Juice Bar - Optimum: Glutamine Powder 1,000gGlutamine is the most abundant amino acid in the body, comprising more than 60% of the free amino acid pool in skeletal muscle and greater than 20% of total circulating amino acids. During prolonged, intense exercise, muscle glutamine levels may be depleted, and this can limit protein synthesis. Glutamine Powder is an easy way to supplement your diet. This instantized powder mixes easily and is unflavored for 'stacking' with protein shakes.