L-glutamine is the biologically active form of the amino acid glutamine. The "L" in L-glutamine refers to its molecular structure, specifically its stereochemistry. In nature, amino acids exist in two forms: L-amino acids and D-amino acids. The L-form is the type found in proteins and is the form utilized by living organisms.

L-glutamine plays a crucial role in various physiological processes, including protein synthesis, immune function, gut health, nitrogen transport, and detoxification, as I mentioned in the previous response.

When people refer to glutamine supplements, they are typically referring to L-glutamine. L-glutamine supplements are commonly used by athletes and individuals seeking to support muscle growth, recovery, immune function, and overall health. These supplements are available in various forms, including powders, capsules, and tablets.

Supplementation with L-glutamine may be beneficial in certain situations, such as during intense exercise, illness, or recovery from surgery or injury. However, it's essential to use them cautiously and under the guidance of a healthcare professional, as excessive intake can lead to adverse effects. Additionally, individuals with certain medical conditions or those taking specific medications should consult with a healthcare provider before starting any new supplement regimen.