Women who followed a Mediterranean-style eating pattern had up to 94% lower odds of endometriosis, suggesting that plant-based, nutrient-dense diets may help reduce inflammation and support reproductive health.
Study: Mediterranean diet adherence and healthy diet indicator might decrease odds of endometriosis. Image Credit: Amnaj Khetsamtip / Shutterstock
In a recent study published in the journal Scientific Reports, researchers explored the relationship between Iranian women’s adherence to the Mediterranean diet and their odds of developing endometriosis. Their findings indicate that following a healthier diet, including the Mediterranean diet, is associated with significantly lower odds of the condition. However, causality cannot be inferred from a case–control design, highlighting the role of diet and nutrition in the epidemiology of endometriosis.
Background
Endometriosis is a chronic, estrogen-dependent disorder in which tissue similar to the uterine lining grows outside the uterus, often in the pelvic region. It affects about 10% of women of reproductive age and is a major cause of pelvic pain and infertility.
The condition’s development involves complex hormonal, inflammatory, and immune processes influenced by genetic and environmental factors. Common symptoms include non-menstrual pelvic pain, dysmenorrhea, and back pain.
Several risk factors, such as physical inactivity, body weight, oral contraceptive use, smoking, and alcohol intake, have been linked to endometriosis, but diet has recently gained attention as a key modifiable factor. Diet can influence inflammation, oxidative stress, hormone balance, and muscle contractions, all of which are implicated in the progression of the disease. Studies suggest that nutritional interventions, especially diets rich in fruits, vegetables, and other plant-based foods, may reduce inflammation and pain symptoms. Additionally, diets high in polyunsaturated fatty acids or low in gluten or nickel may further ease pain perception. Prior research has also shown beneficial associations of fertility-oriented, MIND, and AHEI dietary patterns. While whole grains are often considered valuable for general health, this study found an opposite trend for endometriosis risk.
About the Study
Researchers conducted a hospital-based case–control study in Tehran, Iran, with the participation of 115 women with surgically or histologically confirmed endometriosis and 230 controls without the disease. After exclusions for incomplete data, the final analysis included 105 cases and 208 controls. Eligible participants were between 18 and 49 years old, not pregnant, breastfeeding, or menopausal, and free from major chronic conditions such as diabetes, cardiovascular disease, or cancer. Ethical approval was obtained, and all participants provided informed consent.
Dietary intake over the previous year was assessed using a validated 168-item Food Frequency Questionnaire (FFQ). Trained interviewers, blinded to case status, collected dietary and anthropometric data to minimize bias.
Adherence to the Mediterranean diet was measured using the validated Medi-Lite score (range 0–16), based on intakes of fruits and nuts, vegetables, legumes, fish, whole grains, meat, dairy, and the monounsaturated-to-saturated-fat (MUFA:SFA) ratio; alcohol was excluded from scoring due to insufficient data. A Healthy Diet Indicator (HDI; range 0–9) was derived from WHO dietary guidelines, assessing intake of nutrients such as fats, carbohydrates, fiber, and protein. Group differences were tested using t-tests, Mann–Whitney, and chi-square tests. Logistic regression models estimated odds ratios (ORs) and 95% confidence intervals (CIs) for endometriosis, adjusting for age, body mass index (BMI), energy intake, age at menarche, menstrual factors, smoking, occupation, and family history.
Key Findings
A total of 313 women (105 cases, 208 controls) were included in the final analysis. Controls had significantly higher adherence to the Mediterranean diet, showing a score of 9.21 compared to 5.63 for women with endometriosis, and better overall diet quality (mean HDI: 5.54 compared to 2.80). Women without endometriosis consumed more fruits, nuts, fish, vegetables, and legumes, while those with endometriosis reported greater intakes of saturated fats, meat, and dairy. Whole-grain intake was higher among cases.
High adherence to the Mediterranean diet was associated with 94% lower odds of endometriosis (adjusted OR 0.06; 95% CI 0.02–0.15). Protective associations were observed for higher intakes of fruits and nuts (OR 0.09; 95% CI 0.03–0.28), vegetables (OR 0.18; 95% CI 0.07–0.48), fish (OR 0.16; 95% CI 0.06–0.43), and legumes (OR 0.26; 95% CI 0.10–0.68), whereas meat intake was associated with an approximately ten-fold higher odds (OR 10.36; 95% CI 4.31–24.87) and dairy with about 4.6-fold higher odds (OR 4.58; 95% CI 2.04–10.26). Unexpectedly, higher whole-grain intake was associated with increased odds (OR 2.30; 95% CI 1.10–4.82).
Similarly, women with higher HDI scores had 95% lower odds (adjusted OR 0.05; 95% CI 0.01–0.15). Within HDI components, fruits, vegetables, fiber, pulses, and nuts were protective, while saturated fat (OR 7.01; 95% CI 2.38–20.65) and monounsaturated fatty acids (MUFA) (OR 7.91; 95% CI 2.77–22.61) were linked to increased risk. The authors cautioned that the MUFA finding might reflect population-specific dietary sources or residual confounding rather than a direct effect.
Conclusions
This study demonstrated that strong adherence to the Mediterranean diet and a high-quality diet were associated with significantly lower odds of endometriosis among Iranian women. Diets rich in fiber, fruits, vegetables, fish, and legumes may correlate with lower odds of endometriosis through anti-inflammatory and antioxidant effects and improved hormonal balance. However, the unexpected associations with whole grains and MUFAs should be interpreted cautiously, as the authors attribute them to possible differences in local food composition and unmeasured confounders rather than actual biological risk.
Strengths and Limitations
Strengths include the use of validated dietary tools, blinded data collection, and adjustment for key confounders. Limitations involve the case–control design, potential recall bias, lack of adjustment for socioeconomic status, and unmeasured confounders such as coffee, soy, phytoestrogens, specific oils, and supplement use. Because of its observational design, the study cannot prove causality.
Overall
The findings support promoting Mediterranean-style, plant-based diets as part of broader women’s health strategies, while emphasizing that these associations do not prove preventive or therapeutic effects. Future longitudinal and interventional studies are needed to confirm causality and clarify underlying mechanisms.
Journal reference:
- Noormohammadi, M., Javaheri, F.S.H., Ghasemisedaghat, S., Ghoreishy, S.M., Eslamian, G., Nouri, M., Kazemi, S.N., Nematifard, E., Rashidkhani, B., Taheripanah, R. (2025). Mediterranean diet adherence and healthy diet indicator might decrease odds of endometriosis. Scientific Reports, 15, 36750. DOI: https://www.nature.com/articles/s41598-025-20621-6