Histamine intolerance is obviously a topic of great interest, since many of you have asked questions in the wake of last week’s blog

We are under the impression that histamine intolerance is a rare condition, estimated to happen to 1-3% of the population, with 80% of those being middle-aged and females being more susceptible to it than males.  However, I saw a young man this week with a long history of hay fever, but a recent histamine intolerance had been misdiagnosed.

Andy is 16 and suffers from spring and summer hay fever.  He presented with severe fatigue, yawning all day, recurrent headaches, and dizziness, together with a background of longstanding recurrent abdominal pain.  He had received several courses of antibiotics due to various infections and eventually had a mouth and throat thrush.

He estimated his energy level at 3 out of 10, being too exhausted to concentrate in school.  Given his hay fever and sensitivity to grass and tree pollen, Andy could not attend the school sports days and had an air filter fitted to his bedroom.

“To my amazement, Andy listed all of the histamine-rich foods”

Andy attended the allergy clinic with distressing body itching and recurrent skin rashes.  After detailed testing, he was diagnosed with idiopathic (unknown cause) urticaria.

I reviewed Andy’s food preferences and asked him to list the foods he could not stand. To my amazement, the young man generated a list of classic histamine-rich foods within a minute.  This included tuna, sardines, cheese, tomatoes, avocados, aubergines, spinach, citrus, cranberries, and pineapple.

Given such accuracy, I wondered if Andy had read last week’s blog and had the information still fresh in his mind.  But Andy was adamant that he avoided these foods for many years.

In this blog, we are going to follow Andy’s case, also working out what is good and bad about histamine and what you can do to resolve your own issues with histamine intolerance – or something that looks like it! 

Even though histamine is a powerful chemical blamed for allergic reactions, it also supports important bodily activities such as stomach acid secretion.  It accelerates the heart rate and mediates recovery from exercise and its health benefits.  And it imbues you with enhanced alertness, the secret behind the success of high performing people.

Our muscles are made to release histamine and respond to it.  They have a wide range of histamine H1 and H2 receptors, as well as mast (histamine storage) cells embedded within them.  High and moderate-intensity exercise causes tiny tears in your muscle fibres and activates these mast cells to release histamine to trigger the inflammation necessary for the growth and repair of your muscles.

Histamine causes vasodilatation (vessel dilatation), which explains our post-exercise dizziness and weakness, even in a normal healthy adult, but more so in those with histamine intolerance.

Antihistamines negated exercise benefits

A study in Ghent University, Belgium, showed that participants who took an antihistamine to block histamine receptors experienced significantly less improvement in several parameters related to exercise performance, and they lagged behind in their ability to produce energy, compared with those who received a placebo.

The researchers performed glucose tolerance tests before and after six weeks of training.  Specifically, they found that those given antihistamine had less ability to move glucose from the bloodstream into the cells (to fuel exercise), had less capillary formation in their leg muscles (to deliver oxygen), and showed no increase in nitric oxide synthase – a marker of vessel health.

Histamine response during exercise was also found to improve a variety of cardiometabolic risk factors, from insulin sensitivity to aerobic capacity and blood vessel health.

So, beware – you may lose many of the benefits of exercise if you are taking H1 antihistamine or the stomach acid-blocking agents that interfere with the H2 receptors.

Are you a high histamine type personality?

A high histamine type personality is observed in academic high achievers, highly motivated and competitive individuals, and those who crave routine, order, and control.

When in balance, high histamine type people are highly intelligent, super-productive and tend to be successful in work and life.  If their histamine levels rise further, however, they lose this advantage and succumb to stress, anxiety, or depression.  And stress causes the body to release more histamine, worsening their condition further.

High histamine personality was also found in those who carry a lot of anxiety inside whilst appearing calm from the outside.

High histamine type people practise a high level of perfectionism to avoid being hurt or criticised.  They should take note and manage their perfectionism in order to control anxiety and stress, set priorities and ask for help if they are overwhelmed.  They could, for instance, work with a coach to balance their work and family life.

As we have said, women tend to experience histamine intolerance more than men.  They produce more histamine when they have a sex hormone imbalance (oestrogen dominance.)  Histamine intolerance symptoms are worse just before and during their periods.  Animal studies have confirmed that mast cells degranulation (the release of histamine) happens mostly in the premenstrual phase.

Mimicking histamine intolerance

Cholinergic urticaria typically presents with small, temporary hives but can also involve cutaneous inflammation (wheals) and pain, which usually develops in response to exercise, bathing, staying in a heated environment or emotional stress.  Although these symptoms usually subside within an hour, cholinergic urticaria may significantly impair quality of life, especially in relation to sporting activities.

As far as treatment is concerned, daily forced perspiration by excessive body warming (a hot bath or exercise) may reduce the symptoms through the exhaustion of inflammatory mediators.  You may want to exercise wearing a woolly hat or hood in winter.  Antihistamines prescribed for conventional urticaria have limited effect in cholinergic urticaria.

What about Andy?

Coming back to Andy, we set up a plan to investigate the underlying cause of his histamine intolerance by testing serum diamine oxidase (DAO), histamine, and a stool test to examine the gut flora.

Having low DAO but high histamine suggested that Andy may have either a genetic or an acquired DAO deficiency.  The second possibility is more likely as Andy has suffered from recurrent abdominal pain for many years.  This may have damaged the intestine lining cells that produce DAO.  Andy consumes a lot of inflammatory food such as sugar and processed carbohydrates, but gluten may also be a factor since Andy observed that his cramps were worse after having a carbohydrate-heavy meal, such as pasta or pizza.

With this in mind, we should then focus on gut bacteria.  We know that certain gut bacteria produce histamine and others degrade it.  Andy may have more histamine producers and not enough degraders, leading to high levels in his blood.

We should also keep an open mind in case his high histamine levels are related to the deficiency or activation of the histamine N methyltransferase (HNMT), the other enzyme that breaks down histamine in the circulation.  Activation of this enzyme requires a chemical known as a methyl group (CH3), which may be lacking in some patients with a genetic disorder such as an MTHFR variant.

Does Andy need quercetin?

Quercetin consists of the flavonoids found naturally in onions, berries and apples.  It is an antioxidant and a mast cell stabiliser, inhibiting the release of histamine.  It can reduce itching, watery eyes, sneezing and sinus congestion.

Studies in Finland suggested that a higher quercetin intake was associated with lower asthma attacks.  In the Netherlands, the consumption of apples during pregnancy helped to protect against childhood asthma and allergic diseases.

Andy suffers from hay fever and would benefit from quercetin to stabilise his mast cells and hay fever, but it would have no positive effect on his histamine intolerance.

What can you do to manage histamine intolerance?

Initially, you need to be sure that you are not suffering from a traditional allergy, such as hay fever, asthma or skin allergic reactions. Beware allergic and non-allergic histamine issues often coexist as observed in Andy,

Then, as we mentioned, a low histamine diet supplemented with the histamine-degrading enzyme diamine oxidase (DAO) will reduce your symptoms without curing histamine intolerance.  DAO supplements break down the histamine that enters your body in food and drink.  However, DAO will not affect the levels of histamine made in the body, as this is broken down by a different enzyme called histamine N-methyltransferase (HNMT.)

The aim of the low histamine diet is not to remove histamine-rich foods for the rest of your life.  Remove such food for 30 days to help improve your histamine issues.  After addressing the underlying cause, such as gut dysbiosis or methylation issues, you can start to add these foods back one at a time to find the ones you do need to remove permanently.

People with histamine intolerance could enjoy exercise, but they must find the routine that works for them – this is often some gentle, calming movement that does not cause a surge in histamine.  Antihistamine pills, which cancel the histamine-induced benefits of exercise, are not recommended.

It is also important to avoid stress since this can release stress hormones and histamine, which worsen your condition.

And, as always, my friends, getting a good night’s sleep, enjoying the sunshine, having great loving relationships, and joy and purpose in your life, will do you no end of good in regard to this and so many other health issues!

Please share your thoughts and ask any questions on this subject – in the Comment section below is always best, so that I can respond most quickly – and please do subscribe to the newsletter so that you don’t miss further vital information.  Thank you!

As this is our last blog of 2021, we wish you a Merry Christmas and Happy, Healthy and Vital New Year, and we will be back in January.



What is DAO? Diamine oxidase supplements explained


Origin of DAO deficiency


Is exercise causing you histamine intolerance symptoms?


Regular HIIT exercise enhances health via histamine


Quercetin and its antiallergic immune response


Why high performers can have a high histamine type personality