Written by Registered Dietitian Chloe Hall

The low histamine diet is becoming more widely recognised, largely due to the discussion around HI and long covid. So do we all need to be following a low histamine diet?
In short, no. For most people histamine plays an essential role in our bodies and isn’t a problem because our body has effective pathways to break down the histamine that our bodies make and the histamine we consume in foods1, 2. For some people, however, for many reasons, these pathways don’t work as effectively and they can develop some very difficult symptoms because of the build-up of histamine in the body, above the usually tightly controlled ranges.

What is Histamine?

Histamine acts as a chemical messenger in our bodies and is involved in many physical processes including gastric acid secretion, inflammation and muscle contraction1,2,3,4. Histamine is produced internally by our bodies and released from cells when they are stimulated by a trigger, such as an illness3. There can be many different triggers for stimulating these cells to produce histamine and the main ones are shown in the picture below.

Symptoms of Histamine Intolerance?

Histamine receptors can be found everywhere in the human body and the condition can, therefore, cause a wide range of symptoms from a fast heart rate to diarrhoea1. People with HIT may find that their symptoms fluctuate and sometimes they may have individual symptoms and others they may have multiple symptoms. Because the symptoms can be so varied and can involve multiple body systems, it can be a really hard condition to diagnose.

Why do people experience histamine intolerance?

HIT can occur for multiple reasons. Conditions such as Mast Cell Activation Syndrome (MCAS) or mastocytosis can cause an overproduction of internal histamine1. Alternatively, in others with HI there is no overproduction in histamine but a problem with breaking it down1. Diamine Oxidase (DAO) is the primary enzyme for degrading the histamine we consume when we eat or the histamine that our gut bacteria may produce and the main reason for HI appears to be the impairment of this enzyme5, 6. This can happen for various reasons including gastrointestinal diseases7, medications8 or genetics1.

How do we diagnose and treat histamine intolerance?

There is currently no test that we can do to accurately diagnose someone with histamine intolerance. It should be considered in anyone that presents with more than two of the above symptoms of HIT2. Diagnosis currently relies on a low histamine elimination diet for 2-4 weeks with a gradual re-introduction of high histamine foods to identify a person’s tolerance level and any specific food sensitivities, however this isn’t a diet that you should just follow using Google. It can be extremely complex and nutritionally and socially restrictive if not done with the correct support.

What foods are high in histamine?

One of the reasons that the diet shouldn’t be followed using the internet, is that there are so many different lists online and the diet can end up much more restrictive than it needs to be. There is no list that can 100% guarantee the histamine content of foods as this can be affected by many different including how fresh they are and how they have been stored9. Foods generally considered as high histamine foods can be found in the picture below.

What nutrients may be missing on a low histamine diet?

  1. Fibre: The low histamine diet can restrict a number of high fibre foods such as beans, pulses and a range of fruit and vegetables. Fibre is so important in our diet to help us go to the toilet regularly and keep our hearts and guts healthy. Make sure to include plenty of low histamine fruit and vegetables such as carrots, apples and wholegrain carbohydrates such as wholegrain rice.
  2. Omega 3: These can’t be made by our body so it is essential we get these through diet as they are needed by our cells. Oily fish is a really good source of this but these fish are high histamine so it can be more challenging to get enough of this on the diet. Low histamine options of omega 3 include flaxseeds/linseeds or flaxseed or rapeseed oil.
  3. Protein: Histamine is produced by bacterial breakdown of a building block of protein called histidine found in meat. Although, some types of meat are considered ‘safe’ on the low histamine diet, the less fresh a meat is the more histamine it contains. If you end up avoiding meat because of symptoms, and are avoiding foods such as beans and pulses, cheese and nuts, it is really important to carefully plan your meals to ensure that you are getting enough protein to repair your body. This is particularly important if you are struggling to keep to a healthy weight or are underweight already.

Is there anything else that can help with Histamine intolerance?

  1. Diamine Oxidase: There is some evidence that using Diamine Oxidase Enzymes (DOA) that come in tablet form can help, however those currently available are produced from pigs so may not be suitable for vegetarian’s, vegans or for religious reasons10.
  2. Probiotics: Some gut bacteria may produce histamine and other types can help to break it down so it is important to speak with your Dietitian to ensure that the probiotic you take contains the right bacterial strains, as some probiotics could actually make HIT worse11.

In conclusion

Histamine intolerance can be a very challenging condition to manage and support is crucial to prevent nutritional deficiencies but, also, to ensure that you continue to have a happy, socially enjoyable life.

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Maintz L, Novak N. Histamine and histamine intolerance. Am J Clin Nutr. 2007 May;85(5):1185-96. doi: 10.1093/ajcn/85.5.1185. PMID: 17490952.

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Schmidt WU, Sattler J, Hesterberg R , et al. Human intestinal diamine oxidase (DAO) activity in Crohn’s disease: a new marker for disease assessment? Agents Actions 1990; 30: 267–70

 Sattler J, Hesterberg R, Lorenz W, Schmidt U, Crombach M, Stahlknecht CD. Inhibition of human and canine diamine oxidase by drugs used in an intensive care unit: relevance for clinical side effects? Agents Actions 1985; 16: 91–4

 Skypala IJ, Williams M, Reeves L, Meyer R, Venter C. Sensitivity to food additives, vaso-active amines and salicylates: a review of the evidence. Clin Transl Allergy. 2015 Oct 13; 5:34 doi: 10.1186/s13601-015-0078-3

Schnedl WJ, Schenk M, Lackner S, Enko D, Mangge H, Forster F. Diamine oxidase supplementation improves symptoms in patients with histamine intolerance. Food Sci Biotechnol. 2019 May 24;28(6):1779-1784. doi: 10.1007/s10068-019-00627-3. 

 Pugin B, Barcis W, Westermann P, Heider A, Wawrzyniak M, Hellings P, Akdis CA, O’Mahony L. A wide diversity of bacteria from the human gut produces and degrades biogenic amines. Microb Ecol Health Dis. 2017. 1353881.