What it is
Tryptophan is one of the standard amino acids and a normal component of skin proteins and the natural moisturizing factor. In formulations it is included as a water-soluble conditioning agent that helps attract and hold moisture at the skin surface. It is typically used at low levels as part of amino-acid blends intended to support a soft, conditioned feel.
Safety & warnings
Tryptophan is a naturally occurring amino acid that is generally well tolerated on skin at cosmetic use levels and is not associated with comedogenicity. It is not a recognized fragrance allergen.
Origin & sourcing
Tryptophan occurs naturally as a building block of proteins. Cosmetic-grade material is most often produced by microbial fermentation, and the L-isomer is the biologically relevant form.
Questions everyone asks
Is tryptophan a moisturizer?
It acts as a humectant and conditioning agent, helping the skin surface hold water as part of an amino-acid component, rather than as a standalone occlusive moisturizer.
Which form is used in cosmetics?
The L-isomer (L-tryptophan) is the form typically used, consistent with how the amino acid appears in skin proteins.