You can't stand your dog's shedding problem. No matter how often you sweep, you find drifts of dander piled into every corner. Don't be so hard on the poor pooch, though; you shed too. In addition to the occasional hair you'll find swirling around your bathtub drain, you also scrub away your skin cells. As much as 75 percent of the dust that accompanies that dander is composed of your dead skin cells; in fact, almost nine pounds (four kilograms) of dead skin sloughs off of you each year [source: Reucroft and Swain].
The image of nine pounds of your dead skin in a pile on the floor is pretty gross, but it's part of a natural regenerative process. Dead skin cells are shed from the outermost layer of your skin's surface -- the stratum corneum, or horny layer. Beneath the horny layer are younger, living cells (called keratinocytes) that form the middle epidermal layer. As these keratinocytes die, they replace the cells shed from the horny layer. Below the keratinocytes is the basal layer, where new skin cells are born.
All three layers comprise the epidermis -- the outermost layer of your skin -- and follow their life cycle in an outward push from the bottom of the epidermis to the surface as they form, live, die (in a process called cornification), shed and become dust on your furniture. The horny layer of your skin isn't the most attractive; dead skin is often dry and dull-looking. One way to combat dry skin is to apply moisturizers, which rehydrate the dead skin cells. This solution, unfortunately, is but a temporary one.
You can also treat dry skin by hastening the process of shedding dead skin cells. You can find products designed to slough off the horny layer at drug stores and cosmetics counters. Both hydroxy acids and exfoliants remove cornified keratinocytes from your epidermis, revealing the living cells beneath.
Daily exfoliation sounds like a good idea, doesn't it? It turns out, though, that speeding up the natural process of shedding dead skin cells (known as desquamation) can be harmful when done too frequently.
Why Exfoliating Everyday Isn't a Good Idea
There are a couple of ways to remove the skin's horny layer to reveal the glowing, living cellular layer beneath. Hydroxy acids, either in the form of beta or alpha hydroxy acids, chemically degrade the physical structure of the cornified cells. With this structure disintegrated, your skin has an easier time shedding these dead cells. Exfoliants hasten the process of shedding dead keratinocytes. They commonly use granules with a crystalline structure, like sugar or salt, which scrub the dead cells from the epidermis.
These methods remove much of the horny layer, but speeding up the desquamation process too often can actually damage the skin or make existing damage worse.
A cell dies after it has divided a set number of times -- a process called apoptosis. Following apoptosis, a cell stops functioning, but remains intact. Other cells in the body destroy and remove the cellular debris from the body. The cell structure, contents and the DNA found in the cell nucleus are broken down and enveloped by microphages, which prevent this organic waste from being reabsorbed by the body. In other words, most dead cells are little more than physiological trash.
Skin cells, however, appear to be unique. The dead keratinocytes actually serve to protect the layers beneath. Instead of being absorbed by microphages and carried away from the body following apoptosis, the cells dry out and harden, becoming cornified and offering a layer of defense for the thriving keratinocytes below. This horny layer has been shown to protect skin from damaging ultraviolet rays from the sun [source: Gordon and Fugate].
On a more immediate scale, daily exfoliating can damage skin. Hydroxy acids can irritate keratinocytes once the horny layer is removed. The abrasive granules found in exfoliating scrubs can also harm skin.
Instead of exfoliating every day, you can slough off dead skin by gently using a scrub once a week. If you use a hydroxy acid, then once a week is about as often as you should apply it [source: Flamberg]. If your skin continues to feel irritated, you should stop using these products. Of course, as with most things, you might want to consult a dermatologist before beginning an exfoliating regimen.
Related HowStuffWorks Articles
- Flamberg, Gwen. "How often should I exfoliate?" Fitness Magazine. May 2006, http://www.fitnessmagazine.com/beauty/skin-care/advice/how-often-should-i-exfoliate/
- Gordon, Marsha and Fugate, Alice E. "The Complete Idiot's Guide to Beautiful Skin." Alpha Books. 1998. http://books.google.com/books?id=nE0bz0HYOogC&pg=PA142&lpg=PA142&dq=exfoliating+long-term+effects+on+skin&source=bl&ots=i3LRm6o9nm&sig=FNRcnUP4cjVMzpHZP_zmqq1dBKA&hl=en&ei=hMCSSujdJZaltgfO6MzOBA&sa=X&oi=book_result&ct=result&resnum=4#v=onepage&q=&f=false
- Lippens, S., et al. "Death penalty for keratinocytes: apoptosis versus cornification." Cell Death and Differentiation. June 17, 2004. http://www.nature.com/cdd/journal/v12/n2s/full/4401722a.html
- Nelson, Linda. "Exfoliants." Consumer Guide to Plastic Surgery. June 2008. http://www.yourplasticsurgeryguide.com/facial-rejuvenation/exfoliants.htm
- Reucroft, Stephen and Swain, John. "Does the dust in my house really include my own skin?" Boston Globe. September 1, 2008. http://www.boston.com/news/science/articles/2008/09/01/does_the_dust_in_my_house_really_include_my_own_skin/
- University of Maryland Medical Center. "Dermatology." February 19, 2008. http://www.umm.edu/dermatology-info/anatomy.htm