Amino acid
L-Theanine
L-theanine is an amino acid found in tea leaves that is not used to build proteins. Black and green tea contain it alongside caffeine.
Also listed as Theanine
What makes a product comparable to a study?
A useful comparison starts with the amount of L-theanine and whether the product also contains caffeine or other active ingredients. The 2019 adult trial used an enzymatically produced theanine tablet; research on that tablet does not establish that every tea extract or sleep blend works the same way. 1 2 3