GNC Calcium With Vitamin D-3: Supports Healthy Bones* GNC calcium supplements are a great way to support bone health. Calcium is essential for building and maintaining strong bones and teeth. It also plays an important role in proper nerve and muscle function. Vitamin D regulates calcium absorption. Because getting enough vitamin D can be tough in certain climates, especially during the winter months, the added vitamin D3 helps this supplement work properly. Vitamin D3 is the best form of vitamin D as it’s absorbed well and used effectively by the body. GNC Calcium With Vitamin D-3 provides 600 mg of calcium carbonate and 400 IU of vitamin D3. Calcium is essential for healthy bones and teeth* Vitamin D is essential for the absorption of calcium Vitamin D3 is the most bioavailable form of vitamin D These statements have not been evaluated by the Food & Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.