What is the biochemical composition of olive oil?

The olive oil has a rich biochemical composition, particularly in monounsaturated, polyunsaturated, and saturated fatty acids. These fatty acids account for many of its health benefits, but also for the skin and hair.

• Monounsaturated fatty acids, of which 55 to 83% is oleic acid.

  Among its monounsaturated fatty acids, olive oil is primarily composed of oleic acid. This is a fatty acid that belongs to the omega-9 family. Oleic acid is a component of sebum, a fatty substance produced by the sebaceous glands that serves to protect the skin from external aggressions. The oleic acid found in olive oil creates a moisturizing film on the skin's surface. It thus plays a role in skin protection and maintaining its hydration. Additionally, oleic acid has anti-inflammatory properties that may help soothe irritations. This action is believed to occur through the activation of anti-inflammatory cytokines and the reduction of pro-inflammatory mediators.

• Polyunsaturated fatty acids, of which 4 to 22% is linoleic acid.

  Olive oil also contains linoleic acid, which is part of the omega-6 family. It acts at the level of the stratum corneum. Indeed, linoleic acid has the ability to insert itself into the stratum corneum and play a role as intercellular cement. By filling in the discontinuities between cells, it helps the skin retain water. This fatty acid thus contributes significantly to maintaining the integrity of the skin barrier. It also has regenerative properties by acting as a precursor to the synthesis pathways of regeneration mediators. Linoleic acid thus has moisturizing, nourishing, and healing properties.

• Saturated fatty acids, of which 8 to 20% is palmitic acid.

  Among saturated fatty acids, palmitic acid from the omega-3 family is the one predominantly found in olive oil. Similar to oleic acid, palmitic acid is a emollient agent that allows for the preservation of skin hydration by protecting its surface through the formation of a film. Thus, palmitic acid imparts improved suppleness to the skin.

• Saturated fatty acids, containing 1 to 5% of stearic acid.

  Olive oil also contains stearic acid, which has a long carbon chain. In the same way as palmitic acid, stearic acid has film-forming and protective properties. Moreover, it is known for its nourishing and emollient properties.

Olive oil is enriched with hydrocarbons, among them 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 maintain a good level of skin hydration. Olive oil could contribute, thanks to the squalene it provides, to reduce skin dryness which increases with age. Squalene also helps 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 neutralize them by donating an electron. 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 amount 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 aging by limiting the oxidation of proteins responsible for maintaining 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 signaling 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 has β-sitosterol, Δ5-avenasterol, and campesterol. There are also other sterols found in smaller quantities, such as stigmasterol or ergosterol in olive oil. It contains approximately 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 moisturizing 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), which are 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.

In addition to 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 primarily oleuropein and ligstroside. They possess a antioxidant activity and are specifically capable of transferring electrons and hydrogen atoms to free radicals in order to neutralize them. Oleuropein and ligstroside also have a anti-inflammatory action and contribute to the inhibition of pro-inflammatory factors, such as prostaglandin E2 (PGE2).

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• FERNANDEZ-GUTIERREZ A. & al. Polyphenols in olive oil : The importance of phenolic compounds in the chemical composition of olive oil. Olives and Olive Oil in Health and Disease Prevention (2010). 

• KIRITSAKIS A. & al. Olive fruit and olive oil composition and their functional compounds. Olives and Olive oil as functional foods (2017).