Theanine is an amino acid found in green tea. It is also found in some mushrooms. It is similar in structure to glutamic acid, another amino acid.
People take theanine by mouth for reducing anxiety and stress, for preventing Alzheimer's disease, for treating attention deficit-hyperactivity disorder (ADHD), and improving mental performance and attention. Theanine is also used for reducing blood pressure, preventing the flu, and improving how well cancer drugs work.
How it works
Theanine has a chemical structure very similar to glutamate, a naturally occurring amino acid. Glutamate helps transmit nerve impulses in the brain. Some of the effects of theanine appear to be similar to glutamate, and some effects seem to block glutamate. Theanine may also affect some brain chemicals called GABA, dopamine, and serotonin.
Possibly EffectiveMental performance
Early research shows that taking theanine before a test can reduce the rate of errors. Also, most research shows that taking theanine along with caffeine increases alertness and improves a person's ability to switch attention between different tasks.
Theanine is POSSIBLY SAFE when used by mouth, short-term. Doses of up to 250 mg of theanine have been safely used one time per week for 3 weeks. Also, a specific combination product containing theanine and other green tea ingredients has also been used safely when taken once daily for up to 5 months. It is not known if theanine is safe when used for longer periods of time. Theanine may cause mild adverse effects, such as headache.
Pregnancy and breast-feeding:There is not enough reliable information about the safety of using theanine if you arepregnantorbreast-feeding. Stay on the safe side and avoid use.Are there any interactions with medications?
Children: Theanine is POSSIBLY SAFE for children. Doses of 200 mg of theanine have been safely used twice daily for up to 6 weeks.
Low blood pressure: Theanine might lower blood pressure. In theory, theanine might increase the risk of blood pressure dropping too low in people prone to low blood pressure. If you have low blood pressure, discuss theanine with your healthcare provider before starting it.
Theanine might decrease blood pressure. Taking theanine along with medications for high blood pressure might cause your blood pressure to go too low.Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others.Stimulant drugs speed up the nervous system. By speeding up the nervous system stimulant medications can make you feel jittery and speed up your heartbeat. Theanine might work to slow down the nervous system. Taking theanine along with stimulant medications might decrease the effectiveness of stimulant medications.Some stimulant drugs include diethylpropion (Tenuate), epinephrine, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.