Vitamin D Deficiency: To Supplement or Not?

There has been a significant increase in the number of lab tests ordered by physicians to determine vitamin D levels in the last couple of years, as exhibited by reports from the Mayo Clinic which reported a 74% increase from 2006 to 2007 and from Quest Diagnostics which reported an 80% increase from May 2007 to May 2008. Both labs are top diagnostic labs in the U.S.

Before these two years, testing for vitamin D deficiency was an uncommon occurrence. Recent research, though, has linked a deficiency in vitamin D with a number of diseases, including cancer, some infectious diseases, cardiovascular disease, and some autoimmune diseases. Coupled with research that suggests many Americans are deficient in vitamin D, these research findings have spurned physicians to find out whether many of their patients have the deficiency.

What isn't so certain is what should be done for those found to have vitamin D deficiencies. Most often the treatment is to encourage the patient to eat a diet higher in vitamin D-rich foods, such as fortified milk, sardines, salmon, and mackerel, along with a vitamin D supplement.

Exposure to the UV rays of sunlight also activates one form of vitamin D in the body, but risks of skin cancer from those same rays deters many people from exposure.

Professor of medicine, physiology, and biophysics, Michael Holick, of Boston Medical School has stated that everyone needs to take 1000 IU of vitamin D daily; the Institute of Medicine recommends 200 IU daily for children and 400 IU daily for adults (Mary Brophy Marcus, Vitamin D Tests Soar as Deficiency, Diseases Linked, USA Today, 2008, July 14).

Janet Pregler, director of the Iris Cantor-UCLA Women's Health Center, states the question remains,"Will supplementing D-deficient patients prevent disease?" (M.B. Marcus, USA Today, 2008, July 14).

Pregler isn't the only health care professional who is verbalizing doubts about the efficacy of supplementing with vitamin D for prevention of disease. Dr. Trevor Marshall, professor at Australia's Murdoch University School of Biological Medicine and Biotechnology, relates his concern that supplementing with vitamin D may have an immunosuppressive effect on the body.

As Marshall explains, "Vitamin D is a secosteroid hormone, and the body regulates the production of all it needs. In fact, the use of supplements can be harmful, because they suppress the immune system so that the body cannot fight disease and infection effectively" (http://www.sciencedaily.com­ /releases/2008/01/080125223302.htm).

At this point, Marshall's research has yet to determine if the D-deficiency isn't part of the disease process, rather than the cause of the diseases.

Vitamin D affects the expression of more than 1,000 genes, according to experts, making the understanding of vitamin D and disease all the more complex to understand. According to Marshall, studies of people who are supplementing with vitamin D are not shown to be healthier than those who don't, or healthier than they were before they began supplementation.