The association between dietary index for gut microbiota and colorectal cancer prevalence in US adults: Findings from NHANES 2003 to 2023

Emerging evidence suggests that diet plays a crucial role in shaping gut microbiota, which may influence the risk of colorectal cancer (CRC). This study examined the association between the dietary index for gut microbiota (DI-GM) and CRC prevalence in a nationally representative sample of US adults. This cross-sectional analysis used data from 31,547 adults aged ≥20 years participating in the National Health and Nutrition Examination Survey 2003 to 2023. Weighted logistic regression models estimated odds ratios and 95% confidence intervals for CRC across DI-GM scores, adjusting for demographic, lifestyle, and clinical factors. The mean age of participants was 46.2 ± 17.1 years, and 316 individuals self-reported a CRC diagnosis. CRC cases had significantly lower DI-GM scores than non-cases (3.7 ± 1.5 vs 4.3 ± 1.7, P  < .001). Higher DI-GM scores were inversely associated with CRC prevalence (adjusted odds ratio = 0.89, 95% confidence interval = 0.86–0.98). When analyzed categorically, participants with DI-GM scores ≥6 had 30% lower odds of CRC than those with scores ≤3. Diets that promote a healthier gut microbiota composition are associated with a lower prevalence of CRC.