A recent study examined the effects of genetic variants related to skin pigmentation on vitamin D levels among children. The researchers also evaluated the influence of children’s skin pigmentation on sun exposure behavior and its effects on vitamin D status.
One theory of skin pigmentation suggests that pigmentation evolved in humans in order to receive and maintain sufficient vitamin D in regions of differing ultraviolet exposure. This theory was formulated in an effort to explain why darker skin color originated in areas with high ultraviolet exposure and lighter skin color then developed in areas with low ultraviolet exposure.
Vitamin D production from sun exposure depends on skin color. A pigment in the skin called melanin is responsible for the variance in skin color. Melanin protects against skin damage from too much ultraviolet B (UVB) radiation exposure.
As humans evolved in Africa, they developed a high amount of melanin to protect against exposure to the constant, intense UVB radiation while still allowing for adequate vitamin D production. It is thought that when humans migrated to areas with low UV exposure they evolved to have less melanin and, subsequently, light skin pigmentation to allow for sufficient vitamin D production.