L-tyrosine

L-tyrosine grades and forms

L-tyrosine is the free L-form of a proteinogenic amino acid, bought by supplement manufacturers as a white to off-white powder. In the EU it is neither a vitamin nor a mineral, so national rules govern its use in food supplements, not Annex II of Directive 2002/46/EC. Its low water solubility at neutral pH is the main formulation constraint.

Bulk L-tyrosine powder is usually bought as a food grade or as a grade tested to a pharmacopoeia. The choice depends on your customer’s quality specification, the markets you sell into and the documentation your QA team needs. Ask for the grade you need in the quote form.

Particle size decides how the powder flows, fills and compresses. Enantiomeric identity matters too: specify the L-form and check that the certificate of analysis confirms it. SoleChem sends the specification sheet and the certificate of analysis with its quote.

The production route matters if your label carries a vegan or allergen statement. Confirm it from the supplier documentation before making such a statement. N-acetyl-L-tyrosine is a different substance with its own identity and regulatory status, so it cannot replace L-tyrosine on a label.

EU regulatory status

Directive 2002/46/EC defines food supplements as concentrated sources of nutrients or other substances with a nutritional or physiological effect. Its Annexes I and II list only vitamins and minerals. L-tyrosine, like the other amino acids, falls under “other substances”, for which there is no harmonised EU positive list.

Member states regulate amino acids in food supplements nationally. Some keep lists of permitted substances, some set maximum amounts per daily portion and some require notification before sale. Check the rules of the competent authority in each target market.

Regulation (EC) No 1925/2006 allows the Commission to prohibit or restrict substances through its Annex III. Confirm in the current consolidated text that L-tyrosine is not listed there. Confirm its novel-food status for your intended use as well; the novel food guide explains how to check.

Directive 2002/46/EC requires the amount of each substance with a nutritional or physiological effect to be declared in numerical form per recommended daily portion. For claim wording, consult the EU Register of nutrition and health claims and the health-claims guide.

Formulation notes

L-tyrosine is only slightly soluble in water at neutral pH. It dissolves better in acidic or alkaline conditions. In ready-to-mix powders it disperses rather than dissolves, so expect sediment unless the formula includes a suspension aid. Do not position a tyrosine-containing drink powder as clear without testing.

As a free amino acid, the declared amount equals the powder weight, corrected for the assay on the certificate of analysis. To declare 500 mg of L-tyrosine per two-capsule serving, each capsule carries 250 mg, plus any overage your stability data supports. The overage calculator helps with that step.

• Capsules: fill weight per capsule size depends on the bulk density stated on the specification sheet. A flow aid such as silicon dioxide is common in automatic filling.
• Tablets: fine amino acid powders often need granulation or a direct-compression filler such as dicalcium phosphate. Run compression trials on the actual lot.
• Gummies: low solubility in the aqueous mass can leave a gritty texture. Like other amino acids, L-tyrosine can take part in Maillard browning with reducing sugars under heat.

In amino acid blends with L-theanine or taurine, L-tyrosine is usually the component that limits clarity in water. Store the powder dry and in closed containers, following the conditions on the specification sheet.