The news is out: Vitamin D is a hormone (not a vitamin) that targets more than 2,000 genes in the body—that's 10 percent of the total number of genes in the human body. And that is not all. Deficiencies have been implicated in at least 17 different cancer types, cardiovascular disease, ankylosing spondylitis, birth defects, and more.

Research in the health benefits of vitamin D started in England's early 1600s when one of the earliest causes of Rickets—the softening of bone resulting in deformity and fractures—was discovered. By the 1900s the condition had reached epidemic proportions with at least 80 percent of all children showing signs of the disease. It was not until much later when it was discovered that fortifying milk with concentrations of vitamin D could actually prevent all forms of Rickets.

Close to one hundred years later, further research found additional medicinal benefits of vitamin D in the prevention or treatment of serious diseases. Researchers at the Mayo Clinic found that deficiencies were linked to autoimmune conditions (such as multiple sclerosis, rheumatoid arthritis, and diabetes). But, vitamin D doesn't just play a role in specific diseases and disorders-it affects the body in a variety of ways. Individuals suffering from vitamin D deficiency have a more difficult time with pain management, and deficiencies have been linked to Cancer, Parkinson's Disease, Depression, and other health issues. One other study found a relationship between vitamin D deficiency and increases in serum blood levels of Alkaline Phosphatase, a group of enzymes important for liver and bone health.

Vitamin D Deficiency Today

Twenty years ago, vitamin D deficiency was rare because it was so easily produced by the body with minimal sun exposure. Today however, vitamin D levels among most people are lower due to increased use of sunscreen and the manufacturing of specialized clothing designed to block the sun's UVB rays. Moreover, certain regions of the country carry an increased risk of deficiency due to limited sun exposure. For example, in the city of Boston, adequate sun exposure is limited to March through October.

Categorically, certain groups are more susceptible to deficiencies even with adequate sun exposure. For example, people who have darker skin tones have a greater concentration of pigment, melanin, in their skin, and this acts as a natural sunscreen.

The elderly are also at greater risk of vitamin D deficiency, and both biology and lifestyle play a part. As the body ages, it has a harder time synthesizing vitamin D, and the average elderly person also has a low calcium diet—and calcium is vital to the absorption of vitamin D. Babies may also need vitamin D supplementation. Breast milk contains inadequate amounts of the vitamin, infants on a strict breast milk regimen must supplement.

Vitamin D deficiencies can also occur when people have absorption difficulties, such as with malabsorption syndrome and inflammatory bowel disease (IBS). Other medical problems like hypercalcemia, hyperphosphatemia, and kidney or liver disease for example, can pose problems related to vitamin D absorption.

Treating Vitamin D Deficiency

Deficiencies are treated with both dietary changes and supplementation. The most nutrient-dense sources are found in fatty fish such as sardines, salmon, and eel, or in eggs and fortified milk. Over-the-counter vitamin D may be necessary in cases where dietary changes are insufficient or when a physician prescribes additional supplementation.

Conflicting data exists regarding the proper dosing of vitamin D supplementation, especially when mitigated by calcium needs. Since its initial recommended daily allowance (RDA) of 400 IU (10 ug) back in 1941, practitioners have attempted to use much higher doses. Today, however, the recommended daily dose hovers around 600 IU with increasing doses dependent upon ability to metabolize vitamin D. The American Cancer Society recommends people stay below 2000 IU daily.

Vitamin D should not be taken with certain medications, as it can interfere with proper absorption of magnesium containing antacids, corticosteroids, Thiazide diuretics, and cardiac glycosides for example. Lastly, those individuals who are allergic to ergocalciferol or any derivative of the vitamin should refrain from supplementation.

Remember, vitamin D is important, not just for developing and maintaining strong bones, but for combating diseases, and pain management. Speak to your health care provider about supplementing your diet with vitamin D.

More on Nutritional Supplements from Naturally Savvy

Dr. Linda Mundorff