Cheese intake, probiotics and breast cancer: A Mendelian randomization analysis

Background: Using Mendelian randomization (MR) analysis, this study sought to determine the causal relationship between genetically predicted cheese intake, probiotics and breast cancer. Methods: A MR analysis including univariable and multivariable MR approaches using the public genome-wide association studies summary statistics was conducted to assess the causal effects. Results: Genetically predicted cheese intake per standard-deviation increase was associated with decreased risks of luminal A-like breast cancer (odds ratio [OR] = 0.80, 95 % confidence interval [CI]: 0.66–0.97, P = 0.03). No causal effect was detected between probiotics and breast cancer. Multivariable MR analysis showed that the causal effect between cheese intake and luminal A-like breast cancer might be driven by several major ingredients in cheese, including calcium, vitamin D and IGF-1 levels. Conclusions: Cheese intake is causally associated with luminal A-like breast cancer.