07.01.05
A new study in the journal Chirality suggests that dietary supplements that do not use pure L-theanine may not deliver L-theanine benefits because they fit poorly into the body. Researchers from the Iowa State University study compared the pharmacokinetics of L-theanine, D-theanine and an ingredient commercially marketed as L-theanine that actually was a racemic mixture of theanine, a 50:50 D- and L-theanine mixture, also known as racemate. Researchers orally supplemented rats with three different theanine ingredients, including a commercially available L-theanine that actually was a racemate, pure D-theanine and pure L-theanine. They then followed blood concentrations, urinary excretion and a marker of theanine metabolism in the blood. The results demonstrated that in the animals their metabolism preferentially selects L-theanine, beginning with absorption in the gut. When equal amounts of L-theanine were administered, coming from pure L-theanine or the racemate, the concentration seen in the blood was greater with the pure L-theanine. Taiyo International’s Suntheanine (pure L-theanine) was used in the study.