Swallowing faecal capsules reduces peanut allergy in six adults
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- Rima Rachid at Boston Children's Hospital led the trial of 15 adults (average age 21) with peanut allergy, who swallowed 36 capsules containing faeces from a healthy donor with no food allergies in a single day
- Six of the 15 participants could safely consume greater amounts of peanut four months later; most responders tolerated peanut flour equivalent to one whole peanut, and one tolerated the equivalent of four peanuts
- John Ziegler at the University of New South Wales called it a "small open-label uncontrolled study" and said placebo response could explain the positive outcomes because every participant knew they were receiving the treatment
- Rachid's team is now running a larger randomized, placebo-controlled trial in children aged 12 to 17, which will give a clearer reading on whether the treatment actually works
- When faeces from responders was transplanted into mice, it triggered a thousand-fold increase in Bacteroidales gut bacteria, backing prior research that links low Bacteroidales levels to peanut allergy
- Trial participants still must avoid peanuts and carry EpiPens because researchers do not know how long the protective effect will last; side effects from the capsules (diarrhoea, abdominal pain) were mild and short-lived
Why it matters: For the six responders, peanut tolerance held four months after a single day of treatment — a contrast to oral immunotherapy, which demands daily dosing and loses its effect once stopped. But the open-label, uncontrolled design means placebo response can't be ruled out; the randomized pediatric trial now underway is what will determine whether microbial therapy becomes a real treatment option.
