Diagnosing and treating histamine intolerance is quite complex.
First, for checking neurological levels, you can test your levels of histamine in blood or urine nowadays quite simply. You will find a Histamine Test in the Neurotransmitters section of the shop.
For the immunological side, I will normally start by trying to confirm a high level of histamine in the blood and checking for a low level of the DAO enzyme that helps us to break it down. It can be as simple as boosting DAO levels to bring the histamine down. It’s not always easy to do because the body regulates levels throughout the day with need, but often you can get an overall high level result or people test when they are in a reaction to see if it is histamine-related. Histamine will rise after a meal as it is needed to release gastric acid into the stomach so best to take your sample in between meals. You can see the histamine and DAO test here.
I also found during research that Eosinophil Cationic Protein (EPC) works as an alternative marker to DAO. EPC basically measures an inflammatory allergy reaction; the higher the EPC score, the more severe the allergy reaction is. In the homeopathic study I refer to later, they used EPC as an additional marker and found that as DAO went up during treatment, EPC went down. You can read more about EPC here and you can use a Lab Test Request form on the shop if you need it.
Another little clue I picked up during my research is that sometimes there is a correlation between the basophil levels you find on your normal GP blood tests and histamine levels. Generally, if basophils are high, it can be a clue that histamine could be.
Of course, a food diary might help you discover if histamine is a likely issue for you. I only thought of it for myself when I looked at the histamine lists and realised how my core foods are all low histamine. Aha, I thought! So it can be a useful exercise – what foods do you mainly react to, what meals are your worst, could they be high histameanie ones maybe? You can also extend that to any reactions to meds and probiotics – are you worse after the histamine liberators or DAO decreasers maybe?
If you suspect you have HIT, often you can confirm the problem by doing a low histamine diet trial and seeing how you feel. If you feel better, histamine could be an issue and is worth looking further into. Of course, it could be something else coincidental as lowering histamine often inadvertently helps remove foods with other potential issues – think FODMAPs, common allergens like dairy etc so consider those too.
Do also investigate other conditions that are often confused with histamine intolerance. Those might include IgE allergies, other intolerances, for example to fructose, lactose, oxylates or salicylates, gluten related disorders such as coeliac disease or non-coeliac gluten sensitivity (NCGS), autoimmune disorders and mast cell disorders.
The timing of symptoms in HIT can also give you a clue. The first symptoms often appear within about 10-15 minutes, then more from about 30 minutes to several hours later. The early-onset symptoms may be a clue to DAO deficiency and later symptoms to a methylation or HNMT problem. More on these below.
This is a gross generalisation, but a common pattern might look like this: low level increases in histamine will usually result in an increase in stomach acid (so reflux, indigestion etc) and your heart rate can go up. As it rises, the next symptoms might be a fast or irregular heartbeat, migraine and skin issues such as hives, itching and flushing. Even higher levels can raise blood pressure and if very high, you can get bronchial spasms or asthma-like problems. The symptoms you get will give you a clue to how high your histamine load is!
Hope that review of testing helps! Final part of the series will be on treatment….