Abstaining from eating for a period of two to four days at a time not only helps to protect the immune system from damage, but also leads to cell regeneration according to a groundbreaking new piece of research*.

Scientists at the University of Southern California (USC) in the USA say this is the first time a natural intervention has been found to trigger stem cell-based self-renewal of an organ or system. And the findings could have major implications for healthy ageing.

As people get older, their immune system declines, making them more susceptible to disease. Being able to prevent or reverse this process could help older adults as well as those who suffer from autoimmune disorders. It may also benefit cancer patients whose immune systems are weakened by chemotherapy.

Flipping the switch
Over a course of six months, the scientists looked at the impact prolonged fasting cycles had on mice and patients undergoing chemotherapy. During this time, the mice and people went without food for two- to four-day periods.

In both cases, not eating initially lowered the white blood cell counts – the cells in the immune system that defend the body against disease. And the body started killing off old or damaged cells. “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,” explains lead study author Valter Longo, a professor of gerontology and biological sciences at USC.

Eventually, however, prolonged periods of fasting in mice then “flipped a regenerative switch” which kick-started the stem cells into producing brand new white blood cells. This essentially rebooted the whole immune system.

The PKA enzyme
Importantly, the scientists also found, that when people don’t eat for long periods, levels of the enzyme PKA are reduced. In previous studies, PKA has been associated with the regulation of stem cell self-renewal.
“PKA is the key gene that needs to shut down in order for these stem cells to switch into regenerative mode,” clarifies Longo. “It gives the OK for stem cells to go ahead and begin proliferating and rebuild the entire system.

“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 fasting also lowered levels of IGF-1, a growth hormone linked to ageing, tumour progression and cancer risk.

Further research by Longo and his team will now focus on whether fasting has a similar impact on different parts of the body other than the immune system.

Fasting in spas
Given its link to spirituality and naturopathy, fasting is a good fit for spas. But how can operators get the best results and ensure customer safety? We explore these ideas further on page 50.
*Longo, V et al. Prolonged Fasting Reduces IGF-1/PKA to Promote Hematopoietic-Stem-Cell-Based Regeneration and Reverse Immunosuppression. Cell Stem Cell 14, p810-823. June 2014