What you know about your bones
Bones support your body and allow you to move. They protect your brain, heart, and other organs from injury.
Bone is a living, growing tissue. It is made mostly of two materials: collagen (KOL-uh-juhn), a protein that provides a soft framework, and calcium (KAL-see-uhm), a mineral that adds strength and hardness. This combination makes bone strong and flexible enough to hold up under stress.
Bone releases calcium and other minerals into the body when you need them for other uses.
Think of your bones as a “bank” where you “deposit” and “withdraw” bone tissue.
How bones grow
Think of your bones as a “bank” where you “deposit” and “withdraw” bone tissue. During your childhood and teenage years, new bone is added (or deposited) to the skeleton faster than old bone is removed (or withdrawn). As a result, your bones become larger, heavier, and denser.
For most people, bone formation continues at a faster pace than removal until sometime after age 20. After age 30, bone withdrawals can begin to go faster than deposits. If your bone deposits don’t keep up with withdrawals, you can get osteoporosis (ah-stee-oh-puh-ROH-sis) when you get older. Osteoporosis is a disease in which the bones become weak and more likely to break (fracture). People with osteoporosis most often break bones in the hip, spine, and wrist.
For more information
NIH Osteoporosis and Related Bone Diseases ~ National Resource Center
If you need more information about available resources in your language or another language, please visit our website or contact the NIAMS Information Clearinghouse at NIAMSinfo@mail.nih.gov.
This fact sheet was made for you by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the U.S. Department of Health and Human Services’ National Institutes of Health. For more information about the NIAMS, call the information clearinghouse at 301-495-4484 or toll free at 877-22-NIAMS (226-4267) or visit the NIAMS website at www.niams.nih.gov.
NIH Publication No. 15-7577(B)
For information about healthy bones, visit:
- Juvenile Osteoporosis
- Surgeon General’s Report on Bone Health and Osteoporosis. What It Means to You
For information on calcium and vitamin D, visit the NIH Office of Dietary Supplements:
For information about a balanced diet, visit:
For information on physical activity, visit: