Hi there, I’m Dr Golly. Today we’re going to discuss food allergy, which affects up to 1 in 20 children and 1 in 50 adults. The most common triggers for food allergy are egg, cow’s milk, peanut and seafood. But not all reactions to food are allergies – things like lactose intolerance, reflux or gastro – are not caused by the immune system, the way allergy is. Today I’m going to explain how allergic reactions occur and what you can do to best prevent them from happening.

Although food allergies can appear at any age, they most commonly start under the age of 5 years. It occurs as a result of an over-reaction of the body’s normal immune system, to a seemingly harmless trigger. Let’s jump to the whiteboard and take a look at what happens during an allergic reaction to food.

A mast cell is a type of white blood cell in the body, which plays an important role in wound healing, the formation of new blood vessels and helping fight off worms and parasites. Mast cells live in the skin, bowel, eyes, lungs and nose – and they’re filled with a chemical called histamine.

This histamine will be released when the mast cell gets activated and will cause most of the symptoms you get in an allergic reaction. So what causes a mast cell to activate and release all that histamine?

The mast cell is covered by proteins called IgE antibodies – which act like a keyhole. If someone is allergic to peanut, we call the peanut an allergen, which acts like the ‘key’ to that mast cell. So when the allergen comes into contact with the antibody – the key enters the keyhole – unlocking the mast cell’s histamine.

The symptoms of this histamine release usually occur within half an hour of eating a food, they include: hives, skin flushing, swelling around the mouth, wheeze or cough, light-headedness, stomach cramps or vomiting. Other milder symptoms may be a runny nose, nausea or diarrhoea.

The most severe form of allergy is called anaphylaxis. This involves the breathing and circulation systems and can be life-threatening if not treated urgently. If a child has been exposed to an allergen and shows (list): difficult or noisy breathing, hoarse voice, dizziness or has fainted, this could be an anaphylaxis response and requires urgent attention.

Every person with known anaphylaxis needs an action plan and Adrenaline auto-injector, it’s important to discuss this with your child’s doctor and review the action plan at every visit.

The most effective management of food allergy is avoidance. But it isn’t always so easy. Let’s jump to the whiteboard again, and take a look at this process.

Sometimes the trigger is quite obvious. Other times, a food diary or extensive history can point to a particular ingredient. Allergy specialists are also able to perform skin-prick tests and other blood tests that can help identify potential triggers.

Skin prick tests are performed in a controlled environment, where very small amounts of possible allergens are injected just beneath the skin’s surface, to look for a possible reaction. Any swelling is closely monitored and your child’s doctor will be able to advise what your child is – and is not – likely to react to.

For any food allergy, the most important things to remember are:

  1. Identify and avoid the trigger or allergen.
  2. Recognise the early signs of an allergic response.
  3. Make sure that anyone who looks after your child knows the allergy action plan and is trained to deliver potentially life-saving treatments.

The most up-to-date research suggests that if you want to minimise your child’s chances of developing a food allergy, expose them to as many allergens as possible, from 4 months of age – usually the time most children will be starting solids.

So can children grow out of a food allergy?

Well, most children allergic to cow’s milk, soy, wheat or eggs will be able to tolerate these foods by the time they reach school age, but allergic reactions to nuts and seafood will persist in ¾ of children. When food allergy develops for the first time in adults, it usually persists.

Thanks for watching – I’m Dr Golly, I’ll see you next time.

Last Reviewed: 09/10/2019

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