In modern cosmetic discourse, some terms have become almost automatic: "multivitamin," "ultra-fresh," "nourishing," "fast-absorbing." By reading and hearing them so often, we end up forgetting about a fundamental biological reality: the skin is an organ of protection — not an organ of absorption.
Unlike the stomach or intestines, the skin is not designed to absorb substances into the body. Its primary function, on the contrary, is to regulate exchanges, limit water loss and protect against the environment. It filters, blocks, and defends.
It is also a major sensory organ, thanks to a dense network of nerve receptors involved in touch, pain, pressure and thermoregulation.
The pillars of skin physiology
The skin's protective functions rely on several complementary systems.
The acid mantle
A slightly acidic surface film (physiological pH around 4.5–5.5) contributes to skin homeostasis and limits the proliferation of undesirable microorganisms.
Overly aggressive cleansing or unsuitable formulas can disrupt this balance.
The hydrolipidic film
A true natural shield, it is an emulsion of water and lipids that reduces transepidermal water loss (TEWL) and protects the skin from external aggressions: cold, wind, pollution, friction.
The skin microbiota
The skin hosts an ecosystem of commensal microorganisms.
This microbiota occupies the territory, contributes to the balance of the skin barrier, and limits colonization by potentially pathogenic species.
Cutaneous immune cells
Found in both the epidermis and dermis, they ensure continuous surveillance and trigger an appropriate response in case of intrusion or barrier alteration.
The myth of "skin-nourishing" care
It is often said that a cosmetic product "nourishes the skin" as if it needs to be fed from the outside.
From a physiological point of view, this idea is imprecise — and sometimes counterproductive, especially when it comes to children.
The skin receives its nutrients via blood circulation, not through topical application.
A cosmetic product can hydrate, protect or support the skin barrier, but it does not "nourish" in the biological sense.
Any molecule foreign to the skin environment can be perceived as a potential chemical stress. This does not mean that every ingredient is harmful, but it recalls a simple rule: the more active ingredients one uses, the greater the risk of irritation, imbalance or sensitization.
Why children's skin requires even more simplicity
Children's skin barrier is: thinner, more permeable and still maturing.
It tolerates excesses, overloaded formulas and repeated stimulations less well.
The goal of a child's skincare product is therefore not to "boost" the skin, but to: gently cleanse, respect physiological pH, support barrier function and limit unnecessary chemical stress.
In pediatric cosmetics, the priority is stability and protection — not marketing performance.
Vegetable oils: nourishing... really?
The idea that oils "nourish" the skin is widely accepted.
However, the human skin surface is not comparable to that of a plant.
We are mammals and our natural protection primarily relies on structured waxy lipids (ceramides, cholesterol, specific fatty acids).
Vegetable oils rich in unsaturated fatty acids, when applied in large quantities, can partially solubilize some natural surface lipids. This can disrupt the balance of the hydrolipidic film.
Possible result: in the medium term, the skin may appear drier despite repeated applications.
The observed moisturizing effect primarily comes from an occlusive effect.
However, this effect is often better achieved by biomimetic structures similar to physiological lipids than by highly unsaturated oils.
Vegetable oils can be interesting: as antioxidant carriers, as light emollients, but their intensive use in children is not always ideal.
Penetration enhancers: a false good idea?
To enhance the feeling of absorption and "boost" the effectiveness of active ingredients, some formulas use diols (pentylene glycol, propanediol...).
These molecules can act:
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at low doses: as humectants or auxiliary preservatives
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at higher doses: as penetration enhancers
On adult skin, this effect may be sought.
On a child's skin — or on atopic skin — increasing skin permeability is not always desirable.
A more permeable barrier also means increased exposure to potentially irritating substances.
When it comes to children, the main challenge is not to make more ingredients penetrate, but to preserve the integrity of the skin barrier.
Respect biology before marketing
Marketing trends evolve.
However skin physiology remains constant.
Understanding that the skin is primarily an organ of protection allows us to rethink skincare, especially for children: fewer active ingredients and less stimulation, but more biological coherence and more respect for natural balances.
In pediatric cosmetics, the real luxury is not to do more.
It is often to do less — but better.
If you have any questions about children's skin or their routine, you can write to us at coucou@lilikiwi.fr— we will be happy to answer 🌿