Vitamin D (as cholecalciferol) is a fat-soluble vitamin. It is known as the "sunshine" vitamin because it is formed in the body from the sun's ultraviolet rays on the skin. A key function of Vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, thereby helping to form and maintain strong bones. Without Vitamin D, bones can become thin, brittle, soft, or misshapen.
Deficiency of vitamin D has been linked to a variety of diseases including heart disease, cancer, and diabetes, yet three out of four Americans aren’t getting enough vitamin D, and most don’t even know it.
Who’s at risk? People who get very little sun exposure, and those with dark skin, since the pigment melanin reduces the skin’s ability to produce vitamin D. Being overweight also increases risk, since body fat stores more of the fat-soluble vitamin D, and doesn’t release as much into the bloodstream. And over the age of 50, our skin can’t make vitamin D as efficiently, so supplementation may be warranted.
How do you know if you need to supplement with vitamin D? It is recommended that you see your physician to have your 25 (OH) levels tested. If you are deficient, your physician can help you determine what supplement dosage is best for you.