To understand how skincare ingredients interacts with the skin, let’s kick off with a short refresher on how the skin itself works…
What weighs up to 10 kilos and helps shield the body from danger? It’s the skin, of course! Our skin has many functions, and of them is to act like a barrier to keep our internal organs safe from harmful external factors such as germs, pollution, and the weather amongst other things.5
Which begs the question: if the skin is so effective at keeping things out, how do skincare ingredients do their job?
How does the skin work?
The skin is made up of two separate layers: the epidermis which is a thin outer layer, and the dermis, a thicker and deeper layer.
The epidermis is mostly comprised of skin cells (keratinocytes), which spend their lifespan steadily working a path from the bottom of the epidermis to the top.
By the time they get to the very top layer, known as the stratum corneum, the skin cells are dead and ready to be sloughed away. They’re replaced by the next group of cells and the cycle continues as they’re exfoliated away.
The epidermis that acts as the skin’s barrier layer, while the dermis supports and nourish it. It’s made up of a network of collagen fibres which give the skin its snap and bounce. It also provides blood vessels, nerves, hair follicles and biological systems like the vascular and lymphatic systems.
How do skincare ingredients interact with the skin?
Any time you apply a topical skincare product, it first comes into contact with the stratum corneum. Curiously, even this layer of dead, compressed cells can be leveraged quite differently by skincare, depending on the ingredients in a product. For example, alpha hydroxy acids (AHAs) like glycolic and lactic acids encourage the dead cells in the stratum corneum to turnover and drop off more easily1 by eating away at the cohesive “glue” that holds them together 2. This is especially noticeable in skin that’s ageing or that’s been damaged by the sun, as it’s here that the old skin cells naturally cling on for longer. Sloughing them away more quickly leads to a temporary thinning of the skin’s outer layer 2, and without all those scaly old skin cells hanging around, it can look smoother and feel softer to the touch.
Another skincare ingredient that can be leverage by the epidermis is Glycerin. It’s a humectant, which means that when it’s applied topically, glycerin draws water to the skin’s surface and then seals it in3. Given this nifty ability, it’s perhaps unsurprising that glycerin not only makes the skin feel more hydrated, it’s been found to actually improve the skin’s hydration levels, too 3.
Can skincare really “penetrate the skin”?
It’s fairly simple to see how skincare ingredients can interact with the skin’s outer layers, if it meets the needs of the skin. But does an ingredient really have a chance of reaching the dermis; the denser layer that lies under the epidermis?
Some ingredients are made of molecules that are too big to get through, but research shows that sizeable ingredients are better able to penetrate to the skin’s “deeper layers”. To return to our example of alpha hydroxy acids, if they’re used regularly for a couple of months, it’s been found that AHAs can have a detectable impact on the dermis, leading to increased skin thickness and plumpness.2 Other ingredients aren’t so agile; for example, Vitamin C is believed to be less capable of penetrating all the way to the dermis when it’s applied topically.4
As our largest organ, the skin is a complex network of cells, nerves, and biological systems.
Find the right skincare to suit your needs and concerns by understanding how different ingredients work is key to healthy and happy skin.
1. Yamamoto Y1, Uede K, Yonei N, Kishioka A, Ohtani T, Furukawa F. Effects of alpha-hydroxy acids on the human skin of Japanese subjects: the rationale for chemical peeling. J Dermatol. 2006 Jan;33(1):16-22.
2. van Scott EJ, Ditre CM, Yu RJ. Alpha-hydroxyacids in the treatment of signs of photoaging. Clin Dermatol. 1996 Mar-Apr;14(2):217-26.
3. Greive K. Glycerine: the naturally effective humectant. Dermatol Nurs 2012;11(1):30-34
4. Juliet M. Pullar, Anitra C. Carr, and Margreet C. M. Vissers. The Roles of Vitamin C in Skin Health. Nutrients. 2017 Aug; 9(8): 866.
5. Cologne, Germany: IQWiG. How does skin work?. Informed Health Online [Internet]. 2009 Sep 28 [Updated 2016 Jul 28]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279255/