Identifying Histamine Intolerance
How is Histamine Intolerance Diagnosed?
The short answer is, it isn’t.
Histamine intolerance isn’t a diagnosis in itself, because histamine excess can result from many different causes, conditions and diseases. Tests that measure the level of histamine in the body, or determine DAO activity in an individual, do not show how those levels will affect bodily functions.
While some practitioners offer tests to determine diamine oxidase levels, this will not be helpful as low DAO by itself is neither diagnostic nor particularly helpful in guiding therapy at this stage in our understanding of the condition24. However, other studies25 suggest that tests that indicate low DAO levels in comparison to “normal” controls can be a useful indicator of histamine sensitivity in conjunction with other signs, and suggest further confirmation of the condition, preferably by evaluating the efficacy of a histamine-restricted diet.
Measuring levels of histamine in the patient’s body is unhelpful, as histamine levels fluctuate throughout the day in response to need. For example, after every meal histamine rises because it is required for the release of gastric acid in the stomach, essential to proper digestion, especially of protein.
A medical professional should first conduct a full investigation into the patient’s health, to ascertain whether an underlying medical condition is causing high levels of histamine in the body. Once any other conditions have been eliminated, a putative diagnosis of histamine sensitivity can be made with the following important indicators:
Symptoms that typically resemble allergy in the absence of a diagnosed allergy (see the typical symptom list)
Negative skin and blood tests for allergen-specific antibodies, indicating the absence of allergy
Negative tests and indicators for any disease resulting in excess histamine release such as mastocytosis/mast cell activation disorders (MCAD)
Absence of autoimmune disease that could result in the chronic release of histamine
Symptom relief after a trial of at least two weeks on the histamine-restricted diet
How can Histamine Intolerance Be Distinguished from Food Allergy?
Food allergy is a hypersensitivity reaction of the immune system; immunoglobulin E (IgE) type antibodies are produced when a person consumes a specific food protein. Reactions to food allergies are quick; when even the smallest amount of allergenic food is consumed by a person who is sensitive to it, inflammatory mediators are immediately released, and symptoms usually appear within minutes of the food entering the body.
The same symptoms are often seen in allergic reactions and in histamine intolerance. However, symptoms of histamine intolerance take much longer to appear after histamine-rich foods and beverages are consumed. This is because the level of histamine needs to reach a certain critical level before the tissues respond. So, a small amount of histamine will not cause a response—it is the total amount of histamine in the body, in excess of the body’s requirements, that causes the reaction.
For this reason, tests designed to provoke and measure an immediate response, such as the double-blind, placebo-controlled food challenge (DBPCFC)—regarded as the gold standard for allergy—will not detect histamine intolerance. Often symptoms will appear several hours after consumption of histamine-rich foods, as the total level of histamine in the body gradually rises and overwhelms the enzymes’ capacities to break it down. In the meantime, the patient has usually consumed a number of different foods. Thus, the association between cause and effect is often difficult to demonstrate in histamine intolerance. (Pg.28)
Symptoms of Histamine Excess
When the total body level of histamine exceeds the enzymes’ capacity to break it down, a wide variety of unpleasant symptoms can occur, typically including4:
Pruritus, especially of the skin, eyes, ears, and nose
Flushing or reddening of the skin
Urticaria Including “idiopathic urticaria” and “autoimmune urticaria”
Angioedema, especially of facial and oral tissues and sometimes the throat.
Rhinitis
Rhinorrhea
Conjunctivitis
Digestive problems, including heartburn, indigestion and reflux
Hypotension
Tachycardia
Chest pain
Symptoms resembling an anxiety or panic attack
Headaches
Psychological symptoms including confusion and irritability
Very rarely, there may be a brief loss of consciousness usually lasting for only one or two seconds
Not all of these symptoms will occur in any one person, and the severity of symptoms will increase with the levels of histamine present in the body.
Many of these symptoms are the same as those seen in an allergic reaction; that is because the body releases a great deal of histamine during an allergic response. Given that the symptoms of histamine intolerance and allergic reactions are often identical, and the symptoms of histamine intolerance are so diverse and often misinterpreted, histamine intolerance often goes undetected and underdiagnosed, even though it is estimated that 1% of the general population suffers from it4.
Why Does Excessive Histamine Cause Problems?
The symptoms of histamine sensitivity/intolerance only occur when there is an excessive amount of histamine in the body.
Think of histamine intolerance like a bucket filling up with water. Everything is fine while the water is below the top of the bucket; however, as soon as the bucket overflows, serious problems can occur. Every person has a different sized “bucket”; the point of overflow and the appearance of symptoms is called a person’s limit of tolerance, and this level varies between individuals.
So, why does the bucket overflow at all? It is because, for various reasons, histamine levels in the body can increase to a point that exceeds the body’s ability to remove the excess.
How Does the Body Usually get Rid of Histamine?
Excess histamine is broken down and removed from the body by enzymes, specifically, diamine oxidase (DAO), and to a lesser extent, histamine N-methyl transferase (HNMT). These two enzymes occur in various tissues and act throughout the body8. People with low levels of these enzymes have a significantly lower threshold level of histamine tolerance than the normal population.
The two enzymes work in different ways, which are explored later in this chapter. Under normal conditions, when histamine levels from any source rise above a certain level, these enzymes rapidly degrade the excess. However, when the rate of breakdown is insufficient to deal with the excess, the total level of histamine in the body rises. At a certain critical level, signs and symptoms occur—these are the result of histamine coupling with histamine receptors on specific cells—producing a clinical picture that is often indistinguishable from allergy.
This is obviously most pronounced in people with low points of tolerance. However, people who produce normal levels of DAO can also experience symptoms—including severe headaches and flushing9—if they exceed the capacity of their enzymes to break down histamine (e.g. by eating a meal containing massive amounts of histamine). Even a large bucket can still be overfilled!
It’s therefore important that histamine intolerance sufferers ensure that their histamine levels are manageable, to stop their “bucket” from overflowing and the symptoms from occurring.(Pg.9)
“Histamine Intolerance: A Comprehensive Guide for Healthcare Professionals (Comprehensive Guides Book 1)” by Janice Joneja, Hannah Lawrence
https://a.co/esimJFJ
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