Solgar Vitamin D3 1000IU Softgel contains 25 mcg (1000 IU) Vitamin D3 (Cholecalciferol) as convenient oil-based softgels are easy to swallow and absorb. Vitamin D is required to promote calcium absorption, which helps to maintain healthy bones and teeth. Vitamin D also supports a healthy immune system. Vitamin D3 in this product is the same form produced by the body when our skin is exposed to sunlight. As we age, our bodies may produce this important nutrient less efficiently. This formulation is offered in oil-based softgels to promote optimal absorption and assimilation.