What Exactly Is Hair Made Of?

No matter how you cut it, hair is a very personal thing. From bleach blonde hair color to the trendiest hair accessories we will try anything to make our crowns stand out. Our hair grows in so many different shades, places, hair textures, and types, that everyone’s mane is naturally unique. But when it comes to hair anatomy, all of our strands are essentially the same.

Even if you’ve already mastered your signature hairstyle and hair care routine, learning what your hair is made up of gives you more insight so you can take even better care of all your hair —  not just the parts we can see. Below, we’re breaking down the basics of hair anatomy to help you care for your hair from the inside out.

What Is Human Hair Made Of?

Human hair is made from the protein keratin. Each strand of hair grows from a root located in the base of the hair follicle, which is composed of keratin cells. The keratin that makes up the major part of the hair is formed by amino acids molecules sourced from the food we eat. This protein is also found in our fingernails, toenails, and skin according to the American Academy of Dermatology (AAD).

What Is The Anatomy Of Hair?

There are two key components to your hair structure: the hair follicle and the hair shaft. While working together, each has a distinct role in the composition of your strands, as the National Center for Biotechnological Information (NCBI) explains.

Hair Follicles

The hair follicle sits underneath the skin’s surface and extends down into the dermis layer of your skin. Each follicle has a sebaceous gland that produces lipid-rich sebum (an oil) which naturally protects the hair and moisturizes the scalp. At the base of the hair follicle is a hair bulb. This is where the actual hair growth process occurs.  

Hair grows as your blood vessels deliver nutrients to the cells inside of the hair bulb. As hair cells grow, they are attached to the follicle and the older cells are pushed outwards resulting in the strand-like appearance of your hair. 

Hair Shaft

The hair shaft is the hard filamentous strands visible above the skin’s surface. The shape of the hair shaft and the angle it grows from the dermis plays a major role in determining your hair type. The hair shaft is made of three layers.

The Medullar:The innermost layer is made up of the sugar and amino acids, glycogen, and citrulline. 

The Cortex: The middle layer that surrounds the medulla. It contains keratin bonds that aid in elasticity and melanocytes, special cells that produce melanin pigment that determines hair color.

The Cuticle:The outermost layer of the hair. It’s covered by a single molecular layer of lipids that repels water and gives hair its shine.

The Building Blocks of Hair

Per an NCBI study, these nutrients are important building blocks for keratin protein and a key part of making sure our hair is thick, healthy, and strong.

Biotin

Biotin (B7) is a water-soluble form of vitamin B that supports hair growth and defends hair from environmental damage. Biotin metabolizes amino acids from foods which helps keratin form in hair and is one of the most popular purported vitamins for hair according to the National Institutes of Health.

Iron

Iron supports hair growth because it helps to form red blood cells that deliver oxygen and nutrients to the hair follicles. Hair loss is often a symptom of iron deficiency anemia.

Vitamin C

Vitamin C is a powerful antioxidant and protects hair follicles from damaging free radicals that contribute to discoloration and even hair loss.

Niacin

Niacin (vitamin B3) helps to repair the DNA in hair follicle cells. Without enough niacin, follicles may not produce hair efficiently.

If you’re interested in products formulated with niacinamide, try the L’Oréal Paris Elvive Dream Lengths Restoring Shampoo for Long, Damaged Hair.

Zinc

Zinc is important for hair growth because it supports DNA production. Without enough zinc, the protein structure of the hair follicle can deteriorate, causing hair shedding.

Next: 5 Facts About Hair Growth You Should Know

Written By: Lauren Paige Richeson, Photography: Chaunte Vaughn, Art Director: Hannah Packer, Associate Creative Producer: Becca Solovay