In an old and damaged immune system, fasting encourages stem cell production of new white immune cells. 

Professor Valter Longo, a biochemist and director of the University of Southern California Longevity Institute, has been investigating exactly how fasting (and diets that mimic fasting’s effects) can help immune function. This obviously has implications on longevity, on diseases from cardiovascular to cancer, and even on the body’s ability to deal with viral infections including Govid-19 and vaccinations.

“Fasting, and fasting-mimicking diets, appear to get rid of damaged or misguided cells and replace them with younger and more effective immune cells,” said Longo.