The short answer to the first part is a dipeptide composed of the amino acids Alanine and Glutamine. Before we consider its importance let’s back up and review some basic biochemistry.
The body needs protein to build and maintain tissues for all of its functions. Whole protein molecules are too large to be absorbed in the gut. Proteins must be broken down into smaller units to be absorbed. Proteins may be broken down either by acid hydrolysis or by enzymes. During digestion proteins are broken down into smaller and smaller molecules. In order of decreasing size:
Only dipeptides and amino acids are small enough to be absorbed in the gut. One would think that the smallest molecule, a single amino acid would be the most efficient way to absorb amino acids. A dipeptide is the most efficient form of protein absorption. Specific transporters for dipeptides exist on the gut surface, which accelerate absorption. More energy is required to break dipeptides into amino acids and transporters for amino acids are more limited both in type and number. In other words, the bandwidth for dipeptide upload (absorption) is significantly greater than for amino acid upload as large numbers of individual amino acids compete for limited spots on transporters.
What are the benefits of alanine and glutamine once they have been absorbed?
L-Glutamine is the most abundant non-essential amino acid in circulation and in intracellular pools. It is considered non-essential because it can be synthesized in our bodies. Glutamine may however be considered as “conditionally essential” due to its importance in a variety of metabolic pathways. Glutamine is the most important precursor creating and excreting ammonia in the kidney, it is a substrate for gluconeogenesis (creating glucose from the break down of protein), and it may be used as an oxidative fuel in rapidly proliferating cells. Glutamine helps to regulate increases protein synthesis and decreases protein degradation in muscle, and stimulates glycogen synthesis in the liver. Glutamine also supports immune function and helps to maintain gut mucosa, which prevents intestinal bacteria and toxins from entering circulation. Glutamine metabolism is known to increase significantly in patients suffering from severe illness and in athletes during periods of intense, stressful training. Consequently, glutamine levels are depleted during those times.
L-Alanine is the second most abundant circulating amino acid. Aside from its role in protein synthesis, L-Alanine plays a pivotal role in nitrogen and glucose metabolism. Alanine can be converted to pyruvate, which can be oxidized or converted to glucose. The glucose-alanine cycle is the pathway by which skeletal muscle eliminates nitrogen while simultaneously replenishing its energy supply. Alanine is released into circulation and taken up by the liver. In the liver Alanine is split into an amino group and pyruvate. The amino group is converted to urea and excreted. At the same time the pyruvate is converted to glucose, which may be returned through the blood stream to the muscle. Up to 45% of glucose released from the liver during prolonged exercise (>4 hours) may be derived from Alanine.
Clearly Alanine and glutamine are major players in energy production and tissue maintenance, but the story gets even more interesting when the two are considered as the dipeptide L-Alanyl L-Glutamine (AG). L-Glutamine is rapidly degraded to ammonia when in solution and is poorly soluble. AG is more stable and incredibly water-soluble. As an added benefit, AG appears to increase electrolyte and fluid uptake in the intestinal mucosa In addition to better absorption and hence better bioavailability as mentioned above.(1) Through an enhanced signaling pathway. AG may have significant benefits for endurance athletes by improving hydration and electrolyte uptake. One study examined the effects of dehydration in cyclists when tested to exhaustion. The cyclists were then rehydrated with either water or a solution containing two different concentrations of AG. The group rehydrated with water showed no improvement compared to the dehydrated state, while the two groups rehydrated with a solution containing AG demonstrated significant improvements in performance compared to the dehydrated state.(2) Another similar study in basketball players with hypohydration stress demonstrated benefits from rehydrating with 1 g of AG per 500ml of water by delaying fatigue, maintaining reaction times and fine motor control. The authors suggested that these effects are likely mediated by enhanced fluid and electrolyte uptake, which result in preservation of neural function.(3) Another article, recently published evaluated the effects of AG during a 1 hour run test. In this trial, subjects were either given no hydration, a sports drink, or drinks containing different concentrations of AG. There was no difference in performance between the no hydration group and the group hydrated with a sports drink. (The sports drink used for this study was similar to what is readily available at your corner convenience store.) Both groups hydrated with a solution containing AG demonstrated significantly improved time to exhaustion during high-intensity exercise.(4)
At this point, you, the educated endurance athlete, might be scratching your head and asking yourself, “How does L-Alanine-L-Glutamine help me?” We have just reviewed some of the important roles that Alanine and Glutamine have in energy production, excretion of nitrogenous waste, tissue repair, and immune defense, but that’s not the complete story. The key benefit for endurance athletes happens during absorption in the gut. When the Dipeptide L-Alanyl-L-Glutamine is absorbed through its specific receptor at an enhanced rate, that’s not the only thing that happens: Sodium is also absorbed in solution with water. That’s it. That’s the thing endurance athletes have been looking for since they started drinking water. AG is the thing, which opens up another pathway for athletes to absorb more fluid and more sodium.
The importance of water and electrolyte absorption in endurance sports is not to be overlooked. In a recent study Del Coso examined the effects of salt ingestion during a half ironman triathlon: This study compared two similar groups competing in a half ironman triathlon. One group was given placebo, and the other group was given a salt supplement containing sodium, potassium, magnesium, and chloride. At the end of the race, the salt group had higher serum electrolyte concentrations and higher body mass than the control group. The higher body mass reflects significantly better hydration status at the end of the race. Because body fluids and electrolytes were maintained better, the salt group significantly outperformed the control group by a whopping 26 minutes over the control group.(5)
You don’t have to be a chemist to cobble together the ultimate sports drink. The EFSPro uses this research and technology in its newest formula so athletes can benefit from this superior absorption. EFSPro contains the highest level of electrolytes in an osmotically balanced solution that is further enhanced through the addition of AG.
While the benefits of L-Alanine-L-Glutamine are still being investigated, it does appear to be the this is one ingredient endurance athletes should add to their staple if hoping to go faster and longer. L-Alanine-L-Glutamine can support the endurance athlete in their quest for better. The evidence suggests significant improvements fluid and electrolyte absorption efficiency, improvements in cognitive and physical performance in adverse conditions, and improvements in recovery and immune system function. Unfortunately, you still have to work hard to go faster.
1. L-glutamine absorption is enhanced after ingestion of L-alanylglutamine compared with the free amino acid or wheat protein. Harris RC, Hoffman JR, Allsopp A, Routledge NB. Nutrition Research 32 (2012) 272-277.
2. Examination of the efficacy of acute L-alanyl-L-glutamine ingestion during hydration stress in endurance exercise. Hoffman JR, Ratamess NA, Kang J et al. Journal of the International Society of Sports Nutrition 2010, 7:8
3. Effect of acute L-Alanyl-L-Glutamine and electrolyte ingestion on cognitive function and reaction time following endurance exercise. Pruna GJ, Hoffman JR, McCormack WP, et al. Eur J Sport Sci 2014 Oct 16:1-8.
4. Effects of L-Alanyl-L-Glutamine Ingestion on One-Hour Run Performance. McCormack WP, Hoffman JR, Pruna GJ, et al. J Am Coll Nutr 2015 Jun 22:1-9.
5. Effects of oral salt supplementation on physical performance during a half-ironman: A randomized controlled trial. Del Coso J, Gonzalez-Millan C, Slinero JJ, et al. Scand J Med Sci Sports 2015: doi: 10.1111/sms.12427