Endometriosis is a condition in which tissue similar to the lining of the womb grows outside the uterus, on the ovaries, the ligaments or the wall of the bowel. These lesions respond to hormones with every cycle and keep up a chronic inflammation in the pelvis. The bowel, right next to it, often feels the effects. Bloating, constipation, diarrhoea and cramps are so common that endometriosis is sometimes mistaken at first for irritable bowel syndrome.
Gluten is a group of proteins found in wheat, barley and rye. In people with coeliac disease, it triggers an immune reaction that damages the lining of the gut. Others react to wheat without having coeliac disease, which is called non-coeliac wheat sensitivity. Since endometriosis is an inflammatory condition that also affects the gut, and gluten irritates some guts, the link was made quickly. One study is almost always quoted to back it up.
The Italian study from 2012
A team at Tor Vergata University in Rome followed 207 women with severe endometriosis pain (Marziali et al., 2012). All of them followed a gluten-free diet for twelve months. Pain was scored from 0 to 10 for periods, for pelvic pain outside periods and for pain during sex.
After a year, 156 women, or 75%, reported a clear drop in their pain. The other 51 saw no improvement, and none said they felt worse. Quality of life scores, vitality, mental health and social life, had also gone up.
Why that 75% is not enough to draw a conclusion
The study had no comparison group. No woman carried on eating as before to serve as a reference. Endometriosis pain varies from one period of life to another, treatments change during a year, and twelve months leave time for a lot to shift. Without a control group, there is no way to know how much of the improvement comes from the diet. The analysis was also done after the fact, from patient records.
Pain is scored by the patient herself, and gluten lends itself particularly well to the placebo effect. A woman convinced that gluten harms her may feel better when she stops it, and worse when she eats it again, simply because she expects to. A Dutch review from 2024 stresses this point.
One last limit, perhaps the most important. In Italy, wheat sits at the heart of meals, with pasta, bread, pizza and biscuits. Removing gluten there changes the whole plate and takes away a large share of processed foods. Wheat also contains compounds other than gluten, including a lectin that irritates the gut. So the study cannot say whether gluten alone is to blame, or whether the relief comes from the rest of the change.
What other research says
In the United States, the Nurses' Health Study II followed almost 82,000 premenopausal women for 24 years, 3,810 of whom were diagnosed with endometriosis confirmed by laparoscopy (Schwartz et al., 2022). Those who ate the most gluten did not have more endometriosis. The authors consider it unlikely that gluten is a strong factor in the onset of the disease. This study looks at the risk of developing endometriosis, and it says nothing about pain in women who already have it.
Coeliac disease is a separate case. In Sweden, almost 11,000 women with coeliac disease were compared with women without it, and their risk of endometriosis was 39% higher (Stephansson et al., 2011). The difference in number of cases is small, yet the link is there. When endometriosis comes with marked digestive symptoms, a blood test for coeliac disease is worth discussing with your doctor, before cutting out gluten, because the test becomes less reliable once gluten has gone.
The 2024 review concludes that the evidence is lacking to recommend a gluten-free diet to every woman with endometriosis, unless coeliac disease or wheat sensitivity has been diagnosed. It also points out that no trial with a control group has been published yet.
What to take away
The question of gluten alone remains open. One encouraging study with no comparison, a large cohort that finds no link with the onset of the disease, and no controlled trial on pain. What stands out most clearly from the Italian study is the effect of changing the whole plate, which is hard to pin on a single protein.
Swapping bread, pasta and biscuits for shop-bought gluten-free versions often keeps highly processed products, which does not answer the question the study raised. Inflammatory foods weigh on the gut and the immune system, and endo belly has its own mechanisms. For a woman in pain, what matters is the diet as a whole and the gut, far more than a gluten-free label.
This article is for information only and does not replace medical advice.