What are the Proteins Found in Hair and Nails?

What are the Proteins Found in Hair and Nails?

Proteins are the building blocks of your body. Though we normally associate it with hitting the gym and bulking up, everything from muscle and bone to hair and nails is made up of proteins. Understanding what types of proteins are found in your hair and nails and the roles they play can be important in guiding your health decisions. So with that in mind, let’s take a look at the proteins found in your hair and nails. You might be surprised to learn that the proteins found in your nails and hair are actually quite similar!


What, exactly, are proteins?

Before we dive into what proteins are found in your hair and nails, let’s get to the basics! What is a protein exactly? Proteins are large and complex molecules found in living organisms that do all the heavy lifting (no pun intended) when it comes to life-giving biological functions. From providing physical structure to regulating the function of organs and tissues, proteins do it all! But, proteins aren’t just made up of random molecules. What makes a protein special, is that every single protein in your body (including the proteins found in your hair and nails) can be subdivided into smaller units called amino acids. And on top of that, there are only 20 types of amino acids that our bodies work with. 

List of the 20 amino acids

When hundreds to thousands of these amino acids link together in a long chain in a very specific pattern, they can fold and bend to create unique 3D shapes. This 3D shape is what we refer to as a protein. When it comes to your hair and nails, the main protein found in them is known as keratin.


The many shapes of keratin

The term “keratin” doesn’t refer to one specific type of protein, but rather, it is a broad term for fibrous proteins that play structural roles in mammals and birds (like the proteins found in our hair and nails), and some reptiles. In fact, there are several different types of keratins that occur in nature. The simplest categorization of keratins is alpha keratin and beta keratin. Alpha keratin is shaped like a coil, or as scientists call them, a helix. Beta keratin, on the other hand, is shaped like a pleated sheet of paper. 

Though the shape plays an important role in the function of these types of keratin, the key difference between the two is that alpha keratin is found in mammals and birds (hair, nails, hooves, feathers), and beta keratin is found in reptiles. So, when we talk about the proteins found in nails and hair, we are referring to alpha keratin. 


The role of keratin proteins found in hair and nails

So, now that you know that alpha keratin is the main protein found in hair and nails, what is its role? How are they important to hair and nail health? What about hair and nail function? The short answer is structure and strength. 

Proteins found in hair

If you’ve heard of keratin treatments or keratin in general in reference to hair, there’s a good reason for it! About 95% of hair is made up of keratin. The other proteins found in hair are keratin associated proteins which, as the name suggests, interacts with keratin to strengthen the hair. Structurally, hair has three distinct layers.

  1. Medulla: Soft and oily, innermost layer of hair strand; not always present in all types of hair. 
  2. Cuticle: Thin, waxy, outermost layer of hair strand. Forms a protective envelope around the hair shaft. 
  3. Cortex: Middle layer and main component of hair strand. Contains keratin and other structural components that give hair its physical property. 
Keratin and disulfide bonds

A key feature of keratin that plays an important role in hair type and texture is an interaction known as a disulfide bond. If you’re familiar with perms, you might have already heard this term before. Keratin is rich in an amino acid known as cysteine.

If you notice, on the structure of cysteine depicted above, there is a sulfur group represented by the letter “S.” When 2 cysteines come in close proximity to each other, the sulfur groups form a bond with each other hence the name “disulfide.” Though the curliness of your hair depends on the shape of your hair follicle, disulfide bonds in your hair is what allows your hair to keep the shape in which it was formed. When you get a perm, you are essentially chemically breaking the disulfide bonds and reforming them in the desired shape. 

Proteins found in Nails

Similar to hair, keratin helps with the structure and strength of your nails. If you look down at your hands, the part of the nail that we can see - the part we paint, bite at, etc. - is called the nail plate. This portion of the nails is composed almost entirely of keratin. Underneath your skin, past the nail bed, is the nail matrix. The cells in the nail matrix are continuously growing and dividing allowing for nail growth, unlike hair which goes through cyclical patterns of growth, to also continuously occur. 

Summary: Proteins are the building blocks of hair and nail

To summarize, proteins are the building block of life. They are what makes living organisms function and they are a part of every cell in our bodies. Proteins, including those found in hair and nails, can be divided into smaller units called amino acids. These amino acids can form long, patterned chains that fold into itself to make a 3D shape which is what we refer to as a protein. The type of protein found in hair and nails is called keratin, specifically alpha keratin. Though keratin is a broad term for the fibrous proteins found in hair and nails, they play similar roles in both: structure and strength. 

Profile photo for Avinash Boppana

Reviewed by: Avinash Boppana, BS

Avinash is a computer scientist. He completed his BS from Princeton University, concentrating in Statistics & Machine Learning. He has deep experience in computational research, working for reputable institutions, including Harvard Medical School, the Flatiron Institute, and the NIH.

Written by: Revela Editorial Team

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