100 percent Pure L-Glutamine. Improves muscle recovery. Immune System Booster. 100 Servings. GlutaLean 100 percent Pure L-Glutamine contains only pure Anjinomoto brand pharmaceutical grade L-Glutamine. Glutamine is an amino acid that accounts for approximately 60 percent of all free amino acids in the body. Muscle tissue contains especially high concentrations of glutamine. Supplemental glutamine can help prevent muscle tissue breakdown, increase protein synthesis tissue breakdown, increase glycogen storage (energy stores) in muscle, and supports healthy immune function.