The little-known allergy that could be caused by trees on your street

One woman has shared how she started getting violent allergic reactions when eating certain foods.

Lisa O’Brien said she started getting a red rosacea-like rash across her face which followed shortly after eating. Then it was the occasional diarrhoea.

But it was soon after eating a smoke mackerel sald she felt extremely ill. Lisa, 58, told the Daily Mail: “I had immediate severe diarrhoea and cramps but I also felt faint and breathless.”

The silversmith from soon discovered that all sorts of food caused her discomfort: “Every meal I ate gave similar reactions and for a few weeks, I was only daring to eat boiled plain rice and root vegetables.”

Lisa went to her GP, who then referred her to a gastronenterologist who diagnosed her with . As a result, she cut out grains, dairy and wine which helped reduce the severity of her reactions. However, in 2019, three years following the apperance of her first rash, Lisa’s symptoms got worse.

“I broke out in hives all over my body and my skin was itching,” she said. Not only that but she developed a burning mouth pain, headaches, heart palpitations and vomiting after eating. Her GP provided her with after suspecting an allergy, but they made little difference.

With symptoms of regular tongue and cheek swelling and constant mouth pain, and brain frog, she decided to go back to her GP who over 18 months referred her to an allergist and then a maxillofacial consultant – specalists in conditions and injuries that affect the head, neck, mouth, jaw and face – as well as a dental specialist who was the only one to proivde a diagnosis.

She was told she “was perimenopausal” based on the burning mouth symptom but at that point, many foods including aged beef, anything smoked, overly processed and even tomatoes were triggering her symptoms, so Lisa paid to see a nutritionist and finally got an answer. It was histamine intolerance, a condition which is often confused for an allergy.

Histamine is a naturally occurring compound in many foods including fish and tomatoes, but it’s also made in the body. “Histamine intolerance is where levels of histamine are simply too high for that invdividual’s body,” explains Dr Jose Costa, a consultant allergy specialist at The Children’s Allergy Clinic in the .

The body produces histamine in immune cells and as well as being released in response to injury or allergy, it send messages to the brain and has a role in digestion. Additionally it acts as a vascodilator, widening blood vessels.

However, for some people their bodies do not break it down properly which means eating foods that are high in histamine like red fruits and vegetables, fermented foods including cheese and sauerkraut, cured meat or fish and wine, causes levels to become too high.

The results of the high level of histermine can result in such as bloating, vomiting, diarrhoea and hives, but also in more rare cases shortness of breath and a racing heartbreak.

Symptoms are not life-threatening which can be the case with a severe allergy (anaphylaxis) but ‘can still result in serious symptoms,” says Dr Costa.

A number of reasons can cause histamine levels to become to high explained Dr Costa. Medications “such as antidepressants and antibiotics” can increase histamine levels, as they reduce production of the enzyme diamine oxidase which we need to break down histamine, reports .

“Damage to the lining of the intestine caused by conditions such as Crohn’s or ulcerative colitis or even severe gastroneteritis can have the same effect.” On top of this, Dr Costa revealed that 1% of the population do not produce diamine oxidase.

It is the most common trigger – sensitivity to certain foods containing – that is the least understood, he says and “people may develop it gradually due to diet and lifestyle changes and taking medication.”

Dr Costa says cases have risen “significantly” recently, especially since the pandemic, he shared possibily “bceause people ate more ultra-processed foods containing higher levels of histamine during the lockdowns – they ordered more processed takeways for instance.

“The higher your histamine intake, the higher your chances of developing intolerance.

“Preservatives and additives in ultra-processed foods can also raise histamine levels in food.”

There is no standard test to diagnose histamine intolerance, but a blood test can check for the enzyme deficiency that causes some cases. A urine test can check levels of methylhistamines, which is a substance that is made when histamine is broken down. This will reveal how much histamine is in the body.

However, this test involves collecting all of your urine for 24 hours, and Dr Costa says “access to these tests on the NHS is a postcode lottery”, he also warned that blood and hair strand tests available privately are “unreliable”.

Symptoms of histamine intolerance can also be confused with conditions such as mast cell activation syndrome which causes allergy-type symptoms, often with no obvious cause says Dr Helen Evan-Howells, a GP with a special interest in allergies.

Treatments for histamine intolerance usually focuses on a low-histamine diet and anti-histamines, says Dr Costa. A low-histamine diet improved symptoms in 70% of paricipants in 11 studies, reviewed by scientists at the University of Barcelona in 2021. The authors noted that while evidence for the effectiveness of the diet was “progressively growing”, there was still a lack of agreement on the foods to be avoided.

Some allergy specialists remain sceptical that the condition even exist. The American Academy of Allergy and Immunology doesn’t reconigsed it as a condition.

Dr Patrick Yong, a consultant allergy specialist at Frimley Park Hospital, Guildford, Surrey said:”It’s a murky area and more studies are needed to establish whether it exists. The symptoms may be real, but it may be something else entirely causing them.”