L-theanine

Grades and forms of L-theanine

L-theanine is the N-ethyl amide of L-glutamic acid, a non-protein amino acid that occurs naturally in tea leaves. Manufacturers buy L-theanine powder as a white crystalline solid for capsules, tablets, powder blends and drinks. The choices that matter are stereochemistry, production route and documentation, not physical form.

• Stereochemistry. Only the L-enantiomer is L-theanine. DL-theanine is a racemic material and should not be supplied or labelled as L-theanine. The specification sheet states how enantiomeric identity is controlled, for example by optical rotation.
• Production route. Bulk L-theanine is mostly made by enzymatic or chemical synthesis. Extraction from tea is less common. The route matters for the regulatory assessment described below, so confirm it before you finalise a formula.
• Particle size. Powder blends, capsule filling and direct compression may need different particle size distributions. The specification sheet states the range for each grade.

SoleChem sends the specification sheet and certificate of analysis with its quote. Ask for the grade, particle size and production-route statement you need in the quote form.

EU regulatory status

L-theanine is neither a vitamin nor a mineral. Directive 2002/46/EC harmonises only vitamin and mineral substances, through its Annex II, so that list does not cover L-theanine. The Directive’s definition of a food supplement does include other substances with a nutritional or physiological effect.

Rules on these other substances are largely national. Some member states accept amino acids in food supplements under notification, some keep positive lists and some set restrictions or maximum amounts. Check the rules of each target market with its competent authority. Regulation (EC) No 1925/2006 also covers certain other substances added to foods and can apply alongside national rules.

Novel food status must be checked for the specific material. Under Regulation (EU) 2015/2283, status can depend on the production route and on documented use before 15 May 1997. Check the Union list in Implementing Regulation (EU) 2017/2470 and the novel food guide on this site.

L-theanine has no E number and is used as an ingredient, not as a food additive. Labelling follows Regulation (EU) No 1169/2011 and the supplement-specific rules of Directive 2002/46/EC; see labelling a food supplement in the EU. Any claim must appear in the EU Register of nutrition and health claims; the health-claims guide explains how to check.

Formulation notes

L-theanine is readily soluble in water. It dissolves easily in ready-to-mix powders, stick packs and liquid shots. Its taste is mild, slightly sweet and umami-like, so it adds little taste load to unflavoured or lightly flavoured products.

It is a free amino acid, not a salt, so no conversion factor applies. The declared mass of L-theanine is the mass of the active itself. The only correction is for assay: divide the label claim by the assay fraction on the certificate of analysis. Add any stability overage with the overage calculator.

Format points:

• Capsules. Fill weight per capsule depends on bulk density, which the specification states. HPMC capsules suit plant-based products. A flow aid such as silicon dioxide can help on high-speed fillers; confirm with a trial. See ingredients for capsules.
• Tablets. Compression behaviour depends on crystal habit and particle size. Most formulas need a direct-compression filler and binder. Run compaction trials before scale-up; see ingredients for tablets.
• Powders and drinks. Solubility and mild taste make it straightforward in blends. See ingredients for powders and sports nutrition.
• Gummies. Like other amino acids with a free amino group, it can take part in Maillard browning with reducing sugars at cooking temperatures. Include colour and assay in stability testing.

In liquids held at low or high pH, include L-theanine in stability testing, since the amide bond can hydrolyse over time. It blends without known incompatibility with other free amino acids such as glycine, GABA and L-tyrosine. Other options are listed under amino acids.