A small clinical trial published in Science Translational Medicine has produced the first evidence that faecal transplants can treat food allergy in people. Six of 15 adults with severe peanut allergy could tolerate peanuts four months after receiving odourless, tasteless pills packed with gut bacteria from healthy donors without the allergy. One participant could eat 300 milligrams of peanut protein; five could manage 600 milligrams or more — about two and a half peanuts — up from a starting tolerance of under 100 milligrams.
The phase-1 trial, led by researchers at Boston Children's Hospital and Harvard Medical School, reported no severe side effects. "Up until now, it's been in mouse models. Now we have people. And that's exciting," said immunologist Cathryn Nagler. Bacteria from responders also protected mice from egg allergy in follow-up experiments, hinting the approach could extend beyond peanuts. Researchers caution the results are early, but physicians called the sustained benefit "really, really exciting" — a contrast to existing therapies whose effect fades without continued treatment.
