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

objectiveTo 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.

designProspective 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.

settingNot 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.