What is the biochemical composition of olive oil?

Olive oil is enriched with hydrocarbons, among them is the squalene. It contains approximately 110 μg of squalene per 100 grams of olive oil. This compound is the precursor to squalane, which is frequently found in cosmetics due to its beneficial properties. Indeed, squalene, like oleic acid, is one of the components of sebum. It thus plays a role in the formation of the skin's protective barrier and helps to maintain a good level of skin hydration. Olive oil could contribute, thanks to the squalene it provides, to reduce the skin dryness that increases with age. Squalene also helps to combat the harmful effects caused by free radicals due to its antioxidant properties.

Olive oil also contains β-carotene, approximately 3.1 μg per 100 g. This is a hydrocarbon that plays a powerful role as an antioxidant. Indeed, its polyene chain allows it to trap singlet oxygen, a source of oxidative stress. β-carotene is thus able to capture free radicals and neutralise them through an electron donation. It can also inhibit the production of lipid peroxides, partly responsible for the formation of free radicals. The olive oil would thus contribute to limiting the oxidation process, thanks, among other things, to the β-carotene it provides.

The olive oil in its composition contains a significant proportion of vitamin E, between 15 and 20 mg per 100 g of olive oil. Vitamin E is an antioxidant compound that protects the skin from the action of free radicals. Similar to hydrocarbons, it limits the damage caused by oxidative stress, particularly induced by UV rays. It thus plays a role in the prevention of skin ageing by limiting the oxidation of proteins responsible for maintaining the skin structure, such as the collagen and elastin.

Within olive oil, the vitamin E is primarily found in the form of tocopherols. This vitamin also has anti-inflammatory properties, which can provide some skin relief. Indeed, vitamin E is capable of acting on the NF-κB and JAK-STAT6 signalling pathways. It can thus inhibit the expression of certain pro-inflammatory cytokines. Olive oil contains other types of vitamins, in smaller proportions, such as vitamin A and vitamin K, which are also molecules with an antioxidant role.

Among the phytosterols it contains, olive oil presents β-sitosterol, Δ5-avenasterol, and campesterol. Other sterols are also found in smaller quantities, such as stigmasterol or ergosterol in olive oil. It would contain about 110 to 150 mg of sterols per 100 g. However, it should be noted that the phytosterol content can vary depending on the extraction process used to obtain the olive oil.

These compounds exhibit various properties beneficial to the skin, including moisturising and anti-inflammatory actions. Sterols work by limiting the inflammation process through the inhibition of the activity of two enzymes, cyclooxygenase (COX) and lipoxygenase (LOX), involved in the production of inflammation factors. These properties allow sterols to reduce the onset and development of symptoms related to inflammation, such as irritation and itching. Phytosterols also contribute to limiting water loss and strengthening the hydrolipidic film.

Beyond the constituents previously mentioned, olive oil contains a minority of other active ingredients, such as phenolic compounds and phospholipids, at a concentration of about 0.25 mg per 100 g. The phenolic compounds in olive oil are notably oleuropein and ligstroside. They possess a antioxidant activity and are specifically capable of transferring electrons and hydrogen atoms to free radicals in order to neutralise them. Oleuropein and ligstroside also have a anti-inflammatory action and contribute to the inhibition of pro-inflammatory factors, such as prostaglandin E2 (PGE2).