L leucine

L-Leucine at a glance

L-Leucine is a white powder that dissolves in water. It is one of the essential amino acids, meaning the body cannot make it and must get it from food. In skin and hair it is part of structural proteins such as collagen and keratin. The site lists a typical level of about 0.1 to 0.5% in leave-on serums and emulsions. Confirm the full INCI name and purity on the supplier CoA.

Amino acids in cosmetics

Amino acids make up a large share of the skin's natural moisturizing factor, the mix of small molecules that keeps the outer layer supple. Adding amino acids to a formula helps skin hold water and feel soft. In hair care they help strands feel smoother and stronger. Leucine is a branched-chain amino acid, together with isoleucine and valine, and is often used in amino acid complexes that mimic the skin's own mix.

Product formats

Serums

Water-based serums with amino acids and hyaluronic acid are a light, modern hydration format.

Creams and emulsions

Add leucine to the water phase of moisturizers as part of an amino acid complex.

Hair care

Leave-in sprays and conditioners can use amino acids for a smoother feel.

Amino acid complexes

Combine leucine with other amino acids such as proline, glycine and alanine to build a skin-identical complex.

Processing

Leucine dissolves slowly in cold water. Warm the water phase and stir until the solution is clear, or pre-dissolve it in a small portion of warm water. Add it before thickeners so it dissolves fully. Check the final pH, since amino acids can shift it slightly.

Good partners

L-Proline and alanine complete an amino acid complex. The Natural Moisturizing Factor liquid fits the same idea. Browse more in the actives catalog.

Testing

Check that leucine stays dissolved after storage in the fridge, as some amino acids can crystallize at low temperature. Measure skin hydration before and after use.

Claims

Skin feels hydrated and supple; with skin-identical amino acids.

Characteristics

Form: white powder. Solubility: water soluble, dissolves slowly. Type: essential amino acid. Typical level listed on the site: about 0.1 to 0.5% in leave-on serums and emulsions. INCI and purity: supplier CoA.

Original recipe: amino acid hydration serum, 100 g

Distilled water 89.90 g, glycerin 4.00 g, butylene glycol 2.00 g, L-leucine 0.30 g, L-proline 0.30 g, alanine 0.30 g, sodium PCA 0.50 g, sodium hyaluronate 0.30 g, hydroxyethylcellulose 0.70 g, phenoxyethanol and ethylhexylglycerin 1.00 g, panthenol 0.70 g. Warm the water, dissolve the amino acids, add the cellulose and the remaining ingredients, preserve and check the pH.

Building a skin-identical complex

The skin's natural moisturizing factor contains many amino acids in different shares, with serine, glycine and alanine among the most common. A complex does not need to copy the exact ratio. Instead, choose a few amino acids with different properties and combine them with sodium PCA and lactate. The result is a balanced hydration base that tells a clear, science-based story.

Hair applications

Hair keratin is rich in amino acids. Leave-in products with amino acids help hair feel smoother and less brittle. Keep the level modest and pair them with a light conditioning agent.

Range ideas

A hydration serum, an amino acid toner and a leave-in hair spray can share one amino acid complex.

Lot records

Keep each CoA with the batch file and note the lot used.

Sports and active lifestyle stories

A body lotion or after-workout gel with amino acids can borrow that familiarity for a fresh, active-lifestyle range, while the claims stay about how skin feels.

Storage

Store closed in a dry place. Close the container after use.