Histamine intolerance is a relatively common condition that affects between 3-6% of the population. This condition can result from either an increased availability of histamine or impaired histamine degradation. In healthy individuals, histamine is rapidly eliminated from the body by two enzymes, diamine oxidase (DAO) and histamine n-methyltransferase (HNMT). However, a malfunction in these enzymes, mainly in DAO, can lead to an accumulation of histamine.
Several factors can cause overproduction of histamine. Allergies (IgE reactions), gastrointestinal bleeding, histamine-rich foods, intestinal permeability (leaky gut), mastocytosis (the presence of too many mast cells in the body), small intestinal bacterial overgrowth (SIBO), and mold toxicity are some of the primary causes of histamine overproduction. Additionally, a SARS-CoV-2 infection can cause increased histamine release, leading to the manifestation of symptoms of histamine intolerance.
On the other hand, several factors can cause a low DAO/DAO malfunction. Genetic predisposition, gastrointestinal disorders (e.g., inflammatory bowel disease), foods that block the release of DAO, copper, vitamin C and B6 deficiency, interference by certain medications (e.g., non-steroidal anti-inflammatory drugs, antidepressants, antihistamines, histamine (H2) blockers), and intestinal permeability (leaky gut) are some of the factors that can cause DAO malfunction.
The symptoms of histamine intolerance are wide-ranging and can affect multiple organs and systems in the body. The symptoms can be acute or chronic, mild, or severe. It is common for more than one symptom or disorder to occur simultaneously. The symptoms can be categorised into nervous system symptoms (headache/migraine, dizziness, vertigo), cardiovascular system symptoms (tachycardia, hypotonia, hypotension, arrhythmias), reproductive system symptoms (menstrual cramps), skin symptoms (itching (pruritus), flushing, urticaria, dermatitis, swelling), gastrointestinal system symptoms (bloating, flatulence, postprandial fullness, diarrhoea, abdominal pain, constipation, nausea, vomiting), and respiratory system symptoms (rhinorrhea, rhinitis, nasal congestion, dyspnea, sneezing, asthma).
Some common high histamine foods include fruits such as strawberries, raspberries, lemons, oranges, and other citrus fruits, banana, pineapple, kiwi fruit, pears, papaya, guava, and fermented or dried fruits. Vegetables such as spinach, tomatoes (including ketchup, tomato juice, etc.), eggplant, avocado, olives, pumpkin, fermented and pickled vegetables, and mushrooms are also high in histamine. Cereals, grains, and legumes such as malt, wheat germ, wheat, foods with yeasts (fresh bread, sourdough), chickpeas, lentils, dried beans, soy, and soy products, nuts, and seeds like walnuts, cashews, peanuts, and pistachios are also high in histamine.
A low histamine diet involves several general tips that can help minimise histamine intake. These tips include cooking all your own meals, avoiding processed foods and eating foods as close to their original form as possible, eating as fresh as possible, freezing raw meat or cooking it, eating foods as soon as possible after purchase, reading food labels to find out whether a food contains incompatible ingredients, keeping a food journal to record symptoms and triggers, and seeking guidance from a health/medical practitioner to ensure adequate nutrient intake.
