Calcium is the most abundant mineral in the body, and most of it (about 99%) is deposited in the bone (about 1 kg). There is no doubt that calcium is a fundamental factor in prevention and treatment of osteoporosis. However, there is less agreement regarding precise recommendations for appropriate calcium intake. The calcium recommendation for adults is about 1000 (800–1500) mg a day. The higher values are required by teenage girls, pregnant and lactating women, postmenopausal women who are not taking oestrogen and both men and women over age 50. Today we ingest far less calcium than our ancestors did. In fact, studies reveal that three quarters of Americans are deficient in calcium, with an average intake of only 500–600 mg a day in their diet. For adolescents and young adults, the National Institutes of Health (NIH) consensus statement recommends 1200–1500 mg/day of elemental calcium.