Histamine and Thyroid Health
In this episode Dr. Eric discusses histamine, including the signs and symptoms of a histamine intolerance, some of the common causes, and how it relates to thyroid health.
During this episode you’ll learn:
- What is histamine?
- What causes a histamine intolerance
- The two enzymes responsible for the breakdown of histamine
- Histamine intolerance symptoms
- High histamine foods and histamine liberators
- Histamine-related testing
- The relationship between histamine and the thyroid
- The relationship between histamine and the gut
- The relationship between histamine and estrogen
- How to manage a histamine intolerance
- Foods that can help with high histamine
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Links related to this episode:
Click Here for Beth O’Hara’s Low and High Histamine Food List
Click Here to get access to Alison Vickery’s Histamine Intolerance Food List
Here is the transcript for this episode:
Welcome back to the Save My Thyroid podcast. This is Dr. Eric Osansky. In this episode, I am going to talk about histamine intolerance, and I’ll briefly discuss Mast Cell Activation Syndrome.
Let’s go ahead and start off by discussing what is histamine? Histamine is a chemical messenger that mediates several cellular responses. It plays a role in the inflammatory process as well as allergic reactions. It plays a role in stomach acid secretion. It also acts as a neurotransmitter. Histamine receptors are found in just about all the tissues in the body. Histamine is stored in granules in what are called mast cells throughout the body. Histamine is released in response to tissue injury.
I’d like to briefly discuss histamine metabolism. Histamine is synthesized from the amino acid histidine. There is an enzyme called diamine oxidase or DAO. This is the first line of defense against histamine ingested through the diet or released within the gut. Vitamin B6 is a cofactor of DAO along with Vitamin C and copper. Histamine intolerance is due to an imbalance between levels of released histamine and the ability of the body to metabolize it. DAO is primarily responsible for the metabolism of ingested histamine. There is also another enzyme called histamine n-methyltransferase, or HNMT. This also breaks down histamine. HNMT specifically prevents prolonged binding of histamine to its receptors.
Speaking of the receptors, let’s talk about them. H1 and H2 are the main receptors. When histamine binds to H1 or H2 or both of them, various effects are possible. H1 receptor binding can cause itching, pain, stomach cramps, diarrhea. H2 receptor binding stimulates gastric acid secretion. H2 receptors are bound, which can lead to hypotension, low blood pressure; tachycardia, which is an increased resting heart rate; swelling; or hives.
As far as the symptoms of histamine intolerance, there are numerous. Some people only have one or two, but some could have a dozen. Some of the more common symptoms are heart palpitations and tachycardia. It’s important to interrupt before going over some of the other symptoms that a lot of people with hyperthyroidism have heart palpitations and tachycardia. Just because you are experiencing one or both of those symptoms doesn’t mean it’s hyperthyroidism. If you have hyperthyroidism, it could be that combined with high histamine. Quite frankly, a lot of my patients with hyperthyroidism don’t have histamine intolerance. Point is, if you have a history of hyperthyroidism that seems to be under control with medication, or if you have gone into remission, but then you start experiencing tachycardia or heart palpitations, it could be a relapse of hyperthyroidism. It could also be due to histamine.
As far as some of the other symptoms: headaches or migraines; itching; swelling; hives; gastrointestinal symptoms such as abdominal pain, gas, diarrhea, bloating; hypotension; and sometimes even hypertension. Hypotension is low blood pressure, and hypertension is high blood pressure. Also, fatigue; anxiety (also a common hyperthyroidism symptom); and insomnia.
Why do some people develop a histamine intolerance? There are some genetics involved. For example, someone might have a SNP (single nucleotide polymorphism), which is a common genetic variation. I mentioned the DAO gene is important when it comes to histamine breakdown, so this genetic variation can lower DAO activity, which of course isn’t a good thing, especially with someone who has a histamine intolerance problem.
While histamine intolerance can be caused by genetics, you can have an impairment of DAO activity by gastrointestinal imbalances. Gut dysbiosis such as SIBO (small intestinal bacterial overgrowth) can commonly lead to histamine problems. Proper methylation is also important for breaking down histamine.
I’d like to mention a few of the foods that are higher in histamine, including fermented foods such as sauerkraut, kimchi, alcohol (including wine and beer), vinegar, aged cheese and meats, nuts, dried fruit, avocadoes, mushrooms, smoked foods, canned meats, and wheat-based products. I’m sure there are many lists that relate to high histamine, but there is a list by Alison Vickery called the Histamine Intolerance Food List that I have found to be helpful.
There is also what’s called histamine liberators. These aren’t necessarily high in histamine, but they can cause histamine to be released from the body. These include citrus fruits, chocolate, nuts, alcohol, green tea, black tea, kombucha, aged meats, bananas, milk, and pineapple. You will notice a few of these foods are both high in histamine but also act as histamine liberators. Some of these are not high in histamine but again can liberate histamine.
I’d like to briefly discuss histamine-related testing, as there are a few options. There is a lab called Precision Point Diagnostics, and they have what’s called an advanced intestinal barrier assessment. That looks at histamine, the DAO enzyme, and a marker called zonulin, which relates to the intestinal barrier. If zonulin is high, it could indicate that you have a leaky gut. I will say it’s not the most reliable marker, so if you have normal zonulin levels, it does not rule out a leaky gut.
There is a lab called Biolab, which is in the United Kingdom, that looks at histamine and DAO activity. Local labs such as LabCorp and Quest Diagnostics look at plasma histamine. Quest also offered a urinary histamine test, last I checked. I can’t say I order any of these tests commonly, but they’re options to consider.
Now, let’s talk about histamine and gut dysbiosis. Gut dysbiosis can be a factor when it comes to histamine intolerance. Dysbiosis can cause an increase in histamine-producing bacteria or bacteria that inhibit that DAO enzyme. Antibiotics can cause dysbiosis, but so can other medications, like proton pump inhibitors or even antithyroid medications such as methimazole and PTU. I mentioned earlier SIBO; as the name implies, too much bacteria in the small intestine can be a factor for histamine imbalances. Also, it’s worth mentioning that certain probiotics may worsen histamine production, including lactobacillus casei or reuteri.
How does histamine relate to thyroid health? Thyroid hormone may play a role in the regulation of histamine, especially in the brain. Histamine might be able to physiologically regulate TSH, thyroid stimulating hormone, as well as prolactin secretion through H2 receptors in the anterior pituitary. Histamine also has an effect on dendritic cells, immunoregulatory cells, T cell polarization, and cytokine production. This relates to the immune system. Most cases of hyperthyroidism are Graves’ disease, and most cases of hypothyroidism are Hashimoto’s. Speaking of autoimmunity, histamine also apparently affects the TSH1/TSH2/cytokine balance. That also plays a role in the autoimmune process.
Next, I’d like to briefly talk about histamine and estrogen. Too much estrogen can downregulate DAO activity, which isn’t a good thing. If you downregulate DAO, you will have decreased ability to break down histamine. Estrogen dominance can essentially lead to a histamine intolerance in some cases. Estrogen also sensitizes the mast cells, which can cause more histamine to be released. Progesterone is needed to upregulate DAO. Low progesterone can also be problematic. Hormonal birth control, this can also result in histamine intolerance.
How about stress? Can stress play a role when it comes to histamine intolerance? Greater histamine results in greater amounts of cortisol to control the inflammation. Stress can potentially increase mast cell activation. Anxiety can also increase the release of histamine. The answer is yes, stress can in some cases play a role in the release of histamine.
How do you manage histamine intolerance? You want to remove high histamine foods as best you can. You want to try to remove high histamine liberators. You want to identify the cause of the problem. If someone is having gut dysbiosis—let’s say they have SIBO, and they want to address this—you might want to consider in some cases supplementing with something such as quercetin or DAO. Keep in mind there is also histamine-degrading bacteria in the form of probiotics. There is bifido infantis and longum. You might want to consider taking those. Also, lactobacillus plantarum can degrade histamine.
There are also foods that can help with high histamine. Of course, listen to your body. This doesn’t mean that everybody will find these foods to be helpful. In certain situations, they can cause problems. For example, broccoli is a food that can potentially help with high histamine, but if someone has SIBO, they might have issues with broccoli. Not everybody with SIBO has issues with broccoli, but that is a possibility. There is kale, garlic, onions, apples, asparagus, carrots, celery, olive oil, peppermint, lettuce, pomegranate, and basil.
I mentioned some supplements. Quercetin, I like a lot. Some companies have DAO supplements. If you have problems with your DAO, like genetic variation of your DAO enzyme, then taking a supplement could be beneficial. There is rutin and stinging nettle.
I want to briefly mention Mast Cell Activation Syndrome (MCAS). This is a condition involving the mast cells becoming overactivated. Mast cells offer protection and play a role in wound healing. MCAS results in too much inflammation. This can result in fatigue, body aches, pain, trouble breathing, digestive issues, rashes, brain fog, and a whole host of other symptoms.
To summarize, histamine is a chemical messenger that plays a role in the inflammatory process and allergic reactions. I mentioned DAO, which is primarily responsible for the metabolism of ingested histamine. I also mentioned another enzyme called HNMT, which also breaks down histamine.
Common causes of histamine intolerance include genetics, gut dysbiosis, problems with methylation, and even stress and anxiety. I also discussed a few ways of testing histamine. I mentioned how thyroid hormone may play a role in the regulation of histamine. Histamine affects TSH1/TSH2 balance, which can play a role in autoimmune conditions such as thyroid conditions. Too much estrogen can also downregulate DAO activity.
I recommend trying to remove the high histamine foods and liberators the best that you can while of course trying to identify the cause. Just keep in mind that certain supplements can also be beneficial at times, such as quercetin and DAO supplements.