Hydrolyzed Soy Protein
The details
Hydrolyzed Soy Protein is a water-soluble blend of peptides and amino acids made by breaking down the protein from soybeans into smaller proteins. It's the most widely used hydrolyzed vegetable protein in cosmetics and it acts mainly as a skin and hair conditioning agent. The smaller fragments are water-loving so it forms a thin, moisture-retentive film on skin that helps reduce water loss and leaves things feeling softer and smoother. You'll often see it credited with "firming" or "anti-aging" benefits as well; this claim traces back to lab research like Tokudome et al. (2012). This study added low-molecular-weight soybean peptides to cultured human skin fibroblasts and saw increased type I collagen gene expression + collagen content. The caveat is that this is in-vitro and oral-peptide research so the only solid, well-established role for the topical ingredient is skin conditioning. Typical use concentrations go up to 3.5% in mascara but this ingredient is typically used at low levels well under 1%. It has a reassuring safety profile as well; it's not a skin irritant in testing up to 20% and has limited skin penetration due to its large size and water-loving nature. Anyone with a known soy allergy should definitely patch test or skip this ingredient. There's also a single case of a soy-containing product aggravating rosacea via protein contact dermatitis, but this is very rare.
Effects
Found in (3 products)
Also listed as
hydrolyzed soy protein