Understanding Transepidermal Water Loss (TEWL)

Transepidermal Water Loss (TEWL) is the continuous evaporation of water from the internal dermis through the stratum corneum into the atmosphere. Elevated TEWL levels are the key biomarker of a compromised epidermal barrier.

The Brick and Mortar Model

Dermatological science models the stratum corneum as a brick wall: corneocyte cells represent the bricks, while intercellular lipid lamellae (composed of ceramides, cholesterol, and free fatty acids) act as the mortar. When harsh cleansers or environmental pollutants strip these lipids, the mortar cracks, allowing water to escape rapidly.

Physiological Repair Strategies

Re-establishing optimal TEWL rates requires applying bio-identical phytosterols and ceramides in a 3:1:1 molar ratio. Plant-derived sterols mimic natural human skin lipids, accelerating lipid lamellae reorganization and restoring moisture equilibrium.