Doctors say a potential treatment for peanut allergy has transformed the lives of children taking part in a large clinical trial.
The 85 children had to eat peanut protein every day – initially in small doses, but ramped up during the study.
The findings, published in the Lancet, suggest 84% of allergic children could eat the equivalent of five peanuts a day after six months.
Experts have warned that the therapy is not yet ready for widespread use.
Peanuts are the most common cause of fatal allergic reactions to food.
There is no treatment so the only option for patients is to avoid them completely, leading to a lifetime of checking every food label before a meal.
The trial, at Addenbrooke’s Hospital in Cambridge, tried to train the children’s immune systems to tolerate peanut protein.
Every day they were given a peanut protein powder – starting off on a dose equivalent to one 70th of a peanut.
The theory was that patients started at the extremely low dose, well below the threshold for an allergic response.
Once a fortnight the dose was increased while the children were in hospital, in case there was an reaction, and then they continued taking the higher dose at home.
The majority of patients learned to tolerate the peanut.
Lena Barden, 11, from Histon in Cambridgeshire, said: “It meant a trip to the hospital every two weeks.
“A year later I could eat five whole peanuts with no reaction at all.
“The trial has been an experience and adventure that has changed my life and I’ve had so much fun, but I still hate peanuts!”
One of the researchers, Dr Andrew Clark, told the BBC: “It really transformed their lives dramatically; this really comes across during the trial.
“It’s a potential treatment and the next step is to make it available to patients, but there will be significant costs in providing the treatment – in the specialist centres and staff and producing the peanut to a sufficiently high standard.”
Fellow researcher Dr Pamela Ewan added: “This large study is the first of its kind in the world to have had such a positive outcome, and is an important advance in peanut allergy research.”
But she said further studies would be needed and that people should not try this on their own as this “should only be done by medical professionals in specialist settings”.
The research has been broadly welcomed by other researchers in the field, but some concerns about how any therapy could be introduced have been raised.
Prof Gideon Lack, who is running a peanut allergy trial at the Evelina Children’s Hospital in London, told the BBC: “This is a really important research step in trying to improve our management of peanut allergy, but is not yet ready for use in clinical practice.
“We need a proper risk assessment needs to be done to ensure we will not make life more dangerous for these children.
He warned that 60% of people with a peanut allergy were also allergic to other nuts so a carefree lifestyle would rarely be an option.
Prof Barry Kay, from the department of allergy and clinical immunology at Imperial College London, said: “The real issues that still remain include how long the results will last, and whether the positive effects might lead affected individuals to have a false sense of security.
“Another issue to address is whether there will be long term side-effects of repeated peanut exposure even where full allergic reaction does not occur, such as inflammation of the oesophagus.
“So, this study shows encouraging results that add to the current literature, but more studies are needed to pin down these issues before the current advice to peanut allergy sufferers, which is to avoid eating peanuts, is changed.”
Maureen Jenkins, director of clinical services at Allergy UK, said: “The fantastic results of this study exceed expectation.
“Peanut allergy is a particularly frightening food allergy, causing constant anxiety of a reaction from peanut traces.
Source: BBC news