L-Theanine is an amino acid that is not commonly obtained through dietary sources. It is structurally similar to the neurotransmitters GABA and glutamate, and acts in a similar manner in the brain following oral ingestion. L-Theanine has been found to act as a relaxing agent without causing sedation, as well as reducing stress and improving attention. These properties make it ideal for combining with stimulants as a way to attenuate some of their side effects. The combination of L-Theanine and Caffeine, for example, has been shown to be very effective at improving both general cognitive function and the ability to pay attention.