A flavonoid found in fruit, such as apples and berries, could help reduce illnesses in people who have carried out extensive exercise.
Researchers writing in the Medicine and Science in Sports and Exercise journal found that supplementation of quercetin reduced incidence of upper respiratory tract infections (URTI). This study adds to an increasing body of evidence pointing to the health benefits of the antioxidant, which has been linked to having an ability to fight oxidative stress as well as anti-cancer benefits.
Companies have already started to take advantage of the flavonoid. Energy drink FRS Plus containing quercitin, and aimed at reducing fatigue and boost overall performance by fighting free radicals in the body, was launched in 2002 .
According to the New Scientist, studies of quercetin have been supported by DARPA (the Defense Advanced Research Projects Agency) - the Pentagon's research arm - in the hope it could be used to protect US troops. This too shows the potential of the flavonoid is also being considered outside of the consumer food market.
Lead author David Nieman from Appalachian State University in Boone, North Carolina, said in the New Scientist: "During missions, soldiers are running around for two or three days with heavy packs on. They don't eat or sleep, and infections are as much of a problem if not a more serious issue than injuries,"
Researchers gave 40 male cyclists one gram of quercetin a day, which is the equivalent to eating 100 apples, or a placebo for three weeks. During this time, the cyclists spent a three-day period training at maximum intensity for three hours each day.
Blood and saliva samples were collected before and after each of the three exercise sessions and examined for natural killer cell activity, PHA-stimulated lymphocyte proliferation, polymorphonuclear oxidative-burst activity, and salivary IgA output.
They found that changes in these levels did not differ significantly between quercetin and placebo groups.
However, URTI incidence during the two week post-exercise period "differed significantly."
Source: Medicines and Science in Sports Exercise
Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise
Authors: David Nieman, Dru Henson, Sarah Gross, David Jenkins, Mark Davis, Angela Murphy, Martin Carmichael, Charles Dumke, Alan Utter, Steven Mcanulty, Lisa Mcanulty, Eugene Mayer.