Dietary Fat Intake and Risk of Uterine Leiomyomata

A Prospective Ultrasound Study

Theodore M. Brasky; Traci N. Bethea; Amelia K. Wesselink; Ganesa R. Wegienka; Donna D. Baird; Lauren A. Wise

Disclosures

Am J Epidemiol. 2020;189(12):1538-1546. 

In This Article

Abstract and Introduction

Abstract

Uterine leiomyomata (UL) are associated with severe reproductive morbidity and are the primary indication for hysterectomy in the United States. A recent prospective cohort study of Black women reported positive associations between intakes of marine-sourced ω-3 fatty acids and UL risk. We examined whether intakes of dietary fat were associated with UL incidence in a 5-year prospective study of premenopausal Black women living in Detroit who underwent serial ultrasound. At baseline (2010–2012) and 20, 40, and 60 months of follow-up, participants underwent transvaginal ultrasound. Among 1,171 UL-free women at baseline, incident UL were detected in 277 women. Cox regression was used to estimate hazard ratios and 95% confidence intervals for the association of dietary fat and UL incidence. Intakes of total fat and saturated, monounsaturated, polyunsaturated, and trans-fat were not appreciably associated with UL incidence. Intake of the marine ω-3 polyunsaturated fatty acid, docosahexaenoic acid, was associated with 49% higher UL incidence (quartile 4 vs. 1: hazard ratio = 1.49, 95% confidence interval: 1.04, 2.14; P for trend = 0.01). Intakes of total marine ω-3 polyunsaturated fatty acids were similarly associated with elevated UL incidence (hazard ratio = 1.35, 95% confidence interval: 0.94, 1.93; P for trend = 0.03). It remains unclear whether the fatty acids or persistent environmental pollutants drive the association.

Introduction

Uterine leiomyomata (UL, or fibroids) are associated with severe reproductive morbidity and are the primary indication for hysterectomy in the United States.[1–3] Among reproductive-aged women, the prevalence of clinical diagnosis is approximately 25%–30%.[4] However, a large proportion of UL are undiagnosed,[5] and data from standardized ultrasound screening of women 35–49 years of age indicated that the estimated cumulative incidence of ultrasound-detectable UL by age 50 years was >70%.[4] Black women have a 2- to 3-fold higher incidence of clinically diagnosed UL compared with White women and experience greater symptom severity.[3,4,6] UL are also responsible for significant medical expenditures,[7] with pronounced racial disparities in health-care costs, that disproportionately affect Black women.[8] Aside from racial and reproductive factors, few established risk factors for UL have been identified,[1,9] and these factors do not fully explain the racial disparity in incidence.[3,6]

The underlying sources of dietary fat intake differ between Black and White women in the United States, with Black women generally consuming more dietary fat,[10] and a greater proportion of fat from meat and seafood but less fat from dairy, compared with White women.[11,12] To address whether dietary fat intake could explain part of the racial disparity in UL incidence, it is worthwhile to examine the relationship between dietary fat and UL. The Black Women's Health Study (BWHS), a cohort comprised exclusively of Black women, was the first prospective study to examine associations of dietary fat with UL risk. Investigators reported positive associations of individual dietary monounsaturated fatty acids (MUFAs) and marine-sourced ω-3 polyunsaturated fatty acids (PUFAs) and inverse associations for individual saturated fatty acids (SFAs) with UL risk.[13] No appreciable associations were observed for intakes of total fat or most fat groups, with the exception of total MUFA intake, for which a positive association was reported. The results from this study, however, were likely affected by outcome misclassification because identification of UL cases was based on self-report.

To expand on the existing literature, we examined the association between dietary fat intake and UL incidence in the Study of Environment, Lifestyle, and Fibroids (SELF), a prospective cohort study of Black women who underwent serial ultrasound screening for incident UL.

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