What is keratin and how can it be used in skincare?

Keratin is a large, fibrous, helical (helix-shaped) and insoluble protein found throughout the skin, nails, eyelashes, and hair. While we often associate proteins with muscles, they are actually the fundamental building blocks of the entire body. Muscles, hormones, antibodies, haemoglobin, skin, and hair are all made of proteins. In fact, our DNA expresses itself by encoding proteins, making them the very basis of our identity. When it comes to diet, you may already appreciate the importance of proteins in your food, and we will return to that later in this article.

Keratin is a sulphur-rich protein that is fibrous, forming long, strong fibres that twist around each other to create a resilient yet flexible structure. This structure helps hair resist wear and tear. Keratin is also insoluble, which ensures that hair remains waterproof and protected.

Keratin was first discovered in the 19th century, when it was identified as a component of hard animal tissues, such as horns and hooves. In the early 20th century, J. Hoffmeir successfully extracted keratin from animal horns using lime, paving the way for various extraction methods from sources such as horns, hooves, wool, and hair. These advances have allowed keratin to be used in many fields, including cosmetics, biomedicine, and textiles.

One laboratory has also developed a water-soluble form of keratin, known as cynatin, from New Zealand sheep’s wool. This patented process produces a soluble, 96% bioavailable protein that closely resembles the protein structure of human hair, making it a highly valuable ingredient in cosmetic products.

Keratin is produced in hair follicles by specialised cells called keratinocytes, in a process that occurs in three major successive stages.

Firstly, the keratinocytes use essential amino acids, mainly cysteine, methionine, and glycine, to produce keratin precursors. These precursors are then assembled into keratin filaments, aligned parallel to the cell.

These filaments are then enveloped in filaggrins, proteins that bind to lipids, forming a protective barrier that helps retain water and nutrients.

Finally, the keratinocytes die and release the keratin filaments, which can then harden outside the cell to form dander and, in this case, silky hair on our heads.

This process is regulated by various factors such as hormones, nutrition, age, and environmental conditions. If these factors are out of balance, it can lead to keratinisation disorders such as alopecia, or hair loss.

Keratin is one of the main components of the three layers that make up hair: the cuticle, the cortex, and the medulla.

On the surface, the cuticle forms the hair’s outer layer. It is made up of fine, overlapping scales of dead keratin cells, similar to tiles on a roof. The cuticle acts as a protective layer, shielding the cortex and helping maintain the hair’s natural moisture by preventing water from escaping too quickly.

When the scales of the cuticle are well fused together, the surface is smooth and reflects light, giving hair its shine. If hair appears dull, it is likely that the cuticle is damaged, with scales open in certain areas, making the surface rough.

The cortex, at the centre of the hair, is the thickest layer and accounts for almost 80% of the total mass of the hair shaft. It is composed of approximately 90% keratin, more precisely layers of compact, superimposed keratin cells joined together by an intercellular cement rich in lipids and proteins. This layer is responsible for the hair’s strength and resilience. The cortex also contains melanin pigments, which give hair its natural colour.

Finally, at the core of the hair is the medulla, or hair marrow. Here, keratin is present in the form of loosely packed cells forming a soft, amorphous, and slightly greasy substance.

Keratin can be more or less supple and thick depending on genetics and ethnic origin. This explains why some people have straight, curly, or frizzy hair. The shape and characteristics of keratin are determined by heredity.

Keratin is present at different levels of the nail structure but is mainly found in the visible part, known as the nail plate. This plate consists of several successive layers of compact keratin, produced by the matrix located at the root of the nail, well hidden and protected by the surrounding skin. The matrix is constantly active, continuously producing new keratin cells that gradually move towards the tip of the nail. Beneath the visible part, the underlying keratin cells protect the nail and help keep it attached to the skin.

After years of colouring and straightening, your hair may become dry and brittle, and you might worry that your keratin reserves are depleted. Do not panic; you can support your hair’s repair process by using keratin-based hair care products.

Keratin is available in a variety of forms, including shampoos, conditioning products, styling products, and hair treatments.

It is important to be mindful of the source. Keratin can be derived from natural animal sources such as sheep’s wool, bird feathers, or pig hair, or from synthetic sources created by assembling natural amino acids. Some synthetic forms may contain harmful chemicals, such as formaldehyde.

Fortunately, natural, plant-based forms are available, such as the Phytokeratin cosmetic active ingredient from Aroma-Zone, formulated from wheat proteins.

Keratin can be found in three main forms: shampoos, masks, and in-depth treatments.

Shampoos: Keratin shampoos are an excellent way to maintain hair health and prevent damage. When applied to wet hair, the keratin penetrates the cuticle, helps repair it, and forms a protective film against further damage. This type of shampoo gently cleanses and protects the hair. However, it is important to check the ingredients to ensure the shampoo does not contain irritating substances, such as sulphates, and that it contains a sufficient concentration of keratin. While this is a good first step, it should be combined with other products for a more in-depth treatment.

Masks: To deeply nourish hair and repair damaged areas, regular use of a keratin mask is essential. After shampooing, the mask penetrates deeper to improve the hair’s structure, enhance elasticity, restore shine and softness, and reduce early split ends. For optimum results, it is recommended to apply the mask in the evening and leave it on overnight, then rinse gently with shampoo in the morning.

Hair treatments: Keratin-based hair treatments are popular because they make deep, lasting changes to the hair’s structure, leaving it shinier and silkier. They make hair more manageable for months, which is very appealing, but these treatments can also be controversial. In addition to making hair straighter and smoother, some treatments may contain harmful chemicals such as formaldehyde.

There is nothing quite like regular natural care and protection to repair and maintain the hair’s natural keratin.

Keratin means protein: Since keratin is a protein, it is important to consume enough protein to stimulate its production. However, many of us do not consume sufficient amounts. As a general guideline, you should aim for between 0.8 g and 1 g of protein per kilogram of body weight each day. For example, if you weigh 60 kg, you should consume between 48 g and 60 g daily. To put this into perspective, an egg contains around 6 g of protein, while a 100 g steak contains approximately 25 g.

All sources of protein are beneficial. Red meat provides protein and easily-assimilated iron. Eggs are a good source of protein as well as biotin, which is essential for keratin synthesis. Oily fish, such as mackerel, are rich in omega-3 fatty acids. Seafood provides zinc, and oilseeds offer a variety of minerals.

When it comes to vegetables and fruit, aim to create a rainbow on your plate to benefit from provitamin A, vitamin C, and folate. Season with a good quality olive oil to add vitamin E.

In general, it is best to eat foods that are as unprocessed as possible to retain their micronutrients, and to choose gentle cooking methods, such as light steaming, while also including raw vegetables at the start of your meal.

A keratin treatment can help improve the health and appearance of your hair, particularly if it is damaged, fragile, or dull. Before beginning a course of treatment, it is important to consult a healthcare professional or hair specialist to determine whether it is suitable for your hair type and needs. Next, choose a high-quality keratin supplement, preferably in powder or capsule form, and follow the dosage instructions provided by the manufacturer.

In general, the recommended dosage is 500 mg to 1000 mg of keratin per day, divided into one or two doses according to the manufacturer's instructions.

To incorporate keratin supplements into your daily routine, it is advisable to take them with a meal. If you choose the powder form, you can mix it with a liquid such as water, fruit juice, or a smoothie to make it easier to consume. Capsules can be swallowed with a glass of water. Be sure to follow the recommended dosage carefully and do not exceed the stated amount, as overconsumption of keratin can have undesirable effects.

To complement the supplement, adopt a suitable hair care routine that includes gentle, moisturising treatments and a balanced diet rich in protein and essential nutrients to support healthy hair from the inside out. Finally, be patient and consistent, as the results of a keratin treatment can take several weeks to become visible.