Skin Function – The Epidermis (Part 3) : The Barrier Zone and Your Skin’s True Defense

Deep within the stratum corneum—the outermost layer of the epidermis—lies a powerful line of defense known as the barrier zone. This invisible shield protects your skin from harmful invaders like bacteria and chemical substances that manage to pass through the surface oil layer.

However, many cosmetic products contain synthetic surfactants that can compromise this delicate barrier. A common culprit? Cleansing oils made with mineral oil bases. These substances can strip away the very elements that keep your skin healthy and resilient.

There are two key types of lipids that make up this barrier. The first group includes triglycerides and squalene, secreted by sebaceous glands, accounting for about 90% of surface oils. The remaining 10% are found between skin cells—ceramides and cholesterol—which are vital components of the intercellular lipids.

These intercellular lipids are not only essential for locking in moisture, but also for maintaining the skin’s protective function. Keeping this balance intact is key to supporting radiant, healthy-looking skin.