Does Beta Glucan penetrate the skin?

Anyone that knows me understands that I’m such a stickler for accuracy and rationale when examining the foundational science of ingredients within the skincare ecosystem. I thoroughly evaluate any and all claims made by ingredient manufacturers, and critically analyze the evidence for scientific substantiation that validates (or invalidates) the claims. I lead with skepticism, as most in the scientific field should, as there’s much hocus-pocus to be found.

Beta Glucan is a good place to start. What is it? b-Glucan is a linear, glucose-only polysaccharide naturally found in the cell walls of yeast, fungi, oats, etc., with an average molecular weight WELL over 500 Daltons (closer to 500k Daltons). A very large polymer indeed! They are what’s known as biological response modifiers with immunomodulation properties. Topically, it’s claimed to have wound healing, collagen stimulating, and hydrating benefits. The humectant properties of b-Glucan are clear, given the multiple hydroxyl groups on the molecule. For the other biological properties to occur, this large polymer needs to penetrate the skin. So…does it? The industry wants you to believe it does, but what about the actual evidence?

I did an exhaustive search of the literature and found out that there’s only ONE study that everyone seems to cite, supporting the claim that b-Glucan penetrates the skin, independent of its massive size. The paper was filled with flaws and bias. First of all, the 2015 paper (Pillai, et al) was funded by Symrise, the manufacturer of the raw material. But what really struck me was the testing methodology, and had me scratching my head when reading the lab results. The experiment purports to document that the b-Glucan penetrates deeply into skin, but the protocol takes a skin biopsy and soaks it on a slide surface! This is NOT an intact barrier test they accurately reflects real world in-vivo conditions. The truth is you can get anything to penetrate devitalized epidermis on a slide! I consider this data worthless and a flimflam, yet it’s the one study everyone uses to support the claim.

The truth is, I think it is wise that this molecule doesn’t penetrate the skin. When you look at the evidence in the literature, the biological response seems defensive. The cutaneous immune system treat b-Glucan as antigen, and mounts an inflammatory response. This is evident by the polarization of the M1 macrophage phenotype. I plan to post more about this soon!

Welcome to the world of applied science in skincare! The more you know.