It’s time for me to gush about rosehip oil again! It’s my favourite skincare oil, and it’s my SOS beauty saviour – whenever my skin is looking dull or pimply or otherwise subpar, I give it a break from all my other treatments and just slap on rosehip oil. Today I’m focusing on one of its components: linoleic acid, also known as an omega-6 fatty acid.
What is linoleic acid?
If you remember from my soap chemistry post, all fats and oils are composed of three fatty acids (the blue sections on the right hand side), chemically bound to glycerin (the purple section on the left hand side).
Linoleic acid is one of the many fatty acids that you can attach. It’s unsaturated, which means it tends to stay liquid at lower temperatures. Other unsaturated fatty acids include oleic, alpha-linolenic, gamma-linolenic and ricinoleic acids. There are also saturated fatty acids (lauric, myristic, palmitic, stearic) which are more common in solid fats.
As you can see from the structures, the saturated fatty acids are quite straight, oleic acid is reasonably straight, while linoleic acid is a bit kinky.
What does linoleic acid do for skin?
People who are acne-prone tend to have a low percentage of linoleic acid, and a high percentage of oleic acid in their sebum (natural skin oil). It’s thought that these low linoleic acid levels is one of the things that causes acne.
In one study, rubbing 2.5% linoleic acid on the faces of people with mild acne made their microcomedones (baby pimples) smaller – fantastic news for people looking for acne relief! This is particularly helpful because the most popular acne treatments (benzoyl peroxide, antibiotics, tea tree oil) focus on killing bacteria, so this targets a completely separate part of the process, plus it can help with non-infected clogged pores as well. 0.5% linoleic acid in ethanol was also good for reversing UV-induced hyperpigmentation (aka sun spots) in lab animals.
Linoleic-rich sunflower oil was also more effective at increasing the resilience of premature infant skin than olive or soybean oils (although how applicable these studies are to adult human skin is debatable…but it probably doesn’t hurt!).
Linoleic acid also tends to make oils runnier and less thick-feeling (oleic acid makes oils feel richer), which is great for acne-prone skin since that tends to be oily!
The bad news
There’s two parts to the bad news.
Firstly, linoleic acid is still connected to glycerin in oils, whereas most of these studies used detached linoleic acid (there is a very small amount of free fatty acids in oils, but it’s usually well below 2%, particularly if it’s not rancid). Your skin does have enzymes which can very slowly break off the linoleic acid, so you’d be getting more linoleic acid from a linoleic-rich oil than a low-linoleic oil. But it’s not going to be anywhere near as effective or predictable as a product that contains free linoleic acid (but those are rare).
Oils with a high linoleic acid content will also go off pretty quickly. The antioxidants in rosehip oil help keep it from going rancid quite as quickly, but most linoleic acid-rich oils will only have a 3-6 month shelf life (Trilogy Rosehip Oil Antioxidant+, since it has antioxidants in it, actually has an incredible shelf life of 3 years – one of the reasons this has risen to the top of my rosehip oil roster).
More bad news – oleic acid is often enriched in cooking oils to slow down food from going rancid (it’s a healthier option than saturated or trans fats), so some cooking oils aren’t the same for skincare. If you do buy cooking oil to use on your face, make sure you buy one that isn’t labelled “high oleic”.
What other oils are high in linoleic acid?
Rosehip oil isn’t the only linoleic acid-rich oil – you’ll find high amounts of linoleic acid in lots of other oils (note: the exact fatty acid profile of an oil varies depending on lots of things, like where it’s grown, when it’s grown, the variety, the processing method etc., so these are just rough estimates):
|Oil||% Oleic Acid||% Linoleic Acid||% Linolenic Acid (Alpha & Gamma)||Sources|
|Safflower (low oleic type)||8-21||68-83||<0.5||British Pharmacopoeia 2013|
|Grapeseed||16.2||70.6||Mountain Rose Herbs|
|Rosehip||13.9||44.1||33.9||Mountain Rose Herbs|
|Sunflower||14-40||48-74||British Pharmacopoeia 2013|
|Hemp||9.85||51.96||10.07||Mountain Rose Herbs|
|Sesame||39.21||45.69||Mountain Rose Herbs|
|Evening Primrose||8.4||50-72||7-10||Mountain Rose Herbs, http://www.drugs.com/npp/evening-primrose-oil.html|
|Soybean||17-30||48-58||5-11||British Pharmacopoeia 2013|
|Wheat-germ||12-23||52-59||3-10||British Pharmacopoeia 2013|
As you can see, even though rosehip oil isn’t the highest in linoleic acid, it’s got one of the best ratios of linoleic to oleic acid.
If you’re acne-prone, these oils are great starting oils for oil cleansing or moisturising since the texture’s so light. You can rub a few drops into your skin as part of your skincare routine (I’d recommend near the end of your routine – check out this post about why the order in your routine matters), or mix it into your moisturiser.
The linoleic acid content isn’t the only beneficial aspect of rosehip oil – you’ll also get a hefty dose of vitamin A and antioxidants. I think it’s the combination of these rather than a single component that makes my skin respond so well to rosehip oil. I’ve banged on about vitamin A for skincare in the past. Cold-extracted rosehip oil is also rich in antioxidants, which limit oxidative damage from the sun, pollutants and even just air and being alive. Trilogy Rosehip Oil Antioxidant+ actually has a few extra additions – tomato and cranberry oils, and lycopene – which means you get more antioxidants in one hit. If you’re lazy like me, you might also want to upgrade your rosehip oil to an antioxidant-boosted version!
Trilogy Rosehip Oil Antioxidant+ was provided for review, which did not affect my opinion. This post also contains affiliate links – if you decide to click through and support Lab Muffin financially, thank you! For more information, see Disclosure Policy.