There are things you should do at any age to prevent weakened bones. Eating foods that are rich in calcium and vitamin D is important. Getting enough calcium all through your life helps to build and keep strong bones. Women over age 50 need 1,200 mg (milligrams) of calcium every day. Men need 1,000 mg between ages 51 and 70 and 1,200 mg after age 70. Eat low-fat dairy foods, canned fish with soft bones such as salmon, and some dark-green leafy vegetables. Check labels on foods such as orangenjuice, breads and cereals to find those with calcium added.
Your body uses vitamin D to absorb calcium. Most people’s bodies are able to make enough vitamin D if they are out in the sun without sunscreen for 10 to 15 minutes at least twice a week. You can also get vitamin D from eggs, fatty fish, and cereal and milk fortified with vitamin D. If you think you are not getting enough vitamin D, check with your doctor. Each day you should have 600 IU (International Units) if you are age 51 to 70 and 800 IU if you are over age 70. Check with your doctor to verify the right amounts of calcium and vitamin D for you.
— Source: National Institute on Aging