Diet Linked to Endometriosis

Diet Linked to Endometriosis (to view the article directly, paste the url to a google search window, then click through to the story. Otherwise, if you go to the url directly, they’ll try to make you sign in as a registered user)
News Author: Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd

July 15, 2004 — Dietary fruits and vegetables seem to protect against endometriosis, whereas red meat and ham seem to increase the risk, according to the results of two case-controlled studies published in the July issue of Human Reproduction.

“We found … that there was a 40% relative reduction in risk of endometriosis in women with higher consumption of green vegetables and fresh fruit,” lead author Fabio Parazzini, from the Gynaecologic Clinic of the University of Milan in Italy, says in a news release. “But, for those with a high intake of beef, other red meat and ham, there was an increase of about 80-100% in relative risk.”

The investigators compared dietary patterns in 504 women admitted to obstetrics and gynecology departments for laparoscopically confirmed endometriosis with those of 504 women admitted for acute nongynecological, nonhormonal, nonneoplastic conditions. Median age was 33 years (range, 20 to 65 years) in the cases and 34 years (range, 20 to 61 years) in the controls.

Participants were asked about their diet in the year preceding the interview, including how many weekly portions they ate of selected dietary items, including the major sources of retinoids and carotenoids in the Italian diet. They were also asked about alcohol and coffee consumption.

Compared with women in the lowest tertile of dietary intake, risk of endometriosis was significantly lower for the highest tertile of intake of green vegetables (odds ratio [OR], 0.3) and fresh fruit (OR, 0.6). High intake of beef and other red meat (OR, 2.0) and ham (OR, 1.8) were associated with increased risk.

Endometriosis was not significantly associated with intake of milk, liver, carrots, cheese, fish, whole-grain foods, coffee, alcohol, butter, margarine, or oil.

If these findings are confirmed in prospective studies, the authors suggest that attention to diet could reduce the prevalence of endometriosis from 5% in Italy to around 3% to 4% or about 200,000 prevalent cases (and about 10,000 new cases a year) fewer in Italy and 800,000 fewer prevalent cases in Europe.

Study limitations include data for only a few selected indicator foods, no estimate of portion size or total energy intake, and the possibility that a high intake of green vegetables, fruits, and fish could reflect more health-conscious attitudes and/or greater likelihood of having endometriosis diagnosed. The authors recommend prospective interventional studies to address these issues.

“However, despite these limitations, our study does suggest that there is some link between diet and risk of endometriosis and indicates that we now need a proper prospective interventional investigation to study these factors,” Dr. Parazzini says. “Endometriosis is a distressing condition that affects the quality of life for many women and if there are adjustments that can be made in the diet to lower the risk it is vital that we gain really firm evidence about which foods protect and which foods increase risk.”

The Associazione Italiana per la Ricerca sul Cancro helped support this study.

Hum Reprod. 2004;19:1755-1759

Clinical Context

Endometriosis is said to affect up to five in 100 women in Italy and Europe. Although its pathophysiology is unknown, a study by Britton and colleagues published in the May 2000 issue of Cancer Causes Control linked endometriosis with higher intake of polyunsaturated and vegetable fats, with no risk reduction associated with high vegetable and fruit intake. An inverse relationship has been shown between endometriosis and body mass index (BMI), for example, in a report by Missmer and Cramer in the March 2003 issue of Obstetrics and Gynecology Clinics of North America. There are also suggestions that the condition is related to exposure to higher estrogen levels, which also is associated with fibroids and endometrial cancer.

The authors of this study postulate that a diet high in fats increases the circulation of unopposed estrogens and may predispose to endometriosis. Fats may also influence prostaglandin concentration and affect ovarian function.

This report combines two retrospective case control studies to examine the association between dietary intake and incidence of endometriosis, relying on a single seven-day food intake recall of Italian patients presenting to hospitals.

Study Highlights

• 504 women younger than 65 years with laparoscopically confirmed endometriosis from obstetrics and gynecology departments in 3 cities were matched in 1:1 ratio to 500 age-matched hospital controls without endometriosis.
• In the control group, 31% were admitted for traumatic conditions, 23% had nontraumatic orthopedic conditions, 12% acute abdominal pain, and 34% other illnesses. Absence of endometriosis in these women was not confirmed by laparoscopy.
• Both patients and interviewers were blinded to the purpose of the study.
• Patients completed a structured questionnaire while in the hospital, on medical and gynecological history, lifetime oral contraceptive use, and food frequency diary for the last 7 days covering selected dietary intake of fats, whole-grain foods, retinoids and carotenoids, alcohol, tea, and coffee. Validity and reliability of this method was not defined or compared with other food intake assessment methods.
• Alcohol intake was defined by amount of ethanol in wine (125 mL), beer (40 mL), and spirits (15 g). Wine accounted for more than 80% of alcohol consumed.
• Recall of typical food intake for the prior few years was not recorded. Other lifestyle factors such as smoking and exercise, other gynecologic conditions, and use of hormones other than oral contraceptives was not reported.
• There was no estimate of portion size or daily energy intake.
• BMI was documented as less than 20, 20 to 23, and more than 23 kg/m2 with no separate category for overweight or obesity.
• Intake was subjectively described by patients as low, intermediate, and high for each category which was then converted to tertiles of intake for milk, meat, beef, liver, carrots, green vegetables, eggs, ham, fish, and cheese portions.
• Mean age was 33 years (range, 20 to 65 years). Women in the endometriosis group were more educated, thinner (lower BMI), and more frequently multiparous than the control group.
• There was a significant reduction in risk of endometriosis associated with high intake of green vegetables (OR, 0.3) and fresh fruit (OR, 0.6).
• Increased risk was associated with beef and other meat (OR, 2.0) and ham (OR, 1.8) intake.
• The ORs were 1.0 and 1.8, respectively, for intermediate and high intake of beef and other red meat, and 0.5 and 0.3, respectively, for intermediate and high intake of vegetables.
• These trends were still significant when age, BMI, education, and parity were taken into account.
• Consumption of milk, liver, carrots, cheese, fish, whole grain foods, butter, margarine, oil, coffee, and alcohol were not associated with endometriosis.