Vitamin D, Calcium, and Bone Health

Dr. Nicholas Kaloudis

Bone is a living tissue that is constantly breaking down and being replaced. Throughout your life, your body balances the loss of bone with the creation of new bone. You reach your highest bone mass at about age 30. After that, you begin to lose bone size and strength.

Over time, bone loss can cause osteopenia (low bone mass) and then osteoporosis, a condition in which bones become weak and are more likely to break. Fractures can cause serious health problems, including disability.

Getting enough Vitamin D and Calcium is important in keeping your bones healthy and reducing your chances of developing osteopenia or osteoporosis. Regular, weight bearing exercise also keeps your bones strong.

Vitamin D allows your body to absorb calcium. Vitamin D is the only vitamin made by your own body. Other vitamins like A, B, and C only come from food and supplements. It is a fat-soluble vitamin, which means it is stored in the body’s fatty tissue. People normally get enough Vitamin D through exposure to sunlight, which triggers Vitamin D production in the skin, liver and kidneys. Vitamin D is found naturally in very few foods. In the U.S., it is routinely added to milk and infant formula. Other good food sources are egg yolks, and some types of fish such as salmon and mackerel. You probably don’t get enough Vitamin D: if you spend little time in the sun. Use a strong sunblock. If you have very dark skin. If you are over the age of 50, when the body is less able to make and use Vitamin D efficiently. If you have certain medical conditions such as diseases of the digestive system that interfere with fat and Vitamin D absorption. And if you are overweight, because Vitamin D gets “trapped” in body fat and becomes less available for the needs of the body.

Calcium is necessary for building strong, healthy bones. It is a mineral with many functions. Most of the body’s calcium is stored in the bones and teeth, where it supports their structure. Calcium mainly comes from the foods you eat. Good sources of calcium include dairy products, canned fish, and green leafy vegetables. Like Vitamin D, calcium is also available in supplements. You may need extra calcium if you are a post-menopausal female, or you eat few or no dairy products, or you have a digestive disease that interferes with nutrient absorption. Without enough Vitamin D and calcium, bones may not form properly in childhood and can lose mass, become weak, and break easily in adulthood. Even if you get enough calcium in your diet, your body will not absorb that calcium if you don’t get enough Vitamin D.

The recommended daily intake of Vitamin D and Calcium for adults is:

• If under the age of 50: 400 to 800 IU of Vitamin D and 1,000 mg of Calcium
• If over the age of 50: 800 to 1200 IU of Vitamin D and 1,200 mg of Calcium