Glutamine is technically classified as a non-essential amino acid since the body can produce it endogenously. Glutamine is also found in various protein-rich foods, such as dairy, meat, tofu, poultry, and fish.
However, many would argue that glutamine is at least conditionally essential since there are specific times when the body could benefit from having more than it can synthesize on its own, such as illness, injury, or extreme stress (i.e. intense exercise & dieting). Furthermore, glutamine is one of the most abundant amino acids in the body and is involved in a lot more than just muscle protein synthesis.
Glutamine plays a crucial role in your immune, gastrointestinal, and musculoskeletal systems. In fact, supplementing with glutamine may be even more beneficial for immune function and gut health than enhancing muscle recovery. Some evidence suggests that glutamine utilization of immune and gastrointestinal cells is higher than glucose. This indicates that glutamine is the preferred fuel source for these cells, which is quite different from any other system in the body. The majority of other cells primarily use glucose as opposed to glutamine.
