Natrol Vitamin D3 2000iu is the single most important nutrient recommended for supplementation! Vitamin D is usually obtained through diet or produced by the skin from the ultraviolet energy of the sun. Poor diet and lack of sun exposure can result in inadequate levels of Vitamin D for optimal health. Additionally, there are very few food sources that contain Vitamin D, making it even harder to obtain adequate amounts of Vitamin D, which is needed for superior health. Researchers now know that, in addition to building strong bones, Vitamin D helps regulate healthy cell growth, supports immunity, heart health, breast health, colon and prostate health, normal inflammatory response, and healthy aging. Research over the last decade suggests that vitamin D may be the single most important nutrient recommended for supplementation. Natrol Vitamin D3 2000iu is a great tasting Fast Dissolve tablet which dissolves up to 30 times faster than other pills. Natrol makes this product in the U.S.A.!