by Melissa Wdowik, Phd, Rdn

Vitamin DVitamin D is often called the sunshine vitamin and the key to healthy bones. While these are true attributes, they only tell part of the story. In fact, most people do not get enough vitamin D from the sun, and the consequences go way beyond your bones.

The role of Vitamin D in bone health is proven. This vitamin is critical in assuring the absorption of calcium in the digestive tract as well as into bones. It is needed for ongoing bone growth and remodeling, which occur in both children and adults. Early signs of inadequate vitamin D intake include bone pain and muscle weakness, symptoms that may be ignored or attributed to other causes. Along with calcium, vitamin D protects against the thin, brittle and misshapen bones of rickets, osteoporosis and osteopenia.

While research is inconclusive regarding the specific relationship between vitamin D and other health outcomes, a growing body of evidence shows it is involved in the prevention and treatment of diabetes, glucose intolerance, high blood pressure and multiple sclerosis. It also plays a role in inflammation, immune response, cell growth, neuromuscular function, muscle metabolism and cardiovascular disease. These associations point to a need to pay attention to getting enough vitamin D, whether through sunlight, diet or fortification.

Sunlight does enable the body to convert inactive vitamin D to its active form, D3, in the body via the liver and kidneys. Unfortunately, cloud cover, shade, pollution, glass windows and sunscreen all block UV rays, which produce vitamin D. Individuals with dark skin, head coverings and limited time outdoors are particularly unlikely to obtain adequate vitamin D from sunlight. Additionally, it is strongly suggested that the risk of skin cancer overrides the benefit you would receive from additional sun exposure.

Instead, dietary and supplemental vitamin D sources are more viable options. This nutrient is found naturally in only a few dietary sources, including fatty fish, fish liver oil, and egg yolks. It is also found in fortified milk, orange juice, and breakfast cereal. Be sure to check food labels and aim for the Recommended Dietary Allowance most days; this is 600 international units (IUs) for ages 1 to 70 years, and 800 IUs for anyone over the age of 70.

Many people may need a vitamin D supplement. If you do not get enough vitamin D from your diet, are elderly or obese, or have had gastric bypass surgery, you should consider supplementing with D3, as should anyone with inflammatory bowel disease, celiac disease, cystic fibrosis or liver disease. Check with your health-care provider about any potential negative interactions with medications.

For healthy bones and a healthy body, pay attention to vitamin D. Make it part of an overall balanced diet and stay physically active, which will benefit you in innumerable ways.

Provided by Colorado State University