A sweeping analysis finds promising links between food choices and endometriosis risk, but doctors say dietary tweaks are no substitute for proven care.
Diet and Endometriosis: An Umbrella Review. Image Credit: Andrii Zastrozhnov / Shutterstock
In a recent study published in the journal Food, researchers in Italy evaluated whether specific dietary components can reduce the risk of or alleviate symptoms from endometriosis.
Notably, this research used an umbrella review methodology, synthesizing evidence from systematic reviews and meta-analyses to provide an overview of the relationship between diet and endometriosis.
Background
Every ten United States (US) women who menstruate, one endures endometriosis, a misplaced-tissue disorder stealing productive years and fertility. Annual direct and indirect costs now rival those of diabetes, yet pain and infertility persist. Patients scour social media for food fixes, but headlines conflict: spinach is praised one week, and coffee is blamed the next.
Observational designs, tiny samples, and inconsistent intake definitions cloud guidance. Meanwhile, the global prevalence continues to climb as diagnostic delays persist for more than seven years. Because nutrition is modifiable, reliable synthesis could empower women to shop strategically and experience fewer health issues.
Further research is needed, specifically well-designed randomized trials that can turn clinical clues into clear treatment guidance.
About the study
Reviewers conducted an umbrella review in accordance with the Joanna Briggs Institute Manual for Evidence Synthesis and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Medline, Embase, Scopus, Cochrane Library, Web of Science, and Google Scholar were searched from inception to September 30, 2024, for systematic reviews evaluating any dietary exposure among women with surgically or clinically confirmed endometriosis. Only reviews reporting human outcomes and full-text articles were eligible.
Titles and abstracts were screened in Rayyan, and methodological rigor was assessed using the Assessment of Multiple Systematic Reviews 2 (AMSTAR2); reviews scoring ≤5 in critical domains were excluded. Relative Risk (RR), Odds Ratio (OR), and their 95% Confidence Intervals (CI) were extracted.
A random-effects meta-analysis in the Jamovi Metaumbrella module generated pooled estimates, heterogeneity via the I-squared statistic, tests for excess significance, and small-study effects using Egger regression.
Evidence certainty was graded across five classes, with class I indicating the strongest support. Disagreements were settled by consensus with a third investigator, and the protocol was preregistered in the International Prospective Register of Systematic Reviews. No patient data were collected; therefore, ethical approval was unnecessary.
Study results
The search retrieved 1,169 unique records, and after removing duplicates and quality screening, ten systematic reviews remained, covering more than 120,000 women from Asia, North America, Europe, and Oceania.
According to the umbrella review, three reviews met every AMSTAR2 critical domain; the rest lacked protocol registration or funding disclosure, but none failed the risk-of-bias threshold. Heterogeneity for red meat analyses reached 82%, indicating substantial epidemiologic variability.
Vegetables produced the clearest protective signal. Women in the highest intake category had 41% lower odds of an endometriosis diagnosis compared to those in the lowest category (pooled RR 0.59, 95% CI 0.49-0.71).
Total dairy products followed: the umbrella review's pooled estimate showed an RR of 0.874, with a 95% CI of 0.81-0.95, while one included meta-analysis (Qi et al.) found an RR of 0.83, with a 95% CI of 0.74-0.93.
Cheese alone conferred a 16% advantage, and high-fat milk retained its benefit after fat stratification, suggesting that calcium, vitamin D, and butyric acid may outweigh concerns about saturated lipids.
Conversely, butter raised the risk by 27% (RR 1.27, 95% CI 1.03-1.55), and high caffeine intake (>300 mg/day, roughly equivalent to three large filtered coffees) increased the risk by 30% (RR 1.30, 95% CI 1.05-1.62). A broader definition of caffeine exposure still produced a 13% elevation (RR 1.13).
Of note, the results for trans fatty acids were ambiguous: while most evidence suggests that saturated and trans fats are harmful, one meta-analysis showed a possible protective association for trans fatty acids, a finding that the umbrella review described as “inexplicable” and in need of further investigation. Saturated and trans fatty acids trended harmful, whereas polyunsaturated fatty acids and fish were neutral or mildly favorable, although CIs crossed unity.
The review also highlighted the limited number of studies examining dietary supplements, such as antioxidants, anti-inflammatory agents, and probiotics, with some evidence suggesting that these may reduce endometriosis-related pain; however, the findings remain heterogeneous and inconclusive.
Despite consistent directions, certainty for every association remained class IV (“weak”) because all source studies were observational and seldom used harmonized intake cut-offs or adjusted for confounders such as smoking or body mass index. Tests for excess significance suggested that positive findings might be overrepresented; however, sensitivity analyses excluding lower-quality reviews did not materially shift the pooled magnitudes or directions.
From a public health standpoint, the discussion section suggests that these numbers could translate into meaningful savings; however, no specific population-level projections were calculated in the review.
Because vegetables and affordable dairy foods are widely available, the findings offer an accessible starting point for symptom management while women await specialist care. However, clinicians should frame advice as low-risk experimentation, rather than a proven therapy; large, prospective dietary trials remain essential before firm guidelines can be issued.
Future work should standardize dietary assessment and oversample diverse populations, thereby clarifying whether observed changes reflect causal biology or systemic bias.
Additionally, the umbrella review discusses the possible role of yogurt and probiotics in positively influencing the gut microbiome, which may have relevance for symptom management, although evidence is still emerging.
Conclusions
To summarize, evidence synthesized from ten systematic reviews suggests that diet probably influences endometriosis, yet certainty is low. Consistently, an abundant intake of vegetables and routine dairy consumption are associated with reduced odds, whereas butter and high caffeine appear to be detrimental.
Findings regarding trans fatty acids remain inconclusive and warrant further research. These patterns align with biological theories that involve oxidative stress, inflammation, and estrogen signaling, rendering them plausible despite observational limitations.
Because vegetables, yogurt, and milk are affordable, clinicians may recommend them as low-risk self-management tools while emphasizing that they do not replace established medical care. Dietary supplements and probiotics may offer additional benefits for some individuals, but further research is needed before firm recommendations can be made.