Written by Greg Arnold, DC, CSCS. This study revealed that of 119 mice, 52% of the 37 mice in the exercise plus quercetin group died following infection with the flu virus compared to 74% of the 23 mice in the exercise plus placebo group who died following flu infection.
The flu is commonly associated with winter, the “cold and flu season”, and more than 130 million flu shots that are given (1). It is a condition that will affect 1 in 5 Americans, causing 200,000 hospitalizations and 36,000 deaths each year (2). The flu costs our healthcare system $10 billion per year (3) and a full-blown flu-pandemic could cost $90 billion (4).
Now a new study (5) has found that quercetin may help maintain lung health after exercise.
A 2007 study showed that “quercetin supplements may help maintain lung health after periods of heavy training by athletes” (6). Building on these findings, researchers divided 119 mice into the following groups:
- Exercise with placebo supplementation (23 mice)
- Exercise and quercetin supplementation (27 mice)
- No exercise and placebo supplementation (30 mice)
- No exercise with quercetin (29 mice)
Quercetin was supplemented in the amount of 12.5 mg per kg of body weight. The exercise program was treadmill-running at 36 meters per minute at an 8% incline until the mice reached voluntary fatigue. This was determined when the mice were unable to keep their treadmill pace after continuous hand prodding for one minute.
After the treadmill workout, the mice were then injected with the flu virus and observed for physical symptoms (including ruffled fur, redness around the eyes, nose, or mouth, altered respiration, hunched-back pose, unresponsiveness, and death). They were then assigned a score, with a higher score signaling a worsening of symptoms.
At seven days post-infection, the average symptom score in the exercise-placebo group was 67% higher than the exercise-quercetin group and 250% higher than both control-placebo and control-quercetin groups. While 74% of the exercise-placebo mice died from the flu, that number was 50% in the control-placebo mice, 52% in the exercise-quercetin mice, and 27% in the control-quercetin group. Of the mice who died, the average time was shortest in the exercise-placebo group (12.5 ± 1.3 days). The average time was 27% longer in the control-placebo group (15.9 ± 1.2 days), 32% longer in the exercise-quercetin group, and 48% longer in the control-quercetin group (18.5 + 1.1 days)
For the researchers, “this is the first controlled experimental study to show a benefit of short-term quercetin feedings on susceptibility to respiratory infection following exercise stress”. They also said this study “may lead to an important nutritional strategy to decrease the risk of infection, which can be a problem in athletes and military personnel, who are often exposed to combinations of severe physical, psychological, and environmental stress.”
Source: Davis, J. Mark, E. Angela Murphy, Jamie L. McClellan, Martin D. Carmichael, and J. David Gangemi. “Quercetin reduces susceptibility to influenza infection following stressful exercise.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 295, no. 2 (2008): R505-R509.
© 2008 the American Physiological Society
Posted October 17, 2008.
References:
- “Record Number of Flu Shots Made for 2007-08” posted on the WTOP website.
- “Flu Facts” posted on the Centers for Disease and Prevention website.
- “The National Strategy for Pandemic Influenza” posted on The White House website.
- “The Economic Impact of Pandemic Influenza in the United States: Priorities for Intervention” posted on the Centers for Disease Control and Prevention website.
- Davis M. Quercetin reduces susceptibility to influenza infection following stressful exercise. Am J Physiol Regul Integr Comp Physiol 295: R505-R509, 2008. First published June 25, 2008.
- Nieman DC. Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise. Med Sci Sport Exer 2007; 39(9): 1561-1569.
