Allergies have rushed up the public health agenda with frightening speed in recent years - and with good cause. Now a new study has given us one of the first glimmers of hope in terms of preventing life-threatening allergy in the first place. The results are potentially hugely exciting - but if you're concerned about food allergies for your children, it doesn't change anything today. What is does is to open up a whole new avenue of possibilities for the children of the future.
The study enrolled babies at high risk of developing food allergy, of which peanut is the most common. These children had already developed eczema, which is linked to a much higher incidence of egg and peanut allergy than the general population. They were all tested with skin prick testing to see if they already showed any evidence of allergic reaction to peanuts, and only those who didn't show a severe reaction were included. Children at high risk were then teased out further with a very small (2-4 g) dose of peanut protein. Half the children at low risk were given at least 6 g of peanut protein (not whole peanuts, which can cause choking in children under five) every week until the age of five, with follow-up initially weekly and at least once a month throughout the study.
At the end of the study, all the children were reassessed to see how many were allergic to peanuts. Importantly, the doctors doing the tests didn't know if the children were in the peanut or no-peanut group, so their evaluation of the results couldn't be biased by this. Among children not exposed to peanuts, 13.7% had developed a peanut allergy, compared to just 1.9% of those who had been given peanuts weekly - a reduction of over 80%. Allergy specialists are hopeful that this might open to door to looking at a similar strategy for other foods that commonly cause allergies.
This was a brave study, but a very important one. Deliberately exposing very small babies - from as young as four months old - to something that could kill them in minutes, might be seen foolhardy in the extreme. But the stakes were high. The number of people affected by the life-threatening version of allergic reaction, anaphylaxis, more than tripled in just five years. (1,2) Peanut allergy is the single most common fatal food allergy and between one and three in 100 children are affected - a doubling in western countries in the last decade. Unlike some other allergies, such as egg allergy, most people will continue to need to avoid even the tiniest exposure to peanuts for the rest of their lives.
They, and everyone around them, will also need to be taught how to spot the signs of anaphylaxis - an itchy pale pink rash; sudden hoarseness, wheezing and shortness of breath; swelling of the tongue, throat and lips; tummy pain, nausea and vomiting; palpitations and collapse. They need to know how to administer life-saving treatment with adrenaline by injection as soon as symptoms appear, and how to carry out CPR, or cardio-pulmonary resuscitation in severe cases.
Last year, another study where some children already affected by peanut allergy became tolerant of peanuts using carefully controlled exposure showed that we can sometimes beat allergy. But everyone knows that prevention is better than cure, which is what makes this new research perhaps more important still. But a couple of serious words of caution; this is the first study of its kind, and until more work is done the recommendations for people with food allergies will remain the same. And no matter how tempted you might be to help your baby avoid peanut allergy in the future, do NOT try this at home.
1) Liew J Allergy Clin Immunol 2009
2) Centres for Disease Control and Prevention report 2008
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