L-theanine is an amino acid. The human body does not produce this compound, and it is not essential for humans. Green tea, black tea, and certain types of mushroom naturally contain L-theanine.

L-theanine may affect the levels of certain chemicals in the brain. These include serotonin and dopamine, which influence mood, sleep, and emotion, and cortisol, which helps the body deal with stress.
A change in the balance of these chemicals can change a person’s mood or stress levels.

Chemistry

L-theanine (or L-gamma-glutamylethylamide) was discovered in 1949 and constitutes 1% to 2% of the dry weight of tea leaves. It exists only in the free (nonprotein) form. An enzymatic method for manufacturing synthetic L-theanine (Suntheanine) has been developed.

Benefits And Use

L-theanine has been used for a variety of conditions including anxiety, cognitive impairment, to improve mental alertness, and boost immune function; however, limited clinical information is available to support these claims.

Safety information

After taking advice from experts, the FDA classified L-theanine as “generally recognized as safe.” This classification means that they believe this additive to be safe when people use it as the packaging suggests.
However, women who are pregnant or breastfeeding should not use L-theanine.

Dosage

L-theanine is not a medication, so there are no official guidelines regarding how much a person should take. However, the supplement is unlikely to cause an overdose.

L-theanine is usually available in the form of 200-mg tablets. A person can consult a doctor before taking these supplements to get their advice on dosage.