L-citrulline

L-citrulline grades and forms

L-citrulline is a free amino acid that supplement manufacturers buy as a white powder for drink powders, capsules and tablets. It is not on the EU harmonised vitamin and mineral lists, so national rules govern its use in food supplements. This page covers grade choice, the EU regulatory position and formulation behaviour.

Two things decide which L-citrulline powder you buy: the specification it is made to and its physical form. Food-grade material tested to a supplier specification suits most food supplements. Some brands set their own specification, for example tighter limits on related amino acids or microbiology. The specification sheet shows what each lot is tested for.

Physical form follows the finished format:

• Fine powder for drink powders, stick packs and capsule blends.
• Granulated or agglomerated powder where flow, dust control or direct compression matter.

The production route and any processing aids are stated on the specification. They matter for dietary positioning claims your brand may want to make. SoleChem supplies L-citrulline in bulk to supplement manufacturers and sends the specification sheet and certificate of analysis with its quote. SoleChem is a supplier, not the producer of the material.

EU regulatory status

Directive 2002/46/EC harmonises only the vitamins and minerals in its Annexes I and II. L-citrulline is an amino acid and does not appear on those lists. The directive’s definition of a food supplement also covers other substances with a nutritional or physiological effect, but there is no EU positive list for them.

Member states therefore regulate amino acids such as L-citrulline nationally. Some require notification, some keep national lists and some set national maximum amounts. Rules differ from country to country, so check each target market with its competent authority before launch.

L-citrulline is used as a nutritional substance. It has no E number and is not used as a food additive under Regulation (EC) No 1333/2008.

Novel food status must be confirmed before use. It depends on documented consumption in the EU before 15 May 1997 under Regulation (EU) 2015/2283. See the novel food guide for how to check.

On the label, Directive 2002/46/EC requires the amount of the substance per recommended daily portion in numerical form; the labelling guide sets out the full requirements. Any health claim must be authorised under Regulation (EC) No 1924/2006. Check the EU Register of nutrition and health claims and the health-claims guide.

Formulation notes

Label-claim arithmetic. L-citrulline is supplied as the free amino acid, so the declared amount is the amount of the substance itself. To find the powder input, divide the label claim by the assay on the certificate of analysis, expressed as a fraction. Then add the overage your stability data supports; the overage calculator does this step.

Powders. L-citrulline is water-soluble, which makes it straightforward in drink powders and sports nutrition. It is often blended with L-arginine and beta alanine in pre-mixed powders. Check taste at the intended concentration and adjust the flavour and sweetener system for each formulation.

Capsules and tablets. Per-serving quantities of amino acids are often large relative to capsule fill volume. The bulk density on the specification sheet tells you how much fits per capsule. Fine powders may need a glidant such as silicon dioxide to run on encapsulation machines. For tablets, a granulated grade or a wet or dry granulation step usually improves compressibility.

Maillard reaction. Like other amino acids, L-citrulline has a free alpha-amino group that reacts with reducing sugars under heat and moisture. In blends with dextrose, fructose or maltodextrin this can cause browning and off-flavours over shelf life. Keep water activity low and include colour in stability testing.

Storage. Keep the material in sealed containers, protected from moisture and heat. The storage conditions and retest period are stated on the specification sheet.

For related materials, see the amino acids category.