Bone is a living tissue that is constantly breaking down and being replaced. Throughout life, your body balances the loss of bone with the creation of new bone. You reach your highest bone mass (size and strength) at about age 30, usually between ages 20 to 25. After that, you begin to lose bone mass.
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 (fracture). Fractures can cause serious health problems, including disability and premature death. 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 helps keep your bones strong.
Vitamin D allows your body to absorb calcium. Calcium is necessary for building strong, healthy bones. 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.
Vitamin D is a hormone, although most commonly known as a fat-soluble vitamin, which means it is stored in the body’s fatty tissue. People normally get vitamin D through exposure to sunlight, which triggers vitamin D production in the skin.
Vitamin D is found naturally in very few foods. In the United States, 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. Vitamin D is also available in nutritional supplements. Vitamin D is the only vitamin made by your own body. Other vitamins, like A, B, and C only come from food and supplements.
Calcium 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 (milk, cheese, yogurt); calcium-fortified products (foods and beverages with added calcium); canned fish with bones; and green, leafy vegetables. Like vitamin D, calcium is also available in supplements.