Vitamin D-3 10,000 IU, 240 Softgels, Source NaturalsSource Naturals Vitamin D3 Bone and Immune Health. 10000IU Softgels. Sunlight is a source of life on Earth, but we may not be aware of all the ways it benefits us. Our bodies manufacture vitamin D 3 when the skin is exposed to UV radiation from sunlight, but the ability to do so decreases as we age. Vitamin D 3 helps maintain healthy calcium and phosphorus levels in the body for strong bones, it helps maintain muscle strength in older adults, and it