A simple two-week course of a common antifungal pill did something remarkable for people with inflammatory bowel disease: it eased their symptoms by quietly repairing the ecosystem of microbes living in their guts. In a study published in Nature Medicine, researchers at Weill Cornell Medicine in New York gave 53 patients with mild-to-moderate Crohn's disease or ulcerative colitis either a fluconazole pill that traveled through the entire digestive tract, or a nystatin mouthwash that only worked locally. The patients taking fluconazole came out with healthier guts — and they felt better.
The study, called IVAN (short for IBD Therapy Via Antifungal-driven Microbiota Normalization), grew out of more than a decade of work by Dr. Iliyan D. Iliev, a professor of immunology at Weill Cornell Medicine, who has studied how fungi in the gut interact with the immune system. Working closely with his clinical colleague Dr. Ellen Scherl, founding director of the Jill Roberts Center for Inflammatory Bowel Disease, Iliev noticed that some IBD patients carry too much of a fungus called Candida albicans in their intestines. Certain strains of this fungus make a toxin called candidalysin, which can damage the cells lining the gut and stir up inflammation that makes symptoms worse.
Here is the clever part. The researchers discovered that the Candida strains in a patient's mouth were often the same ones living in their gut. That meant a simple cheek swab could reveal which patients might benefit from treatment — no invasive procedure needed. "In this context, the gut fungi can work against you," said Dr. Xiangyu Pan, the study's first author and a postdoctoral associate. "Overgrowth of fungi and a toxin they produce may affect how a disease progresses and how patients respond to treatment."
After two weeks of fluconazole, patients showed more bacterial diversity in their guts, restored production of butyrate — a fatty acid that feeds healthy gut cells — and improved clinical disease activity. Essentially, clearing out the troublesome fungus let helpful bacteria bounce back, restoring a balance that had been lost.
Iliev sees these results as an early but exciting step toward a new kind of treatment: mycobiome-guided precision therapy, where doctors use a patient's own fungal balance to decide who gets antifungal treatment. "These findings support the concept that disease-associated fungi play a role in the pathogenesis of inflammatory bowel disease in some patients," he said.
The study is preliminary, involving just 53 patients, and larger trials will be needed before this becomes routine care. But it offers real hope for millions of people living with IBD — and a reminder that sometimes the smallest residents of our bodies hold the biggest keys to healing. With a simple cheek swab and an old, affordable drug, the future of IBD care may be getting a little more personal.