the average Japanese tea drinker per day contains about 20 mg of the substance, there are no studies measuring the amount of theanine being extracted by typical preparation methods, or the percentage lost by discarding the first infusion. Therefore, with the Japanese being exposed to possibly much less than 20 mg per day, and Europeans presumably even less, it was the opinion of the BfR that pharmacological reactions to drinks typically containing 50 mg of theanine per 500 milliliters could not be excluded—reactions such as impairment of psychomotor skills and amplification of the sedating effects of alcohol and hypnotics. The combination of theanine and caffeine has been shown to promote faster simple reaction time, faster numeric working memory reaction time and improved sentence verification accuracy. Studies have also concluded that an L-theanine and caffeine combination have improved sustained attention, impulsivity and cognition in children diagnosed with ADHD. Theanine has been reported to raise levels of brain serotonin and dopamine, with possible improvement in specific memory and learning tasks. In brewed teabags A study of teabags sold in British supermarkets in 2011 found that the teabags containing the most L-theanine per cup (24 mg versus 8 mg per cup) were the lower-quality brands containing black tea, with a supermarket brand of black tea having the highest theanine content. The study demonstrates that brewing time is a major determinant of the amount of l-theanine extracted. Addition of sugar and small quantities of milk make no significant difference, while larger quantities of milk reduced the measured theanine content. See also gamma-Glutamylmethylamide Green tea References Further reading AMPA receptor antagonists Anxiolytics Carboxamides Excitatory amino acid reuptake inhibitors Kainate receptor antagonists NMDA receptor agonists Non-proteinogenic amino acids Substances discovered in the 1940s