Dietary factors and risk for endometriosis: a Mendelian randomization analysis

Observational studies have reported an association between dietary factors and endometriosis, but the causality remains unknown. The study aimed to investigate the potential causal association between dietary factors and endometriosis using Mendelian randomization (MR).

We performed a two-sample MR analysis to investigate the effects of 18 diet-related exposure factors (alcoholic drinks per week, alcohol intake frequency, processed meat intake, poultry intake, beef intake, non-oily fish intake, oily fish intake, pork intake, lamb/mutton intake, bread intake, cheese intake, cooked vegetable intake, tea intake, fresh fruit intake, cereal intake, salad/raw vegetable intake, coffee intake, dried fruit intake) on the risk of endometriosis using summary statistics from the genome-wide association study (GWAS). The inverse variance weighted (IVW) method was used to deduce the causal association between dietary factors and endometriosis, and sensitivity analyses were further performed.

Processed meat intake (OR = 0.550; 95%CI:0.314-0.965; p = 0.037) and salad / raw vegetable intake (OR = 0.346; 95%CI:0.127-0.943; p = 0.038) were discovered as protective factors for endometriosis. Heterogeneity test revealed no significant heterogeneity (processed meat intake: p_IVW=0.607, p_MR-Egger=0.548; salad / raw vegetable intake: p_IVW=0.678, p_MR-Egger=0.620). MR-Egger regression test didn't support any evidence for horizontal pleiotropy (processed meat intake: p for intercept = 0.865; salad / raw vegetable intake: p for intercept = 0.725). No causal relationship was found between other dietary intakes and endometriosis.

These findings suggest that processed meat intake and salad/raw vegetable intake are associated with a decreased risk of endometriosis, but further investigation is required.