It is a real thing, it is widely misunderstood, and it is worth understanding before you buy anything with keratin in it.

Protein treatments work by depositing small peptide fragments onto and into the hair, filling the gaps where the fibre's own keratin has been stripped out by bleach, heat or friction. That is genuinely useful. The problem is that protein on its own makes hair stiffer. Stiff is good up to a point — it is what stops hair stretching and snapping. Past that point the hair loses its flexibility, and flexible is what you want. Overloaded hair feels dry, rigid and straw-like, and it snaps more easily rather than less.

Fine hair and low-porosity hair get there fastest, which is why the women most likely to reach for a protein treatment are often the ones it goes wrong for. If you have ever done a bond-building treatment and come out with hair that felt worse — crunchy, brittle, oddly dull — that is what happened.

The fix is not avoiding protein. It is balancing it. Protein needs to arrive alongside lipids that soften, humectants that hold water in the fibre, and film-formers that give slip. Keratin does the structural part; silk, argan, panthenol and collagen amino acids do the flexibility part. Together you get hair that is stronger and still bends.

Kaviora is formulated that way deliberately, and we would rather say so plainly than let you find out the hard way. If a product's ingredient list is protein, protein and more protein, be careful — particularly if your hair is fine.