Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutral, polar amino acid. It is non-essential and conditionally essential in humans, meaning the body can usually synthesize sufficient amounts of it, but in some instances of stress, the body's demand for glutamine increases, and glutamine must be obtained from the diet.

 L-Glutamine is the most prevalent amino acid in the bloodstream.
 L-Glutamine is involved in more metabolic processes than any other amino acid.
 L-Glutamine is converted to glucose when more glucose is required by the body as an energy source.
 L-Glutamine also plays a part in maintaining proper blood glucose levels and the right pH range.
 L-Glutamine serves as a source of fuel for cells lining the intestines. Without it, these cells waste away.
 L-Glutamine is also used by white blood cells and is important for immune function.
 L-Glutamine assists in maintaining the proper acid/alkaline balance in the body, and is the basis of the building blocks for the synthesis of RNA and DNA