Est. 1973 Immune Support Dietary Supplement Lab Verified A Brighter Way Since 1973, we've scoured the globe for the highest quality ingredients, connecting you with the most efficacious supplements that help you live brighter and embrace the moments that matter most. Discussion : L-Glutamine is the most common free amino acid found in the body and one of the key building blocks of protein. L-Glutamine, along with the amino acids L-Cysteine and L-Glycine are used by the body to form Glutathione, the "Master Antioxidant.