Function of the Stratum Corneum:  The Skin's Natural Barrier

The skin is composed of several layers, each of which serves a particular function.  The topmost layer, called the stratum corneum, is actually composed of dead cells glued together with an oil our skin produces called sebum.  Because this layer is the one exposed to the elements, it can easily become damaged, thinned, rough and discolored.  The function of the stratum corneum is essentially to act as a barrier between the environment and deeper layers of our skin which are in fact alive.  The environment contains such harmful things as chemicals, ultraviolet light, and bacteria.  Thus the stratum corneum protects us from exposure to these harmful agents.

Over the past 20-30 years, it has become popular to exfoliate and use abrasives on our skin to effect a smoother, more radiant complexion.  Most of the time, if the skin is healthy, it can handle an occasional facial; however, more and more cosmetics and so-called wrinkle creams contain glycolic acids, retinols or abrasive granules.  Daily use of these products leads to excessive removal of the stratum corneum and reduces its barrier function.

Problems With Exfoliation

Some of the more common problems associated with thinning of the stratum corneum include development of milia , age spots , perioral dermatitis and allergic eczema .  

Milia are those small, hard, white granules just under the skin around your eyes, forehead or cheeks.  They are frequently associated with the use of exfolating chemicals, granules or astringents and they can resolve after several months when these products are discontinued.

Age spots are usually associated with excessive ultraviolet radiation exposure from the sun or tanning beds.  Age spots, known as lentigo or seborrheic keratosis , are benign but can be found alongside malignant conditions of the skin called actinic keratosis .  A visit to your dermatologist is the only way to be sure the age spot is a benign lesion.  Age spots darken with further ultraviolet exposure and can lighten considerably if ultraviolet light is avoided with the use of a wide-brimmed hat or long sleeves.

Perioral dermatitis is usually due to a superficial bacterial infection of the skin around the mouth, nose or eyes.  This condition appears as small red pustules which can be itchy or painful.  Bacteria more easily gain entry to the skin and set up an infection if the stratum corneum is thinned or breached.   This condition usually requires treatment with antibiotics to effect a cure, however some people repeatedly suffer from bouts of perioral dermatitis.  One aggravating factor may be the daily use of exfoliating chemicals or abrasives.

Allergic eczema is another condition caused by thinning of the stratum corneum.   Environmental chemicals such as chlorine, detergents or other allergic sensitizers may gain entry to the deeper layers of the skin when the stratum corneum is not able to exclude these substances.

What if you didn't have to exfoliate to produce smoother skin?  

In fact, topical Vitamin C produces a smooth complexion by normalizing the stratum corneum.  Rather than exfoliating, the stratum corneum retains its normal thickness, but the skin's tone, texture and pore size are improved  in just two weeks of daily use of topical Vitamin C.  Even better results are seen with the combination of a Vitamin E cream.

Studies at Duke University demonstrated that topical Vitamins C and E protect skin cells from sunburn and tanning.   Each vitamin alone shows protection of the skin from ultraviolet radiation and there is a synergistic effect when the vitamins are combined.

Daily use of Vitamins C and E has also reduced the numbers of age spots and milia in some patients. 

Finally, Vitamin C is an important cofactor in the synthesis of collagen. Topical Vitamin C speeds healing after burns and infections.  More rapid wound healing and reduction in fine wrinkles may be related to Vitamin C 's ability to increase collagen synthesis.

Before you run out and buy the first Vitamin C product you find, realize that Vitamin C, when mixed in a solution or cream has a very short shelf life of only two months.  Most Vitamin C is, in fact, mixed by the manufacturers; however in the process of shipping and storing, the shelf life is exceeded in many cases.   Vitamin C turns yellow or brown after two months and it loses most of its effectiveness when it turns color.  Sometimes, coloring or bleaching agents are added to Vitamin C creams so the yellow color is not apparent. To be sure you are getting the most effective Vitamin C product, be sure to buy a product that requires mixing after purchase.   This way, you are probably getting the highest concentration of active vitamin for the entire two months of its shelf life.