Guys, this could be a long one. I’m constantly bringing cosmetics ingredients class to session but forgot to explain its basics- how cosmetics ingredients actually penetrate the skin. A thousand apologies. It’s time we did away with some myths and got some facts straight.
I’ve heard so many misconceptions over the years, ‘Our skin absorbs kilos of cosmetics each year’, ‘every single thing that we apply on our skin is absorbed in the blood stream’,’your pee is green? Oh Lawd, it’s that lotion you used being expelled from your body!’ No, no and thankfully, no (but please see a doctor about that green pee okay?)
As you can tell from the structure of our skin here, it has three layers: the epidermis, the dermis and the fat layer or hypodermis. A cosmetic ingredient would have to travel through aalllllll of that before reaching the blood stream and honestly, not many cosmetics ingredients can actually do that. The Beauty Brains highlight the reasons for this.
The Difference Between Skin Penetration and Skin Absorption
Before we get into the reasons, it would help to learn the difference between skin absorption and penetration.
Skin penetration represents how much of an ingredient can be found between the top layer (stratum corneum) and the bottom layer (stratum basale) of the epidermis. During penetration, the body hasn’t absorbed the cosmetic ingredient and it cannot affect the body. It just penetrates through the upper layers of skin and will eventually be removed as part of the dead skin cells.
Skin absorption is when the topically applied ingredient goes through the layers of the skin to reach the bloodstream. According to Personal Care Truth, ‘whether this chemical becomes a risk is determined by what occurs after absorption. Your body can filter out the chemical via bodily fluids, or bioaccumulation (build up) occurs.’
Basically, our body is smart and efficiently filters toxins that happen to wander into our blood stream. Low levels of toxins are expelled through urine and faeces quite regularly, not waiting for you to ‘detox’ months or years later.
If you have high levels of toxins in your system, then the body’s filtration system would be overwhelmed and the toxins would build up (bioaccumulation) which would be a danger to your health.
What Determines Cosmetics Ingredient Skin Penetration?
1. Size or Molecular weight. The skin is our first defense against the forces of nature and it takes its job seriously (otherwise when you went swimming you would literally absorb water like a sponge) Picture our skin cells as bricks with the lipids/ natural moisturizing factor, as the mortar. This inter-cellular matrix keeps the skin intact.
If a cosmetic ingredients is too large (greater than 500 Daltons, where a Dalton is the standard mass unit on an atomic or molecular scale) to slip between the skin cells or ‘bricks’ then it simply won’t be absorbed by the skin.
2. Solubility. Our skin naturally produces oils and lipids (sebum and NMF party up in here!) so oil soluble ingredients(like salicylic acid) find it easier to penetrate than water soluble ingredients (like AHAs).
3. The Condition and Area of the Skin. Some skin on the body is thinner/thicker than other parts. The skin on the soles of your feet for instance is quite thick and the area around your eyes and on your lips is thin.It’s easier for a cosmetic ingredient to penetrate thin skin and harder for it to penetrate thick skin.Exfoliated skin is also easier for a cosmetic ingredient to penetrate.
4. The Product Formulation. If the cosmetic ingredient is in a leave on formula like a cream or lotion, then it will have more time to penetrate the skin. If it’s in a rinse off product like a cleanser, then it won’t have enough time to penetrate the skin. Sometimes a product will be formulated with penetration enhancers like alcohol which make it easier for ingredients to penetrate the skin.
The Process After the Cosmetics Ingredient has Penetrated the Skin
So, you have cleansed or toned or moisturized. Then what happens to the cosmetic ingredient? Three things could happen. The ingredient could be:
- Perfect for skin cell absorption. When the ingredient is the right size, solubility and in a proper formulation, then you better believe the skin cells will take it up. After it has worked its stuff (e.g. brightening or firming or killing microbes) the skin cells will secrete it. Examples of such ingredients are antioxidants Vitamin C (L-Ascorbic Acid), Vitamin E (tocopherol) and Vitamin A (retinol).
- Too large to penetrate skin cells therefore goes between them. If the ingredients in your product are too large to penetrate the skin cells e.g peptides, they will penetrate between the skin cells, work their magic for a while before being excreted.
- Too large to penetrate skin cells or its surrounding. If the ingredients in your product are not absorbed by your skin cells, they could be temporarily absorbed by some glands. In this process, known as ‘appendageal absorption’ ingredients may be stored within the glands for absorption over time before being released into the bloodstream. This includes ingredients like aluminum,which is usually found in deodorants.
There you have it, a basic run down on how cosmetics ingredients work. At the end of the day, you absolutely need some cosmetic ingredients to penetrate the skin and work their magic from the inside out. You would not be able to reap their benefits otherwise.
The next time someone tells you to fling your designer lipstick to the hills, ask them for hard proof and investigate the matter on your own. Also, ask them if they get their nutrients by applying food on their skin (ha!).