Patients who risked fatal reaction able to eat without fear after experiment

Allergy to peanuts may be curable following positive results from the world's first successful desensitisation programme for peanut allergy, scientists say today. Children who risked suffering anaphylactic shock, a potentially fatal reaction, if they encountered a single peanut have been protected so that they are able to eat without fear.

The finding will bring hope to thousands of families whose lives have been blighted by the allergy, one of the fastest growing in Britain. It is estimated one in 50 young people are affected by peanut allergy and cases have more than doubled in four years.

The desensitisation programme at Addenbrooke's Hospital involved 22 children aged seven to 17, who were given tiny 5mg starting doses of peanut flour. Gradually over six months the daily dose was built up to 800mgs a day, equivalent to five peanuts.

Twelve children have reached the highest dose level and can tolerate twice as much, equivalent to 10 peanuts, without suffering side effects. For the first time their families know they can lead a normal life and be safe.

Andy Clark, who led the research, said: "Every time people with a peanut allergy eat something, they're frightened that it might kill them. Our motivation was to find a treatment that would change that and give them the confidence to eat what they like." He added: "It's not a permanent cure but as long as they go on taking a daily dose they should maintain their tolerance."

All 12 children are keeping up their tolerance by taking the equivalent of up to five peanuts a day. Dr Clark said: "At the moment we know that if they continue to eat five peanuts a day, their tolerance is maintained."

Dr Clark said the children would be followed for the next three or four years to monitor their tolerance levels and future studies would assess whether the dose could be given as a daily pill. After three or four years, the body may have adjusted and there could be a more "permanent cure", he said.

Details of the first four patients are published today in the journal Allergy. Professor Pam Ewan, head of allergy at Addenbrooke's, who oversaw the research, said the technique had not been tried before because researchers had been afraid it was too dangerous and scientists warned parents not to try the technique at home.

Case study: 'You can never go out to a restaurant'

Michael Frost is planning to celebrate his 10th birthday next month with a trip to a Chinese restaurant. It is the first time in his life that his parents have let him eat the food that used to be so risky.

Michael has been severely allergic to peanuts since he was a baby and was one of the first participants in the Addenbrooke's programme.

His mother, Kate, said the trial had been a success. "It's very hard to describe how much of a difference it's made – not just in Michael's life, but for all of us. A peanut allergy affects the whole family. You can't go out to a restaurant.

"If your child goes to a birthday party, he takes a packed lunch. When he goes out, you lose control of what he eats – and for so many years I've had a permanent knot of anxiety in my stomach. Suddenly those feelings have gone."

The growth in peanut allergy has puzzled doctors. Some claim guidance to pregnant women and small children not to eat peanuts may actually have exacerbated the problem.

In parts of Africa where peanuts are made into a soup used for weaning babies off the breast, and in Israel where they are incorporated into a rusk for babies, the problem of peanut allergy does not exist.

Depriving children of exposure to peanuts in early life may increase the risk of an allergic reaction later.