Vitamin D has been widely touted as a miracle" vitamin having a myriad of health effects beyond its basic function of enabling the absorption of calcium from food. Although vitamin D plays an important role in bone health and should be consumed in the form of food or a supplement if necessary there is such a thing as too much vitamin D. A new commentary in the Journal of the American Medical Association written by Drs. JoAnn E. Manson and Shari S. Bassuk of the Division of Preventive Medicine at Brigham and Women s Hospital in Boston discusses this health concern.
Authors emphasize that somehow we ve arrived at a point when some physicians are prescribing large doses of Vitamin D supplements for their patients in the hope of preventing cancer, cardiovascular disease, diabetes, autoimmune disorders and other maladies, despite the lack of evidence that this works. A healthy individual between the ages of 1 and 70 should be consuming 600 international units (IU) of vitamin D daily. That number increases to 800 IUs for individuals over 70, according to the Institute of Medicine. These numbers do not apply to those with clinical conditions or risk factors associated with vitamin D insufficiency such as osteoporosis. However, consuming over 4000 IUs can put one at risk for kidney stones or calcification of blood vessels according to Dr. Manson.
Yet, because of the media attention focused on studies of vitamin D that may seem to suggest some benefit beyond what is scientifically proven at this point, the general consensus surrounding vitamin D is that more is better.
Dr. Manson is currently conducting a clinical trial of almost 26,000 individuals looking at the role of vitamin D in cancer, cardiovascular disease, diabetes, depression, infection, autoimmune disorders and other conditions. However, Drs. Manson and Bassuk urge that doctors should exercise caution and while awaiting the results of the large trials now in progress, physicians would be well advised to follow current USPSTF and IOM recommendations and avoid overscreening and overprescribing supplemental vitamin D.
ACSH s Ariel Savransky adds, The problem is not only that physicians are prescribing vitamin D to patients in the hopes of preventing cancer or cardiovascular disease, among other health effects, but also that individuals believe that the more of a supplement you take the better. And as Drs. Manson and Bassuk point out, the media attention does not help to disprove this viewpoint. However, the fact is that too much vitamin D can be detrimental and doctors should be aware of this fact and should not be prescribing a vitamin D supplement to patients unless there is a medical justification for the prescription. And of course, individuals should consult with a physician before deciding to take a supplement.