A person's entire immune system can
be rejuvenated by fasting for as little
as
three days as it triggers the body to
start producing new white blood cells,
a study suggests
Researchers say
fasting "flips a
regenerativeswitch"which
prompts
stem cells to create brand new
white blood cell.Fasting for as
little as three days can
regenerate the
entire immune system,
even in the elderly,
scientists have found
a breakthrough
described as
"remarkable"
Although fasting diets
have been criticised by
nutritionists for being
unhealthy, new research
suggests starving the
body kick-starts stem
cells into producing new
white blood cells,
which fight off
infection.
Scientists at the
University of Southern California say the discovery could be particularly
beneficial for people suffering from damaged immune systems, such as cancer
patients on chemotherapy.
It could also help the elderly whose immune system becomes less
effective as they age, making it harder for them to fight off even common
diseases.
The researchers say fasting "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 fasting forces the body to use stores of glucose and fat
but also breaks down a significant portion of white blood cells.
During each cycle of fasting, this depletion of white blood cells
induces changes that trigger stem cell-based regeneration of new immune system
cells.
In trials humans were asked to regularly fast for between two and
four days over a six-month period.
Scientists found that prolonged fasting also reduced the enzyme
PKA, which is linked to ageing and a hormone which increases cancer risk and
tumour growth.
"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.
However, some British experts were sceptical of the research.
Dr Graham Rook, emeritus professor of immunology at University
College London, said the study sounded "improbable".
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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