FOR IMMEDIATE RELEASE
September 3, 2008
Contact: Christine Guilfoy
Office: (301) 634-7253
cguilfoy@the-aps.org
Substance Found In Fruits And Vegetables
Reduces Likelihood Of The Flu
Quercetin fights off
flu in mouse study
BETHESDA, Md. (Sept. 3, 2008) — Mice given quercetin, a
naturally occurring substance found in fruits and vegetables, were less
likely to contract the flu, according to a study published by The
American Physiological Society. The study also found that
stressful exercise increased the susceptibility of mice to the flu, but
quercetin canceled out that negative effect.
Quercetin, a close chemical relative of resveratrol, is present in a
variety of fruits and vegetables, including red onions, grapes, blueberries,
tea, broccoli and red wine. It has been shown to have anti-viral properties
in cell culture experiments and some animal studies, but none of these
studies has looked specifically at the flu.
The study, “Quercetin reduces susceptibility to influenza infection
following stressful exercise,” was carried out by J. Mark Davis, E.A.
Murphy, J.L. McClellan, and M.D. Carmichael, of the University of South
Carolina and J.D. Gangemi of Clemson University. The study appears in the
current issue of the American Journal of Physiology-Regulatory,
Integrative and Comparative Physiology.
The study was conducted using mice, but if quercetin provides a similar
benefit for humans, it could help endurance athletes, soldiers and others
undergoing difficult training regimens, as well as people under
psychological stress, according to Davis.
Study builds on previous research
“Quercetin was used because of its documented widespread health benefits,
which include antiviral activity, abundance in the diet and reported lack of
side effects when used as a dietary supplement or food additive,” Davis
said.
Earlier mouse studies have found that stressful exercise can increase
susceptibility to upper respiratory infections, although it is not yet clear
if the same is true for humans. There was also preliminary information that
mice may be more susceptible to the flu when they exercise to fatigue.
The researchers examined four groups of mice. Two groups performed three
consecutive days of running to fatigue on a treadmill to mimic a short
period of stressful exercise. One group of runners received quercetin, the
other did not. The remaining two groups did not exercise. One non-exercise
group received quercetin while the other did not.
All four groups were then exposed to a common flu virus, H1N1. The
authors hypothesized that exercise would increase the chance of the mice
getting the flu but that quercetin would counteract the increased risk.
The researchers found that:
-
Stressful exercise increased susceptibility to the flu.
The mice that exercised to fatigue for three days were more likely to
develop the flu than the mice that did not exercise (91% versus 63%).
-
The mice that exercised developed the flu much sooner than
those that did not (6.9 days versus 12.4 days).
-
Mice that exercised and took quercetin had nearly the same
rate of illness as those that did not exercise. In other words,
quercetin canceled out the negative effect of stressful exercise.
-
The severity of the symptoms among those mice that either
did not exercise or those that exercised but took the quercetin was
about the same.
-
Quercetin had protective effects for the mice that did not
exercise.
Although this study was done with mice, a recent human study found that
people who took quercetin suffered fewer illnesses following three days of
exhaustive exercise compared to those who did not. Unlike the mouse study,
the humans were not inoculated with a virus.
“This is the first controlled experimental study to show a benefit of
short-term quercetin feedings on susceptibility to respiratory infection
following exercise stress,” said Davis. “Quercetin feeding was an effective
preventive strategy to offset the increase in susceptibility to infection
that was associated with stressful exercise.”
Editor’s Note: To arrange an interview
with Dr. Davis, please contact Christine Guilfoy at
cguilfoy@the-aps.org or (301) 634-7253.
Funding: The Defense Advanced Research Projects Agency (DARPA).
Physiology is the study of
how molecules, cells, tissues and organs function to create health or
disease. The American Physiological Society (APS) has been an integral part
of this scientific discovery process since it was established in 1887.
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