The research, as well as the initial trial, was led by Prof. Mimi Tang, of the University of Melbourne's Department of Pediatrics in Australia. The findings were published in the journal The Lancet Child & Adolescent Health.
Food allergies have become more and more common in the past two decades, but unlike allergies to egg, milk, or soy, nut allergies tend to persist in adulthood, say the researchers.
Studies referenced by the authors note that the quality of life among children with food allergies is worse than that of children with diabetes, and accidental exposure to the allergen affects 15 to 20 percent of children with a peanut allergy. Additionally, allergy to peanuts is the leading cause of anaphylaxis, which is a deadly allergic reaction.
In this context, the trial - which was carried out by Murdoch's Children Research Institute and which ended in 2013 - and its follow-up results 4 years later provide much-needed hope for children with a peanut allergy that they will no longer need to watch out for accidental ingestion. The new treatment could allow them to eat peanuts without having to worry about the health risks.
The treatment consists of a combination of probiotics with peanut oral immunotherapy (PPOIT).
The original PPOIT trial
Four years ago, the initial trial examined two groups of children: one group was administered PPOIT - that is, the Lactobacillus rhamnosus probiotic in combination with gradually increasing amounts of peanut protein - and a control group received a placebo.
Both groups were administered either the treatment or the placebo once per day over a period of 18 months.
At the end of the trial, the children were tested for peanut tolerance. Significantly, the vast majority of the children (82 percent) had become tolerant to peanuts. By contrast, in the placebo group, only 4 percent acquired the tolerance.
Since then, the children who were deemed tolerant to peanuts were asked to consume them as part of their regular diet for a period of 4 years after the trial ended, while the children who remained peanut allergic continued to avoid eating them.
PPOIT effective 4 years later
Then, 4 years later, Prof. Tang and colleagues gave a structured questionnaire to the peanut-tolerant children, investigating peanut consumption and documenting adverse reactions to peanuts.
Additionally, the researchers retested these children for peanut allergy. Using peanut skin-prick tests, Prof. Tang and team measured the concentrations of two peanut-specific antibodies: sIgE and sIgG4. Finally, the researchers asked the children to participate in a double-blind, placebo-controlled food challenge, during which their desensitization was assessed.
Prof. Tang summarizes the study's findings, saying, "The [PPOIT] was associated with long-lasting ability to tolerate peanut 4 years after stopping the treatment."
More specifically, says Prof. Tang, "Of the PPOIT-treated participants who achieved short-term tolerance at the end of the original trial, 80 percent were still eating peanut, and 70 percent had long-lasting challenge-proven tolerance 4 years after stopping treatment."
She also stresses the fact that these children did not follow any particular peanut intake guidelines during the follow-up period. "These children were able to eat peanut like children who don't have [a] peanut allergy and still maintain their tolerant state," says Prof. Tang.
In fact, "Over half were consuming moderate to large amounts of peanut on a regular basis, others were only eating peanut infrequently," she adds.
"These findings suggest our treatment is effective at inducing long-term tolerance, up to 4 years after completing treatment, and is safe [...] It also suggests the exciting possibility that tolerance is a realistic target for treating food allergy."
Prof. Mimi Tang
"This is a major step forward in identifying an effective treatment to address the food allergy problem in Western societies," concludes Prof. Tang. "We are now examining whether these beneficial effects of our novel treatment have also resulted in improved quality of life."