American scientists have discovered that some patients who live in fear of a fatal peanut allergy might actually have outgrown their problem.

But because they are too scared to risk a potential fatal peanut reaction they continue to avoid any of the foods that carry the nuts.

About five or six people a year die in the UK from food allergies, but an article in the Journal of Allergy and Clinical Immunology says that as many as 20% of people might outgrow an allergy to nuts.

The new research has been welcomed by sufferers, who hope that for some people this could mean a life free from the daily fear that peanuts could kill them.

Peanuts can be hidden in many food stuffs and sufferers are advised to carry epinephrine shots with them at all times in case they accidentally swallow them.

Allergic reactions can range from hives, swelling and vomiting to breathing problems and a swelling of the tongue or throat which can be suffocating.

Re-testing by doctors

Professor Robert Woods, the lead investigator from Hopkins, the Arkansas Children's Hospital - himself a peanut allergy sufferer - says the only answer is regular re-testing by doctors.

"Until now the rules have been that when you diagnose a patient with peanut allergy you tell them that it is a life-long allergy, with no chance of being outgrown.

"I recommend from this study that children with peanut allergy be re-tested on a regular basis, every one or two years," he said.

Professor Woods found that children who lost sensitivities to other foods like milk and eggs were much more likely to outgrow their peanut allergies than those who did not.

"We saw a few allergic people who did not react when they had an accidental exposure or when they were re-tested as part of our normal follow-up of food allergies.