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Viewpoint: Exfoliation: Right or Wrong?
By: Ben Johnson, MD
Posted: July 23, 2008, from the August 2008 issue of Skin Inc. magazine.
Editor's Note: The opinions expressed in this article are not necessarily those of Skin Inc. magazine.
The entire professional skin care industry has grown dramatically around anti-aging skin care products and treatments. I also think people would agree that skin has continued to age, despite well-intentioned efforts. Are we using the right ingredients? Are the ingredients getting to the right places in order to actually have an anti-aging effect?
The aging process
First, take a look at the aging process of the skin. Even though the dermis thins as people get older, the epidermis doesn’t, regardless of age or sun exposure. The body is designed to continuously replace epidermal layers because a thinned epidermis could let in infection or result in fluid loss, both of which are life-threatening. The only aspect of the epidermis that is significantly affected by age is its rate of turnover.
The reason for the slowdown is the same reason that the dermis thins—the skin is starving for nutrients and the demand for enzymes, lipids, proteins and antioxidants needed to maintain the skin is higher than the blood supply can provide daily. Remember that the dermis is the sole provider of nutrients for itself and the epidermis and, as people age, the blood supply continues to decrease. With less blood, the amount of these essential nutrients also declines. The barrage of free radicals from diet, stress, sun and environmental toxin exposure overwhelm the skin, depleting the antioxidants and devouring the shrinking supply of nutrients needed to keep the dermis at full thickness and the epidermis at a 30-day cycle. The skin is forced to make a choice between allowing the dermis to thin or allowing the epidermis to thin. The best evidence of this is the aging pattern of dark skin types. You will rarely find a wrinkle on 70-year old African-American nonsmokers because their melanin keeps inflammation at a tolerable level that allows the dermis to maintain itself.
Restoring the epidermal barrier is the No. 1 priority of the skin because humans cannot survive with a thinned epidermis. Forced exfoliation with alpha hydroxy acids (AHAs) and other ingredients result in an emergency message from the epidermis to the dermis requesting immediate assistance. The only way to get replacement cells to the surface quickly is to increase turnover temporarily. This does not mean the epidermis or dermis are healthier; it just means that emergency measures were put in place to fix the epidermal deficit. Epidermal exfoliation also increases sun sensitivity, allows for a higher absorption of environmental toxins and dehydrates the skin.