Peanut allergy - light at the end of the tunnel?
When I was a medical student, we had a couple of hours' dedicated teaching on allergies in our whole six years of training. Consultants who specialised just in allergies didn't exist - there were a few doctors working in asthma or eczema who had a particular interest, but it wasn't big news
In the last few years, big (and dangerous) news is precisely what it has become. The most life-threatening complication of food allergy is anaphylaxis - an extreme form of allergic reaction which can cause swelling of the lips, tongue and throat; wheezing and problems breathing; feelings of dizziness or collapse; and sometimes death. The number of people affected by anaphylaxis in the UK almost quadrupled between 1994 and 1998 alone (1,2) and the most common culprit is peanuts. Other leading causes include shellfish, fish, treenuts, eggs, milk, fruits and food additives.
An anaphylactic reaction to food is always a medical emergency - every patient is supplied with pen injectors containing adrenaline and detailed instructions on carrying them with them at all times, spotting the symptoms and how to use the pens. The smallest contact with whatever they're allergic to can trigger a reaction - even dust from peanuts in the air you breathe in. Allergy UK now provides guidance on how to avoid even exposure to peanut dust in the air on aircraft and advice on finding 'nut free flights'. Small wonder that this kind of food allergy has a huge impact on quality of life, affecting food choices, social restrictions and fear of dying more than type 1 diabetes. (3)
Peanut allergy affects about 1 in 2,000 people, (4) but a much higher proportion of children, possibly up to 1 in 50. Unlike allergies to cow's milk and eggs, peanut allergy very rarely goes away on its own. Spontaneous eating is out - every food label has to be scrutinised for hidden traces of peanut. So this study, in which 84% of treated children were able to tolerate the equivalent of five peanuts a day after six months, is exciting stuff for children and their worried parents alike. There have been other studies, but none has been as successful as this. They started by taking in tiny doses of peanut - equivalent to 1/70 of a peanut, and built up gradually, taking a daily 'dose'.
But we're by no means there yet. This was a very specialist trial, carried out on just 85 children. It's not known whether there will be long-term complications (such as inflammation of the oesophagus) from repeated exposure to peanuts in peanut allergic children. It's not known if the effects will last in the long term. Sixty per cent of children who are allergic to peanuts are also allergic to other foods, so they won't be able to let their guard down completely. And finally, more research needs to be done before this treatment can be considered safe to introduce more widely. Even so, if my child were unlucky enough to be affected by peanut allergy, I'd be feeling a little more hopeful today than yesterday.
1) Liew J Allergy Clin Immunol 2009
2) Centres for Disease Control and Prevention report 2008
3) Avery NJ, King RM, Knight S, Hourihane J (2003). Assessment of quality of life in children with peanut allergy. Pediatric Allergy and Immunology. Volume 14 Issue 5 Page 378. October 2003.
4) Kotz D, Simpson CR, Sheikh A. Incidence, prevalence, and trends of general practitioner-recorded diagnosis of peanut allergy in England, 2001 to 2005. The journal of allergy and clinical immunology, January 14 2011 (published online)