Histamine is an inflammatory mediator. When a release of histamine is triggered it helps the immune system respond to threats (e.g. infections, allergies (which are essentially the body’s “imagined” threats)). Capillaries are dilated to increase circulation and become more permeable to help white blood cells get to where they are needed. This is helpful when it’s needed and assuming the process is well-managed within the body.
As with many things in the body (e.g. cholesterol, estrogen, fibrinogen, cortisol), too much of a good, normal, natural thing can become debilitating or even life-threatening. Histamine intolerance is about the body becoming overloaded, where the amount of histamine present outweighs our ability to break it down (detoxify it). Histamine comes from many sources. Externally, we primarily get it from our foods. Internally, we produce it in response to immune threats (as above), and some of the microbes in our gut also produce it as part of their normal metabolism. In a healthy, balanced body, an enzyme in the GI tract (DAO, diamine oxidase) handles the histamine in our food. Internal to the body, another enzyme system handles intracellular histamine (histamine N-methyltransferase or HNMT). Of course, nutrition is key here too, as both of these enzyme systems require B vitamins and minerals as cofactors. And methylation (that pesky SNP issue again!) is also required to reduce intracellular histamine.
Unfortunately there is no single labwork marker or panel that can readily identify histamine intolerance. Single, one-time measurements of histamine in the blood may be elevated due to specific triggers, but that doesn’t mean a person has an imbalance on an ongoing basis. To be a helpful marker, histamine needs to be assessed several times to establish a trend. There are many more advanced, functional testing options that can be helpful (e.g. stool test, lipid peroxides – to assess oxidative stress which can come from sustained, high histamine). But you will find some clues in conventional labwork too, such as looking at the percentages of eosinophils and basophils in a Complete Blood Count. Both of these WBCs secrete histamine. In a healthy, happy, relaxed immune system, eosinophils are usually very low (<3% of WBCs) and basophils will be zero (or nearly zero). Basophils are particularly strong secretors of histamine, so that’s a strong clue. Many clients can also take a look at their total IgE antibody level in the blood, an indication of the body’s immune defenses being armed to secrete histamine. Again, histamine levels can be high (creating the intolerance) due to strong sensitivity (high release) and/or poor detoxification ability (where it builds up over time). Suboptimal Vitamin D and zinc (ideally measured through RBC Zinc) can also contribute to immune system dysregulation.
The easiest way to help a client to determine if they struggle with histamine intolerance is to do an experiment. Help them to implement a low-histamine diet for a full two weeks and also support them with DAO supplements with meals. If histamine is a challenge, they should experience significant relief. My experience is that clients really want to be able to explore and assess their own challenges, so this type of empowered experiment is well-received, especially with your well-worded educational introduction (smile).
Foods high in histamine include dairy foods (especially cheese!), processed lunch meats, beer and wine (especially red wine), foods made with yeast (e.g. bread), all fermented/cultured foods, vinegars, anchovies, avocado, and canned fish (e.g. sardines). But you might be surprised to learn that there are foods which promote histamine release without having high levels themselves e.g. chocolate, eggs, bananas. Diets very high in protein can also be part of the problem, as the amino acid histidine is converted to histamine in the body. A low-histamine diet can be a challenge, but remember that a client doesn’t have to implement it 100.0% in order to have a valid elimination trial and learn how their unique body responds. There are some excellent resources available online to guide your clients (e.g. https://www.mindbodygreen.com/0-11175/everything-you-need-to-know-about-histamine-intolerance.html )
Supplements that can help include
These ideas can help to bring your client some substantial relief (and commitment to their work with you) while you help them to get to the root cause of their challenges. Sometimes our clients have histamine intolerance simply because of genetics such as impaired methylation or impaired production of DAO or HNMT. Supplements can be an easy way to overcome the detriment of genetics. However, most people struggle with histamine intolerance between of a basket of interconnected imbalance in the body that you can in time help them to resolve. Common contributors include low adrenal function (specifically low cortisol which typically promotes more Th2 hyper-reactivity to external threats), microbial imbalance/overgrowth in the gut (aka dysbiosis), too much overall protein intake, insufficient levels of key immune system nutrients (e.g. Vitamin D, Zinc, Copper, B vitamins), toxic environment/burden, chronic stress or lack of sleep, and (yes, believe it or not!) chronic, long-term use of antihistamine drugs (which over-ride the body’s natural regulatory systems and create more sensitivity).
Get comfortable catching and exploring Histamine Intolerance. When you do, you will enjoy some extremely grateful clients, who have often struggled for many years in a medical system that has a hard time acknowledging (much less addressing) this particular dynamic.
If you’re passionate about this topic and want to do a deeper dive (especially if you want to learn more about relevant labwork), I highly recommend Dr. Ben Lynch’s article here.