Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis. Adequate calcium and vitamin D is also important for teens, young adults and post-menopausal women. Each serving of Nature Made Calcium 500 mg with Vitamin D provides 500 mg of Calcium and 10 mcg (400 IU) of Vitamin D3. Calcium helps support strong bones and teeth. Vitamin D helps improves calcium absorption. One tablet taken twice daily meets recommended daily calcium requirements for adults ages 18 to 50.