Fewer people may have peanut allergy

18th January 2010 - Food allergies are thought to affect around one in 12 children and up to one in 50 adults in the UK and food allergy cases have risen sharply over the last 20 years, according to the Food Standards Agency. However, researchers in Manchester now believe a big proportion of people tested positive for peanut allergies may not be at risk from the nuts at all.

Peanut allergy risks and symptoms

A peanut allergy is a reaction that occurs when your body mistakenly identifies peanuts as harmful substances. When you eat peanuts or food containing peanuts, your immune system - the body's natural defence system that fights infections and diseases - overreacts and can cause a serious, even life-threatening response.

Symptoms of peanut allergy can range from mild to life-threatening. If you have a mild reaction, you may get a stomach ache, a runny nose, an itchy skin rash, hives or tingling in your lips or tongue. If your reaction is worse, you may develop additional symptoms such as a tight throat, hoarse voice, wheezing, coughing, feeling sick to your stomach, vomiting, stomach pain and diarrhoea.

Your symptoms may start from within a few minutes to a few hours after eating peanuts or peanut products.

People who are allergic to peanuts may have a life-threatening reaction called anaphylaxis. Symptoms of anaphylaxis can include difficulty breathing and swallowing, vomiting and diarrhoea, dizziness, dangerously low blood pressure, swelling of the lips, tongue, throat, and other parts of the body and loss of consciousness. If not treated, death can result. Anaphylaxis usually occurs within minutes but can occur up to several hours after eating peanuts or peanut products.

Schools will often ban any snacks containing peanuts from children’s lunchboxes for fear of contact with a child with a known or undiagnosed nut allergy.

New tests

993 eight year old children were given brownies containing peanut protein in special tests at University Hospital South Manchester. They were then given a new type of blood test which looks for a reaction to a specific part of the peanut which triggers serious allergic reactions. The existing skin prick tests look for antibodies to much more of the peanut, which the researchers believe gives too many wrong diagnoses.

In the new tests, 80% of children who were believed to have an allergy to peanuts did not suffer any reaction after eating the peanut brownies. The results of the University of Manchester study are published in the Journal of Allergy and Clinical Immunology.

Next steps

The researchers admit the study only looked at a relatively small number of children, but say they have confirmed the presence of peanut allergy is substantially lower than peanut sensitisation.

They write that accurate testing is needed to allow anxious parents to find out whether a child will react to peanuts. They raise concerns about over-the-counter allergy testing kits which may give parents a misleading diagnosis, especially as they are carried out without any consideration of the child’s medical history.

You can find out more about living with a nut allergy here.