Association between dietary inflammatory index and endometriosis in the US population: A cross-sectional study

Background

Endometriosis is a chronic inflammatory disorder affecting reproductive-aged women. The Dietary Inflammatory Index (DII), a measure of diet-related inflammation, has been implicated in various inflammatory diseases, but its role in endometriosis remains unclear.

Methods

This cross-sectional study analyzed 4149 women from the NHANES 2001–2006, including 287 with endometriosis. DII scores were derived from dietary data and categorized into quartiles. Logistic regression models were used to assess the association between DII and endometriosis, adjusting for confounders. Restricted cubic splines (RCS) were applied to explore non-linear trends, and subgroup analyses evaluated effect modifications. LASSO regression identified key predictors, and a nomogram was developed for risk prediction.

Results

Women with endometriosis had higher DII scores than those without (1.69 ± 1.76 vs. 1.48 ± 1.74, P = 0.044). In fully adjusted models, the odds of endometriosis increased with higher DII quartiles (Q4 vs. Q1: OR1.40, 95 % CI: 1.02–1.98, P for trend < 0.001). While non-linear trends were not statistically significant (P-non-linear = 0.128), RCS analysis suggested a steeper risk increase at higher DII levels. Subgroup analyses indicated stronger associations among older women, those with higher BMI, and smokers. The nomogram achieved moderate predictive performance (AUC: 66.6 %, 95 % CI: 63.7–69.5 %).

Conclusion

Higher DII scores are associated with increased odds of endometriosis. Dietary interventions targeting inflammation may offer a novel approach to managing endometriosis.