Quercetin reduces susceptibility to influenza infection following stressful exercise

Abstract

Exercise stress is associated with increased risk for upper respiratory tract infection. We have shown that exercise stress can increase susceptibility to infection. Quercetin, a flavonoid present in a wide variety of fruits and vegetables, has been reported to inhibit infectivity and replication of a broad spectrum of viruses and may offset the increase in susceptibility to infection associated with stressful exercise. This study examined the effects of quercetin feedings on susceptibility to the influenza virus A/Puerto Rico/8/34 (H1N1) following stressful exercise. Mice were randomly assigned to one of four treatment groups: exercise-placebo, exercise-quercetin, control-placebo, or control-quercetin. Exercise consisted of a run to fatigue (approximately 140 min) on a treadmill for 3 consecutive days. Quercetin (12.5 mg/kg) was administered via gavage for 7 days before viral challenge. At 30 min after the last bout of exercise or rest, mice (n=23-30) were intranasally inoculated with a standardized dose of influenza virus (0.04 hemagglutinating units). Mice were monitored daily for morbidity (time to sickness), symptom severity, and mortality (time to death) for 21 days. Exercise stress was associated with an increased susceptibility to infection [morbidity, mortality, and symptom severity on days 5-7 (P<0.05)]; quercetin offset the increase in susceptibility to infection [morbidity, mortality, and symptom severity on days 5-7 (P<0.05)] that was associated with stressful exercise. These data suggest that short-term quercetin feedings may prove to be an effective strategy to lessen the impact of stressful exercise on susceptibility to respiratory infection.

Effect of quercetin supplementation on maximal oxygen uptake in men and women

“…Significant food sources include apples, onions, berries, leafy green vegetables, hot peppers, red grapes, and black tea (Nieman et al, 2007c). The consumption of quercetin may reduce the incidence of upper respiratory tract infection (Nieman et al, 2007c), influenza (Davis, Murphy, McClellan, Carmichael, & Gangemi, 2008b), and certain forms of cancer (Neuhouser, 2004). Although it is known to have anti-oxidant and anti-inflammatory activity (Heo & Lee, 2004), relatively few studies have examined the interaction of quercetin ingestion with exercise-induced inflammation and oxidative stress (Davis et al, 2008b;Henson et al, 2008 ;McAnulty et al, 2008;Nieman et al, 2007aNieman et al, , 2007bNieman et al, , 2007c.…”

“…The consumption of quercetin may reduce the incidence of upper respiratory tract infection (Nieman et al, 2007c), influenza (Davis, Murphy, McClellan, Carmichael, & Gangemi, 2008b), and certain forms of cancer (Neuhouser, 2004). Although it is known to have anti-oxidant and anti-inflammatory activity (Heo & Lee, 2004), relatively few studies have examined the interaction of quercetin ingestion with exercise-induced inflammation and oxidative stress (Davis et al, 2008b;Henson et al, 2008 ;McAnulty et al, 2008;Nieman et al, 2007aNieman et al, , 2007bNieman et al, , 2007c. Nieman and colleagues (Henson et al, 2008;McAnulty et al, 2008;Nieman et al, 2007aNieman et al, , 2007bNieman et al, , 2007c observed that the pre-to post-exercise changes in markers of inflammation and immune function were not affected by chronic quercetin supplementation (1000 mg Á day 71 for 3 weeks).…”

Quercetin supplementation does not alter antioxidant status in humans

“…Dietary flavonols such as quercetin have been reported to have physiological effects, i.e. antioxidative [4,5], anti-inflammatory [6][7][8], anti-pathogenic [9,10], anti-viral [11][12][13], anti-microbial [14], anti-carcinogenic [15], cardioprotective [16] and mitochondrial biogenesis [17] activities and thus provide significant potential in the study of improving human health.…”

Quercitrin treatment protects endothelial progenitor cells from oxidative damage via inducing autophagy through extracellular signal-regulated kinase

“…Quercitrin (3,5,7,3 0 ,4 0 -tetrahydroxyflavone) is a plant-derived flavonoid compound that is used in dietary supplements and as an ingredient in certain foods and beverages due to its proposed health benefits resulting from its antioxidant [21,22], anti-inflammatory [23,24], neuropharmacological actions [25,26], anti-viral [27,28] and anticancer [29,30] properties. In this study, we investigated the role of quercitrin in autophagy of EPCs subjected to oxidant injury and report that through promoting autophagy, quercitrin mediates protective effects on EPCs in vitro and in vivo.…”