Firm skin resists finger pressure and returns to its place in a fraction of a second. This ability relies on two proteins: collagen, which gives the skin its resistance, and elastin, which allows it to regain its shape.
Over time, the production of these two proteins slows down, while enzymes called MMPs (matrix metalloproteinases) degrade them more actively. Two types of skin ageing are generally distinguished: intrinsic ageing, linked to the passage of time, and extrinsic ageing, caused by the environment.
This decline has been precisely measured: a study compared the production of type I procollagen in people aged 18 to 29 and in people over 80, with a reduction of about 32% in the older group. Two cumulative mechanisms explain it: the intrinsic ageing of fibroblasts, and less mechanical stimulation of the dermis, as collagen fibres offer less and less anchoring surface to the cells over time.
Intrinsic and extrinsic ageing: two different logics
An expression line does not have the same origin as a wrinkle etched by years of sun. Yet both fall under the same word: ageing.
Intrinsic ageing, the cellular clock
Intrinsic ageing follows each person's biological rhythm. It is characterised by a progressive thinning of the skin, a loss of density, and small fine lines, with no link to any particular exposure.
Extrinsic ageing, what the environment accelerates
Extrinsic ageing responds to external factors: UV rays, pollution, tobacco. It is recognised by thicker and rougher skin in places, pigment spots, visible small vessels, and deeper wrinkles than those of intrinsic ageing, because these stressors directly activate the MMPs responsible for collagen degradation.
The two mechanisms meet at the level of fibroblasts, the cells that make collagen and elastin: as they age, they slow down their production and release enzymes themselves that damage the surrounding matrix.
A simple benchmark allows you to tell the difference: compare an area regularly exposed to the sun (face, hands, décolletage) to an area that is not, the inside of the arm, for example. If the two look alike, intrinsic ageing dominates. If the difference is clear, with rougher skin, spots, or more marked wrinkles on the exposed area, the sun has done most of the work. Dermatologists also classically use this comparison, between protected skin and exposed skin on the same person, to distinguish the two mechanisms.
A marine active studied for firmness: Alaria esculenta
A Breton brown seaweed has particularly stood out in the field of firmness: Alaria esculenta.
A scientific study measured, on cultured human skin cells, the effect of an Alaria esculenta extract on the production of progerin, a protein whose accumulation is associated with cellular skin ageing. Researchers observed a significant reduction in this production in the presence of the extract.
Other work, conducted this time on fibroblast cultures and human skin explants, highlighted an action limiting the degradation of elastin and collagen by the enzymes elastase and collagenase, as well as a stimulation of type III collagen synthesis. These results come from the laboratory, on isolated cells or tissues: they do not measure what happens on living skin on a daily basis.
A usage test conducted on 20 women applying a cream with 1% extract for 28 days reported a perceived improvement in firmness in 90% of the participants. This figure remains a feeling reported by the users themselves, on a small sample and without an independent comparison group: a useful indication, not clinical proof in the strict sense.
Our Crème Visage N°2 contains an extract of this same seaweed, harvested in Brittany.
How to support skin firmness daily
No skincare product, however well formulated, works alone. Skin firmness is also built outside the cream jar.
The daily habits that count
Sun protection limits the activation of MMPs by UV rays, one of the main drivers of extrinsic ageing. It makes sense all year round, not just in summer: UVA rays pass through clouds and glass almost without losing intensity.
Collagen also needs a specific cofactor to build correctly: vitamin C, essential for the enzymes that stabilise its structure. Skin fibroblasts depend entirely on it to make collagen, even if little data directly links dietary vitamin C intake to the amount of collagen present in the skin. A diet that provides enough of it (citrus fruits, kiwi, bell peppers) remains a favourable environment, without expecting a measurable isolated effect.
Sleep also plays a measurable role. A study compared women sleeping seven to nine hours a night to women sleeping no more than five: the good sleepers recovered 30% faster after disruption of the skin barrier, and their skin recovered better from UV exposure. They also reported being more satisfied with their appearance. Sleep therefore does not only act on perceived fatigue: it conditions the skin's ability to repair what the day has damaged.
What a skincare product can, and cannot, do
A skincare product applied to the skin replaces neither medical treatment nor time. It can, however, offer the skin a more favourable environment: hydration, comfort, actives chosen for their documented action on the mechanisms of skin ageing. You can judge the sincerity of a "firmness" promise by a simple rule: is the species named, does the data come from a verifiable study, does the vocabulary remain measured ("helps to", "contributes to") rather than absolute?
What to remember about skin firmness
Skin firmness depends on two proteins, collagen and elastin, whose production slows down over time while enzymes like MMPs degrade them more actively: a measured decline of about 32% in procollagen between 20 and 80 years.
Alaria esculenta, a brown seaweed from Brittany, has been studied for its action on several of these mechanisms, in the laboratory and on a small panel of users. This data sheds light on the potential of the active ingredient, it does not replace clinical proof on a finished product.
Firm skin does not happen in a single application. It is built over time, between daily habits and actives chosen with the same rigor.
