Preserving Immune Function

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!

Regular exercise has great advantages for the elderly as well. Sedentary women in their 70s have as high as a 50% chance of contracting an upper respiratory illness every year. However that risk gets knocked down to just 20% when they do just 30 minutes of walking a day and when they did even more exercise their risk lowered even more!

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.