A small clinical trial has offered early evidence that changing the gut microbiome could increase peanut tolerance in some people with severe peanut allergies.
Researchers at Boston Children’s Hospital found that several young adults experienced improved tolerance to peanuts after receiving a fecal microbiota transplant designed to introduce beneficial bacteria from healthy donors into their digestive systems.
The findings, published in Science Translational Medicine, could point toward a new approach to treating food allergies, although researchers stressed that much larger studies will be needed before the treatment could become widely available.
Researchers Tested “Poop Pills” in Adults With Peanut Allergies
The study involved 10 young adults with severe peanut allergies who could react to very small amounts of peanut.
Participants received a one-time treatment consisting of 36 frozen, encapsulated fecal material pills taken over several hours. The goal was to introduce bacterial strains associated with protection against allergic reactions.
Four months after treatment, three of the 10 participants were able to eat multiple peanuts during an allergy challenge without experiencing a reaction.
Researchers then examined whether temporarily reducing participants’ existing gut bacteria could make it easier for the transplanted bacteria to establish themselves.
Five additional participants received antibiotics before the microbiome transplant. Three of those participants subsequently demonstrated increased peanut tolerance, eating more than four peanuts before developing an allergic reaction.
The results suggested that the antibiotics may have helped the donor bacteria take hold by reducing competition from bacteria already living in the participants’ intestines.
Gut Bacteria and Bile Salts May Play a Role
The researchers also investigated why some participants responded to the treatment while others did not.
Blood testing showed that people who benefited from the transplant had higher levels of bile salts than those who did not respond. Bile salts are produced by the liver, stored in the gallbladder and released into the small intestine, where they help the body digest fats.
The researchers found that bacteria introduced through the fecal transplant appeared to be particularly effective at metabolizing bile salts.
Additional experiments indicated that this process was associated with increased levels of immune-regulating cells that help maintain tolerance to foods and protect against allergic reactions.
Dr. Talal Chatila, director of translational immunology at Boston Children’s Hospital and a senior researcher on the study, said the findings provided insight into how bacteria, their metabolites and the immune system could interact to influence food allergy.
Study Builds on Earlier Research
The clinical trial followed earlier experiments by Chatila, Dr. Rima Rachid, and their colleagues involving mice prone to food allergies.
In those experiments, mice that received stool samples from infants with food allergies developed severe allergic reactions, while mice given samples from healthy infants were protected.
The researchers subsequently identified several bacterial strains in the healthy infants’ gut microbiomes that appeared to provide protection against allergic reactions.
The new human trial was designed to determine whether introducing similar beneficial bacteria could have an effect in people with peanut allergies.
Rachid, who directs the Food Allergy Program and Allergen Immunotherapy Program at Boston Children’s Hospital, said people with food allergies often want a treatment that could provide lasting protection rather than requiring indefinite therapy.
Results Remain Preliminary
Despite the encouraging findings, the study was small and was primarily designed as an early-stage investigation.
Only a portion of participants experienced increased peanut tolerance, and the researchers have not established that the treatment can prevent severe allergic reactions in everyday life.
Additional clinical trials will be necessary to determine how effective and safe microbiome-based treatments are, which patients might benefit and whether specific bacterial strains could eventually be developed into more targeted therapies.
Researchers are already studying newer formulations that use concentrated microbial preparations rather than the fecal material used in the initial trial.
A separate study is also examining microbiome therapy in teenagers, with participants expected to take the treatment at home under medical supervision before undergoing food challenges to assess whether their peanut tolerance has changed.
A Potential New Direction for Food Allergy Treatment
Peanut allergy is among the food allergies most likely to cause severe, potentially life-threatening reactions. Current treatments can help some patients increase their tolerance, but they do not necessarily eliminate the underlying allergy.
The Boston Children’s Hospital research suggests that the gut may play a more important role in controlling food allergies than previously understood.
The researchers’ findings indicate that beneficial gut bacteria may influence bile acid metabolism and, in turn, affect immune cells involved in developing tolerance to foods.
For now, however, fecal microbiota transplantation remains an experimental approach for peanut allergy. The results provide an early signal that modifying the gut microbiome could eventually become part of a broader strategy for treating food allergies, but the findings will need to be confirmed in larger, controlled studies.
