What Is Keratin?

This naturally occurring protein protects your hair, skin, and nails

Keratin is a blanket term for a wide variety of different intermediate filament-forming proteins. They are found on epithelial cells. Epithelial cells are on the surface of the skin, the lining of organs and glands, blood vessels, and the urinary tract. They are the proteins responsible for the growth and formation of the fingernails, hair, and skin.

The health of the fingernails, hair, and skin will rely heavily on the amount of keratin present in the body at any given time. In the animal kingdom, keratin is found in the hooves, wool, and feathers and can be extracted and used for supplements, treatments, and other products to help with hair, skin, and nail health.

Hair and many hair products contain keratin
 jun xu / Getty Images

Types of Keratin

There are 54 types of keratin genetically encoded by the human genome and produced by the body. They play a role in how cells change from one type to another throughout the body. Out of the 54 types, half of them reside within hair follicles and hold the main occupation of ensuring the growth and health of hair all over the body.

Type I

Type I keratins are categorized as being the smaller and more acidic type of keratin.  They are separated into two groups but work together functionally towards the common goal of epithelial cell health.

Type II

Type II keratins are larger than their type I counterparts and have a neutral charge, which can help balance out the pairings of both types when they are synthesizing proteins and regulating cell activity.


Alpha-keratins are the exclusive form of keratin found in humans and the wool of other mammals. The structure of the alpha-keratin is fibrous and helical, and both types I and II keratins can fall under the category of alpha.


Beta-keratins are categorized as polypeptide chains and are only found in birds and reptiles, although those species can also possess alpha-keratins. They have been a large contributor to the overall evolution of birds throughout history.

Both alpha and beta keratins are used within avian and reptilian animals to maintain the appearance of claws, scales, beaks, skin, and feathers.

Structure and Function

The structure of the keratin protein is categorized by their amino acid chains. These chains are very similar in species across the board. Humans share similar amino acid sequences as both bovine species and rats. The particular amino acid chain will provide a specific function as well.

Keratins cannot be dissolved in water, solvents, acids, or alkalines, so its structure remains intact and they rely on hydration for their overall size and function. To put this into context, wool is full of keratin. When a wool sweater is washed in heated water, it shrinks. This is because the keratin proteins lose their length when breakage occurs at higher temperatures. 

Associated Conditions

Having too much keratin in the body can lead to a variety of different conditions. All of those health issues fall under the umbrella of hyperkeratosis.

Hyperkeratosis occurs when the body undergoes inflammation, and keratin levels rise as an attempt to protect against any health threat. The conditions considered to be caused by hyperkeratosis are generally non-serious and easily treated.

Pressure-related hyperkeratosis occurs when the skin undergoes damage. Keratin is produced in extra quantities as protection, whereas non-pressure related keratosis seemingly happens for no reason and is more likely caused by genetics. Conditions involving keratin include:

  • Keratosis pilaris (chicken skin): Although keratosis pilaris can be unsightly for those who have the condition, it is not dangerous in any way. It is caused by keratin clogging pores and blocking hair follicles.
  • Actinic keratosis: This skin condition causes lesions on the body that often end up feeling like rough sandpaper. They are considered a precursor to skin cancer and your doctor may check your skin more ofter or treat these lesions.
  • Epidermolytic hyperkeratosis: This form of hyperkeratosis is inherited genetically and is present in infants at birth.
  • Lichen planus: Typically affecting the mouth, lichen planus is a type of inflammatory disorder that can be caused by an overproduction of keratin in the body.


Treatment will differ from condition to condition when it comes to hyperkeratosis, and not all forms are created equally. For lichen planus, a corticosteroid cream may be prescribed by your doctor whereas, with actinic keratosis, you may need to undergo cryosurgery to remove the lesions. For genetic conditions such as keratosis pilaris, there is no known cure.

Uses of Supplemental Keratin

Many industries have used keratin or other vitamin supplementations that encourage the production of keratin as a form of assistant to the overall health of the hair, skin, and nails. The beauty industry has especially advertised keratin as a way to combat damaged hair for a full restoration.

Hair Treatments and Products

Keratin is often used for hair treatments to help bring health back to hair follicles for shinier and stronger tresses. Depending on the type of keratin used, the results will vary widely. In the case of isolated animal keratin, results were found to be less efficient overall.


Biotin is a B vitamin that has also soared in popularity because it is said to have a positive impact on the body’s ability to synthesize proteins such as keratin, thus leading to healthier skin, hair, and nails.

Soluble Keratin

As previously mentioned, keratin is not something that is easily dissolvable. The creation of a soluble form of the protein has been targeted towards athletes who wish to supplement their protein intake and thus aid in overall performance.

Risks and Side Effects

Although there is not a lot of evidence to support that the use of keratin by itself can be dangerous to hair, skin, and nail health, the chemicals that are often added to keratin hair treatments can cause more harm than good. Exposure to formaldehyde has been a problem for those who use hair products with keratin regularly.

The use of formaldehyde in these products can then lead to many unwanted health issues including:

  • Itching and stinging eyes
  • Nose and throat irritation
  • An allergic reaction
  • Itchy skin with or without a rash
  • Scalp irritation that may present with burns or blisters
  • Mood changes
  • Hair loss and damage

The extended exposure to formaldehyde has also shown to have carcinogenic effects and could lead to serious health repercussions.

A Word From Verywell

Since keratin is a naturally occurring protein within the body, the use of supplements may not always be necessary. If you suffer from a condition that causes an increase of keratin, talking to a dermatologist can go a long way in the treatment and cure of certain skin conditions.

It’s important to talk to your salon stylist if you are looking to get a supplemental keratin treatment for your hair. It may do wonders in the short-term, but long-term effects can be highly damaging.

Opting for keratin treatments that are free of unwanted chemicals and substances such as formaldehyde will give you the opportunity to improve hair health without adding any unnecessary risk to your overall health.

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