Immunity Challenge
Immunity Challenge
I’m guessing that you probably don’t spend several hours each day bicycling to the point of exhaustion. If you do, then you’ll probably be all set for the Tour de France by next July, Lance.
But this level of physical activity can take a heavy toll, leaving the body vulnerable to attacks on the immune system from common viruses. And while that’s not good news for bicycle champions, it’s an ideal situation in which to examine the effectiveness of a supplement that enhances the immune system.
Putting the pedals down
In 2005, The U.S. Department of Defense awarded more than $1 million to Appalachian State University to test quercetin supplements under conditions that would approximate the relentless physical demands sometimes put on soldiers.
Previous studies have shown that quercetin (a natural antioxidant and anti-inflammatory) helps keep the immune system strong. But according to Appalachian State researchers, theirs is the first double-blind, placebo-controlled trial to show that a plant compound can prevent viral illness.
STUDY PROFILE
- Researchers recruited 50 trained cyclists
- For five weeks, 30 subjects received 1,000 mg of quercetin daily, and 20 subjects received a placebo
- During the third week, each subject cycled for three hours, three days in a row
- Before and after this physical portion of the test, the health of each subject was closely monitored, and muscle biopsies were taken to analyze stored carbohydrate
- In the final days of the intervention period, about 45 percent of the placebo group became ill, but only five percent of the quercetin group reported illness
- Alertness tests showed that subjects in the quercetin group had greater ability to react after intense exercise compared to placebo subjects
When the Appalachian State team presented their findings this past February at a meeting of the American College of Sports Medicine, the researchers noted the possibility that quercetin’s immune enhancing qualities may be most effective when the body is stressed by extremes of physical activity. Further tests will be needed to clarify this point.
And one more caveat: Subjects in the quercetin group also took supplements of niacin and vitamin C. The study is not yet published, and the only reports about the study don’t include details on dosage amounts for these two additional supplements.
Combining & strengthening
Quercetin is a flavonoid – the substance that gives fruits and vegetables their color. And the immune enhancing properties of quercetin may be even greater when combined with another flavonoid called kaempferol.
In the e-Alert “A Cell’s Best Friend” (5/1/03), I told you about a study from the National Public Health Institute in Helsinki, Finland, in which the diets and medical records of more than 10,000 men and women were tracked for many years – as much as 28 years for some subjects.
Researchers found that subjects who consumed more flavonoid-rich foods were less likely to suffer from a number of chronic diseases, including heart disease, lung cancer, stroke, asthma, and type 2 diabetes. Furthermore, those who ate foods that provided a variety of different types of flavonoids tended to live longer.
The two flavonoids that stood out in the study: quercetin and kaempferol. Subjects who had high levels of both of these flavonoids in their diets were found to have a 21% lower risk of heart disease than those who ingested small amounts of the two. In addition, subjects with kaempferol-rich diets had a 30% less chance of stroke.
Quercetin is most abundant in red apples, red grapes, red wine, broccoli, onions, green tea, and citrus fruits. Broccoli and onions are the best sources of kaempferol.
Talk to your doctor before adding quercetin supplements to your daily regimen.
Of course, if the new FDA guidelines are adopted, you may need an actual prescription from your doctor to get quercetin so you might want to stock up now. You can let FDA officials know you oppose their current attempt to unnecessarily over-regulate foods and supplements at this link.
