In the first evidence of a natural intervention triggering stem cell-based regeneration of an organ or system, a study shows that cycles of prolonged fasting not only protect against immune system damage -- a major side effect of chemotherapy -- but also induce immune system regeneration, shifting stem cells from a dormant state to a state of self-renewal.
In both mice and a Phase 1 human clinical trial, long periods of not eating significantly lowered white blood cell counts. In mice, fasting cycles then "flipped a regenerative switch": changing the signaling pathways for hematopoietic stem cells, which are responsible for the generation of blood and immune systems, the research showed.
The study has major implications for healthier aging, in which immune system decline contributes to increased susceptibility to disease as we age. By outlining how prolonged fasting cycles -- periods of no food for two to four days at a time over the course of six months -- kill older and damaged immune cells and generate new ones, the research also has implications for chemotherapy tolerance and for those with a wide range of immune system deficiencies, including autoimmunity disorders.
"We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system," said corresponding author Valter Longo, the Edna M. Jones Professor of Gerontology and the Biological Sciences at the USC Davis School of Gerontology, and director of the USC Longevity Institute.
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