L'arginine is a semi-essential amino acid, one of the twenty that make up the body's proteins. In cosmetics, it has two roles, and the second explains why it is found in almost all well-formulated acid-based products.
As an active ingredient, it is part of theNMF, the natural moisturizing factor produced by the stratum corneum to retain water: supplying it from the outside helps maintain that reserve. Its second role is technical but decisive: as a basic molecule, it brings the pH to the correct level in formulas containing acids. A serum with ferulic or hyaluronic acid, without adjustment, would be too acidic for the face; and correcting it with a physiological amino acid rather than a synthetic alkali is a choice that makes a difference to tolerability.
That is why it appears in serums with acidic active ingredients, often toward the bottom of the INCI list. It is not an ingredient people look for on the label: it is one of those that make the ingredients beside it usable, and its presence reveals how the formula was designed.
A useful distinction, because it causes considerable confusion: arginine taken orally as a supplement has systemic effects on blood circulation that relate to an entirely different use. When reading about arginine and skin, it is always worth checking which of the two is being discussed.
On our blog, you can find an in-depth article on the benefits of arginine for the skin.
