Three factors essential for keeping your bones healthy throughout your life are:

  • Adequate amounts of calcium
  • Adequate amounts of vitamin D
  • Regular exercise

Calcium

Men and women between the ages of 18 and 50 need 1,000 milligrams of calcium a day. This daily amount increases to 1,200 milligrams when women turn 50 and men turn 70. Good sources of calcium include:

  • Low-fat dairy products (200 to 300 milligrams per serving)
  • Dark green leafy vegetables
  • Canned salmon or sardines with bones
  • Soy products, such as tofu
  • Calcium-fortified cereals and orange juice

If you find it difficult to get enough calcium from your diet, consider taking calcium supplements. However, too much calcium has been linked to heart problems and kidney stones. The Institute of Medicine recommends that total calcium intake, from supplements and diet combined, should be no more than 2,000 milligrams daily for people older than 50.

Vitamin D

Vitamin D improves your body's ability to absorb calcium. Many people get adequate amounts of vitamin D from sunlight, but this may not be a good source if you live in high latitudes, if you're housebound, or if you regularly use sunscreen or avoid the sun entirely because of the risk of skin cancer.

Scientists don't yet know the optimal daily dose of vitamin D. A good starting point for adults is 600 to 800 international units (IU) a day, through food or supplements. If your blood levels of vitamin D are low, your doctor may suggest higher doses. Teens and adults can safely take up to 4,000 international units (IU) a day.

Exercise

Exercise can help you build strong bones and slow bone loss. Exercise will benefit your bones no matter when you start, but you'll gain the most benefits if you start exercising regularly when you're young and continue to exercise throughout your life.

Combine strength training exercises with weight-bearing exercises. Strength training helps strengthen muscles and bones in your arms and upper spine, and weight-bearing exercises — such as walking, jogging, running, stair climbing, skipping rope, skiing and impact-producing sports — affect mainly the bones in your legs, hips and lower spine.

Swimming, cycling and exercising on machines such as elliptical trainers can provide a good cardiovascular workout, but because such exercises are low impact, they're not as helpful for improving bone health as weight-bearing exercises are. There is evidence that competitive cyclists have reduced bone mineral density. They should combine strength training and weight-bearing exercises and consider a test for osteoporosis.