Fecal microbiota transplant capsules show promise in treating peanut allergies

A Phase I clinical trial involving 15 adults has demonstrated that fecal microbiota transplant (FMT) capsules may increase peanut protein tolerance in individuals with severe allergies. Led by researchers from Boston Children's Hospital and Harvard Medical School, the study published in Science Translational Medicine showed that six of the 15 participants could tolerate higher levels of peanut protein four months after treatment.

Participants, all of whom reacted to 100 milligrams of peanut protein or less, swallowed 36 capsules containing frozen stool-derived microbes from healthy donors. Of the responders, one participant could tolerate 300 milligrams, while five others could tolerate 600 milligrams or more. The effect appeared to be sustained for at least four months, with some data extending to 12 months.

The researchers identified a potential biological mechanism for this shift: responders showed an increase in tolerogenic regulatory T cells and a decrease in T helper 2 cells associated with allergic responses. This marks the first published human evidence that deliberately reshaping the gut microbiome might influence food allergy.