Endometriosis

More red meat, more endometriosis

By WhyStopHarmingAnimals.com

Women who eat more red meat get endometriosis more often[1]. The Nurses' Health Study II followed premenopausal nurses for two decades, more than a million person-years in all[1], and recorded 3,800 cases of endometriosis confirmed by laparoscopy. Women who ate more than two servings of red meat a day had 56% higher risk than women who ate a serving a week or less[1].

Endometriosis affects roughly one in ten women of reproductive age, and diagnosis often takes years, so a risk factor people can change is worth knowing.

What the nurses' data show

The laparoscopic confirmation is what gives the cohort its weight. Every case was seen during surgery rather than self-reported[1], which removes a large source of error from the count. With 3,800 cases, the study also had enough numbers to split meat by type.

Unprocessed red meat carried the strongest link[1]. Processed meat mattered as well, but less: the highest processed-meat intakes raised risk 20%[1]. The study is observational, so it shows an association in these women and cannot by itself prove that the meat caused the disease.

Diet and pain

Diet also seems to affect how much endometriosis hurts. A 2022 systematic review gathered six studies in which women with endometriosis changed their diet, and every one of them reported less pain[2].

Most of those studies were not randomized controlled trials[2], and pain is subjective. Women who change what they eat may expect to feel better, and without a control group that expectation is hard to separate from the effect of the food. The result is suggestive rather than settled[2].

The two lines of evidence point the same way. The largest cohort to look at the question links red meat to getting the disease[1], and the studies of dietary change link changing what's on the plate to less pain[2].