Osteoporosis, calcium requirement, and factors causing calcium loss

A large percentage of subjects receiving a normal calcium intake of 800 mg per day was in negative calcium balance and increasing the calcium intake to various levels up to 2200 mg per day showed a plateau of the calcium balance at the 1200 mg per day intake, indicating a threshold of calcium absorption at this intake level. Dietary factors, such as a phosphorus intake up to 2000 mg per day and complex proteins, such as red meat, do not cause calcium loss. Several commonly used drugs induce significant calcium loss, particularly aluminum-containing antacids, and, if used for prolonged periods of time, can contribute to the development of osteoporosis.