Diamine oxidase (DAO) deficiency occurs when the body cannot adequately process histamine, a natural compound involved in immune response, digestion, and nerve signaling. When DAO, an enzyme responsible for breaking down histamine, is not functioning adequately, histamine can accumulate in the body. This accumulation can lead to various symptoms.
The Role of DAO
DAO is an enzyme primarily found in the lining of the small intestine, though it is also present in the kidneys and, during pregnancy, in the placenta. Its main function is to break down excess histamine ingested through food or produced within the body. DAO acts as a biological barrier, preventing excessive amounts of histamine from being absorbed into the bloodstream from the gut. This process helps maintain balanced histamine levels.
Why DAO Levels Can Be Low
Several factors can contribute to insufficient DAO activity in the body. Genetic predispositions play a role, as variations in the gene responsible for DAO production can reduce the enzyme’s activity or expression, making individuals more prone to histamine buildup.
Certain medications, including some antidepressants, antihistamines, pain relievers, and antibiotics, can inhibit DAO activity. Gut health issues like inflammatory bowel disease, “leaky gut,” or small intestinal bacterial overgrowth (SIBO) can also impair DAO production or function, as most DAO is produced in the gut lining.
Nutrient deficiencies can impact DAO activity, as copper, vitamin C, vitamin B6, zinc, vitamin B2, and magnesium are important cofactors for the enzyme. Inadequate intake or absorption of these nutrients can reduce DAO effectiveness. Additionally, alcohol and some foods can temporarily inhibit DAO or trigger histamine release, further elevating histamine levels.
Common Indicators of DAO Deficiency
When DAO activity is low, histamine can accumulate in the body, leading to a wide range of non-specific symptoms that can affect multiple body systems. Digestive issues are common, including bloating, abdominal pain, diarrhea, nausea, and reflux, often resembling irritable bowel syndrome.
Skin manifestations like hives, eczema, itching, flushing, and swelling are also frequent, sometimes mistaken for allergies. Respiratory symptoms may include nasal congestion, sneezing, runny nose, or asthma-like symptoms such as wheezing and shortness of breath.
Neurological indicators can encompass headaches or migraines, dizziness, fatigue, anxiety, and brain fog, with some individuals also experiencing sleep disturbances. Cardiovascular symptoms may include heart palpitations, an irregular or fast heart rate, and low blood pressure. Other possible indicators include menstrual irregularities and muscle pain. The varied nature of these symptoms makes identifying DAO deficiency challenging, as they often mimic other health conditions.
Identifying and Addressing DAO Deficiency
Identifying DAO deficiency involves a comprehensive assessment of symptoms and dietary history. There are no universally accepted direct diagnostic tests for histamine intolerance, making diagnosis a process of elimination. While blood tests can measure DAO activity or histamine levels, their results can vary due to histamine’s rapid metabolism. A common diagnostic tool is a low-histamine elimination diet, where high-histamine foods are temporarily removed to observe symptom improvement.
Addressing DAO deficiency often involves a multifaceted approach. Dietary modifications are a cornerstone of management, focusing on reducing intake of histamine-rich foods like aged cheeses, fermented products, processed meats, and alcohol. Minimizing foods that trigger histamine release or inhibit DAO function is also important. Over-the-counter DAO enzyme supplements, often derived from porcine kidney extract, can be taken before meals to aid in breaking down dietary histamine.
Addressing underlying causes of low DAO is also a key strategy. This may involve improving gut health through dietary changes, probiotics, and prebiotics to support the gut microbiome and intestinal lining. Correcting nutrient deficiencies can also support DAO synthesis and activity. Managing stress through techniques like mindfulness and yoga can indirectly support histamine regulation. Consulting a healthcare professional is important for proper diagnosis and to develop a personalized management plan, as self-diagnosis may not be effective.