new avenues to explore with your healthcare team. It helps explain why your tolerance levels might fluctuate and offers a framework for understanding your body more deeply.
For those with a recognised DAO deficiency, it is possible to support your body's digestive processes. DAO supplements like our Aperitif are designed to be taken before you eat, providing your digestive system with a supply of the enzyme to help with the breakdown of histamine from your food and drink. As per the instructions on the packaging, one to three capsules taken 15 to 20 minutes before a meal can help with the digestion of histamine. Do not exceed the maximum daily dosage of three capsules.
Ultimately, managing histamine intolerance is a personal journey. By understanding the factors that can influence your DAO levels, you are better equipped to have informed conversations with professionals and make choices that support your wellbeing. For a list of dietitians specialising in histamine intolerance, please see our About page.
This article is for informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional for advice specific to your situation.