All guides · Ingredients
Hydrolyzed keratin: reading the hair-fibre research
What the laboratory work measured, and what it does not say about this tonic.
Hair has a protein structure, which is why “protein” appears on hair-care bottles. The useful question is which protein, in which formula, and for what job. Dr. M Hydrolyzed Protein Hair Tonic (NOT220105815K) uses hydrolyzed proteins from keratin as its ingredient story.
Hydrolysis breaks a protein into smaller pieces, often called peptides. “Smaller” describes the ingredient. It is not a full answer about how a finished bottle performs.
What one laboratory study found
A study by Malinauskyte and colleagues, published in the International Journal of Cosmetic Science, tested different sizes of keratin-derived peptides on chemically relaxed textured hair samples. Lower- and medium-molecular-weight material could enter the hair fibre in that work, while larger peptides mainly sat on the surface. Selected peptide treatments changed mechanical properties and reduced breakage in the tested fibres. The full text the preview links is PMC7820954. The journal article’s abstract link is PubMed 32946595.
That is cosmetic science about hair fibres in a laboratory. It does not show that the Dr. M tonic produces the same result. An ingredient solution, a finished shampoo and a finished tonic are different test materials. A microscope image, a fibre measurement and how hair feels to a person are different outcomes.
The tonic’s own directions stay simple: after washing and towel-drying, apply to the scalp in sections, massage gently for 2–3 minutes and leave it in. Compare bottles by purpose, directions, the full label and the price.