Theanine ( /ˈθiːəniːn/), also gamma-glutamylethylamide or 5-N-ethyl-glutamine, is an amino acid and a glutamic acid analog commonly found in tea (infusions of Camellia sinensis), primarily in green tea, and also in the basidiomycete mushroom Boletus badius and in guayusa. More specifically, this compound is called L-theanine, being the levorotatory enantiomer. In 1950, the tea laboratory of Kyoto successfully separated theanine from gyokuro leaf, which has high theanine content. Theanine is an analog to glutamine and glutamate, and can cross the blood–brain barrier. It is sold in the US as a dietary supplement, and is FDA confirmed as generally recognized as safe (GRAS). The Japanese Ministry of Health and Welfare approved the use of theanine for universal consumption in 1964.

Able to cross the blood–brain barrier, theanine has psychoactive properties. Theanine has been shown to reduce mental and physical stress, and improves cognition and mood in a synergistic manner with caffeine.

While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on postsynaptic cells. Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter GABA. Theanine also increases brain dopamine levels and has a low affinity for AMPA, kainate and NMDA receptors. Its effect on serotonin is still a matter of debate in the scientific community, with studies showing increases and decreases in brain serotonin levels using similar experimental protocols. It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of 5-hydroxyindoles in the brain. Researchers also speculate it may inhibit glutamic acid excitotoxicity. Theanine also promotes alpha wave production in the brain.

Walter Reed, better known as Killah Priest, Iron Sheik from the Middle East, or Masada, is an African-American rapper and Wu-Tang Clan affiliate who was raised in Brooklyn. He is known for intensely spiritual lyrics loaded with metaphors and religious references. He is connected to the Black Hebrew Israelites through his rhymes, and is known for controversial and Afrocentric subject matter. He is also a part of supergroup the HRSMN along with Canibus, Ras Kass, and Kurupt. He has a hardcore fan base and has been known to be very generous and giving of his time to his fans and various charitable organizations.

Priest first made himself known to the hip hop world rapping on two songs on the Gravediggaz album 6 Feet Deep in 1994, and followed this with two appearances on each of two Wu-Tang Clan solo albums, Ol' Dirty Bastard's Return to the 36 Chambers: The Dirty Version and GZA's Liquid Swords, both from 1995 (see 1995 in music). Liquid Swords in fact included a Killah Priest solo track titled "B.I.B.L.E. (Basic Instructions Before Leaving Earth)". Also in 1995, Priest's group Sunz Of Man with rappers Hell Razah, 60 Second Assassin, Prodigal Sunn were signed to Wu-Tang Records and released three 12" singles through the label. Initially Sunz Of Man included Shabazz the Disciple, who had previously been in a duo with Priest called The Disciples, but Shabazz basically left the group before the contract with Wu-Tang Records was signed, thus only appearing on the B-side "5 Arch Angels".