Why use a hair oil?

Thehair oil is a concentrate of lipids, whose main role is to hydrate and nourish the hair. Generally rich in vegetable oils, it forms a lipid veil on the surface of the hair fibers, reinforcing the hydrating and protective action of the hydrolipidic film. Hair oils thus limit the dehydration of the fibers and prevent any "straw hair" effect.

Furthermore, most oils are formulated to penetrate the hair fiber and insert themselves between the scales of the cuticle, the outermost layer of the hair. Indeed, they serve to strengthen the intercellular cement and restore cell cohesion. This property of hair oils comes from their richness in fatty acids. Having a chemical structure similar to that of the lipids in the cuticle, they can easily insert themselves through biomimicry. When the scales of the hair are well aligned and structured, the hair gains elasticity and softness.

A recent study conducted with certain plant oils often found in the composition of hair oils examined their ability to improve fiber strength. After seven days of daily application, the results showed that hair treated with olive oil and Brazil nut oil exhibited an increase in breakage strength and a reduction in combing force. It thus appears that plant oils, and by extension, hair oils, are interesting treatments for hair care.

All hair types can benefit from the advantages that hair oils have to offer, especially dull and lackluster hair. Indeed, as mentioned earlier, oils nourish the hair fibers and strengthen the intercellular cement of the cuticle. They thus help to restore the alignment of the scales. Now, when the structure of the hair fiber is solid and the scales forming its cuticle are properly linked, the hair appears shinier, as they are capable of reflecting light. Regular application of a hair oil can therefore be beneficial for reviving the shine of one's hair.

It's worth noting that the study by CAMPOS, previously mentioned, also evaluated the shine of fibers after daily application of vegetable oils for seven days. The results indicate an overall increase in hair shine, although precise quantitative data is not available. Several other scientific studies report on the ability of vegetable oils to enhance hair shine.

Hair is subjected all year round to various external factors that weaken it: the heat of the hairdryer, UV rays, pollution, pool chlorine, sand, and sea salt... These different elements can damage the structure of the hair fibers, alter their color, and promote the occurrence of split ends, each to their own extent. By strengthening the hydrolipidic film that naturally coats the hair, hair oils form a first line of defense between the fibers and environmental aggressions.

The protective action of coconut oil, a vegetable oil sometimes used to formulate hair oils, was demonstrated in a study. This research highlighted that its application before and after the shampoo significantly reduced the protein loss from hair, whether it was intact or damaged. By coating the fibers with a film and penetrating the cuticle, the lipids contained in hair oils protect the hair scales from the detergent agents present in most shampoos.

Furthermore, hair oils are often formulated with antioxidant plant oils. They can thus help to combat oxidative stress, which is harmful to the fibers. Indeed, free radicals attack various components of the hair, such as the lipids of the cuticle, but also proteins like keratin and melanin. These oxidative damages cause a loss of strength and elasticity in the hair, making it drier and more prone to breakage. To protect them, it is recommended to use a hair oil once or twice a week, according to the instructions provided on the care product.

Hair oils can finally be used as a daily styling treatment by individuals with textured hair, meaning wavy, curly, or frizzy hair. Indeed, by reforming the hair's natural lipid barrier, these products help retain moisture within the fibers, making the hair less prone to frizz. Additionally, hair oils enhance the elasticity of the hair and promote its resistance to stretching and its ability to regain its natural shape after deformation. They are thus frequently used to help define curls.

Indeed, by providing intense hydration to the hair and strengthening its structure, these products allow curls to form more easily and maintain their shape throughout the day, thereby reducing the need for additional styling products. For individuals with textured hair, hair oils serve multiple functions: they protect the fibers, provide softness and shine, and enhance their hold.

• MOHILE R. B. & al. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. Journal of Cosmetic Science (2003).

• CAMPOS P. & al. Development and efficacy evaluation of hair care formulations containing vegetable oils and silicone. International Journal of Phytocosmetics and Natural Ingredients (2018).

• MESINKOVSKA N. & al. Coconut, castor, and argan oil for hair in skin of color patients: A systematic review. Journal of drugs in dermatology (2022).