L-Glutamine is SWORN by all the old school bodybuilders to be the best recovery agent on the market. It is true that Glutamine is used up and used in recovery, but the question is whether any of it actually makes it to the muscle to be used in recovery and regeneration. Oral L-Glutamine is very good for you and it is metabolized in the gut by intestinal bacteria. It helps them grow and produce positive metabolites that give the intestines proper balance. Additionally, Glutamine is converted to sugars by the body, so it is not really evident that supplementing L-Glutamine does anything positive for the bodybuilder. Still, one can’t dismiss the many positive reports of Glutamine supplementation. Research shows that after intensely working out, glutamine levels in the body are reduced by as much as 50%, which is the basis for its view as a recovery agent. It has also been given to burn victims to help in their recovery, which shows at least some absorption. Glutamine has been shown to increase growth hormone levels, so there is really mixed reporting on its effects and in combination with Creatine to help strength and power in trained athletes.
The free form amino acid has been shown to be used in the gut for fuel by the intestinal bacteria and is the usual choice for supplementation. It comes in pills, powders and chewable tablets. The big question is if it helps increase recovery. Glutamine is certainly delpeted during exercise, but many studies show that oral Glutamine has very little effect on muscle glutamine levels.
These are wheat glutens that are partially digested. I am not a big fan of these because so many people have a partial or full allergy to wheat. Peptides can have better absorption than the straight amino acids, but peptides from wheat and other sources that are partially hydrolyzed are not as good as those formed from free form amino acids in my opinion.
Glutamine Ethyl Ester
This is the ethyl ester version of Glutamine, which has really no data to support its use and seems counterproductive to taking amino acid complexes. There is no real reason to take Glutamine Ethyl Ester and I would avoid it. Similar technologies like Creatine Ethyl Ester have been shown in at least two studies to not have any positive effect on absorption and may inded reduce this effect.
Amino Acids: Glutamine