I think you are just wasting your money.
Glutamine and Protein Synthesis — The other side of the coin
We've seen the theory that glutamine levels in the blood and muscle may decrease during or following exercise, and that this decrease correlates with reduced levels of protein synthesis. Several studies have addressed whether this relationship between glutamine and protein synthesis was a coincidental or a causal (meaning that one caused the other) relationship.
The first study compared the abilities of glutamine and the amino acid alanine to stimulate protein synthesis in rats with artificially reduced blood and muscle glutamine levels.(23) As expected, glutamine infusion increased intramuscular glutamine levels, while alanine didn't. Surprisingly, even depleting muscle glutamine levels by 60% had no effect on protein synthesis. What may also surprise you is that restoring blood and muscle glutamine levels to normal had no effect on protein synthesis compared to rats receiving no glutamine treatment! Additionally, even though whole body protein turnover didn't change, alanine stimulated protein synthesis!
In support of this contention, researchers studied the effect of glutamine supplementation on septic rats. Sepsis is a severely catabolic condition, during which glutamine levels (and protein synthesis) fall. Again, this study showed that despite increasing muscle glutamine levels to even higher than normal, it had no effect on protein synthesis or the catabolic state of the rats.(11)
Cumulatively, these studies show that decreased or increased levels of glutamine in the muscle has no effect on protein synthesis.
Another study, performed on people, examined the effect of adding glutamine to an amino acid mixture on muscle protein synthesis .(30) Ultimately, infusion of the original amino acid mixture increased protein synthesis by nearly 50%, but adding glutamine to this mix had no additional effect. This study is particularly relevant because most consumers of glutamine do so following a workout, along with other amino acids (or a whole protein).
Finally, Wusteman et al., used a drug to reduce muscle protein synthesis, along with muscle glutamine levels, in rats.(29) Much like the Olde Damink et al. study, restoring muscle glutamine levels to normal had no effect on protein synthesis. This study further supports the concept that blood and muscle glutamine levels have no bearing on protein synthesis and protein turnover.
Another One Bites the Dust
You may recall that the theory of exercise induced immunosuppression is often cited, based on the fact that glutamine levels decrease after exercise, as does our immunity.(10)
What we must now address is whether the relationship between the body’s glutamine stores and the effects of exercise on the immune system exhibit a causal or coincidental relationship (just as we did for protein synthesis). A recent review article in "The Journal of Applied Physiology" examined this connection between plasma glutamine and exercise-induced immunosuppression.(15)
The study admitted that there are conflicting reports about plasma glutamine levels following long duration exercise, repeated high intensity bouts, as well as short single high intensity bouts. This indicates that plasma glutamine concentrations may be affected differently depending on the intensity and duration of exercise.
Even data on blood glutamine concentrations following eccentric exercise is mixed, which can relate directly to bodybuilders and their use of heavy loads. Based on the relatively small reductions in plasma glutamine that might occur following exercise, supplementation with glutamine wouldn’t likely affect the immune cells.
More importantly, there are several studies showing that glutamine supplementation doesn't alter exercise-induced suppression of the immune system! The bottom line is that blood glutamine levels, whether they drop or not following exercise, don’t seem to affect immunity to any great extent, which precludes the use of glutamine for this reason.
Another recent review looked at over 75 research papers pertaining to the effect of glutamine on immunity and muscle growth, and came to the following conclusion: "Overall, although glutamine obviously plays important metabolic roles within the body, supplementation does not appear to provide consistent beneficial or therapeutic effects, except during certain catabolic situations. Glutamine availability, therefore, does not seem to be a limitation in many challenge situations."(19)
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