How meat consumption impacts endometriosis risk

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Red meat consumption may be a substantial modifiable risk factor for endometriosis, according to a prospective cohort study of premenopausal American nurses.

The study in the American Journal of Obstetrics & Gynecology also found that women with endometriosis who had not reported infertility and therefore were more prone to present with pain symptoms were especially candidates to change their diet to reduce risk. 

“Only two previous studies have examined the association between meat intake and endometriosis, with conflicting results, and both were retrospective studies,” said co-author Holly Harris, ScD, an assistant professor of epidemiology at the Fred Hutchinson Cancer Research Center in Seattle. “Thus, our research team, which has previously studied other dietary factors and endometriosis risk, sought to examine the association between meat intake and endometriosis risk using a prospective study design.”

A total of 81,908 participants from the prospective Nurses’ Health Study II were followed from 1991 to 2013, for which diet was assessed every 4 years, based on a food-frequency questionnaire.

During the 22-year follow-up period, there were 3,800 reported cases of endometriosis confirmed by laparoscopy.

Women who consumed more than two servings of red meat per day had a 56% higher risk of endometriosis diagnosis (95% CI: 1.22 – 1.99) compared to those who consumed one or fewer red meat servings per week.

This connection was strongest for unprocessed red meats (odds ratio 1.57; 95% CI: 1.35 – 1.83 for more than two servings daily versus one or fewer servings per week).

In addition, women in the highest category of processed red meat intake had a higher risk of endometriosis diagnosis (odds ratio 1.20; 95% CI: 1.06 – 1.37 for five or more servings per week versus less than one serving a month).

“These associations were strongest among women whose endometriosis was most likely diagnosed as a result of pelvic pain symptoms,” Dr. Harris told Contemporary OB/GYN. 

In contrast, intakes of poultry, fish, shellfish, and eggs did not impact endometriosis risk. 

Because red meat consumption has been previously associated with other adverse health outcomes, the study’s results were not surprising, according to Dr. Harris, and was consistent with the investigators’ prior hypotheses.

Still, the physiological mechanism of how diet affects endometriosis is unclear, although it has been hypothesized that circulating steroid hormones play a role. Animal fat in meat may also be a factor. 

There is also evidence that reduced fat consumption results in a decrease in endogenous estrogens. Conversely, increased endogenous estrogen can stimulate the formation of prostaglandins, thus inducing release of the P450 aromatase inhibitor that promotes the inflammatory nature of endometriosis.

Moreover, red meat might influence estrogen levels directly by exogenous exposure of sex steroid hormone-treated animals.

“However, more rigorously designed studies are necessary before dietary modifications can be recommended to specifically address endometriosis symptoms or incidence,” Dr. Harris said. “But the research is accumulating that eating less red meat is likely beneficial for overall health, so replacing red meat with plant-based foods could contribute to positive health benefits.”

Recommendations for changing to a more beneficial diet include “eating an overall dietary pattern that is high in fruits, vegetables, whole grains, nuts and legumes, and low in red meats and sugar-sweetened beverages,” Dr. Harris said. “Consuming fewer trans-fats is a great place to start working toward eating a healthier diet.” 

Disclosures:

Dr. Harris reports no relevant financial disclosures.