Nutrition Nerd: Immunonutrition Support for Runners
Posted Mar 01 2012 9:18am
Written by Tanya, Nutrition Nerd. Getting sick is the pits. It ruins training, eating, sleeping, working, etc. Unfortunately, there is evidence that athletes training hard or who have recently completed an endurance/ultra endurance event are at an increased risk of falling ill, with the most common illness being upper respiratory tract infections (URTI) [ 1 , 2 ]. When we perform prolonged bouts of strenuous exercise and engage in periods of intense training with little recovery it can compromise our body’s immune system, reducing its ability to fight opportunistic infections such as colds and the flu. Psychological/physiological/environmental stress, lack of sleep, and inadequate diet (factors which can easily creep in to our lives) also result in immunosuppression. Combine that with increased exposure to pathogens - such as crowds at a race – and we runners are set up for an increased risk of infection. Yikes! So what can we do about it? Well for starters we can have a great “ Nutritional Base ” and we can take a Multivitamin/mineral supplement to correct nutritional deficiencies (see Sarah’s latest post on this topic here ). But there is more we can do!
A variety of nutrients and nutritional supplements have been proposed to “boost immunity”, lower the degree of physiological stress our hard training confers and thus decrease URTI risk. Some have scientific evidence to back them up. Some do not. Unfortunately most of the “stuff” the high-school/college-aged clerks at the natural food or supplement shops will try to sell you is basically a bunch of bologna.
So to separate fact from fiction, below is a chart indicating both the proposed rational as well as the current recommendation based upon the scientific literature of several immunonutrition supplements. (Note: I went to the experts in this field for the information and therefore please know that this chart is reproduced from the book chapter “Supplements to Boost Immune Function” written by David Nieman, DrPH in the book Sports Nutrition: From Lab to Kitchen , which is edited by Asker Jeukendrup, PhD ).
Recommendation Based On Current Evidence
Exerts anti-inflammatory effects post-exercise
Not recommended; no different from placebo
Quenches exercise-induced reactive oxygen species (ROS) and augments immunity
Not recommended; may be pro-oxidative with heavy exertion
Quenches ROS and augments immunity. Reduces cortisol response to exercise.
Not recommended; relatively small effects on cortisol compared with carbohydrate; immune measures no different from placebo
Important immune cell energy substrate that is lowered with long exercise
Not recommended; body stores exceed exercise lowering effects
Maintains blood glucose during exercise, lowers stress hormones, and thus counters immune dysfunction
Recommended, but 60g/hr in heavy exertion helps dampen immune inflammatory responses, but not all aspects of immune dysfunction.
Receptors found on immune cells, and animal data show supplementation improves innate immunity and reduces infection rates.
Not recommended; human study with athletes showed no benefits.
Herbal extract that is a popular supplement among athletes. Claimed to boost immunity via stimulatory effects on macrophages and there is some in vitro evidence for this.
Not recommended; human study showed no benefits.
Probiotics are live microorganisms which when administered orally for several weeks, can increase the numbers of beneficial bacteria in the gut. This has been associated with a range of potential benefits to gut health, as well as modulation of immune function.
Recommended; human studies show improvements in some aspects of acquired immunity and reduced incidence of respiratory illness and GI problems.
In vitro studies show strong anti-inflammatory, anti-oxidative, and anti-pathogenic effects. Animal data indicate increase in mitochondrial biogenesis and endurance performance.
Recommended; human studies show strong reduction in illness rates during heavy training and mild stimulation of mitochondrial biogenesis and endurance performance in untrained subjects.
Quercetin with EGCG
Flavonoid mixture promotes anti-inflammatory and anti-oxidative effects, and immune function improvement, superior to just quercetin alone.
Recommended; human study showed strong anti-inflammatory effect, with modest anti-oxidative effect and improvement in innate immunity.
This is an area of research which is still under investigation and likely to expand in the future. Keep your eyes open for new information, but also remain skeptical or bold claims which are not backed up by sufficient, reliable scientific evidence!
Do you tend to come down with cold/flu-like symptoms during periods of heavy training or following a marathon or ultra? Do you take any “immune boosting” supplements? What has your experience with them been?
(Tanya is a Registered Dietitian (RD) and is pursuing her PhD in Nutrition and Exercise Science at Virginia Tech. After graduating with her Bachelor’s in Dietetics, Tanya completed an American Dietetic Association (ADA) approved Dietetic Internship through the University of Houston. She has completed many road races from 5k to 25k. Follow her on Twitter @nutritionnerd and at her personal blog Dine, Dash & Deadlift .)