The skin barrier, often called the stratum corneum, is the name given to the top layer of the skin. Under a microscope, the skin barrier, when healthy, looks like a brick wall. The “bricks,” called corneocytes, are the dead skin cells in the stratum corneum. They are held in place by something like a “mortar." This “mortar” is made up of lipid bilayers and moisture.

In a common-sense way, the lipid bilayer is so named because it is composed of 2 layers of fatty acids. Its role is to help "lock in" moisture in the skin.  The accompanying illustration is an artistic representation of the spatial relationship between the lipid bilayer and corneocytes.

You now know that the top layer of the skin is partially made up of corneocytes. Not surprisingly, then, each time you wash, scrub, or use certain cleansers and soaps, you remove corneocytes and lipid bilayers. That’s why it’s crucial to provide the raw materials to rebuild the lipid bilayer and keep the “bricks” close together. These tightly packed "bricks" help restore the skin’s natural protective function.

So, what are the raw materials that rebuild the lipid bilayer? There are 3 types of lipids that combine to form the lipid bilayer. They are ceramides, cholesterol, and fatty acids. Each of these lipids has the ability to both attract and repel water. When working together these lipids alternate between bringing moisture in and keeping moisture out of the skin.

Enemies of the Skin Barrier

©2006 CORIA Laboratories, Ltd.