Histamine Intolerance
TL/DR
· Histamine intolerance is a GI condition that causes diarrhea, bloating and abdominal pain. It is an often-overlooked cause of IBS symptoms.
· The best way to think about HIT is that it is very similar to Lactose Intolerance – symptoms result from lack of the enzyme needed to digest it.
· Histamine is a substance that is found naturally in foods, and it is broken down by an enzyme that resides in the lining of the small intestine. Some people don’t make enough of this enzyme (called DAO) and others have lost their enzyme stores because of damage to the lining.
· There is no sure-fire test for diagnosing HIT, so we do a survey of symptoms, try a low-histamine diet, and sometimes measure Diamine Oxidase (DAO) levels. If DAO levels are very low, it supports the diagnosis, and suggests that you would benefit from supplementation.
· There are two ways to approach symptoms – one is to avoid histamine in foods (similar to using lactose-free milk) and the other is to supply the missing enzyme (similar to using Lactaid). You may also benefit from a histamine blocker. I recommend you do all of these things for two weeks, then gradually re-introduce foods and reduce histamine blocker and DAO enzyme use. This is best done with the help of a knowledgeable dietician.
· In addition to the above, stop/avoid using probiotics because they may contribute to the problem.
· As always, optimize your microbiome by eating a diversity of plants, since HIT may be a result of dysbiosis.
Histamine intolerance (HIT) is a condition that causes symptoms throughout the body, but because 75% of our histamine receptors are in the gut, this is a major area where symptoms manifest. Diarrhea, bloating, abdominal distension, gas and abdominal pain are common. Half of patients have constipation, and there can also be nausea and vomiting. It is an often-overlooked cause of IBS symptoms, and one that traditional medicine is only beginning to come around to.
HIT can be thought of in the same way that we think about lactose intolerance – histamine is present in foods, and requires an enzyme, Diamine Oxidase (DAO) to break it down. When we don’t have enough of the enzyme, we get symptoms.
Histamine is found in high levels in canned fish and shellfish, chocolate, leftovers (because of the action of bacteria), fermented food (cheese, salami, beer and bread included) and even peanut butter. When ingested, if it is not broken down, it goes on to do what histamines do – it turns on our allergic system. Most of the histamine receptors in our bodies reside in the small intestine, and when they get turned on, you get bloating due to congestion in the wall of the small intestine, diarrhea from the release of lots of water into the intestine (similar to a runny nose) and pain related to the bloating and diarrhea.
In addition to consumption of histamine in foods, some people’s microbiome makes histamine. With their DAO enzymes already busy, any additional histamine from the diet triggers symptoms. Probiotics often contain these types of bacteria, so it is best to avoid taking probiotics.
HIT can sometimes be triggered after use of medications that cause a loss or reduction of DAO. *(see table below).
There are histamine receptors in the skin, too, so you may get facial flushing, itching or splotchy skin.
Headache is common, and may be the real reason that people get headache after drinking red wine (rather than a sulfite allergy). DAO capsules or an antihistamine typically help this kind of headache.
You may also have a runny nose, wheezing or asthma-type symptoms, heart palpitations or a rapid heartbeat, and even painful menstrual periods.
Histamine intolerance is seen in celiac disease, Crohn’s disease, chemotherapy, and indeed anything that damages the lining of the gut.
Unfortunately, there is not a good test for diagnosing it. I typically ask a bunch of questions, screening for typical histamine reactions. If we think it likely, we look at a sheet containing histamine-rich foods to see if they are known triggers for you (insert A-HA! moment) and we put you on a low-histamine diet. This calms symptoms if we are on the right track. We can also test your serum levels of DAO, not a very reliable test, but if your levels are low, use of a DAO replacement enzyme can be expected to help, and may be needed long-term.
Interestingly, people with Ehlers-Danlos and POTs are more likely to have HIT, for unclear reasons.
The way to approach HIT is threefold – avoid the foods that are highest in histamine, use an enzyme to break down any that gets in, and use an anti-histamine like Zyrtec or Pepcid (depending on what symptoms dominate) to block receptors that histamine would otherwise bind to. People with true histamine intolerance usually get better after 2-4 weeks on the diet and should then work on liberalizing their diet and stopping their anti-histamine. This is best done with the guidance of a knowledgeable dietician.
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Choose a DAO supplement with the most HDUs – 1 million if you can find it. This is a source available on Amazon:
