Cartoons of woman walking in sunshine, calcium rich foods and a woman lifting weights.Our bones are alive. We might not think of them that way—but to keep themselves strong and usable, our bones are always changing. “Bone is living, growing tissue,” says Dr. Joan McGowan, a scientist at NIH. “It’s constantly breaking down and building up. It keeps refreshing itself.”

But as you get older, your bones may be at increased risk for osteoporosis (oss-tee-oh-pore-OH-sis), when the bones become weak, fragile and more likely to break. And once they break, they take longer to heal. This can be both painful and expensive. Current estimates suggest that around 10 million people in the U.S. have osteoporosis, and 34 million more have low bone mass, which places them at increased risk. 

Osteoporosis is a “silent” disease. You may not realize you have it until a sudden strain, twist or fall causes a broken bone (also called a “fracture”). With osteoporosis, even a minor tumble can be serious, requiring surgery and hospitalization. If you have osteoporosis, you can get a broken bone even though you haven’t fallen—by shoveling snow, for example.

A spinal fracture, a break in one of the small bones in your back, may be subtle and go unnoticed. Or it may cause back pain, which you shouldn’t ignore. “A large part of osteoporosis and fracture risk is inherited,” says McGowan. “If close relatives have suffered a fracture in their later years, this may be a clue to think carefully about your own risk. But diet and physical activity are major ways to build and maintain the best possible skeleton.”

NIH-funded research shows that childhood is the best time to build up bone tissue. Most bone is built by age 18 in girls and 20 in boys. Start with a well-balanced diet rich in calcium and vitamin D. Most of our bone is made of a rigid protein framework. Calcium (a mineral) adds strength and hardens that framework. Vitamin D helps the intestine absorb calcium.

Calcium is found in many foods, but the most common source for Americans is milk and other dairy products. One 8-ounce glass of milk provides about one-third of the recommended intake for younger children and about one-fourth of the recommended intake for teens. Your body makes vitamin D in the skin when you’re out in the sun. Some people get all they need from sunlight, but others need to take vitamin D pills. Talk to your doctor or see the chart at to find out how much calcium and vitamin D you should get each day.

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