Going for a jog. Dancing. Or just doing some gardening… How taking exercise can trigger a deadly food allergy
22:54 GMT, 3 September 2012
Traton Steven was suffering from anaphylaxis, a severe allergic reaction where the body's immune system over-reacts to an allergen
Eating vegetables and taking exercise are the cornerstones of healthy living advice.
But for Traton Steven, these two innocuous sounding activities have a far from positive effect.
In fact, he’s allergic to them.
Traton, 18, is one of half a million Britons who suffer from a condition called food-dependent exercise-induced anaphylaxis (FDEIA), where physical exercise sparks a severe and potentially fatal allergic reaction.
Indeed, it was only because of his father’s quick thinking that Traton survived his first attack at the age of 14.
He was helping out at his parents’ garden centre two hours after eating a meal of cannelloni.
‘I’d always had hay fever and allergies to horses, but I suddenly got what I can only describe as really bad hay fever, terrible stomach ache and, without being too dramatic, a sense of doom,’ says Traton.
‘I went to wash my hands and change my clothes, which usually helps with my hay fever, but it got worse.’
Traton’s father put him in the car and rushed him to nearby Maidstone hospital.
/09/03/article-2197842-14D2918B000005DC-709_468x530.jpg” width=”468″ height=”530″ alt=”Since Traton was diagnosed with FDEIA, he avoids greens and salad. He feels healthy and works at the family garden centre part-time” class=”blkBorder” />
Since Traton was diagnosed with FDEIA, he avoids greens and salad. He feels healthy and works at the family garden centre part-time
But in an estimated ten to 20 per cent of people with a food allergy, the reaction is only sparked when they exercise.
It typically occurs two to four hours after ingesting food, but in some people it can be as much as 12 hours later.
Wheat and prawns are the most common culprits, but fruit, vegetables and nuts can also cause anaphylaxis.
The patient may go through life eating the food they are allergic to without any reaction, and it’s only when they exercise afterwards that the anaphylaxis strikes.
‘The exercise involved can be moderate — one patient suffered anaphylaxis when pushing her baby’s pram up a hill — and in many different forms, from labouring on a building site or dancing in a nightclub to taking a walk or going for a run,’ says Dr Till.
But it’s thought that the more the person exerts themselves, the stronger the reaction.
Diagnosis is based on a patient’s history, what they ate and when they ate it before exercise, plus blood tests commonly used to detect food allergies.
‘Classically, anaphylaxis will occur if the patient exercises two hours after eating the food, but sometimes it can be much longer,’ he says.
‘One patient, a triathlete, reacted to something she had eaten the night before a race.’
Allergy consultants estimate they see one or two patients with FDEIA a month, but all agree the number of undiagnosed sufferers is likely to be much higher.
In an estimated ten to 20 per cent of people with a food allergy, the reaction is only sparked when they exercise
Why exercise should spark anaphylaxis is unknown, but there are theories that it increases the permeability of the gut, changes the way the blood vessels react to allergens or has an effect on the body’s neuroendocrine cells (specialised nerve cells that produce hormones such as adrenaline).
Heat, alcohol, anxiety and mental stress are also thought to exacerbate the problem.
The first case of FDEIA was recorded in a marathon runner in 1979, who collapsed when he ran after eating prawns.
However, there has been no other research into the condition — due, in part, to the danger of inducing a potentially fatal condition.
But this year, doctors will begin a three-year study, funded by the Food Standards Agency, looking at the effects of exercise on food allergies.
Dr Andrew Clark, a consultant in paediatric allergy at Addenbrooke’s hospital in Cambridge, is leading the study that will involve 100 people with a peanut allergy.
‘Each will eat peanuts on four occasions and, under strictly controlled conditions, exercise on a static bike,’ he says.
The researchers expect exercise to lower the threshold at which patients can tolerate peanuts before suffering a reaction.
They think that even people with a food allergy who do not have full-blown FDEIA, exercise may make reactions worse.
‘We will take blood tests to see if there are changes in the blood vessels, gut or allergy cells during exercise,’ says Dr Clark.
Whatever the causes, once a diagnosis is made, avoiding the food causing the reaction is often all that’s necessary for cure.
Alastair Lockhart, 70, from Oban, avoids wheat after an attack earlier this year.
‘For many years I would sometimes get “the itches” — hives and red blotches around my mouth — but thought nothing of it, until the day I walked a mile to the nearby village in the sunshine after a meal,’ he says.
‘I started to get itchy, so I stopped at the local shop to buy antihistamine.
'But soon I was shaking and shivering and couldn’t keep still. I felt as if I was losing consciousness.’
Luckily, a builder in the shop spotted the signs of anaphylaxis and called the local GP, who administered adrenaline.
Alastair was referred to Professor Jonathan Brostoff at King’s College London, and was diagnosed with FDEIA with an allergy to wheat.
‘Working out what foods contain wheat has been tricky — even some whiskies do,’ he says.
As well as food avoidance, patients must have adrenaline with them at all times.
If anaphylaxis strikes, Professor Brostoff advises them to lie down and raise their legs so blood goes back to the heart.
‘Take an antihistamine or adrenaline as soon as possible, call the doctor and, when you are better, ask your GP for a referral to an allergist,’ he says.
Some patients also need to work with a dietitian so they can identify the culprit food.
Since Traton was diagnosed, he avoids greens and salad. He feels healthy and works at the family garden centre part-time.
‘I can eat cauliflower, carrots and red cabbage as well as fruit,’ he says.
‘Luckily for me, I’m a meat and potatoes person, so I don’t mind.’