I thought people were dosing themselves with a base amino acid. Duh. Theanine is an amino acid found in green tea, but not a base amino acid, ie doesn't form proteins. Can cross the blood-brain barrier and can certainly modulate brain function.

Not to be confused with:

* Thiamine: Vitamin B1, a molecule your body does not produce so you a get it from a food source. Needed for biochemical pathways that convert carbohydrates into energy. Not an amino acid.

* Thymine: One of the four nucleotide bases in DNA, pairs with Adenine. Synthesized in the body from the pyrimidine synthesis pathways

Also not to be confused with:

* Threonine: One of the 20 base amino acids, forms proteins. You need to get it from a food source.