Fasting for 3 Days Can Regenerate Entire Immune System, New Study Finds

A person’s immune system can be completely restored by fasting for three days, a new study suggests.

Researchers claim that fasting "flips a regenerative switch" which triggers the process of creating new white blood cells. Photo: SANTI BAÑON/Flickr

Researchers claim that fasting “flips a regenerative switch” which triggers the process of creating new white blood cells. Photo: SANTI BAÑON/Flickr

Fasting for just a few days can completely revitalise the entire immune system, even in the elderly, scientists have found in a breakthrough study described as “remarkable”.

Although starving diets have been considered by nutritionists for being unhealthy, a new research shows that fasting the body kick-starts stem cells into producing new white blood cells, which fight off infection.

Researchers at the University of Southern California are sure that the results of the study could appear to be extremely omportant and beneficial for those who suffer from damaged and weak immune systems, such as cancer patients on chemotherapy.

Which is more, the breakthrough could also be helpful for the elderly whose immune system becomes less effective with the course of time, making it harder to fight even common diseases.

The researchers explain that starving “flips a regenerative switch” which prompts stem cells to create brand new white blood cells, essentially regenerating the entire immune system.

“It gives the ‘OK’ for stem cells to go ahead and begin proliferating and rebuild the entire system,” said Prof Valter Longo, Professor of Gerontology and the Biological Sciences at the University of California.

“And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting.

“Now, if you start with a system heavily damaged by chemotherapy or ageing, fasting cycles can generate, literally, a new immune system.”

Prolonged starving the body promts usage of stores of glucose and fat and also breaks down a significant portion of white blood cells.

“We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system,” added Prof Longo.

“When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged,” Dr Longo said.

“What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?”

Fasting for 72 hours also protected cancer patients against the toxic impact of chemotherapy.

“While chemotherapy saves lives, it causes significant collateral damage to the immune system. The results of this study suggest that fasting may mitigate some of 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.”

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

Chris Mason, Professor of Regenerative Medicine at UCL, said: “There is some interesting data here. It sees that fasting reduces the number and size of cells and then re-feeding at 72 hours saw a rebound.

“That could be potentially useful because that is not such a long time that it would be terribly harmful to someone with cancer.

“But I think the most sensible way forward would be to synthesize this effect with drugs. I am not sure fasting is the best idea. People are better eating on a regular basis.”

Dr Longo added: “There is no evidence at all that fasting would be dangerous while there is strong evidence that it is 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 very 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, but it looks very promising.”

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