Mediterranean diet and infertility: a systematic review with meta-analysis of cohort studies

Abstract Context The Mediterranean diet (MD) is a dietary pattern with evidence of positive health impact, and some nutrients in this diet have already been researched for their effectiveness in fertility. However, there are still questions about whether high adherence to the MD could be a factor that contributes to positive fertility outcomes in infertile men and women. Objective A systematic review and meta-analysis were conducted to determine whether a greater adherence to the MD can improve fertility markers and outcomes in infertile men and women. Data sources The MEDLINE, BVS, SciELO, CENTRAL, and Embase databases and gray literature were searched from their inception to May 2022. Study selection Data were included from cohort studies that addressed MD and outcomes. Data extraction Data searches, article selection, data extraction, and risk-of-bias assessments were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results A total of 11 studies met the inclusion criteria (n = 13 157 women and 1338 men). Greater adherence to the MD was associated with live births (I2 = 83.16%; odds ratio [OR], 0.652; 95%CI, 0.408–3.194), pregnancy rate (I2 = 93.83%; OR, 1.192; 95%CI, 0.349–4.325), sperm concentration >15 × 106/mL (I2 = 32.97%; OR 2.862; 95%CI, 1.583–5.174), and sperm count > 39 × 106/mL (I2 = 48.1%; OR, 2.543; 95%CI, 1.319–4.904); however, in an inconsistent scenario regarding the meta-analysis. Conclusion Current evidence of high adherence to MD and fertility markers is insufficient to support their clinical application, even though it indicates sperm improvement and a possibility of better pregnancy outcomes. Systematic Review Registration PROSPERO registration no. 169396.