Theanine is an amino acid in fungal and plant species such as green tea. Its primary use is to treat high blood pressure, anxiety and to increase the effectiveness of cancer drugs. Theanine is also an ingredient in stimulant drugs such as diethylpropion and phentermine.
Individuals suffering from high blood pressure take theanine along with medications for high blood pressure to reduce blood pressure levels. Theanine has a positive effect on the human cardiovascular system. In the United States, the Food and Drug Administration has granted theanine Generally Recognized As Safe status, as of 2015. In Japan, theanine was approved in 1964 for use in all types of foods, including soft drinks and chocolates, except foods for infants.
Some research links theanine to an increased level of serotonin and dopamine production in the brain. Some studies also suggest that this amino acid helps improve human memory and learning capabilities, especially for people with concentration problems. Theanine blocks excessive stimulation of the cells in the brain to prevent brain damage. It also stimulates the production of new brain cells by releasing proteins necessary for brain growth. Scientifically, theanine is listed as “L-theanine.” The letter “L” represents the scientific notation of its structure.