A Very Cool Dipeptide

L-alanyl-L-glutamine, or L-AG, is a dipeptide that has a storied use in clinical settings. Some years ago its safety was demonstrated by the lack of evidence of genotoxicity in the Ames assay and in the in vitro CHL cell chromosome aberration study.¹ In another study, in which post-op patients were randomized to receive either standard intravenous nutrition or intravenous nutrition supplemented with l-alanyl-l-glutamine, clinical outcome was measured by average length of stay in the intensive-care unit and hospital and the mortality in the intensive-care unit and within 30 days and six months. In the L-AG group, plasma glutamine concentrations significantly increased within six to nine days. The dose was 0.3 grams per kilogram of bodyweight per day, or roughly 27 grams for a 200-pound person. Six-month survival was significantly improved for patients treated for at least nine days—66.7 percent for the glutamine supplemented vs. 40 percent for the controls. So this stuff is clearly safe in superhigh doses.² What about performance?

An interesting study done by Dr. Jay Hoffman examined the effects of acute L-alanyl-L-glutamine intake on performance changes and various stress and recovery markers in response to exhaustive endurance exercise and different scales of hydration. Ten active men exercised under five different conditions:

1) Normal hydrated state

2) Dehydrated by 2.5 percent of bodyweight

3) Rehydrated to 1.5 percent of bodyweight with water

4) Rehydrated to 1.5 percent of bodyweight with an L-AG-supplemented drink of 0.05 grams per kilogram of bodyweight

5) Rehydrated to 1.5 percent of bodyweight with an L-AG-supplemented drink of 0.2 grams per kilogram of bodyweight

Note that the last condition just used a greater amount of L-AG.

The data showed that AG supplementation provided a significant ergogenic benefit by increasing time to exhaustion during a mild hydration stress.

That effect was likely helped along by an enhanced fluid and electrolyte uptake.³ In fact, the highest dose of L-AG produced the greatest benefits for exercise performance. For a 200-pound man, that dose is roughly 18 grams.³

What’s interesting is that water alone did not appear to  help. Water is the most used ergogenic aid. If you go back 20 to 30 years, many exercise physiologists were skeptical of sports drinks and certainly any that contained amino acids. Funny how dead wrong some of the eggheads can be when entrepreneurial types come up with products that later prove in scientific investigations to be safe and effective. With L-AG, the sports drink segment has a very interesting player on hand. Forget the sports drinks that contain just sugar and electrolytes. You gotta have dipeptides, baby!

Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (www.theissn.org); also check out his site www.TheWeekendWorkout.com.

References

¹ Oda, S., et al. (2008). Safety studies of l-alanyl-l-glutamine (l-AG). Regul Toxicol Pharmacol. 50:226-38.

² Goeters, C., et al. (2002). Parenteral L-alanyl-L-glutamine improves 6-month outcome in critically ill patients. Crit Care Med. 30:2032-7.

³ Hoffman, J., et al. (2010). Examination of the efficacy of acute L-alanyl-L-glutamine ingestion during hydration stress in endurance exercise. J Int Soc Sports Nutr. 7:8.