New Study Shows Prolonged Fasting is Beneficial for Immune System

Outcomes of a new research on mice and a phase 1 clinical trial recommend that extended cycles of fasting – for 2-4 days continuously – not just secure against toxic effects of chemotherapy, but also lead to stem cell regeneration of new immune cells and clearing out of old, harmed cells.

The research, by investigators from the University of Southern California published in the journal Cell Stem Cell, is the initial to demonstrate that a natural involvement can lead to regeneration of an organ or system via stem cells.

The team considers the results could help individuals with immune system damage, for instance if they have obtained chemotherapy therapy for cancer. It could also advantage the seniors, whose immune systems are weakened by aging, making them more vulnerable to disease.

The researchers say extended fasting seems to shift stem cells of the immune system from an inactive state to an active state of self-restoration.

Outcomes from studies with mice and a phase 1 trial demonstrated that extended periods of fasting considerably lowered levels of white blood cells. In the mice, it turned a switch that modified the signaling pathways of hematopoietic stem cells – a group of stem cells that produce blood and immune systems.

“We could not forecast that extended fasting would have this sort of a remarkable impact in promoting stem cell-based renewal of the hematopoietic system,” states Valter Longo, director of the USC Longevity Institute. He states that that when you avoid eating, the human body uses up stored glucose, ketones and fat, and also reuse worn out and damaged immune cells.

“What we noticed in both our human and animal research is that the WBC count goes lower with extended fasting,” he describes. “Then when you re-feed, the blood cells return. So we started thinking, well, where does it arrive from?”

In mice, extended fasting restore worn out immune cells with new ones

In mice, extended periods of fasting – repeated cycles of 2-4 days with no food – over the course of six months, wiped out older and damaged immune cells and developed new ones.

Throughout each fasting cycle, the fall in white cell levels activated a stem-cell based re-growth of new immune cells. In specific, prolonged fasting decreased PKA, an enzyme that the group had earlier discovered is engaged in increasing lifespan in simple organisms.

Other research has also connected PKA to the control of stem cell self-renewal and pluripotency – the level to which they can become various cell-types.

Extended fasting also lead to a fall in IGF-1, a growth factor hormone connected to aging, cancer and tumor development.

Switching off the gene for PKA is the essential step that activates the stem cells to move to regeneration, Prof. Longo claims. “It provides the OK for stem cells to go forward and start growing and restore the whole system.”

And the great news, he adds, is that the human body also rids itself “of the parts of the system that may be harmed or old, the ineffective parts, while in the fasting. Now, if you begin with a system greatly damaged by chemotherapy or aging, fasting cycles can produce, literally, a new immune system.”

Three-day fast protected cancer sufferers from harmful chemo effects

In a clinical trial including a small group of cancer sufferers, the group also identified that fasting for 3 days prior to obtaining chemotherapy protected them from its harmful effects.

While chemotherapy helps you to save lives, it also leads to considerable damage to the immune system, and the team hopes their results show that fasting may assist to minimize some of that harm.

Meanwhile, there is no recommendation that individuals should try to get these same results by extended fasting, which should only be done within medical supervision.