Osteoporosis is a symptom-free disease until a fracture occurs DALLAS, Oct. 28 (UPI) -- Osteoporosis is a "silent" bone disease because most people -- the disease affects 10 million U.S. adults -- are unaware of it until a fracture, an expert said. Dr. Khashayar Sakhaee, chief of the mineral metabolism division at the University of Texas Southwestern Medical Center in Dallas, said most often osteoporosis affects postmenopausal women who undergo a dramatic drop in estrogen -- a hormone that assists in the absorption of calcium and prevents calcium loss from the bone. However, the disease can affect anyone with a hormone imbalance, including men who have been treated for prostate cancer. Proven osteoporosis risk factors include: race -- Caucasians have 50 percent to 60 percent more risk -- a family history of the disease, lack of exercise, low body weight and smoking. Patients who take high dosages of corticosteroids are also more susceptible to fragile bones, Sakhaee said. To help prevent development of the disease, Sakhaee advised to: Exercise and eat a healthy diet rich with vegetables, fruits and sources of dairy. Postmenopausal women and everyone older than 70 should get 1,200 milligrams of calcium every day through diet or supplements. The best source of calcium is always dairy products; one 8-ounce glass of milk includes 800 milligrams of calcium, and one slice of cheese or a single serving of yogurt both have about 200 to 300 milligrams of calcium. Postmenopausal women and people over 70 years of age should get 1,000 units of vitamin D each day. At age 50, all women should ask their physicians for a bone-density test.