What Are Hair and Nails Made Of? The Science Behind Keratin

Ever wondered why your hair and nails keep growing throughout your life? The answer lies in keratin – a tough, fibrous structural protein. Both hair and nails are made primarily of keratin, the same protein found in animal horns, hooves, and claws.

The Keratin Connection: What Hair and Nails Have in Common

Keratin is a fibrous structural protein that serves as the main building block for both hair and nails. This remarkable protein comes in two types: alpha-keratin (in mammals) and beta-keratin (in reptiles and birds). The protein molecules arrange in long chains that twist together like rope, creating incredible strength and durability.

Hair Structure and Composition

Hair consists of three distinct layers: The cuticle (outer protective scales), the cortex (middle layer with keratin fibers), and the medulla (inner core). The cortex contains disulfide bonds between sulfur-containing amino acids, which give hair its strength. This is why chemical treatments that break these bonds can reshape hair.

Nail Anatomy: Layers and Growth

Nails are made of harder, more compact keratin than hair. Key parts include:

Nail Plate: The hard, visible part made of compacted keratin
Nail Matrix: Growth zone under the cuticle where new cells form
Lunula: The pale crescent at the nail base
Cuticle: Protective seal between nail and skin

Nails grow 2-3mm per month through a process called keratinization, where new cells harden as they’re pushed forward.

The Role of Amino Acids in Hair and Nail Health

Keratin is built from amino acids, especially cysteine. Your body needs adequate protein and nutrients including biotin, zinc, iron, and vitamins A, C, and E for healthy keratin production. Poor nutrition can result in weak, brittle nails and dull, fragile hair.

Why Hair and Nails Are So Strong

The exceptional strength comes from disulfide bonds linking protein chains together. Nails are harder than hair because they contain more densely packed keratin with minimal space between fibers. Hair has a more flexible arrangement that allows bending without breaking.

Common Myths About Hair and Nail Composition

Myth: Nails are made of calcium.
Fact: Nails are predominantly keratin protein, not calcium. The hardness comes from compact keratin structure.

Myth: Hair is alive and needs to “breathe.”
Fact: The visible hair shaft is made of dead keratin cells. Only the follicle beneath skin is alive.

Myth: Frequent trimming makes hair and nails grow faster.
Fact: Trimming doesn’t affect growth rate, which is determined by the follicle or matrix.

FAQ

Are hair and nails made of the same material?

Yes, both are primarily made of keratin. However, nails contain a more compact form, making them harder than hair.

Is it true that nails are made of calcium?

No. While nails contain trace calcium, they’re predominantly keratin protein.

What nutrients strengthen hair and nails?

Protein, biotin, zinc, iron, and vitamins A, C, and E. The amino acid cysteine is particularly important for keratin formation.