Here we go again! Another one of my pet peeves (I know.. there are quite a few but I really care about spreading good information and the truth and well.. there is a LOT of bad information on the internet!).
The myth: The majority of ingredients in cosmetics absorb into the bloodstream. I often see the number 60% but I've even read 100% in some places! Such fear mongering!
Have you seen this number pushed by people and/or businesses?
That number sounds awful scary doesn't it?! It certainly works well to sell ''natural'' skincare. In fact, that's where I see this myth pushed hard.. by those who are selling their version of natural skincare and cosmetics. Often times at a high markup. But wait.. don't I currently sell natural skincare? Why would I want to bust this myth? It benefits me that people think this is true! The thing is.. I like the truth more than I like profits and I'm not in the business of lying to any of you.
So here's the thing, our skin is not a sponge. It is, in fact a wonderful barrier with many layers. The stratum corneum (the top most layer of our skin) in particular is the most important in limiting absorption. If our skin absorbed 60% of everything it touches, we'd have been goners long ago. Just think about all the things your skin touches every day. Now think about 60% of that absorbing into your bloodstream! Every time we took showers, we'd be riddled with edema. Think of all the stuff floating around in the ocean or flying around in the sky that touches your skin.
The truth is.. FAR less absorbs all the way into the bloodstream. I have found the estimation to be much less than 10%. This is why trans-dermal medications make up a small percentage of pharmaceuticals.
To better understand and explain this, I'll cite research on percutaneous absorption (absorption through the skin but not necessarily into the bloodstream). The science is a bit complex and I'll spare you the chemistry and formulas you can read them here (1). The bottom line is that the stratum corneum is a complex and effective barrier that protects us. It is our anatomical armor.
Two words I see often confused and conflated are absorption and penetration. Defining these terms matters so I will. Penetration is what a good cosmetic formula aims for and is achieved in various ways. You want the actives in your formula to actually penetrate into the dermis and stay there so that it works on the skin. It is a crucial factor in skincare as it directly affects the efficacy of products and the overall health of the skin. When skincare products are applied to the skin, they need to penetrate in order to deliver their active ingredients to the deeper layers of the skin where they can have the most impact. There are various factors at play and methods used to increase penetration of cosmetic ingredients. Absorption refers to movement beyond the dermis and into the bloodstream. That is what this article will mostly focus on.
What factors effect absorption?
First.. molecule size. The ingredient needs to have small enough molecules to actually get into and move through the many layers of the skin.
Second.. polarity. Our skin is made of watery and oily parts. The ingredient needs to have the right balance of oil soluble and water soluble in order to effectively absorb.
Third.. the strength of the skin, the humidity levels and temperatures also effect the rate and speed of absorption.
Fourth.. Skin Type. One of the most significant factors that affect absorption in skincare is skin type. Different skin types have varying levels of permeability, which can affect how well a product is absorbed. For instance, people with dry skin tend to have a weaker skin barrier, which means that their skin is more susceptible to moisture loss and can absorb products more easily. On the other hand, people with oily skin have a stronger skin barrier, which can make it more difficult for products to penetrate the skin.
Both "natural" and synthetic ingredients have potential to be absorbed and it is very important to know the ingredients you're working with and their safe levels of use. Every cosmetic ingredient has detailed guidelines on it's usage levels and requirements. Not following these guidelines can be dangerous and damaging! Interestingly, essential oils are one of the ingredients that do absorb and people often use them carelessly under the notion that they're natural and therefor safe.
This article has been focused on absorption of cosmetic ingredients into the bloodstream. I want to mention that topical reactions that happen inside the layers of the skin are of course a big consideration. These are very individualized and it's important to know your body and your skin and observe it's reactions to any given product.
References:
1. Brisson, Paul. Percutaneous Absorption. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1947480/
2. https://onlinelibrary.wiley.com/doi/full/10.1002/anie.202107960
Comments
Our bodies are so complex! I loved this deep dive and thank you so much for sharing.
Thank you for breaking this down! Everyone should read this. It could really make a difference in how people view their skincare needs.
Great article. I especially liked the skin illustration. We are subject to so much incorrect information that we assume is in our best interest. Good to read and see facts not targeted to profit. Thank you
Thank you so much for sharing this information! I have also seen this myth being pushed in online spaces and everything you said makes so much sense! Thank you for sharing your knowledge on this and breaking it down for me to understand!