Faecal capsules improve peanut allergy tolerance in early study

A faecal microbiota transplant may ease life-threatening peanut allergies in adults, according to a study reported by ERR. In the first human study of its kind, nearly half of 15 participants developed a higher tolerance threshold for peanuts.

Food allergies, particularly severe peanut allergies, are a serious health concern. Current treatment mainly focuses on avoiding the allergen and using an adrenaline injection after accidental exposure.

Researchers changed the participants’ gut microbiomes using oral capsules containing gut bacteria from healthy donors without food allergies. Each participant swallowed a total of 36 frozen capsules over several hours.

Ten young adults received only the faecal capsules, while five were given a course of antibiotics beforehand to make room in the gut for the donor bacteria. Three people in each group showed improved peanut tolerance several months later, meaning the treatment was more effective proportionally among those who had received antibiotics.

Before treatment, the participants reacted to microscopic amounts of peanuts. After successful treatment, five participants tolerated at least 600 milligrams of peanut protein, while one was able to eat four peanuts.

In a second part of the study, the researchers transplanted stool from treated patients into sterile mice. The microbiome of patients who responded well to treatment protected the mice from allergy, while bacteria from patients who did not respond did not provide the same protection.

The researchers linked the treatment’s success to bacteria from the Bacteroides family, which help process bile acids. Patients who responded to treatment had higher levels of bile salts in their blood than those who saw no benefit.

Processed bile acids affect the immune system in the gut by increasing the number of regulatory T cells. These cells help calm the immune system and teach the body to tolerate harmless food proteins such as peanuts. This natural tolerance mechanism is disrupted in people with food allergies.

Further studies are needed to confirm the findings and identify the beneficial bacteria involved.