Sunscreens Demystified June 01 2015
Keep in mind that there are two types of UV (ultraviolet) rays from the sun: UVA and UVB. UVA rays are primarily responsible for skin damage from excessive sun exposure that can lead to cancer and skin aging. Although UVB rays can also cause damage and sunburn, they are necessary for your body to produce its own cancer protective vitamin D via the skin.
Sunlight is by far the optimal way to produce your vitamin D. Blocking UVB rays may inadvertently be increasing your cancer risk by blocking vitamin D absorption.