Geri-Care Vitamin Supplement Vitamin D3 1,000 IU Strength Tablet 200 per Bottle - BottleVitamin Supplement Geri Care Vitamin D3 1,000 IU Strength Tablet 200 per Bottle Vitamin D 3 is necessary because your body can only absorb calcium, the dominant component of bones, when it has enough vitamin D; vitamin D also regulates many other cellular functions in your body. One vitamin D 3 (as cholecalciferol) tablet provides 125% of the daily value of vitamin D.