DEAR DR. BLONZ: I was diagnosed with chronic idiopathic urticaria, and it is important that I go on a low histamine diet -- at least, that is what I have read. Is there any guidance that you might provide? There is little information available about histamine in foods. -- S.I., San Jose, California
DEAR S.I.: First, to break down the diagnosis for your fellow readers: Urticaria is a condition that can involve hives and itchy rashes. The "chronic" descriptive means that it is an ongoing condition, as opposed to an itch from an insect bite that annoys and then is history. "Idiopathic" means it's something you have developed and it is unclear why.
The idea of a low-histamine diet is somewhat misleading, because preformed histamine is not found in foods to any appreciable degree. You may not be seeking a diet that is "low in histamine" so much as one that limits foods that tend to trigger a histamine release within body.
Histamine is involved with inflammation, and while we tend to think of inflammation as a bad thing, it is an important element in systems designed to increase blood flow to specific regions. It can also facilitate tissue repairs, the elimination of unwanted substances, and immunological responses to microbiological invaders. The body makes its own histamine from histidine, an essential amino acid; histamine is then stored in "mast cell" reservoirs that are distributed throughout the body.
As can be discerned by the existence of "anti-histamine" products, histamine also has a dark side. It is responsible for the cold- or allergy-like symptoms of sneezing, itchy eyes, runny nose and, in your case, urticaria. Because of these effects, we often turn to antihistamines to provide a measure of symptomatic relief.
A low histamine-producing diet is a quest to identify offending foods. Because histamine is often involved in allergic-type reactions, the first type of food to avoid are those most likely to promote allergies or hypersensitivity reactions, including: shellfish, eggs, cheese, hard sausage, sauerkraut, chocolate, nuts, tomatoes, berries, wine and beer. This would have to be tailored to your situation, and that can mean keeping a log of foods and any untoward experiences related to your condition.
I have also seen lists that say to eliminate food additives such as sulfites, benzoates, nitrites, salicylates, preservatives, artificial colors (especially tartrazines), as well as other foods such as milk, citrus, cola, cinnamon, peas, beans, pork and wheat.
The next foods to consider avoiding are those with unusually high concentrations of "free" histidine. While not an issue with the histidine that is a part of protein, free histidine in foods is a potential problem because there are enzymes that can change this histidine into histamine.
Foods with high levels of free histidine include fish such as tuna, bonito, mackerel, blue marlin, sardines, herring and anchovies. Avoiding these high-histidine foods removes another possible contributor to an increased histamine level in the body.
A study published in the February 2000 issue of the European Journal of Clinical Nutrition found that this strategy has potential: Patients with chronic idiopathic urticaria experienced significant improvement after 21 days on a diet that decreased the types of foods above. Consider consulting with a dietitian to help formulate your strategy.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.