Everything you need to know about olive oil.

The olive vegetable oil (INCI: Olea Europaea Fruit Oil) is extracted from olives, most often through a cold extraction process. Its discovery dates back to several millennia before Christ. It was widely used in antiquity, particularly by the Egyptians for the formulation of skin care products. They reportedly used olive oil combined with beeswax as a cleansing agent.

It is also said that Cleopatra herself formulated a facial treatment made from milk, honey, and olive oil. Furthermore, the cultivation of olive oil, known as oleiculture, has been practiced for nearly 6,000 years in countries near the Mediterranean. Olive oil, as much appreciated in the food sector for its distinctive smell and taste as in the cosmetic field, presents a clear appearance and a golden color that can vary depending on the olives from which it is extracted.

The olive oil is rich in bioactive compounds, responsible for its numerous benefits, both on the skin and hair.

The olive oil offers numerous benefits for the skin, making it a coveted ingredient in cosmetic formulation. It can be used alone or incorporated into various skincare products.

• The olive oil reportedly exhibits significant antioxidant activity.

  This vegetable oil has a composition rich in antioxidant compounds, such as vitamin E or polyphenols (oleuropein and hydroxytyrosol). These constituents help to combat oxidative stress induced by the action of free radicals produced in excessive quantities and causing a deterioration of DNA chains at the cellular level. Antioxidants work by neutralizing free radicals through the donation of an electron or hydrogen atom. Moreover, a study has shown that olive oil itself could reduce the development of cancer cells related to UV exposure in mice. This antioxidant activity could allow the olive oil to prevent signs of aging and other harmful effects caused by free radicals, such as hyperpigmentation.

• Olive oil acts against skin inflammation and soothes the skin.

  Olive oil also appears to have the ability to reduce levels of TNF-α, a pro-inflammatory cytokine that plays a significant role in sensations of pain and itching. This property of olive oil is attributed to its high oleic acid content.

• Olive oil, an antibacterial vegetable oil.

  Olive oil, due to the polyphenols it contains, appears to have an effect on Staphylococcus aureus, a Gram-positive bacteria found on the skin. According to an in vitro study, olive oil could induce a reduction in intracellular ATP concentrations as well as a depolarization of the bacterial cell membrane, leading to a decrease in bacterial protein content and their leakage into the cytoplasm. Therefore, olive oil could have a powerful antibacterial effect that could potentially extend to other microorganisms. However, further studies are needed to confirm this.

• The olive oil as a moisturizing and nourishing oil.

  The high oleic acid content in olive oil allows it to form a moisturizing film on the skin's surface, providing protection against external aggressions such as exposure to UV rays, pollution, and tobacco, and maintaining skin hydration. Additionally, olive oil contains linoleic acid, which plays a key role in strengthening the intercellular cement, essential for limiting water loss. Thus, olive oil could help maintain the integrity of the skin barrier, although studies on this subject are still contradictory.

Beyond its numerous properties for the skin, the use of olive oil is also relevant for hair care.

• Olive oil to promote hair growth.

  The oleuropein found in olive oil is believed to have the ability to increase the size of hair follicles, thereby improving the anchoring of hair fibers. It is also thought to promote cell proliferation at the follicle level by inducing the expression of β-catenin, which could positively regulate the anagen phase of the hair growth cycle. However, the majority of existing studies to date have been conducted on mice. Therefore, an application on a human scale would be interesting to confirm this process.

• Olive oil nourishes and hydrates the hair.

  Thanks to the fatty acids it contains, such as oleic acid and linoleic acid, olive oil has a moisturizing and nourishing effect on the hair. Their combined effects allow for the creation of a film around the hair fibers as well as the strengthening of the already existing hydrolipidic film. Moreover, linoleic acid has the ability to insert itself between the scales of the cuticle, thereby strengthening its structure and ensuring the hair's impermeability. Olive oil thus prevents hair dryness.

• Olive oil limits hair oxidation.

  Hair can undergo several types of daily damage. Olive oil, with its strong antioxidant power, helps combat oxidative stress by limiting the oxidation of hair fibers through the neutralization of free radicals. This neutralization occurs through the donation of electrons or hydrogen atoms. Among the components that allow olive oil to perform its antioxidant activity, we can mention Vitamin E, beta-carotene, and oleuropein.

Olive oil is considered safe to use, even suitable for pregnant and/or breastfeeding women. However, some research conducted on atopic-prone skin shows that it could increase transepidermal water loss in these skin types. Although these studies were conducted on very small samples, the application of olive oil on very dry skin or skin prone to xerosis is discouraged as a precautionary measure.

Furthermore, olive oil is somewhat comedogenic, with a comedogenicity index of 2. This means it has the potential to clog the pores of oily skin and cause the formation of comedones. Therefore, it is advised to avoid applying pure olive oil if you have oily skin. However, this does not mean that you should abandon all cosmetics containing olive oil. Indeed, it's important to remember that the comedogenic nature of a product is not solely determined by the ingredients it contains, but also by their percentage and its texture.

Finally, to limit the risk of allergies, it is recommended to perform a tolerance test on a small patch of skin before the first use.

• TSIMIDOU M. & others. Olive oil composition. Olive Oil, Chemistry and Technology (2006).

• VIOLA M. & et al. Virgin olive oil as a key nutritional element and skin defender. Clinics in Dermatology (2009).

• PARK T. & others. Topical application of oleuropein stimulates anagen hair growth in telogen mouse skin. Journal Public Library of Science (2015).

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

• RIBEIRO H. & al. Investigations of by-products extracts from the olive oil industry with potential skin benefits in topical formulations. Multidisciplinary Digital Publishing Institute (2021).