Dairy Processing and Breast Cancer: A Hypothesis-Generating Framework Linking Bioactive Lipid Derivatives to Epidemiological Heterogeneity.

The relationship between dairy consumption and breast cancer risk remains complex and heterogeneous, with epidemiological studies reporting divergent associations depending on the type of dairy product and its degree of processing. Although nutritional composition has traditionally been considered the main explanatory factor, emerging evidence suggests that technological processing may also influence the biological properties of dairy foods. In this narrative review, we propose a hypothesis-generating framework that integrates epidemiological findings with experimental data on lipid oxidation and sterol-derived metabolites produced during dairy processing. In particular, cholesterol oxidation products and other bioactive lipid derivatives have been shown in experimental models to modulate pathways involved in inflammation, oxidative stress, and hormone signaling. However, direct evidence linking dietary exposure to these compounds and breast cancer risk in humans remains limited. Recent research highlights that food processing may generate a wide range of bioactive molecules beyond conventional nutrients, some of which may act at low concentrations and influence key regulatory pathways. These include both potentially deleterious and protective sterol-derived metabolites, whose balance may be affected by technological processing. Identifying such compounds, quantifying their dietary exposure, and understanding their biological effects represent important challenges for future research. Although current evidence remains insufficient to establish causal relationships, this framework supports the hypothesis that processing-related molecular changes may contribute to the heterogeneity observed in epidemiological studies.