What is the difference between nourishing and moisturising?
You often find the words moisturising and nourishing on cosmetics, but are these actions the same thing?
Moisturising and nourishing the skin are two quite distinct actions that can sometimes be confused. It is not always possible to distinguish between dry skin, which therefore needs nourishment, and dehydrated skin, which therefore needs moisturising.
The main difference between moisturising and nourishing is that all skin types can have periods of dehydration, even the oiliest skin, while more or less deep nourishment is a typical need for dry skin. Using a nourishing cosmetic on skin that is dehydrated, and therefore in need of hydration, could be counterproductive and make the skin too shiny and greasy.
Water is present both inside and outside the skin cells and, physiologically, tends to evaporate with a phenomenon known as ‘trans-epidermal water loss’, or TEWL.
When we speak of hydration, we must not think that the water present in cosmetic products is sufficient to replenish the fraction of water lost, because instead, the moisturising activity is the work of functional ingredients known as humectants, such as glycerine, propylene glycol and hyaluronic acid. These molecules, by their intrinsic nature, are able to bind water molecules and draw them into the various layers of the skin, thus bringing hydration.
The term nourish, on the other hand, refers to the reconstitution of the hydrolipid film: a thin layer of oils that is physiologically present on the skin and which prevents excessive evaporation of water and protects the skin from external stresses. A suboptimal hydrolipidic film is typical of dry and very dry skin. Cosmetics capable of nourishing the skin by softening it and replenishing the appropriate fraction of lipids contain substances called emollients that are lipophilic in nature. Emollients are therefore able to reconstitute the hydrolipid film of dry skin, making it soft to the touch and more radiant.
Among the Gen-Hyal products, the two essential serums PLUS and PREMIUM have an important moisturising action, as they are composed only of high percentages of Hyaluronic Acid; while ELARGAN, containing a high percentage of argan oil, has a nourishing function.