Phytosterols: Which are the most commonly used in cosmetics?

The phytosterols are natural compounds belonging to the sterol family. They are found in various plants, notably nuts, certain seeds, leafy green vegetables and some fruits. The interest in phytosterols is largely due to the numerous health benefits they provide, particularly to the cardiovascular system. They are notably capable of reducing the absorption of cholesterol in the intestine, which contributes to lowering cholesterol levels in the blood.

From a chemical perspective, sterols are molecules that possess four rings. Three of these are composed of 6 carbon atoms, while the last is a 5-carbon ring. Sterols are also characterised by the presence of an alcohol group (-OH) in the C3 position and a side chain of 8 to 12 carbon atoms in the C17 position. The various Cx positions mentioned refer to specific carbon atoms and are in reference to a nomenclature used by chemists.

The phytosterols are found in a wide variety of plants. They are obtained by purifying the oil extracted from these plants. Among the main sources of phytosterols, we find soybean oil, corn oil, avocado oil, rapeseed oil, certain whole grains and some berries. A large part of the phytosterols extracted from these plants can then be incorporated into cosmetic care. The most commonly used are:

• Beta-sitosterol : This is the most abundant and extensively studied phytosterol. It is derived from plant sources such as vegetable oils, seeds, and nuts. Beta-sitosterol is valued for its moisturising, soothing, and repairing properties for the skin. Beta-sitosterol is also recognised for its anti-inflammatory virtues. It has a side chain composed of 10 carbon atoms in the C17 position.

• Campesterol : This phytosterol is also derived from plant sources and is found in vegetable oils such as soybean oil and corn oil. Campesterol is known for its nourishing and protective properties for the skin. It has a side chain composed of 9 carbon atoms in the C17 position.

• Sitostanol : This phytosterol is found in certain foods such as nuts, seeds, and vegetable oils. It helps to strengthen the skin barrier and limits water loss. Sitostanol is also recognised for its soothing and anti-inflammatory properties. Unlike most phytosterols, sitostanol does not have a double bond in the C5/C6 position. It has a side chain composed of 10 carbon atoms in the C17 position.

• Campestanol : it can be found in foods such as vegetables, nuts, and seeds. Its cosmetic properties are similar to those of other phytosterols. Indeed, campestanol has soothing and anti-inflammatory properties, accompanied by moisturising and repairing virtues for the skin. Unlike most phytosterols, sitostanol does not have a double bond in the C5/C6 position. It has a side chain composed of 9 carbon atoms in the C17 position.

• Stigmasterol : This is found in various plants and vegetable oils, notably sunflower oil, olive oil, and coconut oil. Stigmasterol is valued for its anti-inflammatory and antioxidant properties. It has a side chain featuring a double bond and composed of 10 carbon atoms in the C17 position.

• Ergosterol : This phytosterol is naturally found in fungi, yeasts, and plants. Ergosterol is used in cosmetics for its moisturising, softening, and regenerative properties. It has a side chain featuring a double bond and composed of 9 carbon atoms in the C17 position.

• CABRAL J. & al. Phytosterols: applications and recovery methods. Bioresource technology (2007).

• PUGLIA C. & al. In vitro Percutaneous Absorption of Niacinamide and Phytosterols and in vivo Evaluation of their Effect on Skin Barrier Recovery. Current Drug Delivery (2016).