Often referred to as the “sunshine vitamin,” vitamin D3 is synthesized when bare skin is exposed to ultraviolet B (UVB) light. However, studies show that most people do not get the recommended amount from sunlight alone. Factors that can inhibit vitamin D3 production include the time of day sun exposure occurs, season, latitude, skin color, age, clothing, and sunscreen use. In fact, according to Mayo Clinic, 25% to 50% or more of the general population may be vitamin D deficient. NatureWise Vitamin D3 delivers the same biologically active form of vitamin D produced in the body as a result of direct sunlight -- without the risk of unprotected UVB exposure.