John Berardi - Appetite For Construction, Nov 8 2002
Should I Spend my Hard-Earned Money on Glutamine or Hookers?
Q: In a recent T-mag article, glutamine was described as pretty much worthless if you're already taking care of protein and post-workout protein/carb/amino needs. What's your opinion? Is glutamine overrated?
A: Well, for starters, glutamine is the most abundant free amino acid???
Aww hell; I'm not going start my response off with the standard opening line that just about everyone uses to indirectly affix grandiose importance to this amino acid! Sure, it's conditionally essential (meaning that although it's not absolutely necessary in the diet, our requirements for glutamine can exceed our production of it in certain conditions).
Yes, it makes up 2/3 of the muscle's free amino acid pool (which is a pretty damn small part of the muscle's total amino acid content anyway) and sure, glutamine has been shown to have some pretty amazing benefits in wasting conditions, postoperative patients, and in TPN (total parenteral nutrition).
But as bodybuilding/fitness writers, it's about time we put aside this useless trivia and discuss the utility of glutamine supplementation for athletes, weight lifters, etc. A few years ago there were no data and therefore we could speculate all we wanted about the theoretical potential of glutamine supplementation. But nowadays, we've got the data and the data demonstrate that our theories may have been wrong.
To this end, I applaud my good friend David Barr on his excellent articles (Glutamine ??? Destroying the Dogma Part I and Part II) that revealed that despite all the conjecture about how glutamine supplementation may help increase muscle mass, muscle strength, and prevent overtraining, each and every research investigation examining the effects of glutamine supplementation on exercise performance, body composition, and protein degradation has shown that it offers no benefit. Because of the great job that Dave did in his literature review, I certainly don't have to provide a reference list ??? they're all right there at the end of his article.
To reiterate a few of the key points that Dave brought up in his article and that I brought up at the SWIS seminar:
??? A high protein diet provides a big whack of glutamine as it is. In fact, if you follow standard bodybuilding protein recommendations, about 10% of your total dietary protein intake is composed of glutamine (milk proteins are composed of somewhere between 3 ??? 10% glutamine while meat is composed of about 15% glutamine). This means that a high protein diet (400g/day) already provides me with about 40g of glutamine.
??? While the theorists still cling to the idea that since glutamine helps clinical stress, it might help with exercise stress, it???s important to note that exercise stress has got nothin??? on surgery, cancer, sepsis, burns, etc. For example, when compared with downhill running or weight lifting, urinary nitrogen loss is 15x (1400%) greater in minor surgery, 25x (2400%) greater in major surgery, and 33x (3200%) greater in sepsis. When it comes to the immune response, it???s about 9x (800%) greater with surgery. When it comes to metabolic increase, it???s 7x (600%) greater with burn injury, and when it comes to creatine kinase release; it???s about 2x (100%) greater with surgery. As I said, exercise has got nothin??? on real, clinical stress. It???s like trying to compare the damage inflicted by a peashooter and that inflicted by a rocket launcher.
??? The major studies examining glutamine supplementation in otherwise healthy weightlifters have shown no effect. In the study by Candow et al (2001), 0.9g of supplemental glutamine/kg/day had no impact on muscle performance, body composition, and protein degradation. Folks, that's 90g per day for some lifters.
??? The majority of the studies using glutamine supplementation in endurance athletes have shown little to no measurable benefit on performance or immune function.
??? And with respect to glycogen replenishment in endurance athletes, it's interesting to note that the first study that looked at glycogen resynthesis using glutamine missed a couple of things. Basically, the study showed that after a few glycogen depleting hours of cycling at a high percentage of VO2 max interspersed with very intense cycle sprints that were supramaximal, a drink containing 8g of glutamine replenished glycogen to the same extent as a drink containing 61g of carbohydrate.
The problem was that during the recovery period, a constant IV infusion of labeled glucose was given (i.e., a little bit of glucose was given to both groups by IV infusion). While this isn't too big of a deal on its own since the infusion only provided a couple of grams of glucose, the other problem is that during glycogen depleting exercise, a lot of alanine, lactate, and other gluconeogenic precursors are released from the muscle.
What this means is that there's a good amount of glucose that will be formed after such exercise, glucose that will be made in the liver from the gluconeogenic precursors and that will travel to the muscle to replenish glycogen. Therefore, without a placebo group that receives no calories, carbohydrates, or glutamine, we have no idea of knowing whether or not the placebo would have generated the same amount of glycogen replenishment as the glutamine group or the glutamine plus carbohydrate group. To say it another way, perhaps there's a normal glycogen replenishment curve that was unaffected by any of the treatments.
??? And finally, with respect to the claims that glutamine might increase cell swelling/volume (something I once believed was a reality), we decided to test this theory out in our lab using multifrequency bioelectric impedance analysis as well as magnetic resonance spectroscopy. The pilot data that's kicking around has demonstrated that glutamine supplementation has no effect on total body water, intracellular fluid volumes, or extracellular fluid volumes (as measured by mBIA) and has no effect on muscle volume (as measured by nMRS).
Therefore, at the present time, I think it's safe to conclude that glutamine supplementation probably offers little to no benefit with respect to athletic performance or body composition when given to well-fed, healthy athletes. But I don't want to totally burst anyone's little glutamine bubble. After all, I'm not saying that glutamine supplementation is totally worthless. As Dave Barr pointed out in his article, there may be some circumstances in which glutamine supplementation is of benefit. Here are some of them:
??? Steroid users who are improperly coming off a cycle might need some. When coming off a steroid cycle, blood Testosterone concentrations are dismally low while cortisol levels become quite elevated. If said steroid user continues training (which he/she must to try to preserve their muscle mass), the catabolic stimulation might be significant. It still doesn't approach clinical catabolism but it may just become bad enough that some extra glutamine might help. This is just a guess, however.
??? When trying to get really lean, many bodybuilders restrict energy intake and increase exercise volume and might need some glutamine. This type of energy deficit may signal the body to begin using protein as an energy source, cutting into valuable muscle resources. In addition this catabolic stimulus will be compounded by the exercise stress and may lead to excess catabolism. Perhaps glutamine may help out in these scenarios. Again, a guess.
??? In elite endurance athletes training intensely 2 or 3 times in a given day, I might prescribe some. Although I rarely recommend glutamine to my clients, my elite cross country skiers are encouraged to take it mostly during their trips to altitude camp and for glacier training. These athletes train 2-3 times per day for a week or two at a time while living in tents on a glacier at altitude. Add on the fact that nutrition on such excursions is bare bones, so that's some stress that glutamine might help with.
??? When injured and trying to prevent wasting or facilitate wound/soft tissue injury, take some. Williams et al (2002) demonstrated that daily supplementation with 3g of HMB, 14g of glutamine, and 14g of arginine can lead to increased wound healing.
So when all is said and done, I pretty much agree with Dave's appraisal of the value of glutamine supplementation for well-fed weightlifters and bodybuilders. Considering how much protein most bodybuilders consume, additional glutamine supplementation are probably worthless. However, like any other question, there isn't a black and white answer. There do remain a few situations, as discussed above, that glutamine might be a supplement to consider. Personally, I only prescribe it to my skiers during altitude and glacier training, to steroid users coming "off," to bodybuilders during the last few weeks of competition dieting, and to people who are injured and trying hard to recover. And, of course, to those with legitimate wasting conditions. If you don't fall into any of these categories, spend your money on more groceries.
