It's an ingredient in green tea, it's what makes people calm after drinking tea. What I've found so far says this helps to calm as well as concentration. I have a friend who's a naturopathic doctor who said this works on the same brain receptors that food dye does, but in the opposite way. Food dye severly affects my daughter. I want to try it but I have no clue about dosages. I read one person used 100mg 3xday and that seemed to work well. One person used 200mg 2xday and it did nothing. 50mg is what "they" consider a normal dose in something like tea.