Research suggests that intermittent fasting may have a protective effect on cancer incidence and progression, as well as improve the recovery experience on cancer patients.
Prolonged fasting is also known to enhance pro-growth signaling and increase activity in pathways that enhance resistance to toxins. In particular, during treatment of cancer with chemotherapy, starvation preferentially protects host cells, but not cancer cells. Indeed, a link between insulin-like growth factor 1 (IGF-1) levels and chemotherapy protection has been shown.1
It is thought that a great deal of the short and long-term side effects from chemotherapy results from the damage to bone marrow, and the production of immune cells in the blood. Multiple cycles of prolonged fasting have been shown to reduce the immunosuppression and mortality due to chemotherapy, as well as reverse the age-dependent reduction in immunity.2
Studies have shown that intermittent fasting in rats prone to developing cancer, resulted in lower overall incidence rates of neoplasia.3
A recent report, demonstrated that periodic, 3 day cycles of fasting could ameliorate symptoms in a mouse model of multiple sclerosis. The intermittent-fasting type diet was effective in reducing clinical symptoms in all mice, and reversed all symptoms in 20% of mice. At a molecular level, the numbers of regulatory T-cells increased, and pro-inflammatory cytokins TH1 and TH17 were reduced. Together these data demonstrate that fasting can have powerful effects on the immune system, even in the context of severe inflammatory diseases.4
Lee, C., Safdie, F. M., Raffaghello, L., Wei, M., Madia, F., Parrella, E., . . . Longo, V. D. (2010). Reduced levels of IGF-I mediate differential protection of normal and cancer cells in response to fasting and improve chemotherapeutic index. Cancer Res, 70(4), 1564-1572. doi:10.1158/0008-5472.can-09-3228
Cheng, C. W., Adams, G. B., Perin, L., Wei, M., Zhou, X., Lam, B. S., . . . Longo, V. D. (2014). Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810-823. doi:10.1016/j.stem.2014.04.014
Brandhorst, S., Choi, I. Y., Wei, M., Cheng, C. W., Sedrakyan, S., Navarrete, G., ... & Di Biase, S. (2015). A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance, and healthspan. Cell metabolism, 22(1), 86-99.
Choi, In Y., Piccio, L., Childress, P., Bollman, B., Ghosh, A., Brandhorst, S., . . . Longo, Valter D. A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms. Cell Reports. doi:10.1016/j.celrep.2016.05.009