We all know that exercise has benefits. One of the many benefits is
improved immunity and decreased illness rates. This is hardly breaking medical
news but even small amounts of exercise can make a big difference! One study
found that just 6 minutes of kids running around was enough to boost their
white blood cells circulating around their blood stream by more than a third
and another study found that athletes tend to need 15-50% fewer sick days!
However, sometimes we can also over-exercise, and when we do this we temporarily weaken our immunity system. Over-trained athletes put so much excess stress
on their bodies that they lower their immunity and increase their risk of
infection. Recently I experienced this when I had to endure 24-hour cold-like
symptoms a few days after a strenuous five-hour bike ride (to be fair, this was
also an unusually busy week which caused me to get less sleep than usual). This
was the first time I’ve been sick in several years and while it didn’t last too
long, I feel almost certain it was, in part, a result of over-exerting myself
during the ride and then failing to recover properly.
However a new study shows that we can better maintain our levels of
circulating white blood cells after exhaustive exercise by consuming a specific
type of fiber found in baker’s yeast and nutritional yeast.
Basically the study had active people cycle for two hours in
a humid room at a hard effort and then tested their blood both pre and post
ride to check their immunosuppression levels. Those who were given a supplement
of baker’s yeast were found to have high levels of white blood cells even after
the strenuous exercise, while the control group had significantly lower levels,
leaving the researchers to suggest that yeast had the potential to alter
immunity.
When this was then tested on a group of marathon runners, those
who were given a daily spoonful of nutritional yeast were half as likely as
those on a placebo to get an upper respiratory illness.
Both baker’s yeast and nutritional yeast were found to have these
protective properties; however, nutritional yeast is both full of nutrients, as
its name implies, and can be consumed without any processing making it more
ideal than the bitter-tasting nutritionally-void baker’s yeast.
While this is not yet conclusive, it is highly suggestive, and
since my Green Mac ‘N Cheese recipe linked above is so delicious and easy to
make, nutritional yeast is pretty easy to incorporate into your life.
Even if you’re not doing strenuous exercise on a regular bases, if
these studies are correct, using nutritional yeast could potentially also help
to boost our immunity from other forms of stress found in our daily
lives. With flu season approaching, adding some of this delicious and
relatively cheap yeast is probably worth the tiny bit of effort it takes.
K. C.
Carpenter, W. L. Breslin, T. Davidson, A. Adams, B. K. McFarlin. Baker's yeast
β-glucan supplementation increases monocytes and cytokines post-exercise:
Implications for infection risk? Br J Nutr. 2012 10:1-9
C. D.
Schwindt, F. Zaldivar, L. Wilson, S.-Y. Leu, J. Wang-Rodriguez, P. J. Mills, D.
M. Cooper. Do circulating leucocytes and lymphocyte subtypes increase in
response to brief exercise in children with and without asthma? Br J Sports Med
2007 41(1):34 - 40.
M. Gleeson. Can nutrition limit exercise-induced
immunodepression? Nutr Rev. 2006 64(3):119-131.
A version of this article was recently highlighted in the Athlete Recovery Center's weekly Newsletter
As always the information presented in this blog is for educational purposes only. It should not be considered as specific medical, nutritional, lifestyle, or other health-related advice.
This is a very fun, and timely post, what with true winter on the horizon. I had no idea that nutritional yeast had any immune boosting properties, but I'm always on the lookout for another excuse to put it on everything :)
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