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Sebum composition + Acne

Updated: May 13, 2023

It's an old and common misconception that oily skin and acne go hand-in-hand.


When it comes to oil and acne-risk, quality is just as important as quantity. In my nine years as a skin therapist, I've seen plenty of dry skins with acne, and plenty of oily skins that were beautifully clear. It's time we delved into the link between oil and acne, and dispelled some of the confusion.


First let's nail down what we mean when we talk about "oil". Your skin actually produces two distinct types of oil, but in this case we are talking about sebum, the oil that is associated with acne development and severity.


Human sebum is made up of a blend of different lipids. These include triglycerides and fatty acids (including linoleic acid), wax esters, and squalene, which normally makes up a small portion of sebum (around 12-15%).


The above is a typical sebum composition - but sebum composition is not static. It can change, and fluctuations in its lipid ratios can seriously impact the skin - in particular, changes in linoleic acid and squalene levels.



Linoleic Acid


Linoleic acid is an essential fatty acid that is vital to the composition of sebum. It provides the building blocks required for the skin to produce ceramides, and keeps sebum from becoming too viscous/"sticky".


When linoleic acid levels in the skin are depleted, several things happen:


- sebum becomes thicker/more viscous and "sticky", which can lead to congestion in follicles, ultimately creating blackheads and acne


- without the linoleic acid building blocks, ceramide levels in the skin decrease. This leads to dehydration, barrier dysfunction, and inflammation


- it's also been hypothesised that decreased linoleic acid levels can induce a process called follicular hyper-keratinisation - a key process in the development of acne. Follicular hyper-keratinisation is when skin cells within skin follicles shed abnormally fast - resulting in blockages in the follicle that ultimately can become pimples or blackheads. Imagine that in a normal follicle, cells should shed at a steady rate and make their way out of the follicle to shed. In the case of follicular hyper-keratinisation, there are too many cells shedding too fast - and the result is a bottleneck at the opening of the follicle (the pore), thus creating a blockage.



And now, let's talk about squalene


Squalene is a highly unstable lipid that is only found in human sebum.


Because of it's instability, squalene is prone to oxidisation. It reacts to environmental stressors, in particular UV from the sun, and oxidises to form a product called squalene peroxide.


Squalene peroxide is problematic for the skin in several ways:


- it induces inflammation in the skin, which can trigger acne development


- it's thought to be capable of initiating the previously discussed process of follicular hyper-keratinisation


- it is comedogenic - meaning it causes blockages in skin follicles, resulting in blackheads, and acne


- squalene peroxidation by-products have been shown to increase follicular hyperkeratinisation, and stimulate sebaceous glands.


Normally, squalene only makes up around 12-15% of the lipids in sebum - so our skin experiences minimal harmful effects from squalene oxidation.


But in cases of acne, the ratios are skewed - with increased levels of squalene (up to 35% more than normal skin). Compounding this, high squalene levels seem to correlate with depleted linoleic acid levels - for reasons that are still not clear.


So, how is this relevant to individuals with acne?


The good news is, there are ways to mitigate the effects of low linoleic acid and high squalene.


For people with acne, using topical ceramides to support their skin barrier and reduce inflammation can be incredibly beneficial. It's also worth consulting a nutritionist (we recommend this to many acne clients anyway) to discuss whether essential fatty acid supplementation would be beneficial.


On the squalene front, we know that UV is a major factor in oxidation - so preventing this is key. This would be in the form of a good quality sunscreen.


Topical antioxidants like vitamin E and C, can mitigate the oxidisation of squalene and reduce its harmful effects. This is best in the form of a targeted serum.


In conclusion


It's long been hypothesised that inflammation is actually the first event in the development of acne, and that other factors like follicular hyper-keratinisation, c.acnes proliferation, and over-production of sebum are all secondary processes initiated by the inflammation.


Understanding that linoleic acid depletion and squalene oxidation can induce inflammation (and trigger other acne-causing processes) is important, because we can then explore how to support our skin and mitigate these processes.


The bottom line: if you suffer from acne, supplementing the skin topically with ceramides and anti-oxidants, and protecting it from the sun, can reduce inflammation and reduce other key processes in acne development.


If you are dealing with inflamed acne, and need guidance - book a consultation. It's free, no-pressure, no strings attached - we're here to help.

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2 Comments


Loved your article. Just following up on a thought - would it be best to not use products that have squalane in daytime use for acne prone skin types?

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Greta Ryan
Greta Ryan
Jun 06, 2023
Replying to

Thank you! Ah - so it's important to note here that squalEne and squalAne are different - squalane is a lot more stable than squalene, so it doesn't oxidise like squalene does. For that reason, it's actually totally safe for acne-prone skin :)

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