What is Histamine Intolerance?
Actually, let’s start off with what is histamine? This is going to be important for you to know if you deal with any of the multitude of histamine overload symptoms: hives, swelling, headaches, anxiety, tightness in the chest, itchiness anywhere in the body, anxiety, stuffy or runny nose, digestive symptoms, flushing of the skin, and the list goes on.
Histamine is a chemical found in almost all the tissues of the body. Mostly, it is stored in cells called Mast Cells. Ever heard of them? Mast cells are a major player in our immune systems but I’ll explain more about this in the next blog post. Histamine is responsible for a lot of the allergy type symptoms people get when they are exposed to something they are allergic to, like itching and running nose. It is not just a nuisance chemical though, it actually does a lot of good things and we need it. It does thinks like signal the production of stomach acid so you can digest your food better and acts as a neurotransmitter, which helps your cells communicate with each other in things like our sleep-wake cycle. Histamine is excitatory and so it can impact your sleep, not letting you fall asleep well or waking you up in the middle of the night when it is in excess in our bodies.
Histamine is made endogenously (within our own bodies) and we also get it from our food. Different foods have different levels of histamine in them. That’s why a low histamine diet can help alleviate symptoms for people with Histamine Intolerance (spoiler, it does not cure Histamine Intolerance and only helps to manage symptoms). We also get histamine from our food when we break down an amino acid called histidine. There is another way we get histamine in our bodies, and that is from bacteria in our stomach and intestinal system. I’m sure you have heard of probiotics. Those are ‘friendly’ bacteria that live in our guts and help us do all kinds of things like make vitamins and nutrients. There are good bacteria and some not so great bacteria that can affect our health in a negative way. Some bacteria are just outright bad and we don’t want them, like those nasty pathogenic strains of E Coli that can make us very sick, although note there are friendly strains of E coli! Some bacteria also make histamine. Even worse some of these bacteria actually upregulate our conversion of that amino acid histidine into histamine. Double whammy!
Our bodies have built in ways of processing histamine so that it does not build up in our system. One way is through an enzyme largely made in our intestinal lining, called Diamine Oxidase (DAO). This enzyme helps us break down histamine that comes in from our food or is otherwise produced in our intestines. It is also found in our kidneys. Another enzyme called Histamine N-Methyltransferase (HNMT) metabolizes the histamine that circulates throughout our bodies. Another way histamine can get processed is through our livers, and specifically through a phase 2 detoxification pathway called acetylation (more about phases of liver detox in an upcoming blog). Histamine Intolerance occurs when we have too much histamine in our body and not enough ability to clear it out. So, Histamine Intolerance is not a case of true allergy but rather indicates an imbalance in our bodies. There are all kinds of reasons for imbalances leading to Histamine Intolerance to occur. But before we dive into that, I want to explain more about Mast Cells. Histamine Intolerance can be part of a continuum of Mast Cell Disease, such as Mast Cell Activation Disorder. This is a more serious condition. Some experts disagree with me about this all being on a continuum, and sometimes it is not, but I have been all over this continuum myself and it’s important to understand mast cells when we are talking about Histamine Intolerance. You will learn all about this in my next blog!
