Periods of not eating for several days might be good for the body, protecting against damage to the immune system. Researchers from the University of Southern California found that prolonged fasting might even trigger immune system regeneration.
“[Prolonged fasting] activates stem cells, which can then generate a variety of immune cells,” said Valter Longo, corresponding study author and director of the USC Longevity Institute.
Extended periods of fasting were found to drastically reduce white blood cell counts in mice, as well as humans in an early trial. According to Longo, the effects can be traced back to energy conservation. During periods of fasting, the body recycles old, damaged immune cells in an effort to save energy. When white blood cells go down, it ignites the regeneration of new immune system cells.
Researchers also found prolonged fasting to cut levels of a growth-factor hormone called IGF-1, which has been associated with tumor growth, cancer and aging.
Longo says that prolonged fasting would be four to five days per month for two to three months (under the supervision of a doctor).
The study is especially relevant for cancer patients, who experience immune system damage from chemotherapy. Fasting may help counteract this, researchers say. The findings are equally exciting for people with immune system disorders.
There is a wealth of previous research supporting the potential health benefits of periodic fasting. Animal studies have linked it to extended lifespans and reduced risk of heart disease, diabetes and cancer. Another study suggested that a low-nutrient diet may have similar effects.
Longo says the next step in the research is to conduct human clinical trials on normal subjects who fast for two to three months.
By Marianne Hayes