Fact Sheet Osteoporosis Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased risk of fractures of the hip, spine, and wrist. It is often called a “silent” disease because it has no discernable symptoms until there is a bone fracture. Like other tissues in the body, bone tissue is in a state of constant flux – remodeling and rebuilding. There are many influences on bone mass and strength, such as genetics, hormones, physical exercise and diet (especially intake of calcium, phosphate, vitamin D, and other nutrients). Osteoporosis occurs when there are problems with these factors, resulting in more bone loss than bone rebuilding. Osteoporosis can strike at any age and affects both men and women. One out of every two women and one in four men over 50 will have an osteoporosis-related fracture in their lifetime. In the U.S. today, 10 million individuals already have osteoporosis and 34 million more have low bone mass, placing them at increased risk for this disease.