We moisturize, we apply serum after serum, and yet the skin feels tight, fine lines are accentuated, and the complexion remains dull. This paradox is very common, and it is explained by a fundamental confusion: mistaking surface skin hydration for deep skin hydration. These are not the same mechanisms, not the same active ingredients, not the same results. Here's how to understand the difference and act effectively.
Understanding how the skin retains water
Water accounts for about 70% of the skin's weight. It is unevenly distributed among the layers: abundant in the dermis, rarer in the superficial layers of the epidermis. This hydration gradient is maintained by two complementary systems.
The first is the skin barrier, a lipid structure composed mainly of ceramides, cholesterol, and free fatty acids that form a cement between the cells of the epidermis. This barrier controls transepidermal water loss: when it is intact, water stays inside. When it is weakened, water escapes and the skin gradually dehydrates regardless of the amount of cream applied.
The second is the natural moisturizing factor (NMF), a set of hygroscopic molecules, including pyrrolidone carboxylic acid, urea, and amino acids, present in the epidermal cells, which capture water from the environment and retain it in the skin.
Below, in the dermis, hyaluronic acid ensures most of the water retention. A hyaluronic acid molecule can hold up to a thousand times its weight in water. Its production, provided by dermal fibroblasts, decreases with age, contributing to loss of volume and accentuation of fine lines.
A cream hydrates the epidermis. Only internal action hydrates the dermis. Both levels are necessary, but they are not interchangeable.
Why cream is not enough
Moisturizing creams act on the most superficial layers of the epidermis. They can provide short-term water, form an occlusive film that slows its evaporation, or contain active ingredients like topical hyaluronic acid that create a temporary plumping effect on the surface. These effects are real but limited in time and depth.
Hyaluronic acid applied in a cream, even in small molecules, remains mostly on the surface. It does not reach the dermis. Topical ceramides partially compensate for a weakened barrier but do not replenish the ceramide capital of the deep layers. And no cream can stimulate dermal fibroblasts to produce more endogenous hyaluronic acid.
This is why chronically dehydrated skin that does not respond to surface treatments often needs internal action to treat the cause, not just the symptom.
Deep internal hydration: what science shows
Internal supplementation acts on deep skin hydration through several complementary and well-documented mechanisms.
Ceramosides, phytoceramides extracted from wheat grains and standardized in active phytoceramides, are absorbed by the intestinal mucosa and distributed via the bloodstream to the epidermal cells. They increase the concentration of ceramides in the layers of the skin barrier, significantly and durably reducing transepidermal water loss. Clinical data from Ceramosides™ show a +35% increase in skin ceramides and a +27% improvement in hydration after 60 days.
Type I marine hydrolyzed collagen stimulates dermal fibroblasts to produce not only collagen but also endogenous hyaluronic acid. Clinical studies show a significant improvement in deep skin hydration after 8 weeks of supplementation, with persistent effects over time.
Essential fatty acids such as GLA from borage oil nourish the phospholipid membranes of skin cells, improving their fluidity and their ability to retain water. A well-constituted cell membrane is a condition for intracellular hydration.
Dry skin or dehydrated skin: an essential distinction
Before acting, it is useful to understand what problem is being addressed. Dry skin is a constitutive skin type, linked to insufficient sebum production by the sebaceous glands. It lacks oil. Dehydrated skin is a temporary and reversible skin condition that can affect all skin types, even oily skin. It lacks water.
Characteristic signs of dehydration include tightness, a dull complexion, accentuated fine lines especially around the eyes, a feeling of tightness after cleansing, and skin that is less bouncy when gently pinched. These signs do not necessarily indicate that the skin is naturally dry: they indicate that the skin barrier is weakened or that the dermis's water reserves are insufficient.
- Ceramosides™ Rebuild the lipid skin barrier from within. Reduce transepidermal water loss. +27% skin hydration and +35% skin ceramides in 60 days according to clinical data.
- Naticol® Marine Hydrolyzed Collagen Stimulates the production of endogenous hyaluronic acid by dermal fibroblasts. Clinical improvement in deep hydration from 8 weeks of regular intake.
- GLA — Borage Oil Powder Nourishes the phospholipid membranes of skin cells, improving their fluidity and their ability to retain intracellular water.
- Thymoquinone — Black Seed Oil Reduces chronic inflammation that weakens the skin barrier and exacerbates water loss. Complementary action to ceramosides in protecting the barrier.
- Vitamin E Protects the membrane lipids of the skin barrier against oxidative peroxidation that degrades them and increases skin permeability.
The complete approach: internal and external together
For deep and lasting hydration, both levels of action are necessary and complementary. On the surface, skincare that respects the skin barrier: gentle cleansers, alcohol-free formulas, occlusive active ingredients like petroleum jelly or shea butter that form a protective film limiting evaporation. Humectants like hyaluronic acid or glycerin that capture available water and retain it in the superficial layers of the epidermis.
Internally, active ingredients that act on deep mechanisms: Ceramosides™ to rebuild the barrier, Naticol® to stimulate endogenous hyaluronic acid production, GLA to nourish cell membranes. These active ingredients do not produce their effects in a few hours like a cream: they act gradually, over a cycle of 4 to 8 weeks, by structurally modifying the skin's ability to retain water.
This is precisely the logic at the heart of DE AUREA's Protocol N°79: a formula developed by Doctors of Pharmacy that combines the best-documented active ingredients to act on deep skin hydration, the lipid barrier, and the inflammation that weakens it.
Deeply hydrating your skin means giving it the tools to retain water itself. Not just providing it from the outside.
Frequently asked questions about skin hydration
To deeply hydrate your skin, you need to act on two levels: strengthen the skin barrier to reduce water loss with ceramides and essential fatty acids internally, and stimulate the production of endogenous hyaluronic acid in the dermis with marine hydrolyzed collagen. These active ingredients act where moisturizing creams cannot reach.
If the skin remains dry despite cream, it is often because the skin barrier is weakened and water loss is too great to be compensated on the surface. Cream hydrates the superficial epidermis but does not rebuild the deep lipid barrier. Internal action with ceramides and essential fatty acids is necessary to treat the cause.
Superficial hydration concerns the epidermal layers and is ensured by the hydrolipidic film and topical treatments. Deep hydration concerns the dermal layers, where water is retained by hyaluronic acid produced by fibroblasts. Only internal action can sustainably act on this deep level.
Yes. Clinical studies show that internally taken ceramides improve skin hydration by +27% in 60 days. Marine hydrolyzed collagen stimulates endogenous hyaluronic acid production in the dermis. These active ingredients act on the deep hydration mechanisms that creams cannot reach.
Dry skin is a skin type linked to insufficient sebum production. Dehydrated skin is a temporary condition that affects all skin types: it lacks water. Tightness, dull complexion, accentuated fine lines, and a feeling of tightness after cleansing are characteristic signs of dehydration, regardless of skin type.
