What Is Hair Made Of?

What Is Human Hair Made Of?

According to the Cleveland Clinic, human hair consists primarily of keratin, a type of protein that’s also found in the nails and skin. Each strand also contains small amounts of natural lipids, water, minerals, and melanin—the latter of which is responsible for your natural hair color. The exact ratio of these compounds can affect how your hair looks, feels, and behaves.

What is keratin made of?

Nutrients in the foods we eat help our bodies produce keratin, and in turn, healthy-looking hair. There are several nutrients and micronutrients needed for healthy hair growth, but per Harvard Health, these are among the most important:

• Vitamin D: This essential vitamin, found in fatty fish, egg yolks, cheese, and fortified cereal, helps create the cells that develop into hair follicles. It’s also important for maintaining a healthy, functioning immune system.
• Iron: Iron helps your blood carry oxygen throughout your body and to your hair follicles. If you’re low in iron, your hair follicles may not get the oxygen they need to produce healthy, resilient hair.
• Vitamin C: Vitamin C, which is found in citrus fruits and leafy greens, helps your body absorb iron from your diet. It’s also a powerful antioxidant that can help protect your cells against oxidative damage.

Other nutrients that can help support healthy hair growth include vitamin B3 (niacin), vitamin B7 (biotin), and zinc. As Harvard Health notes, most people can obtain the necessary nutrients for strong, healthy hair by maintaining a well-balanced diet.

Each strand of hair consists of two main structures: the follicle, which exists beneath the skin’s surface, and the shaft, which is the part that you see.

1.) Hair follicles

The hair follicle, as mentioned, lies beneath the skin’s surface, typically extending into the dermal layer of your skin. Close to the surface, there’s a sebaceous gland, which produces oil to help lubricate your scalp and strands. At the base of the follicle is the hair bulb, the structure where your hair roots emerge and growth begins.

Hair grows as blood vessels deliver nutrients to the cells within the bulb, creating the root. As these cells multiply, older cells are pushed upward and out through the scalp, forming a visible strand of hair. This process occurs in three phases: anagen (active growth phase), telogen (rest phase), and catagen (transition phase). According to the Cleveland Clinic, the entire growth cycle can take up to seven years. However, you can typically expect to see roughly one centimeter of hair growth per month, or about six inches per year.

2.) Hair shaft

The hair shaft refers to the visible strands that exist outside of your skin. The shape of the hair shaft and the angle at which it grows from the skin play a major role in determining your hair texture. The shaft is composed of two (or sometimes three) layers:

• Cuticle layer: The cuticle is the outermost layer of your hair. It consists of dead, overlapping keratin fibers, as well as natural lipids that help protect your strands against external stressors, such as chemicals and heat.
• Cortex layer: The cortex makes up the bulk of your hair. This thick inner layer plays an important role in determining how your hair looks and feels. The cortex is composed primarily of keratin linked together by hair bonds. These bonds play a crucial role in maintaining your hair's smoothness, strength, and healthy appearance.
• Medulla layer: Those with thick hair may also have a medulla layer. If present, it’s the innermost layer of the hair and acts as a “core” of sorts.

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