Fecal Capsule Treatment Improves Peanut Tolerance in Some Adults

The participants, average age 21, took 36 capsules of fecal matter from a healthy donor without food allergies over one day. Most of the six responders could safely ingest peanut flour equivalent to one whole peanut, and one tolerated up to four peanuts. Lead researcher Rima Rachid of Boston Children's Hospital called the responses a marked improvement, though some participants dropped out or showed no benefit, possibly due to failed gut colonization.

Side effects like diarrhea and abdominal pain were mild and short-lived. John Ziegler of the University of New South Wales cautioned that the small, open-label, uncontrolled study may be subject to placebo effects. A larger randomized trial in children aged 12 to 17 is underway.

The study also found that feces from responders increased gut bacteria called Bacteroidales a thousand-fold in mice, supporting earlier research linking these bacteria to protection against food allergy. While promising, participants still need to avoid peanuts and carry an EpiPen as the protective effect's duration is unknown. The findings were published in Science Translational Medicine.