What is osteoporosis?

Osteoporosis, which means "porous bones," causes bones to become weak and brittle — so brittle that even mild stresses like bending over, lifting a vacuum cleaner or coughing can cause a fracture. In most cases, bones weaken when you have low levels of calcium, phosphorus and other minerals in your bones. 

A common result of osteoporosis is fractures — most of them in the spine, hip or wrist. Although it's often thought of as a women's disease, osteoporosis also affects many men. And aside from people who have osteoporosis, many more have low bone density. 

It's never too late — or too early — to do something about osteoporosis. You can take steps to keep bones strong and healthy throughout life. 

Causes

The strength of your bones depends on their size and density; bone density depends in part on the amount of calcium, phosphorus and other minerals bones contain. When your bones contain fewer minerals than normal, they're less strong and eventually lose their internal supporting structure. 

Scientists have yet to learn all the reasons why this occurs, but the process involves how bone is made. Bone is continuously changing — new bone is made and old bone is broken down — a process called remodeling, or bone turnover. 

A full cycle of bone remodeling takes about two to three months. When you're young, your body makes new bone faster than it breaks down old bone, and your bone mass increases. You reach your peak bone mass in your mid-30s. After that, bone remodeling continues, but you lose slightly more than you gain. At menopause, when estrogen levels drop, bone loss in women increases dramatically. Although many factors contribute to bone loss, the leading cause in women is decreased estrogen production during menopause. 

Your risk of developing osteoporosis depends on how much bone mass you attained between ages 25 and 35 (peak bone mass) and how rapidly you lose it later. The higher your peak bone mass, the more bone you have "in the bank" and the less likely you are to develop osteoporosis as you age. Not getting enough vitamin D and calcium in your diet may lead to a lower peak bone mass and accelerated bone loss later.

Fractures are the most frequent and serious complication of osteoporosis. They often occur in your spine or hips — bones that directly support your weight. Hip fractures usually result from a fall. Although most people do relatively well with modern surgical treatment, hip fractures can result in disability and even death from postoperative complications, especially in older adults. Wrist fractures from falls also are common. 

What keeps bones healthy

Three factors that you can influence are essential for keeping your bones healthy throughout your life: 

Regular exercise 
Adequate amounts of calcium 
Adequate amounts of vitamin D, which is essential for absorbing calcium 

Prevention

Getting adequate calcium and vitamin D is an important factor in reducing your risk of osteoporosis. If you already have osteoporosis, getting adequate calcium and vitamin D, as well as taking other measures, can help prevent your bones from becoming weaker. In some cases you may even be able to replace bone you've lost. 

The amount of calcium you need to stay healthy changes over your lifetime. Your body's demand for calcium is greatest during childhood and adolescence, when your skeleton is growing rapidly, and during pregnancy and breast-feeding. Postmenopausal women and older men also need to consume more calcium. As you age, your body becomes less efficient at absorbing calcium, and you're more likely to take medications that interfere with calcium absorption.