Six adults with peanut allergy have become more tolerant of peanuts after swallowing capsules containing the faeces of someone with no food allergies. The finding from the small clinical trial adds to growing evidence that food allergy is related to the mix of microbes in a person鈥檚 gut, and may be relieved by altering this mix. 聽
鈥淭his study provides the proof of concept that microbial therapy is an intervention that should be further evaluated for treatment of food allergy,鈥� says at Boston Children鈥檚 Hospital, who led the research.
The trial involved 15 adults with an average age of 21 who experienced allergic reactions, like hives or lip swelling, if they ate even small traces of peanut. Over the course of a day, they were asked to swallow 36 capsules that contained the faeces of a healthy donor with no food allergies. The idea was to try to colonise their guts with the gut microbes of the donor.
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When the participants were tested four months later, six were able to consume greater amounts of peanut without allergic reactions. Most could safely ingest peanut flour at a dose equivalent to one whole peanut, and one participant was fine with all the doses that were tested 鈥� including the equivalent of four whole peanuts. 鈥淭hese responses represent a marked improvement,鈥� says Rachid.
Other participants dropped out of the study or didn鈥檛 become more tolerant of peanuts, possibly because the microbes from the donor faeces failed to colonise their guts, she says.
Some of the volunteers reported side-effects from the capsules, like diarrhoea or abdominal pain, but they were mild and short-lived.
at the University of New South Wales in Australia says it鈥檚 too early to judge the treatment鈥檚 efficacy because it was a 鈥渟mall open-label uncontrolled study鈥�. In other words, all the participants knew they were receiving the treatment, so any positive responses might have been due to the placebo effect.
Rachid and her colleagues are now running a larger trial in children aged 12 to 17 with peanut allergy who have been randomised to take capsules containing concentrated faecal microbes from a healthy donor or a placebo. This will provide a clearer picture of whether the treatment works, she says. 聽
At the moment, peanut allergy is mostly managed by avoiding peanuts and carrying an EpiPen to inject in the event of accidental exposure. It is sometimes treated with oral immunotherapy, which involves daily ingestion of gradually increasing doses of peanut powder to desensitise the immune system. But some people find this regime too burdensome, and its protective effect wears off after discontinuation.
This is why it is promising that a single day of treatment with the faecal capsules reduced peanut allergy four months later in some participants, says Rachid. For now though, these participants still have to avoid peanuts and carry an EpiPen because 鈥渨e do not know how long the protective effect will last,鈥� she says.
An interesting finding of the study was that when the faeces of participants who responded to the treatment was transplanted into the guts of mice, it resulted in a thousand-fold increase in gut bacteria called Bacteroidales. This backs up other research suggesting that Bacteroidales bacteria are protective against food allergy. For example, a of 1400 Canadian children found that peanut allergy was associated with low Bacteroidales levels in their guts.
In a previous , Rachid and her colleagues also showed that treatment with Bacteroidales bacteria prevented food allergies in allergy-prone mice. The reasons for this protection are still being figured out, she says.
Faeces capsules have also been successfully used to treat and auto-brewery syndrome. They are more convenient than traditional faecal microbiome transplants, which involve infusing donor faeces through a tube into recipients鈥� guts.
Science Translational Medicine
