Preventing Trans-Epidermal Water Loss For Lasting Hydration

What is trans-epidermal water loss?

If your skin feels tight, dull or dehydrated even after moisturising, trans-epidermal water loss, often shortened to TEWL, may be the reason. TEWL is the loss of water from the skin through evaporation into the environment. A certain amount happens naturally every day, but when the skin barrier is incomplete or compromised, TEWL increases and the skin struggles to hold on to the hydration it needs.

It helps to distinguish this from dehydration, which describes a lack of water content in the skin. Dehydration is often the visible result, while TEWL is one of the processes driving it. Understanding the difference is the first step towards caring for your skin in a way that lasts.

The skin barrier: your first line of defence

To understand why water escapes, we need to look at the outermost part of the skin. The epidermis is made up of epidermal cells, which form many different sublayers. At the very top sits the skin barrier, which works much like a brick wall. The cells act as the bricks, and they are bound together with lipids that act as the mortar.

This structure has two jobs. It keeps possible irritants and bacteria out of the skin, and it keeps hydration and nutrients in. Fatty acids play a key role here, as they are a type of lipid that builds the skin's barrier alongside cholesterol and ceramide. When the balance of these lipids is disrupted, gaps appear in the wall, water escapes more easily and the skin becomes more vulnerable to external stresses.

A strong barrier also depends on healthy cell cohesion, which is the process in which cells interact and attach to neighbouring cells to provide a healthy extracellular matrix. When cells are held together well, the barrier is more complete and water is far less likely to slip away. Supporting cell cohesion is therefore an important part of any approach to reducing TEWL and maintaining lasting hydration.

One of the ingredients we love for supporting the skin is Green Caviar, a micro-algae extract that absorbs sea minerals and vitamins to nourish the skin. It also helps to preserve the skin's youth by preventing premature ageing. Because it is so rich in nutrients, it is a wonderful addition to a routine aimed at keeping the skin comfortable, healthy and resilient.

Micro-Cellular Actives: Hyaluronic Acid Function

We use sodium hyaluronate, a low-molecular weight hyaluronic acid that is longer lasting and deeper penetrating. Low-molecular weight means that the molecule size is a nano particle, and it can therefore be absorbed past the epidermis rather than simply sitting on the surface. Once it is working within the skin, sodium hyaluronate helps to maintain moisturised, firm skin and works to improve cell cohesion, which ties back to the strong, complete barrier we have just discussed. It also aids in the process of collagen synthesis, which promotes healthy, bright and firm skin. Amino acids, the molecules within the skin that help to build elastin and collagen, are part of this wider picture of firmness and structure.

Discover the Green Caviar Collection: GREEN CAVIAR PROBIOTIC