Skin Hydration – Cosmetics September-October 2007
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Skin Hydration – Cosmetics September-October 2007

The Doctor Is In: Skin Hydration

By Alix Fuller

Cosmetics: To begin, how does the skin maintain its natural moisture balance?

Dr. Lisa Kellett: The function of the skin is to act as a protective barrier to outside influences. The maintenance of moisture balance in the skin is the result of complex physiological interactions in the skin and the environment. Our skin constantly monitors both internal factors and external factors and responds accordingly. For example, if the relative humidity in the air drops outside as it does in the winter, the skin will respond by increasing sebaceous gland secretion.

C: What is the function of water within the different layers of the skin? 
Dr. LK:
 Water helps ensure that the structure of the skin is optimal.  

C: Does drinking lots of water help? 
Dr. LK:
 Yes and no. When you drink a lot of water and you’re healthy, that shows in your skin since it reflects overall health. But, you can drink a lot of water and still have dry skin because the two are unrelated. The water goes into the bloodstream, it doesn’t get sucked into the skin. Look at people with eczema, or some other, similar disease that manifests itself as dry skin. They can drink all the water they want, and it won’t cure the dryness.

C: How do skin types vary? 
Dr. LK:
 Some skin is quite oily and doesn’t require any additional moisture. An oily skin type, though, can be superficially dry with a lot of dead skin cells on the stratum corneum so if you were to use an alcohol-based product, you’d have some flaking. In that case, you might need to use some sort of water-based, oil-free moisturizer. If your skin is already quite oily and shiny, you don’t need a moisturizer. Remember, your skin type is not written in stone. It might be oilier when you are having your period, for instance. Or, if you have oily skin during the summer, it can become quite dry in winter when the humidity level drops. Age is a factor as well; after the age of 30, sebaceous gland activity decreases, and when that happens there is less oil sitting on top of skin and it appears flakier or drier. So, you need to chance your skincare regimen accordingly.

C: What’s the role of moisturizer?

Dr. LK: Skin is dry. The dead skin cells don’t hold water, and what you want to do by putting moisturizer on is keep moisture in, reducing trans epidermal water loss. When you decrease this loss, the skin will appear less dry and flaky.

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