What it is
Sodium alginate is a high-molecular-weight polysaccharide extracted from brown algae and supplied as its sodium salt, where it dissolves in water to form viscous, gel-like solutions. In cosmetics it is used to thicken formulas, stabilize emulsions, and form light surface films. In sunscreens it can help adjust texture and contribute to an even, cohesive layer.
Safety & warnings
Sodium alginate is generally well tolerated and considered low-irritation in topical use. It is not a recognized fragrance allergen and is non-comedogenic in typical use.
Origin & sourcing
Natural marine-derived polysaccharide extracted from the cell walls of brown seaweeds (such as Laminaria and Macrocystis species) and neutralized to the sodium salt.
History
Alginates have been used industrially for over a century as gelling and thickening agents across the food, pharmaceutical, and cosmetic industries.
Questions everyone asks
What does sodium alginate do in a formula?
It thickens water-based systems, helps stabilize emulsions, and can form a light film, all of which support a smooth, even texture.
Where does sodium alginate come from?
It is extracted from brown seaweed as alginic acid and then converted to its water-soluble sodium salt.