Chronic indoor mold exposure is associated with significant disruption of the gut microbiome, potentially contributing to irritable bowel syndrome, leaky gut syndrome, and inflammatory bowel disease, according to emerging research presented at the American Gastroenterological Association annual meeting in March 2026.
Researchers analyzed stool microbiome samples from 180 patients with documented water-damaged building exposure and compared them to 180 matched controls. The mold-exposed group showed significantly reduced microbial diversity, decreased populations of beneficial Lactobacillus and Bifidobacterium species, and elevated markers of intestinal permeability.
The proposed mechanism involves mycotoxin absorption through the respiratory tract and gastrointestinal system, where these compounds can directly damage intestinal epithelial cells and alter the chemical environment in ways that favor pathogenic over beneficial bacteria.
Of the 90 mold-exposed patients who completed remediation and a targeted probiotic protocol, 67 showed measurable improvement in microbiome diversity at six-month follow-up, and 54 reported significant reduction in gastrointestinal symptoms.
The research is preliminary but adds to a growing body of evidence that mold exposure has systemic health effects far beyond the respiratory system. Gastroenterologists are being urged to include environmental exposure history in their workups for treatment-resistant digestive disorders.
