Mention “histamine” and the word “allergy” pops to mind. Rightly so, because during an allergic reaction certain white blood cells known as mast cells and basophils release an inordinate amount of histamine, a chemical that then travels through the bloodstream and fits into “receptors” in cells that make up our tissues, much like a key fits into a lock. And when the “key” fits, it unlocks the typical symptoms such as the watery eyes, runny nose, hives, itching and breathing problems that we associate with allergies. Simply put, an allergy is a hypersensitivity disorder of the immune system, essentially a response to substances that most people’s bodies perceive as harmless. “Antihistamines” control allergy symptoms by blocking histamine activity. But our body can also produce enzymes such as histamine-N-methyltransferase and diamine oxidase (DAO) capable of inactivating histamine. A deficiency in these enzymes leads to a disease known as histaminosis or histamine intolerance (HI). This can be a real nuisance for the 2% of the population that suffers from this condition. The problem is that histamine is not only produced by cells in our immune system, it can also occur naturally in some foods such as champagne, wine, beer, sauerkraut, vinegar, pickles, mayonnaise, tofu cheese, sausages, processed meats, mushrooms, prepared salads, tinned vegetables, dried fruits, seeds, nuts, yeast, chocolate, cocoa cola and crustaceans. Fish present a particular problem because naturally occurring bacteria in fish produce an enzyme called histidine decarboxylase that forms histamine from histidine, an amino acid that is released when fish proteins decompose.
Even people who do not suffer from the enzyme deficiencies that cause histaminosis can react to large amounts of ingested histamine with vomiting, diarrhea, skin rash, headaches, dizziness, itchiness of the skin, tingling of the mouth and lips and a peppery taste sensation. The term used in this case is “scromboid poisoning” after the family of fish such tuna, sardines, mahi-mahi, swordfish and marlin that are the most likely to be tainted with histamine. Contrary to popular belief, histamine cannot be destroyed by cooking or freezing. Fish should be purchased from reputable suppliers who store fish on ice or under refrigeration because as soon as fish starts to decompose, histamine is released. In case you should ever find yourself a victim of scromboid poisoning, remember to take oral antihistamines. But for those with histamine intolerance, antihistamines may be ineffective. That’s because there are different types of histamine receptors and antihistamines block only some. Since there is no cure for histamine intolerance, patients must adjust to a low-histamine diet. A major problem, however, is that people may suffer for a long time from an array of symptoms that can include digestive problems, migraines, “brain fog” and respiratory issues before they are ever diagnosed with histaminosis. It takes a vigilant physician to think of ordering a test for the specific enzyme deficiencies involved. But when a diagnosis is made, adherence to a low histamine diet can change what seems like an endless misery to a life worth living.