I referred the writer to this link for some general info on glutamine(from my SupplementWatch educational site - based on the content from my 2 textbooks on dietary supplements)...
http://www.supplementwatch.com/SupplementWatch/Library/Entries/2009/2/18_Glutamine_-_Professional_Version.html
The I answered a bunch of question for her on the phone - and then handled a question about “how much can glutamine levels become depleted by exercise?” - to which I answered:
30-50% is probably a good range - the depletion of glutamine is very much dependent on the overall intensity of the challenge - so extremely intense catabolic conditions (such as burn patients) might deplete glutamine levels by 90% - while the casual exerciser would have little to no glutamine depletion. A hard-training athlete would be someplace in between - for example, we know that running a 1/2-marathon or full marathon will suppress immune function enough to result in upper respiratory tract infections in about 70% of finishers - so the more intense the effort, the greater the glutamine depletion is likely to be.
...and another = “How does glutamine increase glycogen levels?” - to which I replied:
Glutamine directly increases the activity of an enzyme - glycogen synthase - that creates glycogen in muscle/liver cells (glycogen = the stored form of glucose). Most studies suggest that this effect only happens if you have depleted your glycogen stores pretty significantly (very intense or long duration exercise). From a practical perspective, most people can “get away” with restoring glycogen levels after exercise with just eating carbs (provide the glucose for glycogen synthesis) - but in very depleted states, the added glutamine will enhance the glycogen storage - which could be important for athletes training/competing hard day after day.
...and finally - a very good question about some of the research on glutamine supplements not showing much of anything...
A lot of hard research does not indicate that glutamine does much - if anything - when taken as a supplement. Is this because the use of single amino acids can’t be substantiated somehow? Or is it because they need to work together with other nutrients to be effective? Or are they more effective when taken as BCAAs?
Hi Lxx - I think that most of the "no effect" studies come down to 2 factors:
1. the intensity of the intervention was not high enough - this is based on the fact that the most "extreme" situations (burns, post-surgery, and very intense/long exercise) tend to respond more predictably to glutamine supplementation - while the trials of shorter/easier interventions are hit/miss. It goes back to what I said before - that glutamine is a great supplement to consider if you are training HARD and need some help in "keeping" that muscle and enhancing repair - but if you're not going "hard enough" to get yourself into that hyper-catabolic state, then glutamine will probably not add much for you.
2. compliance with the supplementation regimen - I see this all the time with university-based research on supplements. A grad student will conduct a study on a small number of subjects, give them some capsules to take during a training program, and then not "manage" either the subjects or their supplement well enough (the subjects forget to take their pills or miss a few of the training sessions) - which results in a "no effect" result from the study because the subjects did not "go hard enough" (to create that hypercatabolic state) or even adhere to their supplementation regimen (they can't work if you don't take them).
There is also another factor that is more of a practical consideration when it comes to formulating products:
3. glutamine (which is cheap) is more effective when taken with BCAAs (which are expensive) - this is a harder one to tease out, but since the immune system cells are using all 4 of these amino acids as an energy source, it makes sense to take them together. We have found very good results on reducing post-exercise URTIs (upper respiratory tract infections after marathon running) with a combination of glutamine (1 gram) plus BCAAs (leucine, valine, isoleucine in a 3:1:1 ratio). NOTE: this is the specific "3:(3:1:1)" blend of glutamine/BCAAS that we have in Recover-Ease
Hope that helps!
Shawn
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Shawn M. Talbott, Ph.D., FACSM, CNS, LDN
CEO (Chief Endurance Officer)
Wicked Fast Sports Nutrition
www.wickedfastsportsnutrition.com
Shawn@WickedFastSN.com
801-576-0788
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