Cystine/theanine and immunity
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25th Mar '10, 11:19am
Post-exercise immune suppression (where immunity dips temporarily following exercise) is a well documented but undesirable phenomenon in sportsmen and women because it can increase the risk of illness and infection, especially when training loads are high. Last year, we reported on the immune-enhancing effects of supplementing cystine and theanine (PP 276) and now a new Japanese study seems to provide further evidence for this effect.
In the study, 15 well trained men were divided into two groups; the placebo group was administered a powder containing inert cellulose (950mg) and glutamate (30mg), whereas the cystine/theanine group was administered a powder containing cystine (700mg) and theanine (280mg), once daily for two weeks. The subjects trained using high-intensity resistance exercise according to their normal schedule (three times per week in the first week) but then trained at double the frequency (six times per week) in the second week in order to stress the body. The effects on subsequent immunity were then observed.
The results showed that the concentrations of some immune markers such as immunoglobulin (Ig)M, interleukin (IL)-6, IL-8, and salivary IgA didn’t change significantly following the two week protocol in either group. However (and crucially), in the placebo group, there was a significant decrease (over 30%) in the activity of key cells in immunity called ‘natural killer’ (NK) cells but not in the cystine/theanine group, suggesting that the cystine/theanine group were protected during intense training.
These findings make sense because cystine/theanine is known to enhance the production of a naturally occurring compound called glutathione in the body, which has been shown to boost the activity of immune cells. Indeed, the researchers went on to conclude that ‘cystine/theanine supplementation would be useful for athletes to prevent attenuation of NK cell activity (helping to maintain immunity) during high-intensity and high frequency training’.
J Strength Cond Res 24(3): 846-851, 2010
