Humans with light skin pigmentation living in low sunlight environments experience increased vitamin D synthesis compared to humans with dark skin pigmentation due to the ability to absorb more sunlight. Almost every part of the human body, including the skeleton, the immune system, and brain requires vitamin D. Sunlight is necessary for the production of vitamin D. Vitamin D production in the skin begins when UV radiation penetrates the skin and interacts with a cholesterol-like molecule produce pre-vitamin D3. This reaction only occurs in the presence of medium length UVR, UVB.