1. Osteoporosis Slideshow Pictures
2. Super Foods for Your Bones Slideshow Pictures
3. Take the Osteoporosis Quiz

Medical Author:

Bruce A Baethge, MD

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Bone is made mostly of collagen, a protein that is woven into a flexible framework. Bone also contains calcium phosphate and calcium carbonate, minerals that add strength and harden the framework. The combination of calcium and collagen gives the bone its strength and flexibility. The flexibility (or ability to withstand stress) of the bone protects it from breaking. Bone is strong because of calcium, but bone also acts like a storehouse for calcium. In fact, more than 99% of the body's calcium is contained in the bones and teeth. The remaining 1% is in the blood.

Even though it is mostly made of protein and minerals, bone is living, growing tissue. Throughout a person's lifetime, old bone is broken down (a process called resorption) and new bone is added to the skeleton (formation). When more bone is broken down than is added to the skeleton, bone loss occurs.

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