Impact of milk and dairy consumption on the development and progression of breast cancer

Abstract Recent studies have shown a link between the consumption of bovine milk and human breast cancer, apparently by agonizing the estrogen receptor (ER), which results in the proliferation of the breast tissues, leading to formation of a tumor. Bovine milk may also promote tumor formation via insulin-like growth factor-1 (IGF-1) signaling. In addition, numerous potentially carcinogenic compounds have been found in bovine milk, including exosomal microRNAs (miR-148a-3p, miR-21-5p), aflatoxin M1, bisphenol A, pesticides, and micro- and nanoplastics. Subjects with specific genetic mutations (e.g., BRCA 1 loss-of-function) and polymorphisms (e.g., FTO and IGF-1 upregulation) that enhance IGF-1/mTORC1 signaling might be especially susceptible to ER+ breast cancer promoted by the consumption of bovine dairy products. However, in the previous large-scale meta-analyses, data about the milk processing methods, such as pasteurization and ultra-high temperature treatment, are lacking, thus limiting the accuracy of risk assessments. Clearer and more convincing evidence, detailed milk processing information, and data regarding the timing of exposure (consumption) are required because the current evidence suggests that the dietary recommendations regarding milk and dairy consumption may need to be reevaluated.