Dietary fat intake, erythrocyte fatty acids, and risk of uterine fibroids.

Objective To prospectively evaluate the association between dietary fat intake and risk of uterine fibroids; and to evaluate the association between erythrocyte membrane fatty acid (FA) levels and fibroid risk. Design Prospective cohort study. Cox proportional hazard models were used to calculate hazard ratios and 95% confidence interval (CI). In a subset of participants 34 individual FAs were measured and logistic regression analysis was used to estimate odds ratios (ORs) and 95% CI for the association between FA tertiles and fibroids. Setting Not applicable. Patient(s) Premenopausal US women (81,590) in the Nurses’ Health Study II, aged 25–42 years at enrollment in 1989 for whom diet was assessed by a food frequency questionnaire. A total of 553 participants with erythrocyte FA measurements. Intervention(s) Not applicable. Main Outcome Measure(s) Cases of fibroids were defined on the basis of self-reported ultrasound or hysterectomy confirmation. Result(s) A total of 8,142 cases of ultrasound-confirmed or hysterectomy-confirmed were diagnosed during an 18-year period (1991-2009). No associations were observed between intake of any dietary fats and fibroids in the multivariable models. However, when erythrocyte FAs were examined, an inverse association was observed between total n-3 polyunsaturated FAs and likelihood of fibroids (OR for third versus first tertile, 0.41; 95% CI 0.19–0.89). In addition, total trans FAs were associated with more odds of fibroids (OR for third tertile, 3.33; 95% CI 1.50–7.38). Conclusion(s) Our findings provide preliminary suggestions that n-3 polyunsaturated FAs and trans FAs may play a role in fibroid etiology; however, these results should be confirmed in future studies.