Target trial emulation of preconception serum vitamin D status on fertility outcomes: a couples-based approach.

Objective: To evaluate associations between preconception 25-hydroxyvitamin D (25(OH)D) levels and biomarkers in female and male partners on live birth (LB), pregnancy loss, and semen quality.

Design: Secondary analysis using the folic acid and zinc supplementation trial of couples seeking infertility treatment at four US centers (2013-2017). A target trial emulation framework was applied to estimate associations.

Olive oil and risk of breast cancer: a systematic review and dose-response meta-analysis of observational studies.

Olive oil consumption has been suggested to be inversely associated with breast cancer risk, probably due to its high MUFA and polyphenol content. The purpose of this meta-analysis was to assess the association between olive oil and breast cancer risk, including assessing the potential for a dose-response association. We performed a systematic search of PubMed, Web of Science, CINAHL and Cochrane Central Register of Controlled Trials through June 2020, identifying ten observational studies (two prospective studies and eight case-control studies) for meta-analysis.