Fecal Transplant Pils Help with Peanut Allergy

In people, fecal transplants — which take feces from healthy people and transplant it into ill individuals, usually by colonoscopy — have become a standard treatment for recurrent Clostridium difficile infections. But it wasn’t until research showed that fecal material could achieve comparable success when delivered as oral capsules that scientists started thinking about doing a trial in people with peanut allergies.

Scientists collected stool samples from healthy donors without allergic diseases and encapsulate the fecal matter into odorless, tasteless pills. The donors had avoided peanuts and tree nuts for a week, and their stool was analyzed by liquid chromatography and mass spectrometry to ensure it contained no traces of nut proteins. The study enrolled 15 adults with severe peanut allergies. At the start of the trial, each had an allergic reaction to 100 milligrams of peanut protein (less than half a peanut). The first 10 participants took 36 “poop pills” over a three-hour period. After one month, 30 percent (3 of 10 participants) could safely consume a 100-milligram dose of peanuts, and by four months, two of these individuals had increased their tolerance to at least 300 milligrams (about one peanut), enough to guard against most accidental exposures.

Fecal matter transferred to pills (shown) shows promise for treating allergies. The remaining five participants had the same poop pill regimen, except that beforehand they took a four-day course of antibiotics with the aim of killing some of the bacteria naturally found in the body in order to clear space in the gut for the transferred microbes. That strategy seemed to work better. Sixty percent (3 of 5 participants) raised their peanut threshold beyond 300 milligrams by month four. (The COVID-19 pandemic lockdown prevented data collection from several participants at the one-month timepoint.) In an analysis of participants’ blood samples, the researchers found increased levels of regulatory T cells only in the six people whose peanut threshold rose with bacteriotherapy — confirming what was previously observed in mice. The results are exciting. The fact that fecal transplant pills helped a subset of individuals without needing exposure to a specific allergen suggests the approach could potentially be useful for patients with multiple food allergies.

CITATIONS R. Rachid. Microbiome interventions in food allergy. American Academy of Allergy, Asthma & Immunology annual meeting, Phoenix, February 26, 2022.

A. Abdel-Gadir et al. Microbiota therapy acts via a regulatory T cell MyD88/RORgt pathway to suppress food allergy. Nature Medicine. Published online June 24, 2019. doi: 10.1038/s41591-019-0461-z.