SAVED BY HAYFEVER PILLS AND CUTTING OUT CHEESE
ABSOLUTELY desperate to improve the crushing mental and physical fatigue she suffered as a result of long Covid, Clare Richardson made a concerted effort to eat ‘healthy’ foods, turning to spinach smoothies, fermented cabbage kimchi and avocados.
But the foods she thought would help get her back on her feet — literally, as she was wheelchair-bound for eight months — made the problem worse, she now believes.
For Clare, 48, who lives in Carmarthen, west Wales, with her husband Sam, 45, a farmer, and their two children, later learned she’d chosen foods that were high in histamine, a natural chemical also released by the body during an allergic reaction.
Histamine is a powerful chemical released by mast cells (part of our immune system) in response to a threat, such as an allergen, causing symptoms such as itching and sneezing designed to flush out the dangerous substance. Histamine can cause inflammation in blood vessels and tissue around the body — and this has been proposed as one of the mechanisms of long Covid, with the infection triggering an over-response from the body, prompting it to release too much histamine and causing longer-term symptoms such as fatigue and brain fog.
Some doctors and dietitians believe patients with long Covid could benefit from antihistamine medication combined with a low-histamine diet.
The suggestion is that this may be particularly true for people with an underdiagnosed and recently recognised condition called mast cell activation syndrome (MCAS), where mast cells are already ‘faulty’ and easily stimulated to produce too much histamine.
There is no reliable test for MCAS and diagnosis relies on a doctor’s clinical judgment and an improvement after taking drugs that dampen down mast cell action.
But now antihistamines are set to form part of a major UK study into long Covid.
THE STIMULATE-ICP study, involving 4,500 people and led by University College London (UCL), will look at whether antihistamines and other existing drugs can reduce symptoms.
As the lead researcher, Professor Amitava Banerjee, a consultant cardiologist, told Good Health: ‘Patient experience and preliminary data has suggested for quite some time that histamine released from mast cells could be important in some of the symptoms of long Covid.’
He adds that research has already shown that people with long Covid have increased levels of histamine and mast cells.
And a recent study (with 49 long Covid patients) at the Physicians’ Clinic in London, found that 60 per cent of those treated with antihistamines experienced an improvement in their symptoms, compared to 24 per cent not given the medication.
Dr Paul Glynne, a consultant physician at the Physicians’ Clinic and University College London Hospital NHS Foundation Trust, was prompted to run the study after seeing many long Covid patients with symptoms similar to allergic reactions, including runny noses and rashes.
This approach is ‘potentially exciting, as antihistamines are cheap, easily available and very safe’, says Dr Glynne, adding that larger trials are needed.
Dr Tina Peers, a consultant doctor with special interests in women’s health, who runs the Menopause Consultancy clinic in Surrey, is already combining antihistamine medication with a low-histamine diet for her patients with long Covid.
She prescribes relatively high doses of well-known antihistamines such as loratadine and fexofenadine (which block histamine receptors).
Foods thought to be high in histamine include some generally accepted as important to a healthy diet, such as tomatoes and avocados, and fermented food such as sauerkraut, and experts warn that patients should consult their GP before embarking on such a radical regimen and not follow it longterm because it excludes many foods that are vital for health.
Hannah Hunter, a specialist allergy dietitian at Guy’s and St Thomas’ NHS Foundation Trust, suggests long Covid patients could try a low histamine diet for two to four weeks, monitoring for any reactions.
‘Following a low-histamine diet means avoiding a lot of everyday foods, and that isn’t easy,’ she says.
‘Someone recovering needs a balanced, healthy diet, so this approach should only be undertaken with help from a dietitian or doctor.’ The British Dietetic Association also urges caution about ‘restrictive and time-consuming’ low-histamine diets, citing a lack of evidence. Yet Clare is convinced this approach helped her. She developed Covid in February 2020, and was ill at home for a month with fever, exhaustion and aches. Then, eight weeks after she’d recovered, she suddenly found herself engulfed with long Covid.
‘I could hardly make it out of bed and my brain ceased working. It was terrifying.’
Then, earlier this year, she learned about antihistamines via an online long Covid support group and contacted Dr Peers, who prescribed two stronger antihistamines, fexofenadine and famotidin — and a low-histamine diet.
‘It was no fun at all,’ says Clare. ‘For the first six months I ate just low-histamine veg, soft, fresh cheese, and rice. I started to reintroduce other foods a few months ago, starting with fish fingers with the breadcrumbs picked off.’
Clare is now better and eating more normally again. But she says: ‘I still won’t go near alcohol, coffee or fermented food as they make me react a bit.’