05/03/2026
The industry often talks about barrier health in isolation. But the epidermis does not work this way. Yes, it needs protection, that’s a given, but its competence is the outcome of cellular activity throughout the tissue.
One way to visualise this is to think of the epidermis as a sandwich.
The top slice of bread is the stratum corneum. This is the structure we see and measure. It regulates water loss, protects against environmental stress and is often where therapists direct most of their attention.
The bottom slice of bread is the basal layer. This is where keratinocytes are born. It is the proliferative engine of the epidermis, continuously generating the cells that will migrate upward and ultimately become the corneocytes of the barrier.
Between those two slices is everything that gives the sandwich substance, the differentiating keratinocytes moving through the spinous and granular layers, synthesising lipids, forming proteins and organising the structures that will ultimately create a functional barrier.
If the basal layer is not producing healthy cells, the barrier above it cannot be strong. The corneocytes will be poorly formed and the lipid matrix incomplete.
But equally, if the stratum corneum is repeatedly disrupted through excessive intervention, the environment of the living epidermis is affected. Increased transepidermal water loss, shifts in pH and inflammatory signalling place stress on the very cells responsible for maintaining epidermal renewal.
The top and bottom of the sandwich are therefore connected by a continuous biological process.they are essential to the structure of the sandwich.
This is why does not treat the barrier as a superficial problem to be managed from the outside alone. A competent barrier reflects healthy cellular activity from the basal layer upwards.
Support the cells and you support the barrier.
Disrupt the barrier and you challenge the cells that must rebuild it.
The can be overwhelming for our client, but the sandwich analogy creates a visual picture that helps explain.
Feel free to try it.
Maria 💫
