Does powering up at the gym also power up our immune system? Research has shown that moderate exercise improves immunity and decreases illness rates. According to an article in the American Journal of Lifestyle Medicine, “the most important finding that has emerged from exercise immunology studies during the past two decades is that positive changes in our immune system take place during each bout of moderate physical activity. Over time, this translates to fewer days of sickness from, for example, the common cold and other upper respiratory infections.” The best available evidence suggests a 25% to 50% reduction in sick days. Name one drug or supplement that can do that!
And it doesn’t take much. Let kids run around for just six minutes and we can boost the number of immune cells circulating in their blood stream by more than a third.
At the other end of the life cycle, exercise may help prevent age-related immune decline. Sedentary women in their 70s may have a 50% chance of getting an upper respiratory illness during the fall season every year. But with just a half-hour walk each day, their risk is down to 20%. The runners in the group got it under 10%–five times better!
While regular physical activity improves immune function and lowers upper respiratory infection risk, sustained and intense exertion may have the opposite effect, forming a so-called J-shaped curve relationship (you can see this curve diagram in my video, Preserving Immune Function in Athletes With Nutritional Yeast). As we go from inactive to active, our infection risk declines. But if we overtrain, as hardcore athletes do, we may actually put excessive stress on our body and increase our risk of infection. Then we could lose training days, and our performance could suffer.
So how can we fight off sickness while continuing to train? Traditional sports medicine doesn’t appear to offer much help, advising athletes to basically not pick their nose, avoid sick people, and get a flu shot.
But there may be a natural solution. A new study found that we can better maintain our level of circulating white blood cells after exhaustive exercise by consuming a special type of fiber found in baker’s, brewer’s, and nutritional yeast. (Brewer’s yeast is bitter, but nutritional yeast has a nice cheesy flavor. I use it mostly to sprinkle on popcorn). Normally, two hours after hardcore cycling, there can be a dip in circulating white blood cells, one of our first lines of defense. However, after strenuous exercise, those who ate the equivalent of less than three quarters of a teaspoon a day of nutritional yeast ended up even better than when they started. But does this increase in immune cells translate into fewer illnesses? Researchers studied competitors in the Carlsbad Marathon to find out.
In the weeks following the race, a significant number of runners began experiencing upper respiratory tract infection symptoms while taking a placebo. Those runners who were taking the equivalent of a daily spoonful of nutritional yeast cut their rates of infection in half. And they felt better, too. They were asked how they felt on a scale of one to ten. People taking the sugar pills were okay, down around four or five, but those taking identical looking capsules of the fiber found in nutritional yeast were up at six or seven. Elite athletes tend to normally experience deterioration in mood state during intense training periods, and before and after a marathon race. Sprinkle on a little spoonful of nutritional yeast, though, and you may feel less tense, less fatigued, less confused, even less angry (and my personal favorite, they had significantly “increased vigor”).
Don’t have time to exercise? Yes you do! See Standing Up for Your Health.
Find more on the benefits of exercise in:
- Exercise & Breast Cancer
- Reversing Cognitive Decline
- What Women Should Eat to Live Longer
- Is It the Diet, the Exercise, or Both?
- Enhanced Athletic Recovery Without Undermining Adaptation
What else can we do to preserve our immune function? See:
- Boosting Immunity While Reducing Inflammation
- Preventing the Common Cold with Probiotics?
- Sleep & Immunity
- Boosting Immunity Through Diet
Nutritional yeast that’s fortified can also be a convenient source of vitamin B12 (Safest Source of B12).
-Michael Greger, M.D.
PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.
Image Credit: Jeff Gunn / Flickr