A prospective study of dietary patterns and the incidence of endometriosis diagnosis.

BACKGROUND: Although endometriosis is a common condition-affecting ∼10% of premenopausal individuals-its etiology is unknown. Diet receives large patient attention, but studies of the role of diet are limited. Examining dietary patterns is essential to provide new insight.

OBJECTIVE: We sought to determine whether dietary patterns are associated with laparoscopically-confirmed endometriosis diagnosis.

STUDY DESIGN: We conducted a prospective cohort study among 81,997 premenopausal participants of the Nurses' Health Study II, who were followed from 1991-2015. Diet was assessed with validated food frequency questionnaires every four years. We examined six dietary patterns: Western, Prudent, Alternative Healthy Eating Index (AHEI-2010), Dietary Approaches to Stop Hypertension (DASH), an estrogen-associated pattern, and a pro-inflammatory pattern. Cox proportional hazard ratios (HR) and 95% confidence intervals (CI) were used to quantify the association between each of these patterns and laparoscopically-confirmed endometriosis diagnosis.

RESULTS: 3,810 incident cases of endometriosis were diagnosed during 24 years of follow-up. Adherence to the AHEI-2010, reflecting a healthier dietary pattern, was associated with a 13% lower risk of endometriosis diagnosis (5th vs 1st quintile 95% CI=0.78-0.96; ptrend =0.02). Participants in the highest quintile of the Western dietary pattern, characterized by high intake of red meat, processed meat, refined grains, and desserts, had a 27% higher risk of endometriosis diagnosis compared to those in the lowest quintile (95% CI=1.09-1.47; ptrend =0.004). The Prudent, DASH, and estrogen-associated dietary patterns did not demonstrate clear associations with endometriosis risk, and there was the suggestion of higher risk of endometriosis diagnosis among those with a higher pro-inflammatory diet score (HR for 5th vs 1st quintile=1.10; 95% CI=0.99-1.23; ptrend =0.01).

CONCLUSION: Our results suggest that consuming a dietary pattern that adheres to the AHEI-2010 recommendations lowers the risk of endometriosis diagnosis, potentially through a beneficial impact on pelvic pain. In addition, consuming a less healthy diet high in red/processed meats and refined grains may have a detrimental impact on endometriosis symptoms.