Common Misconceptions about Diet and Breast Cancer: An Unclear Issue to Dispel

Simple Summary Breast cancer is the most prevalent cancer among women. Extensive research has been conducted on eating patterns, and increasing evidence suggests that diet significantly influences the development, progression, and prevention of breast cancer. However, besides the well-known role of alcohol and red and processed meat, the impact of other dietary components remains a subject of debate. Specifically, the potential connection between sugar, dairy components, and soy with breast cancer risk raises questions. Focusing on the studies conducted in the last decade, our literature review shows a negative association between breast cancer incidence and both dairy product and soy consumption, while complex data emerged about sugar intake by itself. However, high heterogeneity across studies' findings was observed, thus highlighting the need for comprehensive investigations considering both patient- and cancer-related factors to develop preventive strategies that should be incorporated into international guidelines.Abstract Breast cancer (BC) constitutes a prevalent health condition among women. Recent years have witnessed the identification of dietary proto-oncogenic factors that deserve attention. Besides the well-known role of alcohol and red and processed meat in BC development, the impact of other dietary components remains unclear. Our narrative review aims to explore the diet-BC relationship, focusing on sugar, dairy, and soy consumption. We conducted a PubMed literature search covering the last decade (2013-2023) and included 35 papers. We found limited evidence on the association between high sugar intake and BC incidence. On the other hand, dairy and soy consumption displayed a protective effect in the majority of the analyzed papers. However, a significant degree of heterogeneity was reported among the results. Menopausal status and the specific BC molecular subtypes were the main factors influencing the interpretation of the results. Exploring dietary factors and BC revealed inconsistencies: high glycemic index post-menopause may be a risk factor, while sugar-sweetened drinks and artificial sweeteners yielded conflicting results; fermented dairy showed potential benefits, non-fermented dairy presented inconsistent findings; soy impact on BC varied according to molecular subtype, with some studies suggesting a positive association in luminal-like BC. Hence, further investigation is crucial to obtain a uniform consensus on the diet-BC relationship.