Keratin & Proteins for Hair: What Hydrolyzed Proteins Can Do

Ingredient Glossary · K

INCI: Hydrolyzed Keratin, Hydrolyzed Soy Protein, Hydrolyzed Corn Protein, etc.

Your hair consists mostly of keratin, a robust fibrous protein. So it’s no wonder that keratin and other proteins are highly sought after in shampoos and hair treatments. Find out here what they can actually do—and why not every product labeled “protein” actually contains keratin.

What is keratin?

Keratin is the structural protein found in hair, nails, and the outermost layer of the skin. In hair, it forms long fibers connected by disulfide bonds. Heat, coloring, UV light, and mechanical stress damage this structure—the hair becomes rough, brittle, and loses its shine.

In hair care products, keratin is not present as a whole protein but in hydrolyzed form: broken down into smaller fragments so that it becomes water-soluble and can adhere to the hair. In addition to keratin, many other proteins are processed in this way, such as those derived from soy, wheat, corn, peas, or silk. They have similar effects but are not actually keratin.

Effect: What’s Been Proven

Three out of five bars: It has been well documented that hydrolyzed proteins adhere to the hair’s surface, especially where the hair is damaged. The hair feels smoother, is easier to comb, and retains moisture better. Some of the smaller fragments also penetrate the outer layer of the hair.

The truth is: Proteins condition, but they do not repair. Split ends cannot be permanently “glued back together,” and the effect washes out over time. Incidentally, a keratin straightening treatment at the salon is a completely different process than a protein shampoo.

Usage & Combination

You can use hydrolyzed proteins every time you wash your hair. KUNDAL’s Honey & Macadamia Treatment Baby Powder contains real hydrolyzed keratin, combined with hydrolyzed collagen, silk, and soy protein. The Protein Bonding Shampoo, on the other hand, relies on small amounts of soy, wheat, and corn protein—the INCI list even specifies 750 ppb per protein. The Protein Bonding Hair Mist contains hydrolyzed vegetable protein and a pea peptide, but no keratin.

Keratin & Proteins in the BONSANA Line

Frequently Asked Questions About Keratin & Proteins

Does every protein shampoo contain keratin?

No. Many products use proteins derived from soy, wheat, corn, or peas. You can tell if it contains keratin by looking for “Hydrolyzed Keratin” in the INCI list.

Can keratin repair split ends?

Not permanently. Hydrolyzed proteins smooth the hair’s surface and make split ends less visible. However, split ends do not grow back together.

Where does the keratin in hair care products come from?

Hydrolyzed keratin is usually derived from animal sources such as wool or feathers. Plant-based proteins from soy, corn, or wheat are a common alternative.

Can proteins weigh down the hair?

This is possible with very fine hair, especially with frequent use of rich treatments. In that case, it helps to alternate protein products with lighter care products.