As professors of dermatology and skin scientists, we want to provide the public with reliable, up to date and scientifically sound information about our skin and how it functions to keep us well.

Just as there is more to owning and operating a car then simply filling the gas tank and turning on the ignition, so, too, taking a closer look at how the skin operates will make us better stewards of its health and beauty. We offer both in-depth articles based upon the latest scientific understanding and research and shorter answers to commonly asked questions.

We welcome your comments and suggestions.


How is pigmented skin more acidic?

 How is Pigmented Skin More Acidic?


As we discussed in an earlier post, darkly pigmented skin is superior to lightly pigmented skin. It functions better in holding in body water. It does a better job of preventing skin infections. And it is better at resisting mechanical trauma.  We then discussed work from the Elias laboratory demonstrating that this superiority is due to the lower pH of the skin surface.  In other words, darkly pigmented skin is more acidic. Yet darkly pigmented skin has the same number of pigment-forming cells (‘melanocytes’) as does lightly colored skin.  So, what then is the difference in the melanocytes of darkly- vs. lightly-pigmented skin? Well, one big difference is in the the clusters of pigment (or ‘melanin granules’) made by melanocytes in darkly pigmented skin. They are larger and more numerous than the sparser and smaller melanin granules made by pale skin. Melanocytes transfer these granules to the cytoplasm of neighboring epidermal cells (‘keratinocytes’) using their long arms (or ‘dendrites’).  This transfer process happens in both light and dark skin, but here’s where things proceed differently.


Comparison of melanin granules in darkly pigmented (left side) vs. lightly pigmented (right side) epidermis. Both skin types have the same endowment of pigment cells or melanocytes. But, the pigment granules produced by melanocytes in dark skin are larger and more numerous than those in light skin. When transferred to cells of the epidermis (keratinocytes), pigment granules in dark skin (left side) persist as the cells move towards the skin surface and some of the granules “escape” into the spaces outside the cells. In contrast in lighter skin (right side) the small granules tend to cluster over the top of the nucleus (‘nuclear cap’) where they can protect the DNA from sun damage. Very few make it into the outer skin cell layers and few of those are found outside the cells there. Drawing by Jessica Kraft.

The small, crumbly (read ‘crummy’, if you wish) pigment granules of very lightly pigmented skin are degraded within the keratinocytes well before they can reach the outermost layers of the epidermis. In contrast, the larger, more robust melanin granules of darkly-pigmented skin persist within cells as they mature and move outward towards the skin surface. [Continue Reading…]

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Image by Mary L. Williams, M.D.

Black Skin Is Better

This proposition - that black skin is better skin - is not a political statement. Rather, it is based upon scientific observations. Darkly pigmented skin is functionally superior to lighter colored skin in several ways. Our purpose here is give our readers a scientific perspective to a socially … [Read More...]

More Inside the Skin Barrier >>


Thoughts on the Rational Treatment of Atopic Dermatitis

This is the 4th in our series of updates on atopic dermatitis. In the preceding articles we considered why so many more children nowadays are developing eczema, what we know about the genetic underpinings of the disease, and how defects in the skin barrier and loss of the acidic pH on the skin … [Read More...]

More Skin Disorders >>

Q & A

Do pores on the skin need to breathe?

  Pores on the skin represent openings of hair follicles and sweat ducts.  These pores do not ‘breathe’ in the usual sense – our lungs take care of that need.  Yet, it can help to keep your pores open.  Sweat gland openings can become obstructed – for example, by wearing skin tight clothing … [Read More...]

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When The Skin Barrier Fails: Barrier Repair Therapy

Know anyone with psoriasis or some type of eczema? Most of us do. These are common skin conditions: one child in five has atopic dermatitis; 2% of the population has psoriasis. That’s a lot of people! Treatment is an ongoing battle for many who are affected by one of these conditions. They must … [Read More...]

More Repairing the Skin Barrier >>

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Disclaimer: This website is for informational purposes only. Use of this website is not intended to substitute for professional medical judgment or advice. This website does not provide medical advice and nothing contained herein is intended to constitute professional advice for medical diagnosis or treatment.You should always consult a doctor regarding any skin care or medical problems or conditions. See our Terms of Use.