Is Keratin a Protein? Expert Guide for Hair and Skin

Yes, keratin is a protein that serves as a key structural component of hair, skin, and nails. It forms strong, protective fibers that help these tissues resist damage and maintain flexibility. 

Composed of amino acids and polypeptide chains, keratin acts as a natural shield against heat, friction, and environmental stress. Understanding how keratin functions in the body provides insight into why it’s central to healthy hair and skin care. 

This guide from RootMD, supported by expert insight from Dr. Ross Kopelman, provides a detailed explanation of its biological role and practical applications.

Key Takeaways

• Keratin is a structural protein that forms the foundation of hair, skin, and nails, protecting these tissues through strong disulfide bonds and durable keratinized layers.

• Different types of keratin – including type I and type II keratins – combine to create resilient fibers found in human hair, nails, and even internal organs.

• Keratin’s strength comes from its polypeptide chains and crosslinked structure, which also appear in animals’ feathers, horns, and claws.

• Healthy hair relies on balanced keratin levels, supported by nutrients, keratin-infused shampoos and conditioners, and careful use of keratin treatments.

• A dermatologist, such as Dr. Ross Kopelman at RootMD, can help identify keratin-related damage and recommend personalized, science-based care for lasting hair and skin health.

What Is Keratin and How Does It Work

Keratin is a protein that forms the main structural component of hair, skin, and nails. It serves as a protective building block that helps maintain strength and flexibility in these tissues. Found in large amounts within the hair follicle, keratin protects epithelial cells and epidermal cells from damage, friction, and environmental stress.

Is keratin a protein or carbohydrate?

Keratin belongs to a family of fibrous structural proteins, not carbohydrates. These keratin molecules are tough and resistant to wear due to their strong disulfide bonds, which give them remarkable durability. 

They create protective layers in keratinized tissues, such as hair, nails, and skin, and are also responsible for forming horns, claws, and hooves in animals. This resilience explains why keratin is essential for maintaining healthy tissue over time.

Keratin structure and where it’s found in the body

Keratin exists in many forms across the body. Human keratins are divided into type I and type II keratins, each contributing to specific layers of tissue. Type I keratins are acidic, while type II are neutral or basic, together, they form the robust fibers that make up your hair, nails, and skin surface. 

Keratin also reinforces internal organs, providing strength to delicate epithelial linings.

Is keratin the same as protein?

All keratin is protein, but not all proteins are keratin. While collagen provides flexibility, keratin adds toughness and protection. These structures and functions work together to shield the body from physical and environmental damage. 

The presence of keratin in birds and reptiles, which forms scales, feathers, claws, and hooves, highlights its role as one of the most durable biological materials in nature.

The Role of Keratin in Hair Health

Keratin gives hair its strength, elasticity, and resistance to damage. It bonds to the hair cuticle, forming a smooth surface that locks in moisture and protects each strand from breakage.

Is keratin a protein for hair growth?

Keratin supports hair health by strengthening the existing strands. It’s not a growth stimulant but rather a stabilizer that protects the hair follicle and outer cuticle. Among all hair keratins, alpha-keratin is the most common form found in human hair. 

Keeping your scalp healthy ensures your body can produce the keratin your hair needs naturally.

How keratin strengthens and protects hair

Keratin fills in weak areas along the hair shaft, reinforcing its natural strength. The disulfide bonds in keratin proteins crosslink to create stability, making the hair stronger against everyday wear. 

Without enough keratin, the hair’s outer layer loses smoothness, leading to dryness and frizz.

Does your hair need keratin or protein?

Both play key roles. Protein treatments rebuild damaged strands from the inside, while keratin smooths the outer surface. If your hair feels brittle or dull, using a product infused with keratin can restore shine and manageability without changing your natural structure.

Keratin Treatments and Hair Products

What happens during a keratin treatment

A keratin hair treatment coats the hair with hydrolyzed keratin and other conditioning ingredients. When heat is applied, reducing agents in the formula temporarily break some of the disulfide bonds within the hair, allowing keratin to fill in damaged areas. Once sealed, this process smooths the hair and reduces frizz for several weeks.

Natural vs. salon keratin effects

Natural keratin is produced within keratinized tissues, while salon keratin treatments use external sources to coat and smooth the surface. The biological form supports growth and protection, while the cosmetic version provides temporary shine and a more appealing appearance. 

Overuse of treatments or harsh reducing agents can weaken natural keratin; therefore, moderation is essential.

Is keratin a protein in hair products?

Yes. Many shampoos and conditioners contain hydrolyzed keratin to strengthen the polypeptide chains of damaged hair. These products enhance resilience and help repair the cuticle. 

When selecting hair care products, look for formulas infused with keratin and specifically designed for gentle, long-term support.

Keratin Supplements and Nutrition

Keratin supplements and protein powder

Many people look for ways to boost keratin through hair growth supplements that combine vitamins and amino acids essential for protein formation. While some use keratin supplements, a balanced diet usually provides enough nutrients to sustain production.

Can you take too much keratin?

Taking excessive keratin may cause digestive issues or thickened nails. The body needs balance, it uses what it requires and discards the rest. For most people, a diet rich in protein and vitamins is more effective than high-dose supplementation.

Best foods to boost natural keratin

To naturally support keratin formation in hair, skin, and nails, include foods high in:

• Protein: Eggs, fish, lean meats, and legumes.

• Biotin: Found in almonds, eggs, and sweet potatoes, and plays a key role in supporting keratin production and hair health, as explained in this guide on biotin for hair growth.

• Vitamins A and C: Essential for forming strong keratin molecules and maintaining healthy epithelial cells.

Good lifestyle habits – such as hydration, balanced nutrition, and avoiding excessive heat styling, can help preserve your body’s natural keratin balance.

When to See a Dermatologist

Signs of keratin deficiency or damage

If you notice brittle nails, rough skin, or thinning hair, you may have a keratin imbalance. Stress, poor diet, or external damage can disrupt keratin production in keratinized tissues. Seeking expert advice early can prevent further deterioration and protect your hair and skin’s natural barrier.

Online dermatologists specialize in caring for hair and skin.

When self-care isn’t enough, consulting a professional helps identify the root cause. A dermatologist can evaluate your hair keratins, scalp health, and skin barrier integrity, and may recommend products to encourage hair growth as part of a consistent care routine.

Take the Next Step Toward Stronger, Healthier Hair

If you’re ready to protect and strengthen your hair from the root, explore RootMD’s dermatologist-developed products. Our DHT-Blocking Shampoo helps reduce buildup and maintain a balanced scalp environment, while the Hair Growth Oil nourishes and revitalizes weak strands with essential nutrients. 

Together, they support natural keratin structure, improve scalp health, and help you achieve thicker, stronger hair over time. Start your RootMD routine today and see the difference expert care can make.