Beyond bacteria: why researchers are now looking at gut viruses and fungi in IBD

When people talk about the "gut microbiome," they usually mean bacteria. For inflammatory bowel disease — ulcerative colitis and Crohn's disease, where parts of the gut become inflamed [1] — bacteria have been the main focus of research for years.

A 2026 review makes a simple point: bacteria are not the only residents of the gut. Viruses (together called the virome) and fungi (the mycobiome) live there too, and the review argues they have been comparatively neglected — while possibly playing a role in IBD as well [2].

It's worth being precise about what this is. This is a review — a summary of existing evidence and open questions — not a single new experiment, and not a result that changes how IBD is diagnosed or treated [3]. It points at a direction researchers think is worth more attention, which is different from saying anything is settled.

For someone living with IBD, the practical takeaway is small and honest: the science of the gut is still expanding, and "microbiome" is broader than bacteria alone. It is not a reason to change anything you are doing. If you are weighing what any of this means for your own situation, your clinician knows your case best — ask them first.