Oleic Acid in Skincare

When it comes to using oils as a part of your skincare routine, having a better understanding of some of the constituents that make up the oil and give it its properties, is important. Oleic acid is a fatty acid that makes up a significant percentage of many extracted vegetable oils. There are nutritional health benefits from consuming a diet rich in oleic acid.

There are also oleic acid benefits for skin when used topically, and multiple oils rich in oleic acid can be found in facial oils.

What is Oleic Acid?

Oleic acid is a monounsaturated fatty acid with the chemical formula C18H34O2. It is liquid at room temp and has a melting point of around 13℃. The molecule has a hydrocarbon chain with 18 carbon, one double bond, and a carboxylic acid group (-COOH). The single, double bond is why it's called 'monounsaturated', and the carboxylic acid component is what makes it a fatty acid.

Oleic acid is an important component of many oils and fats, including olive oil, almond oil, and avocado oil. It's also found in small amounts in animal fats and is a component of many soaps and cosmetics.

A diet rich in oleic acid, a monounsaturated fatty acid, may have a number of potential health benefits. Some studies have suggested that monounsaturated fats, including oleic acid, may help to lower cholesterol levels and reduce the risk of heart disease. They may also help to reduce inflammation.

How is Oleic Acid Used in Skincare?

Oleic acid can be isolated in its pure form through a process called hydrolysis. In this process, the triglycerides (fats) in the oil are broken down into their free fatty acids, including oleic acid, through the use of enzymes or chemical agents. The resulting mixture of fatty acids is then purified and separated through a process called fractionation. Pure oleic acid is a clear, colourless liquid with a faint, fatty odour. It is mostly used in commercial applications, including the production of soaps, detergents, lubricants, and plastics.

In skincare, oleic acid is not added or used in an unmodified form (ie. you wouldn't find a face oil that specifically has oleic acid added to it). It's a common chemical used in the synthesis of other skincare ingredients, like polyglyceryl oleate and various emulsifiers.

The oleic acid that ends up in your skincare products is gets there because it is a constituent of the parent oil that's cold-pressed and unrefined. Some examples of oils known to have high oleic content are macadamia, olive, and avocado.

If you were to put FREE oleic acid on your skin, it would be an irritant and disrupt the skin barrier. Practically speaking, however, free fatty acids are not what your skin comes into contact with when using plant oils. They remain primarily in their form as triglycerides, which are nourishing and protective.

Oleic Acid vs Linoleic Acid

In the skincare realm, considerable attention has been paid to the differences between oleic and linoleic acids. While there are differences, there are also similarities, and both have benefits for your health and your skin.

The key difference is related to skin feel, where oils high in oleic acid are better for people with mature or dry skin because they feel heavier and take longer to sink in. This makes them not the best choice for oily skin types or acne-prone skin. The best face oils for mature skin are often higher in oleic acid because aging skin usually needs more moisturization. 

High linoleic acid carrier oils are preferable for people with acne because they tend to be more anti-inflammatory. This is another reason why some of these seed oils are so useful in sensitive skin as well.

Does Oleic Acid Clog Pores?

The concept of comedogenicity is controversial because it is a grey area with a lot of nuances. High oleic vegetable oils are often the ones more likely to clog pores, but it isn't specifically due to the oleic acid content.

Oleic acid itself does not have a comedogenic rating, as it is not applied directly to the skin. Some oils that are higher in oleic acid, such as olive oil and avocado oil, have a relatively low comedogenic rating (2-3) and are considered unlikely to clog pores.

Another example is Argan oil which is one of the least likely oils to clog pores, and it's considered excellent for all skin types. Yet it often has an oleic acid content of around 50% which is higher than it's linoleic acid content (approx 40%). It's the balance between the two that makes argan so great for skin.

The determination of comedogenicity is based on a variety of factors, including the size and shape of the molecules, whether the oil is unsaturated or saturated, the presence of other phytochemicals, etc. Many of the worst face oils have high oleic acid levels, but that is only part of the story. 

Best High Oleic Oils Used in Skincare

Remember that the actual fatty acid composition of a specific oil can change based on everything ranging from growing conditions to extraction methods. Also, it's possible for a carrier oil to be high in both linoleic and oleic acids, though the ratio between the two of them factors into the skin effects and benefits. 

These are the common carrier oils used for skin that also (usually) have oleic acid levels higher than 45%:

SUMMARY

Many oils high in oleic acid are excellent for face care, especially for dry and aging skin. It has a heavier skin feel and is slower to absorb, which is partly why it's such a powerful emollient. The likelihood of clogging pores has more to do with the oil as a whole, not specifically just the oleic acid content level. Skin care can be enhanced by using oils, and they shouldn't be overlooked in your routine, just be sure to choose the best oils for your skin type. 

National Center for Biotechnology Information. PubChem Compound Summary for CID 445639, Oleic Acid. https://pubchem.ncbi.nlm.nih.gov/compound/Oleic-Acid. Accessed Dec. 28, 2022.

Sales-Campos H, Souza PR, Peghini BC, da Silva JS, Cardoso CR. An overview of the modulatory effects of oleic acid in health and disease. Mini Rev Med Chem. 2013 Feb;13(2):201-10.

Lin TK, Zhong L, Santiago JL. Anti-Inflammatory and Skin Barrier Repair Effects of Topical Application of Some Plant Oils. Int J Mol Sci. 2017 Dec 27;19(1):70.

Boelsma E, Tanojo H, Boddé HE, Ponec M. Assessment of the potential irritancy of oleic acid on human skin: Evaluation in vitro and in vivo. Toxicol In Vitro. 1996 Dec;10(6):729-42.

E. Boelsma, H. Tanojo, H.E. Boddé, M. Ponec, Assessment of the potential irritancy of oleic acid on human skin: Evaluation in vitro and in vivo, Toxicology in Vitro, Volume 10, Issue 6, 1996, Pages 729-742.