L-Theanine Capsules

L-theanine (CAS 3081-61-6) is (2S)-2-amino-5-(ethylamino)-5-oxopentanoic acid, also written N5-ethyl-L-glutamine or gamma-glutamylethylamide: molecular formula C7H14N2O3, molecular weight 174.20 g/mol. It is the N-ethyl amide of L-glutamine and one of the few amino acids that is not proteinogenic yet accumulates heavily in a food plant, making up roughly 1 to 2 per cent of the dry weight of green tea leaf, more in shaded leaf such as gyokuro and matcha. As an isolate it is a white to off-white crystalline powder, water-soluble at around 20 mg/mL at room temperature, with the faint sweet-umami note that carries through into a chewable or a stick pack. Two source routes are offered and they are not interchangeable on a label. The fermentation route builds theanine enzymatically from L-glutamine and ethylamine: it is vegan, caffeine-free by route, and gives the tighter purity profile, which is why it is the default fill. Purification from Camellia sinensis leaf is available where a brand wants tea provenance, but tea-derived material can carry residual caffeine and catechins, so a caffeine limit and a catechin position are written into the specification before the first lot ships rather than argued about afterwards. Either way only the L-enantiomer is accepted: optical rotation reported at about +8 degrees (c = 5, water) is the goods-in check, because racemic DL-theanine made by straight chemical synthesis is a cheaper material and a known adulterant in this category. The capsule is where the origin declaration is decided. An HPMC shell keeps the finished unit vegan and cellulose-based; a bovine gelatin shell is available on request but makes the product bovine and has to be declared, which closes off vegan, vegetarian and several religious certifications. The fill itself carries no milk, egg, soy, fish, crustacean, gluten, peanut or tree-nut allergen. On regulatory position, L-theanine has been the subject of US GRAS notifications, including one covering use at up to 250 mg per serving, and Japan has permitted it in foods other than infant food since 1964; permitted use and permitted wording still vary by market, so buyers should check their own national positive list and keep on-pack claims with the brand owner.