What Causes Darkness of the Skin?
Skin darkness is caused by the compound melanin. There are several things that can cause increased production of melanin including sun exposure. Here you will learn about melanin and what stimulates its production. Then we will learn about How to Lighten Dark Skin.
**What is Melanin?
Melanin is a pigment or color. In humans, it is responsible for the color of the skin and hair. It is found in other parts of the body as well, including some glands and portions of the eyes, brain and inner ear.
Melanocytes are specialized cells responsible for melanin production. The skin's melanocytes are found in the bottom layer of the skin's epidermis, which is known as the stratum basal.
Most humans have between 1000 and 2000 melanocytes per square millimeter or stratum basal, constitution between 5 and 10% of the cells in that layer. The difference in skin-color seen in different races is not due to the number of melanocytes, but to the type of melanin produced and the presence of an enzyme called tyrosinase. A lack of tyrosinase results in the very pale skin-color present in albinos.
**Differences in Melanin Level
Differences in melanin production are responsible for the slight differences in skin-color seen in people of the same race. That brings us to the causes of increased melanin production.
**Sun Exposure Cause
Sun exposure is the most common cause. Overexposure for long periods of time can lead to skin roughness, as well. The skin roughness is not specifically due to melanin, but to changes in cellular DNA caused by free radical activity and to the drying effect of the sun.
UVB rays of sunlight can cause direct or indirect damage of the melanocytes' DNA. Direct DNA damage results in a tan. Indirect DNA damage can lead to cancer of the melanocytes, which is known as melanoma.
Other causes of increased melanin production include hormonal activity and exposure to toxins. Excessive intake of beta-carotene can cause a skin darkness that appears to be an orange-colored tan. Vitamin D and B-5 can enhance the tanning process and are sometimes used as naturally tanning
aids.
**Freckles and Skin Spots
Age spots and freckles are ultimately caused by clumps of melanin. Most of the clumping is due to sun exposure. Free radicals damaging the melanocytes' DNA are believed to be involved.
Rough patches sometimes appear as people age. In some cases the rough patches look a little darker than the surrounding epidermis.
Heavily pigmented patches of varying shapes and sizes may be due to increased hormonal activity due to pregnancy. This is sometimes referred to as the "mask of pregnancy". Hormonal changes that occur during menopause are associated with an increased incidence of age spots, although excessive sun exposure is likely involved as well.
**Uneven Skin Tone
Generalized unevenness of pigmentation is commonly found in older people. While melanin is involved in these changes, another factor is involved.
The outermost layers of the epidermis are constantly replaced throughout a person's life. Mother cells also found in the stratum basal are responsible for this replacement process.
The new cells produced are referred to as keratinocytes. If melanin production has been stimulated, the keratinocytes will be darker in color. If not, they will be lighter in color.
Age, irregular sun exposure and decreased production of new keratinocytes combine to create uneven pigmentation and skin darkness. Now that you know about the causes, you correct the problem. That is the subject of my next article.