In fact, evidence shows that fasting‐mimicking diets can downregulate heme oxygenase 1 (HO1) expression in breast cancer cells, making them more susceptible to CD8+ cytotoxic T cells, possibly by countering the immunosuppressive effect of regulatory T (Treg) cells (Di Biase et al., 2016; de Groot et al., 2019). This evidence concerns the gene HMOX1 and breast cancer.