A study published by The American Physiological Society has found that mice fed the flavanoid quercetin were less likely to get the flu.
Quercetin is a flavanoid with antioxidant properties that is found in fruits and vegetables including apples, nuts, berries, onions, cauliflower and cabbage, with apples being particularly high in quercetin.
The study also found that quercetin counteracted the increased susceptibility to the flu after stressful exercise.
A recent human study has already established that after three days of exhaustive exercise, participants who took quercetin were less likely to suffer illness than those who did not.
A summary of the research findings:
- 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.
1. J. Mark Davis, E.A. Murphy, J.L. McClellan, and M.D. Carmichael, J.D. Gangemi. Quercetin reduces susceptibility to influenza infection following stressful exercise. The American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
2. Arai Y, Watanabe S, Kimira M, Shimoi K, Mochizuki R, Kinae N. Dietary intakes of flavonols, flavones and isoflavones by Japanese women and the inverse correlation between quercetin intake and plasma LDL cholesterol concentration. J Nutr. 2000 Sep;130(9):2243-50. PMID: 10958819.