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SKINCARE DECODED • 48 MOISTURIZERS • 49

Corneocyte

Lipid Matrix

Natural

Moisturizing

Factors

(NMFs)

Cermide

Free

Fatty Acid

Why Moisturize

T

o understand the long-term importance of moisturizing,

we should first revisit some of those Skin Biology 101

terms and concepts. Remember, your skin is like an onion—

it’s got many layers. The outermost layer is called the stratum

corneum, or just SC.

Most skincare products are mainly geared toward treating the topmost layer

of the epidermis, the stratum corneum. (If you need a refresher on skin basics,

refer to page 14 to get your bearings.)

Skin Barrier Function 1: Keep the Bad Guys Out and Water In

Your stratum cornem is the outermost layer of your skin. It’s your first line

of defense against water loss and outside aggressors. Your moisturizers, in a

nutshell, are there to help support your SC in its barrier role.

Skin Barrier Function 2: The Water-Based Stuff

The other component to healthy skin-barrier function is natural moisturizing

factors (NMFs). NMFs are found in the corneocytes of your stratum corneum

and make up about 20–30% of the dry

weight of your stratum corneum.

These water-based molecules

keep the skin elastic and play

an integral part in the good-

enzyme activity that is key to

healthy cell turnover. Common

NMFs in your skin are sodium

PCA, lactic acid, free amino

acids, and urea. Remember:

Healthy cell turnover = healthy

skin barrier = healthy skin.