New research suggests starving the body may kick-start stem cells into producing new white blood cells, which help in fighting off infection.

Scientists at the University of Southern California say the discovery could be particularly beneficial for people suffering damaged immune systems or the elderly whose immune system becomes less effective from aging, making it harder for to fight off common disease.

“Fasting flips a regenerative switch essentially regenerating the entire immune system. It gives the OK for stem cells to go begin proliferating and rebuild the entire system,” said Prof Valter Longo, Professor of Gerontology and the Biological Sciences at the University of California.

“The good news is the body got rid of the parts in the system which might be damaged or old and inefficient parts, during the fasting. If you start with a system heavily damaged by chemotherapy or ageing, fasting cycles can generate, literally, a new immune system.”

Fasting Triggers Stem Cells

In trials, humans were asked to regularly fast for between two and four days over a six-month period. Prolonged fasting was found to reduced the enzyme PKA, linked to ageing and increased risk of cancer and tumor growth:

“We couldn’t predict  prolonged fasting would have such a remarkable effect in promoting stem cell based regeneration of the hematopoietic system,” added Prof Longo. “The system must save energy, and  to save energy, it recycles significant unnecessary immune cells. We started noticing in both our human work and animal work white blood cell numbers diminish with prolonged fasting. When you begin feeding the body again, the blood cells come back. We started to ask, where does it come from?”

Fasting for seventy-two hours protected cancer patients against the toxic impact of chemotherapy:

“Chemotherapy causes significant collateral damage to the immune system. The results of this study suggest fasting may mitigate the harmful effects of chemotherapy,” said co-author Tanya Dorff, assistant professor of clinical medicine at the USC Norris Comprehensive Cancer Center and Hospital. “More clinical studies are needed, and any such dietary intervention should be undertaken only under the guidance of a physician.”

Professor Longo adds:

“We are investigating the possibility that these effects are applicable to different systems and organs, not just the immune system.”

Some are skeptical of this sort of treatment. Dr Graham Rook, emeritus professor of immunology at University College London believes the study to be “improbable”. Chris Mason, Professor of Regenerative Medicine at UCL, said:

“There’s some interesting data here. It sees fasting reduces the number and size of cells, then re-feeding at 72 hours sees a rebound. This may be potentially useful because the time length isn’t terribly harmful to someone with cancer. A sensible way forward could be to synthesize this effect with drugs because I am not sure fasting is the best idea compared to eating on a regular basis.”

Dr Longo added:

“There’s no evidence fasting would be dangerous but strong evidence it’s beneficial. I have received emails from hundreds of cancer patients who have combined chemo with fasting, many with the assistance of the oncologists. Thus, far the great majority have reported doing well and only a few have reported some side effects including fainting and a temporary increase in liver markers. Clearly we need to finish the clinical trials, though it looks promising.”

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