Until her mid-40s Lisa O’Brien gave little thought to what she ate – but suddenly certain foods started to trigger strange, sometimes violent reactions.
First came the onset of a red rosacea-like rash across her face shortly after eating. Then came occasional diarrhoea.
But soon after having a smoked mackerel salad she felt extremely unwell: ‘I had immediate severe diarrhoea and cramps but I also felt faint and breathless,’ says Lisa, 58, a silversmith from Reading.
Yet Lisa soon found all sorts of foods 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 referred her to a gastroenterologist who diagnosed irritable bowel syndrome.
She cut out grains, dairy and wine which helped reduce the severity of her reactions. But in 2019, three years after her first rash appeared, her symptoms got much worse.
‘I broke out in hives all over my body and my skin was itching,’ she says. On top of that she developed a burning mouth pain, headaches, heart palpitations and vomiting after eating.
Lisa O’Brien was referred to a gastroenterologist who diagnosed irritable bowel syndrome when certain foods started to trigger strange, sometimes violent reactions
Her GP, suspecting an allergy, gave her antihistamines which made little difference. With her tongue and cheek regularly swelling and by now suffering from constant mouth pain, fatigue and brain fog, she went back to her GP who over 18 months referred her to an allergist and then a maxillofacial consultant – specialists 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 offer a diagnosis.
‘Based on the burning mouth syndrome he said I was perimenopausal [it can be a symptom] – I got to the point where I thought I was going mad,’ says Lisa.
By now many foods from aged beef to anything smoked or overly processed and even tomatoes were setting off her symptoms so Lisa paid to see a nutritionist and at last found an answer.
She was told she has histamine intolerance, a controversial condition, which is often confused for an allergy and cases of which have risen ‘significantly’ in recent years say experts.
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 individual’s body,’ explains Dr Jose Costa, a consultant allergy specialist at The Children’s Allergy Clinic in the West Midlands.
The body produces histamine in immune cells and as well as being released in response to injury or allergy, it relays messages to the brain and has a role in digestion. It also acts as a vasodilator, widening blood vessels.
But in some people the body doesn’t break it down properly – this means that eating foods that are high in histamine such as red fruits and vegetables (strawberries and tomatoes) fermented foods such as cheese and sauerkraut, cured meat or fish and wine – pushes levels too high.
This can lead to allergy-like symptoms such as bloating, vomiting, diarrhoea and hives, but also in rarer cases shortness of breath and a racing heartbeat.
Symptoms won’t be life-threatening as can be the case with a severe allergy (anaphylaxis) but ‘can still result in serious symptoms’, says Dr Costa.
‘One woman I saw recently had ten severe reactions in two years,’ says Dr Costa. ‘She experienced significant swelling, severe stomach cramps, and shortness of breath and needed adrenaline.’
Dr Jose Costa is a consultant specialist at The Children’s Allergy Clinic in the West Midlands
There are multiple reasons why histamine levels may climb too high says Dr Costa. Medication ‘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.
‘Damage to the lining of the intestine caused by conditions such as Crohn’s or ulcerative colitis or even severe gastroenteritis can have the same effect.’
What’s more 1 per cent of the population don’t produce diamine oxidase says Dr Costa.
It is the most common trigger – sensitivity to certain foods containing histamine – that is the least understood, he says.
‘These people may develop it gradually due to diet and lifestyle changes and taking medication.’
Dr Costa says cases have increased ‘significantly’ recently, especially since the pandemic, possibly, he says ‘because people ate more ultra-processed foods containing higher levels of histamine during the lockdowns – they ordered more processed takeaways 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.
‘Tinned fish has histamine levels 20 times higher than fresh fish, due to both processing and adding preservatives.’
There is no standard test to diagnose histamine intolerance. A blood test can check for the enzyme deficiency that causes some cases – or a urine test can check levels of methylhistamines (a substance made when histamine is broken down) to work out how much histamine is in the body. But this involves collecting all your urine for 24 hours, and ‘access to these tests on the NHS is a postcode lottery’, adds Dr Costa (he also warns that blood and hair strand tests available privately are ‘unreliable’).
A further complication is the symptoms of histamine intolerance can be confused with conditions such as mast cell activation syndrome which causes allergy-type symptoms with often no obvious cause says Dr Helen Evans-Howells, a GP with a special interest in allergies.
Treatment for histamine intolerance normally focuses on a low-histamine diet and anti-histamines, says Dr Costa.
A low-histamine diet improved symptoms in 70 per cent of participants in 11 studies, reviewed by scientists at the University of Barcelona for a paper in the journal Nutrients in 2021. The authors noted that while evidence for the effectiveness of the diet was ‘progressively growing’, there was still a lack of consensus on the foods to be avoided. The worst ten foods and drink for histamine in the review were: dry fermented sausages such as salami, cured cheese such as gouda or manchego, beer, wine, fish, tomatoes, spinach, sauerkraut, citrus fruit and strawberries.
Lisa cut out grains, dairy and wine which helped reduce the severity of her reactions. But in 2019, three years after her first rash appeared, her symptoms got much worse.
And histamine levels fluctuate according to food’s freshness, storage and bacterial contamination as bacteria encourage the release of more histamine, explains dietitian Nishti Udeh.
She says: ‘Rather than strictly avoiding all high histamine foods, focus on eating a well-balanced diet using fresh foods and properly storing them such as putting leftovers in the freezer rather than the fridge to slow down bacterial activity.’
Some allergy specialists remain sceptical that histamine intolerance exists – the American Academy of Allergy and Immunology doesn’t recognise it as a condition, for instance.
‘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,’ says Dr Patrick Yong, a consultant allergy specialist at Frimley Park Hospital, Guildford, Surrey.
‘Many of the histamine intolerance symptoms such as fatigue, swelling, rashes and brain fog could be due to other conditions,’ he adds.
Lisa however is convinced her diagnosis is correct. By the time she was diagnosed she says: ‘I could only eat protein, veg and fruit.’
Within two weeks of adopting a low histamine diet her skin had cleared and she no longer suffered digestive upsets, fatigue or brain fog.
‘It made such a big difference,’ she says. ‘I could get out and do things and enjoy myself again.’
Lisa is now in an online group of other people with histamine intolerance and says: ‘It’s extraordinary how many people are ignored or dismissed by doctors who don’t consider it.’
Additional reporting: JULIE COOK
