While chemotherapy can save lives, it can also cause many
side effects, including the depletion of immune cells. Also, even in the
absence of chemotherapy, normal aging takes a heavy toll on the immune system,
leading to immune deficiencies and a higher risk of developing leukemia and a
variety of malignancies with age. Now researchers reporting in the June 5th 2014
issue of the Cell Press journal Cell Stem Cell have found that a simple dietary
intervention—periodic fasting—may combat both chemotherapy-induced and
aging-related changes in immune cell function by replenishing stem cells in the
blood. The findings suggest that fasting may provide benefits for cancer patients,
the elderly, and people with various immune defects.
It's estimated that more than one-fifth of cancer-related
deaths are hastened, or even caused, by toxic effects of chemotherapy rather
than the cancer itself. These toxicities can reduce the overall effectiveness
of anticancer treatments by limiting the dosage and frequency of
chemotherapeutic interventions that are tolerable to patients. Currently there
are no interventions to lessen the side effects that chemotherapy has on the
immune system or to prevent the immune cell dysfunction that occurs with aging.
Previous work by Dr. Valter Longo, of the University of
Southern California, and his colleagues revealed that temporary nutrient
restriction could increase stem cells' resistance to certain stressors. In
their latest work, they tested whether fasting could have protective effects
for immune cells such as white blood cells. "We show that prolonged
fasting periods cause a major reduction in white blood cell number followed by
its replenishment after refeeding," said Dr. Longo. "We discovered
that this effect, which may have evolved to reduce energy expenditure during
periods of starvation, is able to switch stem cells to a mode able to not only
regenerate immune cells and reverse the immunosuppression caused by
chemotherapy, but also rejuvenate the immune system of old mice." The
researchers found that protection against white blood cell loss also occurred
in human patients who fasted for a single 72-hour period prior to
platinum-based chemotherapy as part of a phase 1 clinical trial.
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