People generally only think about histamine when they have an allergic reaction or seasonal allergies. However, histamine has numerous other roles in the body. Histamine is sent to a receptor in your stomach, for example, when you think about or eat food. Your stomach then releases acid and other digestive enzymes to begin significant digestion of that food. In fact, there are at least four different histamine receptors throughout your body. Histamine is critical to many biological pathways and therefore necessary for typical bodily functions. Without histamine, you would not be alive.
Many living things produce histamine. Plants have varying levels of histamine present at different points of maturity and the more ripe the edible portion of a plant is the more histamine is likely to be present. Some of this is due to the work of bacteria present inside and all over all just about everything. Food which is intentionally aged or fermented in anyway is therefore high in histamine content. Additionally there are histamine producing organisms living in your digestive system helping to digest what you have consumed.
The histamine present in your body then is related to how much histamine it has made, how much histamine the organisms in the digestive track have made and how much histamine was consumed.
Since the body makes and consumes histamine, it also produces two enzymes which degrade histamine: DAO (formerly known as histaminase) and histamine-N-methyltransferase (HNMT). DAO is found in only particular areas of the body while HNMT is widely expressed in human tissues. When these enzymes encounter histamine they degrade it. Enzymes are finely tuned biological molecules. Since there always has to be a baseline amount of histamine present for normal bodily function, DAO and HNMT are never supposed to totally eliminate histamine's presence in your body.
Now, consider your body's ability to degrade histamine to be represented as a bucket. Inside that bucket is the amount of histamine in your body that has not yet been degraded. The bucket can be mostly empty or mostly full but you feel the same - totally fine. Histamine is doing what it is supposed to be doing in your body and you have not surpassed the capacity of the bucket.
What can make your bucket overflow?
- An allergic reaction.
- Consuming large quantities of histamine in your diet
- Producing more histamine than is needed for general bodily function
- Not having appropriate DAO and/or HNMT activity in your body
The crazy thing about this is that your histamine bucket can be rather large or rather small depending on the activity of DAO and HNMT at a given time. Additionally, the histamine present comes from multiple sources and is additive. So your bucket might be quite full on one day because you made a lot of histamine and ingested a lot of histamine. It is likely on that day nearly anything else will cause your bucket to overflow. On another day, you made very little histamine and ate very little histamine. It would then take a much larger amount of histamine to cause your bucket to overflow.
Since I was ten years old I have often described my body as being in "freak out mode" for days, months and even years. For some reason, my body's "histamine bucket" is often overflowing.
My next post will deal with what might cause you to make more histamine and what might decrease your body's ability to degrade histamine.