I’m a huge advocate of regular exercise. Any natural health advocate ought to be. I always make time for it, even if it only amounts to a 20-minute run around the block. But when I do have time for a full exercise session, I often have to fight the urge of over exercising. Over exercising is counterproductive; it can lead to serious injury, osteoporosis, stress fractures and increase the chances of getting sick (moderate exercise does the very opposite).

But according to new research, a chemical found in lots of fresh fruits and vegetables can help prevent the flu-like symptoms that often results after several “all out” exercise sessions.

The chemical that says “Shoo!” to the flu is known as quercetin, a naturally occurring chemical that’s found in red onions, broccoli and other colorful fruits and vegetables like strawberries and blueberries, kale and cabbage. It’s long been known to have some anti-viral and anti-inflammatory properties (not to mention its effectiveness in reducing the risk of cancerous cell growth) so when researchers fed some groups of rats quercetin and had them exercise to exhaustion, they felt fairly confident that the quercetin would makes them less susceptible to flu-like symptoms that often result from exhaustive exercise regimens.

After three days worth of analyzing four groups of rats – two of which endured short periods of exercising to exhaustion while only one of them took quercetin; the other two groups did not exercise at all but one of the groups received quercetin – they found that, indeed, over exercising did increase the chances of developing the flu (over 90 percent of the rats that over exercised experienced flu-like symptoms), but that those rats that took the quercetin were about as likely to experience flu-like symptoms as those rats that didn’t exercise (63 percent of the rats that did not exercise got the flu). This finding led the researchers to believe that quercetin greatly reduces the chances of getting sick if one were to exercise for extended periods of time.

The researchers’ next study will determine if the findings that pertain to the rats is in any way synonymous with how quercetin affects humans that over exercise. A similar study found that quercetin did, indeed, have some inoculating qualities after two groups exercised rigorously for an extended period of time, but the group that took the quercetin was less likely to develop sickness afterward.

This finding shouldn’t suggest that exercise addicts can now overdo it and not have to worry about getting sick. Not at all. Quercetin doesn’t protect people from stress fractures, muscular injuries or the emotional injuries associated with overdoing it (depression, fatigue, insomnia and a general listlessness are very common symptoms of over exercising). Anyone who believes they may be exercising compulsively needs to receive professional help; it’s a very dangerous habit, a very serious health concern that needs to be addressed with professional counseling and a genuine recognition of the problem (80 percent of people who receive professional help are able to go on and live healthy, fulfilled lives). But for those of us who are training to compete in a marathon or a triathlon, over exercise is hard to avoid. It seems quercetin can help quell some of the over exercise side effects.