The high incidence of breast cancer, its relatively long development phase and the financial burden to the NHS in relation to treatment makes it a prime target for dietary preventative strategies. Epidemiological and experimental investigations suggest several key dietary components that may reduce breast cancer, in particular isoflavones and selenium. Few dietary intervention studies have been conducted to investigate putative protective effects, but with our growing understanding of cancer biology and the application of new -omics technologies it is now possible to use early biomarkers of risk to assess the potential efficacy of intervention studies.