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  • Clare Backhouse

more on histamine

Let’s look at non-food factors in histamine overload, which can cause or worsen conditions like:

- hay fever

- skin rashes

- allergies

- migraines

- stomach acid problems

- Long Covid

Last blog, we saw how food can be a factor in histamine excess.

This excess is commonly called ‘histamine intolerance’, but it’s important to remember that histamine is a useful substance found naturally in the body, and only causes problems when it builds up too much.

One of the easiest ways to find out if you have too much histamine, is to take an over-the-counter anti-histamine. If your symptoms clearly reduce, then it may be worth dealing with the root causes of high histamine.

So, as promised, we’ll now look at some non-food factors high histamine. And we’ll also look at some specific nutrients which may help recover from histamine-related symptoms.

Non-food factors which may cause histamine problems

1. Medications

2. Gut bacteria / parasites

3. Genetics

4. Household toxins

5. Nutrient status

1. Medications

Several medications can inhibit the DAO (diamine oxidase) enzyme which breaks down and reduces the amount of histamine in the body. Even over-the-counter medications can do this, like high-dose acetylsalicylic acid (aspirin) and non-steroidal anti-inflammatory drugs (eg. aspirin, ibuprofen).

Maddeningly, even some anti-histamine medications actually inhibit the function of histamine-degrading enzymes that are naturally present in the body.

So if you experience symptoms of high histamine, it may be worth checking with your pharmacist or GP about any drugs you take.

2. Gut bacteria and parasites

Common gram-negative bacteria such as Klebsiella pneumoniae, Hafnia alvei and Morganella Morganii can live in the gut and quietly encourage the production of excess histamine in the body.

These bacteria can be detected in a good stool test, which will also provide clear protocols for dealing with them if found. It’s not cheap, but Invivo’s GI Ecologix home test is brilliant for this. (Though NB I don’t get any benefit for mentioning it – indeed I receive no benefit for mentioning anything in this blog!).

Another gut inhabitant which can cause and overload of histamine is Helicobacter Pylori, or H. Pylori, a common parasite. It’s thought that up to half of the world’s population carries it, but not all react severely.

The good news is that H. Pylori can also be detected in a good stool test, and it can be eradicated if necessary without having to use antibiotics (I use a protocol involving a medical device called Toxaprevent).

Finally, for anyone on probiotics: some healthy strains of bacteria, such as Lactobacillus casei and Lactobacillus bulgaricus, may be histamine-producing. Do get in touch if you would like to find out about histamine-safe probiotics.

However, not all causes of high histamine can be dealt with so simply; some have to be ‘worked around’ a bit, because they are genetic.

3. Genetic issues

Genes can affect how well our enzymes work. And certain enzymes help to degrade histamine and render it less abundant in the body. So we can have gentetically less-effective histamine-degrading enzymes.

Histamine N-methyltransferase (HNMT) and Diamine Oxide (DAO) are the top two histamine-degrading enzymes. So if HNMT and/or DAO don’t work well, histamine may accumulate too much within the body.

This is why certain DNA variations (also called ‘Single Nucleotide Polymorphisms’, or SNPs), which can inhibit the working of these histamine-degrading enzymes, may cause you to experience ‘histamine intolerance’ more easily, provoking, for example, hay fever or asthma symptoms.

Some people don’t want to delve into this sort of thing and would rather just support their DAO and HNMT enzymes generally with nutrients (on which more below).

But for others, knowing for certain what is causing their histamine imbalance is a critical part of their recovery. For these, tests like the LifeCodeGx Histamine Intolerance Report may be an excellent step towards clarity.

4. Household toxins

Household toxins can trigger or worsen histamine-type symptoms such as rashes, hay fever, rhinitis, etc. And one of the most common household toxins is mould.

Mould releases mycotoxins which trigger an inflammatory response in the body, and cause ongoing oxidative stress. The result is a lot more histamine in the body.

Mould’s mycotoxins can also damage the gut itself and alter its balance of beneficial bacteria. And beneficial bacteria are required to keep inflammation in balance and to help excrete excess histamine.

Mould is often hidden but present in buildings that have a history of water damage or are not well-ventilated. If you live or work in such a building, it would be possible to have a perfect diet, but a very unhappy micro biome nonetheless. Or a histamine problem.

A classic sign that your problem is environmental, is that your symptoms reduce when you’re away from home (or the place where you work for example).

But not everyone is affected similarly by mould. Two people could live in one mouldy house but only one experience a reaction. Matthew Moore from Air Testing Ltd in Cambridge is an expert in household mould and has been a brilliant source of advice for me personally.

If you’re interested to hear more on household mould and chronic illness, Datis Kharrazian has come out with a useful podcast on the subject here and I interviewed a senior nutritionist about working with people facing mould-related illness here.

5. Nutrient status

If Diamine Oxidase, or DAO, is a key enzyme for degrading food-source or microbiome-sourced histamine in the body, then nutrients which support this enzyme will be crucial to consume.

For example, one of the most important co-factors of DAO is Vitamin B6, which can be found in beef, chicken, turkey, salmon, potatoes, sunflower seeds, bananas, cabbage, cauliflower, and pumpkin seeds.

And Vitamin B6 is also important for the other histamine-degrading enzyme, HNMT.

Vitamin C is another co-factor in producing DAO, and can be found in kiwi fruits, oranges, red peppers and broccoli among other foods.

Then there are other nutrients which help to set the stage for better tolerance of normal histamine levels.

For example, Vitamin B12, present in animal-sourced foods like meat, or supplements for vegans, is important to ensure good tolerance of ‘amines’ in general, including histamine.

Vitamin D3 helps to stabilise mast cells, which contain and release histamine, and therefore may calm down histamine release. The UK’s National Health Service recommends that we supplement Vitamin D throughout the winter due to lack of sun, which is the best supplier in the summer.

Zinc actually inhibits the release of histamine from basophils and mast cells, but, like Vitamin D you may have to supplement this, especially if you’re vegetarian or vegan. The top foods are beef, chicken, beans and chickpeas (but feel free ask me if you’d like ideas on supplements because not all are created equal!).

Finally, Magnesium not only regulates the release of histamine but can also act as an anti-inflammatory in general. Top magnesium foods include brazil nuts, rice, nuts, avocado, mackerel, chickpeas, banana, but magnesium can also be absorbed across the skin, which is why I often recommend magnesium sulphate baths, or magnesium creams.

Some useful plants

And last but not least, let’s not forget the ordinary plants which are naturally anti-histamine foods.

Sources of the anti-histamine substance Quercetin include: garlic, red onions, organic apples, and blueberries.

Finally, a common natural histamine blocker is nettle, which in my experience, taken as a strong tea (2 teabags steeped for 15 minutes in one covered mug of almost-boiled water, three times a day), works wonders in reducing histamine symptoms.

You could also make a nettle soup. But heed the immortal words of forager John Wright when he warns, ‘this can taste like boiled army blankets if you do not use a good stock and thicken it with a potato or celeriac’ !!

So there you have it – some of the considerations I bear in mind when dealing with high histamine:

- excess of food sources of histamine

- medications

- gut micro biome problems

- genetic variations

- household / environmental toxins

- nutrient status

Finally, it’s worth saying that overly high histamine needn’t be all down to one cause. It may instead result from several mild to moderate factors.

And each person’s causes and triggers will be unique to them, as will the best way forward.

If you would like some guidance with tracking down histamine-related issues, or indeed any other health concern, I encourage you to have a look at how I work, my distinctives and some testimonials, to find out more.

And come and get in touch directly to say hello and discover how I can support your health goals. I offer free, no-obligation conversations so you can see if my approach is a good fit for you.

Meanwhile, I hope this has been a useful overview!

To your very best of health,


Clare Backhouse, dipION, Registered Nutritionist MBANT

Registered Nutritional Therapist CNHC

Consultations online

Histamine references

Afrin, L.B., Weinstock, L.B., Molderings, G.J., 2020a. Covid-19 hyperinflammation and post-Covid-19 illness may be rooted in mast cell activation syndrome. International Journal of Infectious Diseases 100, 327–332.

Branco, A.C.C.C., Yoshikawa, F.S.Y., Pietrobon, A.J., Sato, M.N., 2018. Role of Histamine in Modulating the Immune Response and Inflammation. Mediators of Inflammation 2018, e9524075.

Busse, W.W., Knuffman, J.E., 2006. Histamine, in: Laurent, G.J., Shapiro, S.D. (Eds.), Encyclopedia of Respiratory Medicine. Academic Press, Oxford, pp. 279–283.

Deiteren, A, De Man, J.G., Pelckmans, P.A., De Winter, B.Y., 2015. Histamine H4 receptors in the gastrointestinal tract. Br J Pharmacol 172, 1165–1178.

Hrubisko, M., Danis, R., Huorka, M., Wawruch, M., 2021. Histamine Intolerance—The More We Know the Less We Know. A Review. Nutrients 13, 2228.

Landucci, E., Laurino, A., Cinci, L., Gencarelli, M., Raimondi, L., 2019. Thyroid Hormone, Thyroid Hormone Metabolites and Mast Cells: A Less Explored Issue. Front. Cell. Neurosci. 0.

Magen, E., Mishal, J., 2013. Possible benefit from treatment of Helicobacter pylori in antihistamine-resistant chronic urticaria. Clinical and Experimental Dermatology 38, 7–12.

Maintz, L., Novak, N., 2007a. Histamine and histamine intolerance. The American Journal of Clinical Nutrition 85, 1185–1196.

Mlcek, J., Jurikova, T., Skrovankova, S., Sochor, J., 2016. Quercetin and Its Anti-Allergic Immune Response. Molecules 21, 623.

Nuutinen, S., Panula, P., 2010. Histamine in Neurotransmission and Brain Diseases, in: Thurmond, R.L. (Ed.), Histamine in Inflammation, Advances in Experimental Medicine and Biology. Springer US, Boston, MA, pp. 95–107.

Rosell-Camps, A., Zibetti, S., Pérez-Esteban, G., Vila-Vidal, M., Ferrés-Ramis, L., García-Teresa-García, E., 2013. Histamine intolerance as a cause of chronic digestive complaints in pediatric patients. Rev Esp Enferm Dig 105, 201–206.

San Mauro Martin, I., Brachero, S., Garicano Vilar, E., 2016. Histamine intolerance and dietary management: A complete review. Allergologia et Immunopathologia 44, 475–483.

Schnedl, W.J., Enko, D., 2021. Histamine Intolerance Originates in the Gut. Nutrients 13, 1262.

Smolinska, S., Jutel, M., Crameri, R., O’Mahony, L., 2014. Histamine and gut mucosal immune regulation. Allergy 69, 273–281.

Thangam, E.B., Jemima, E.A., Singh, H., Baig, M.S., Khan, M., Mathias, C.B., Church, M.K., Saluja, R., 2018. The Role of Histamine and Histamine Receptors in Mast Cell-Mediated Allergy and Inflammation: The Hunt for New Therapeutic Targets. Front. Immunol. 0.

Wright, John, 2019. The Forager’s Calendar: A Seasonal Guide to Nature’s Wild Harvests. Profile books, London, pp. 93-96.

See also the Pauling Institute for useful references on micronutrients


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