A Prospective Study of Dietary Fat Consumption and Endometriosis Risk

Stacey A. Missmer; Jorge E. Chavarro; Susan Malspeis; Elizabeth R. Bertone-Johnson; Mark D. Hornstein; Donna Spiegelman; Robert L. Barbieri; Walter C. Willett; Susan E. Hankinson


Hum Reprod. 2010;25(6):1528-1535. 

In This Article

Abstract and Introduction


Background: Endometriosis is a prevalent but enigmatic gynecologic disorder for which few modifiable risk factors have been identified. Fish oil consumption has been associated with symptom improvement in studies of women with primary dysmenorrhea and with decreased endometriosis risk in autotransplantation animal studies.
Methods: To investigate the relation between dietary fat intake and the risk of endometriosis, we analyzed 12 years of prospective data from the Nurses' Health Study II that began in 1989. Dietary fat was assessed via food frequency questionnaire in 1991, 1995 and 1999. We used Cox proportional hazards models adjusted for total energy intake, parity, race and body mass index at age 18, and assessed cumulatively averaged fat intake across the three diet questionnaires.
Results: During the 586 153 person-years of follow-up, 1199 cases of laparoscopically confirmed endometriosis were reported. Although total fat consumption was not associated with endometriosis risk, those women in the highest fifth of long-chain omega-3 fatty acid consumption were 22% less likely to be diagnosed with endometriosis compared with those with the lowest fifth of intake [95% confidence interval (CI) = 0.62–0.99; P-value, test for linear trend (Pt) = 0.03]. In addition, those in the highest quintile of trans-unsaturated fat intake were 48% more likely to be diagnosed with endometriosis (95% CI = 1.17–1.88; Pt = 0.001).
Conclusion: These data suggest that specific types of dietary fat are associated with the incidence of laparoscopically confirmed endometriosis, and that these relations may indicate modifiable risk. This evidence additionally provides another disease association that supports efforts to remove trans fat from hydrogenated oils from the food supply.


Endometriosis is the third leading cause of gynecologic hospitalization in the USA (Eskenazi and Warner, 1997). Despite the high morbidity and health care cost associated with endometriosis, the etiology has not been fully delineated and few modifiable risk factors have been identified. The pathophysiology likely includes hormonal, anatomic, genetic, immune and inflammatory factors. Risk may be associated with factors that increase the volume, frequency and duration of retrograde menstruation and promote implantation and growth of endometrial plaques (Oral and Arici, 1997).

Dietary factors have been the focus of a growing number of endometriosis patient-directed books and web-sites. Unfortunately, there is little direct scientific evidence to support these suggestions. Only one animal study has directly investigated the relation between diet and the incidence of endometriosis (Covens et al., 1988), which suggested that fish oil could induce regression of surgically induced endometriosis. In the one human study focused upon dietary intake, laparoscopically confirmed endometriosis was positively related to red meat consumption [odds ratio (OR) = 2.0, 95% CI = 1.4–2.8] and inversely related to current green vegetable (OR = 0.3, 95% CI = 0.2–0.5) and fruit consumption (OR = 0.6, 95% CI = 0.4–0.8). However, this study did not observe a significant association with butter, margarine or oil intake (Parazzini et al., 2004) Additionally, a study of organochlorines and endometriosis risk observed no relation between specific foods about which intake data were collected based upon their hypothesized potential organochorine content (Heilier et al., 2007).

There is also a growing body of literature suggesting relations between dietary factors and the physiologic processes or symptoms believed to be associated with endomEtriosis. Smooth muscle contractility, estrogen levels, inflammation, prostaglandin metabolism and menstrual cyclicity are some of the factors that may contribute to endometriosis and can be influenced by diet. For example, specific dietary fatty acids are known to influence the circulating levels of IL-6 and other inflammatory markers found in higher levels among women with endometriosis (Baer et al., 2004). Also, an inverse relation between fish oil supplementation and circulating levels of series 2 prostaglandins and inflammatory symptoms have been observed (Bartram et al., 1993). In addition, a double-blind crossover study involving fish oil supplementation showed a significant reduction in dysmenorrhea (Harel et al., 1996), and another study observed that menstrual pain increased as intake of alpha-linolenic acid decreased (Deutch, 1995). To follow-up on these findings, we used data from the Nurses' Health Study II, an ongoing, prospective cohort study of premenopausal USA nurses that began in 1989, to evaluate the relation between dietary fat consumption and the incidence of laparoscopically confirmed endometriosis.


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