The Lowdown on Hair Composition

It is common knowledge that our hair is a fair indicator of our general state of health, but what is it actually made of?

The main ingredient is keratin, a sulfur-rich protein which is also found in our nails, teeth and skin. Every strand of hair is therefore made up mainly of protein, 97% to be exact, and the rest is moisture. Protein is what gives hair its strength, while the 3% “moisture” hydrates it.

Each hair begins its journey in the follicle, a pouch-like formation buried inside the dermis layer of the scalp.

The hair shaft is made up of three main parts from the inside out—the air-filled medulla, which is the centermost section and can sometimes be absent in fine hair, the cortex and the cuticle.

The cortex takes up the bulk of the strand, making up 90% of its weight. This is the part that dictates the hair's elasticity, strength and, due to its melanin content, also its color. The cortex is made up of millions of hard protein fibers.

The cuticle, the outermost part of your hair shaft, is composed of a single layer of keratinized cells and is the hair’s protective sheath. Caring for the cuticle means shinier and healthier hair.