Higher Dietary Index for Gut Microbiota (DI-GM) scores were associated with lower odds of IBS and more favorable inflammatory profiles, but strong correlations between symptom severity and inflammation suggest reverse causality may be present, and causal inference is not permitted due to the cross-sectional design.
IBS patients had significantly lower DI-GM scores than matched controls.
Participants in the highest DI-GM tertile had significantly lower levels of gut permeability and inflammatory markers compared to those in the lowest tertile.
Higher DI-GM scores were associated with lower IBS symptom severity and lower psychological scores.
Logistic regression indicated that individuals in the highest DI-GM tertile had substantially lower odds of IBS compared to those in the lowest tertile.
IBS symptom severity showed strong positive correlations with inflammatory markers, suggesting possible reverse causality whereby symptoms may drive dietary modifications rather than diet determining disease.
This research suggests that people with irritable bowel syndrome (IBS) tend to have much lower scores on the Dietary Index for Gut Microbiota (DI-GM), a measure of how well a person's diet supports a healthy gut microbiome, compared to people without IBS. In a study of 350 adults (175 with IBS, 175 without), those who ate diets more supportive of gut health had lower levels of several markers associated with intestinal leakiness and inflammation, including zonulin, LPS, and CRP. People with higher diet quality scores also reported less severe IBS symptoms and better psychological well-being. However, the researchers flag an important limitation: because this was a case-control (cross-sectional) study, it is impossible to determine which came first — the poor diet or the IBS. The strong link between symptom severity and inflammation raises the possibility of reverse causality, meaning that having severe IBS symptoms might cause people to change what they eat and experience more inflammation, rather than a poor diet causing the disease in the first place. This is a critical distinction the study cannot resolve. This research matters because it highlights a meaningful relationship between diet quality, gut health markers, and IBS, and points to the DI-GM as a potentially useful tool for studying diet-gut interactions. However, the findings should be interpreted cautiously. Prospective studies — those that follow people over time before they develop IBS — are needed to understand whether improving diet quality could actually reduce the risk or severity of IBS.
Wang Y, Zhang G, Lin S, Zhuang X. (2026). Dietary index for gut microbiota (DI-GM) and irritable bowel syndrome: a case-control study.. Scientific reports. https://doi.org/10.1038/s41598-026-50647-3