Darkly pigmented skin, advanced age, and low UV index (e.g., winter months in northern latitudes) are some of the factors that decrease the amount of vitamin D produced by the skin in response to sun exposure. Because of the dual impact of the sun's UV rays (skin cancer induction and vitamin D production) those with the lightest skin pigment are at the highest risk of sun damage resulting in skin cancer, while people with darker skin pigment are at lower risk of skin cancer but higher risk for vitamin D deficiency.