#AskGrizzly – Glutamine
I got bored at work and asked Twitter to give me something to do. A friend asked about Glutamine supplementation – something I’ve seen a lot of, especially in my “Muscle and Fitness” days, but have since let fall off the radar. Let’s start with what Glutamine is, thanks Wikipedia!
Glutamine (abbreviated as Gln or Q) is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid, but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders.
Why take Glutamine?
There are several arguments for the theory behind Glutamine supplementation. The first, is that Glutamine plays a role in bicarbonate production, thus under physiological loads when acid production is high (as we discussed last weekend) glutamine is required to buffer. Further, in resistance trained athletes Glutamine levels appears to be decreased, inhibiting proper anti-inflammatory responses, and hindering recovery. Finally, oral Glutamine has been posited to increase growth hormone levels as well.
In this study, nine subjects are given 2g of glutamine with a “cola drink” and eight of the nine responded with serum glutamine levels and growth hormone increases. Nine is hardly a large sample, and the administration with a cola drink doesn’t sit right with me. Further, the study simply measured blood levels, not actual results. In other words, they didn’t prove that an increase in blood levels of glutamine translate to better buffering, increases in bicarbonate production, or increase in muscle function or recovery. None of this was measured.
Most studies have far too many variables to conclusively say glutamine plays a roll specifically. For instance this study, uses whey, casein, BCAA, and glutamine in various combinations but never glutamine alone. At least they used more than 9 participants and a proper negative control. In good news the glutamine group showed increases in lean mass and strength, but then again, casein and whey protein can have that affect. This study also looks at glutamine but never outside of creatine monohydrate, with something like 800 studies supporting it, it’s hard to demonstrate glutamine supplementation above and beyond.
Then we have this study which used 28 trained individuals with at least 2 years experience. This is much closer to the population that interests us. This study concludes that “This study demonstrated that the supplement group did not enhance MS (muscular strength), ME (muscular endurance), or BC (body composition) significantly more than control after an 8-week resistance-training program.”
This study is my favorite though. 28 subjects, double blind with placebo controls, 6 weeks of controlled training, and measured muscle protein degradation. “We conclude that glutamine supplementation during resistance training has no significant effect on muscle performance, body composition or muscle protein degradation in young healthy adults.” Uh-oh, not looking good for glutamine. In many reviews, glutamine appears as ambiguous, “Although glutamine supplementation may increase plasma glutamine levels, its effect on enhancement of the immune system and prevention of adverse effects of the overtraining syndrome are equivocal” (Williams 1999)
There’s pretty strong evidence that oral glutamine supplementation can increase glutamine levels in the blood, but all that really means is that your body is capable of absorbing and assimilating amino acids. Without that we’d probably have other issues, you know like ridiculous weight loss because you can’t digest amino acids a.k.a. protein. This is where the well dries up, in my albeit brief search I didn’t find one study that showed only glutamine supplementation could increase muscle strength, endurance, power output, or even body composition. Here’s the other problem, glutamine can be produced by your body, you don’t need to take it; add that to the fact that most regular whey protein also contains a sizable amount of glutamic acid or so-called ‘glutamine precursors.’ Thus, I’d be hard pressed to conclude anything other than supplementing with oral L-glutamine is a waste of money.
Disagree?? Hit me with some links! I love a good research paper.