Dark complexions have both advantages and disadvantages when it comes to sun exposure. On one hand, dark skin is less likely to get sunburned and less likely to develop skin cancer. On the other hand, because dark skin naturally provides protection from the sun's ultraviolet rays, it prevents dark-skinned people from producing the necessary amount of vitamin D [source: Zelman].
When people with lighter complexions spend time in the sun, their bodies produce melanin, the pigment that gives color to skin and creates a tan. Melanin serves as a natural defense against UV rays, and people with dark complexions, especially those with olive, brown or black skin, already have a high concentration of melanin in their skin. This high concentration of melanin is responsible for their dark complexions and protects them from burning easily. In fact, as the amount of melanin increases, so does the natural protection from sunburn. But while a higher concentration of melanin provides some sun protection, it doesn't prevent skin cancer. In fact, many African-Americans with skin cancer don't catch it early enough, which is why skin cancer fatality rates are higher among African-Americans than other ethnic groups [source: National Cancer Institute].
But everyone needs some sun exposure to produce vitamin D. Vitamin D, also known as the "sunshine vitamin," helps the body absorb calcium, which maintains bone density and prevents osteoporosis [source: Zelman]. And research shows that vitamin D may also help protect against chronic diseases such as diabetes, cancer, rheumatoid arthritis and heart disease [source: Kotz]. However, dark-skinned people's high concentration of melanin makes it more difficult for them to produce enough vitamin D. In fact, dark pigment in the skin reduces the skin's ability to synthesize vitamin D from sunlight by 95 percent. Lighter-skinned people can get enough vitamin D after 10 to 15 minutes of sun exposure a few times a week, but people with dark complexions may need five to 10 times more sun exposure to synthesize that same amount of vitamin D [source: Zelman].
Even though vitamin D is important to your health, you should always wear sunscreen when spending long periods of time in the sun. If you're concerned about vitamin D levels, speak to a doctor or dietician. Keep reading to learn more about how the sun affects people with dark complexions.