L-theanine is a natural amino acid primarily found in tea leaves, especially in green tea. It is known for its calming and relaxing properties, often used to promote a sense of relaxation without causing drowsiness. L-theanine is most commonly extracted from tea leaves, which involves steaming the leaves to release the L-theanine, followed by filtration and purification processes. Once extracted, L-theanine can be used in the food industry as a natural flavoring agent or dietary supplement, often added to various products such as functional beverages, health drinks, and supplements aimed at promoting relaxation and reducing stress.