Quercetin Boosts Immunity and Helps Maintain Mental Performance

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In February 2007, researchers at Appalachian State University announced the results of a clinical study on the flavonoid quercetin at the Southeastern Regional Meeting of the American College of Sports Medicine, held in Charlotte, N.C. Their results showed that quercetin may help reduce illness and maintain mental performance in physcially stressed test subjects. I’ve written about the antioxidant quercetin in a previous article as an alternative to dichloroacetate (DCA), a chemotherapeutic agent that was recently shown to selectively inhibit cancer cell growth in lung, breast and brain tumor cells grown in culture and lung tumors grown in immunocompromisted rats.

In December 2005, the Defense Advanced Research Projects Agency (DARPA) awarded Appalachian State University 1.1 million to fund a two-year study of the effects of quercetin [1]. DARPA is seeking ways to maintain troop immune systems during times of physical and cognitive stress. Dr. David Nieman is the principal investigator of the study and a professor in the Department of Health, Leisure and Exercise Science at Appalachian State University. He has been investigating the influence of exercise and nutrition on the immmune system for the last 23 years.

The double-blind, randomized, placebo-controlled study provided 1,000 mg/day of high-purity quercetin, a polyphenol, plus niacin and vitamin C to aid in absorption, to 20 trained cyclists for five weeks. A second group of 20 cyclists received a placebo. Three weeks into the study, participants rode a bicycle to the point of exhaustion three hours per day for three days. Blood and tissue samples were collected and analyzed to track any physicological changes that occurred.

Only 5% of the group that received quercetin reported illness after being physically stressed, compared with 45% of the participants who received placebo. No adverse side effects were observed. Surprisingly, the immune-boosting properties of quercetin weren’t readily observable until after the three-day intense exercise period. Additionally, when given an alertness test, those participants that were given quercetin better maintained their ability to react after exhaustion.

Said Dr. Nieman [2]:

It appears that it takes significant stress to bring out quercetin’s infection-fighting properties. This all happened when athletes were under high oxidative stress, when stress hormones were high, and they were also undergoing muscle damage.

Nieman plans a follow-up study to see if quercetin has any benefits for people who are undergoing everyday mental stress.

More about quercetin can be found in these posts:


  1. Defense Dept Funds $1.1 Million for Research. The College of Fine & Applied Arts, Appalicain State University. 2005 Dec 7.
  2. Research at Appalachian State Indicates Natural Plant Substance Helps Reduce Illness in Physically Stressed Athletes; Findings May Have Military Application. Appalachian State University News. 2007 Feb 8.
  3. Sampson et al. Flavonol and flavone intakes in US health professionals. J Am Diet Assoc. 2002 Oct;102(10):1414-20.
    View abstract
About the Author

Walter Jessen is a senior writer for Highlight HEALTH Media.


  1. Does wine contain quercetin?

  2. Hi Berci! High concentrations of quercetin are specifically found in red wine. When red wine is made, grape skins, seeds and stems are used far into the wine-making process. In contrast, those ingredients are removed early on when white wine is made. Red grape skins contain a variety of bioflavonoids (including quercetin) and non-bioflavonoid polyphenols (including resveratrol) and is thought to be the reason why red wine offers a number of health benefits if drank in moderation.

    For more information, see my article on quercetin.

    Thanks for stopping by!

  3. I like to see the full paper of the DARPA study if you have it. I’ve been looking at the research on curcumin, quercetin, egcg, and other compounds that manage to inhibit telomerase, which is the cancer enzyme that grants replicative immortality and stem cell like, fetus like growth and survival features to cancer cells and cancer stem cells.

    In yesterdays Edmunton Journal there are reports of people with long term, no hope cancer, having astounding results from dichloroacetate, and there are a couple of other folks too. Health Canada said in the article that its not illegal, DCA treatment in Canada at least will now proceed with the blessing and control of physicians and oncologists who can perform tests, manage patients ph, etc. Keep in mind, most of these patients have been given the go home and die advice by their doctor. They have of course every right to try DCA and for some the difference is profound.

    You have a good piece here on quercetin, perhaps you would be interested in my website, http://www.geocities.com/prime3end. I’ve found a lot of good work showing that there are many compounds that inhibit telomerase, that are available now!!!!!

    We need to use several of them in a trial to see if they can work. Most of the compounds are indirect inhibitors, but work just the same in cells or animals. Nobody has looked for synergy in using several of them at once.

  4. Thank you for the long answer! 🙂