Vitabiotics Ultra Vitamin D 1000 IU Optimum level 96 tablets support normal immune system function. Ultra Vitamin D provides 1000 IU vitamin D3. Safeguarding the diet with vitamin D is recommended to help maintain optimum levels throughout the year, during the winter months. The tablets are important for those who have restricted or limited exposure to the sun. Vitamin D plays a truly remarkable role in the body for all-around health and wellness. It contributes to the normal function of the immune system, normal absorption and utilisation of calcium in the body and the maintenance of normal bones and teeth, and the maintenance of normal muscle function. Vitamin D also has an important role in the process of cell division. It also contains Vitamin D3 (cholecalciferol), the preferred form of vitamin D produced naturally by the body on exposure to sunlight.