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What I was wondering was L-glutamine is glutamic acid with B6 (& ammonia) added,
As Dr. Misner pointed out, L-glutamine is not glutamic acid plus B6, it is glutamic acid plus an amino group.
so if you took BCAA's with l-glutamine would the l-glutamine be broken down (either in the digestive system
The question regarding whether L-glutamine would be broken down in the digestive track and absorbed as another AA, such as glutamic acid, the answer is no. Glutamine is absorbed into the intestinal cell via carrier-mediated mechanisms and enters the intestinal cell as is. Glutamine supplementation in rats and humans will raise circulating glutamine levels, implying that glutamine can be delivered unmodified into the blood from the intestinal cell.
or within the body somewhere),
"Glutamine is an important energy source in intestinal mucosa, the small intestine is the major organ of glutamine uptake and metabolism and plays an important role in the maintenance of whole body glutamine homeostasis." (Peng X, et al. Burns. 2004 Mar;30(2):135-9.) You will find statements such as these in many Medline indexed journal articles that study the metabolism of glutamine in severe trauma (burns, sepsis, cancer). Knowledge of the small intestine's use of a decent fraction of ingested glutamine should however have no bearing on one's dosing strategy. One's dosing strategy should be based on any toxicological research (as stated by Dr. Misner) and efficacy studies in the non-trauma condition.
There is very little research on the effect of glutamine on protein metabolism, muscle mass, or performance in the healthy athlete. From a recent lit search I found only a handful of studies on glutamine supplementation in the context of exercise, and the they primarily addressed overtraining, immune function, and glycogen sparing in endurance athletes.
Unfortunately, it seems that supplement manufacturer claims regarding glutamine stem largely from the wide body of research in severe trauma. Wilmore DW. J Nutr. 2001 Sep;131(9 Suppl):2543S-9S. "From available data, GLN supplementation enhances net protein synthesis (particularly muscle), decreases length of postop. hospital stay, prevents immunosuppression in burn patients, and decreases rate of infection in burn patients." This conclusion suggests that GLN supplementation has important effects in catabolic patients, but the exact mechanisms that explain the effects remain unknown and thus cannot in any way be directly applied to non-trauma conditions. You might also want to check out the following article to get a good sense for the degree to which we do not yet understand the issue at hand: Rutten EP, et al. Skeletal muscle glutamate metabolism in health and disease: state of the art. Curr Opin Clin Nutr Metab Care. 8(1):41-51;2005.
> or would you need to find a separate source of B6 & glutamic acid to get the best effect when supplementing with BCAA's???
Thus, the answer to needing a "separate source" of B6 and/or glutamic acid is no.
Regarding whether glutamine has any impact on the effects of BCAA supplementation, I was able to find one recent article in rugby players (Ohtani M, et al. Amino acid mixture improves training efficiency in athletes. J Nutr. 2006;136(2):538S-543S) that found positive effects. I'm not sure how the training of the rugby players would translate into body building, if that is indeed the sport which applies to your question. Keep in mind that there is very little research on the effect of BCAA alone and resistance trained athletes. Although some of the effects of BCAA seen in endurance athletes seem to suggest that there would be a benefit to resistance trained athletes, the empirical evidence is not yet there (Kreider RB. Dietary supplements and the promotion of muscle growth with resistance exercise. Sports Med. 1999;27(2):97-110.) The only other study I located easily was in septic or irradiate rats: M Holecek. Nutrition 2002;18(2)130-3. It only seemed to confirm the known interplay between glutamine and BCAA metabolism in that BCAA are considered a glutamine precursor (Castell L. Sports Med. 2003;33(5):323-45).
So, the bottom line of all the evidence I was able to readily access is that to date there is no clear evidence that glutamine or BCAA supplementation, either alone or in combination, would have meaningful benefits in resistance training.
Regarding Dr. Misner's statement that glutamine stimulate GH secretion, I personally have not been able to find a credible source supporting that statement. The only amino acid secretagogues I have seen reported in the research literature are arginine, ornithine, and lysine (see R Maughan, et al. J Sports Sci, 22:95-113;2004). In fact, some of the latest studies in trauma patients administer GH plus glutamine, suggesting the glutamine would not be a potent GH secretagogue. Besides, “The balance of the evidence suggests that, in healthy adults, growth hormone does not build muscle and provides no athletic advantage. Growth hormone abuse, however, does cause disease.” (MJ Rennie, Br J Sports Med 37:100;2003). Another good review article, although now a bit "old", is by MH Williams, Facts and fallacies of purported ergogenic aid supplements. Clin Sports Med 18(3):633-49;1999.
An important thing to remember when critiquing information is that any claim of a "400% increase" is by itself meaningless. You want to follow up on such claims by looking at research that will provide a context within which you can answer questions such as: is that a lot, is that too much, how does it compare to other stimuli of GH release, etc. In terms of reliable sources on GH release, again from the Medline indexed exercise literature, MH Williams (1999) states, "Current data, including results for several well-controlled studies, indicated that supplementation with arginine, ornithine, or lysine, either separately or in combination, does not enhance the effect of exercise stimulation on either hGH or various measures of muscular strength or power in experienced weightlifters." The most potent physiologic stimulators of GH secretion are sleep and exercise (aerobic and resistance) MJ Rennie. Br J Sports Med 37:100-105;2003 Also, on page 224 of Essentials of Strength and Conditioning (NSCA, 2nd ed.), there is a nice graph that consolidates results of 4 studies to show the relative effects of AA (ingested or infused) and exercise on GH release. It shows that infused arginine and resistance exercise have similar effects, at most a 10 fold increase in GH levels. With that in mind, you'll get twice the effect of 2g glutamine ("400% increase") simply by working out, right? Now if you're thinking of taking arginine instead, think about the next question: Would the oral dose of arginine needed to produce the same effect as in the infused condition be tolerable or affordable?
I hope all of this helps you make a more informed decision regarding supplements. Unfortunately, there is often no easy answer to an exercise and nutrition question.
Best wishes,
Annie C. Wetter, PhD, CSCS
Assistant Professor of Nutrition & Dietetics
Coordinator of the Nutritional Science Master's Program
School of Health Promotion & Human Development
University of Wisconsin-Stevens Point
CPS Bldg, room 224
Stevens Point, WI 54481
T: 715.346.2108
F: 715.346.2720
E: Annie.Wetter@...
Assistant Professor of Nutrition & Dietetics
Coordinator of the Nutritional Science Master's Program
School of Health Promotion & Human Development
University of Wisconsin-Stevens Point
CPS Bldg, room 224
Stevens Point, WI 54481
T: 715.346.2108
F: 715.346.2720
E: Annie.Wetter@...
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