L-theanine is an amino acid analog of the proteinogenic amino acids L-glutamate and L-glutamine. It is primarily found in tea leaves, particularly in green tea (Camellia sinensis), and is known for its potential calming effects. L-theanine is believed to promote relaxation without drowsiness, making it a popular supplement for stress relief and cognitive enhancement. It is also thought to influence neurotransmitter levels in the brain, including serotonin and dopamine, contributing to its mood-enhancing properties. In food science, L-theanine is valued for its ability to enhance the umami flavor profile of foods and beverages.