In response to the plethora of new studies about vitamin D and resulting need for direction, the American and Canadian governments asked the Institute of Medicine (IOM) for guidance. New IOM recommendations were released on November 30, 2010, taking into account expert testimony and new data from nearly 1000 studies.[1] The panel found a large amount of evidence confirming the importance of vitamin D and calcium in maintaining bone health, so they focused on both. The panel acknowledged that more definitive research is needed to determine fully the role, if any, of vitamin D in preventing other diseases, including heart disease, cancer, autoimmune diseases, and diabetes.
These new IOM guidelines set recommended dietary allowances of vitamin D at 600 IU per day for everyone age 1 through 70, and at 800 IU for adults age 71 and older. The panel concluded that serum levels of 25- hydroxyl-vitamin D in the range of 20-30 ng/mL are sufficient for bone health. This level is generally attainable without adding supplements, but supplements are usually required to get blood levels above 30 ng/mL. The panel warns that when evaluating vitamin D blood tests, check the units carefully. Although the United States expresses measurements in nanograms per milliliter, other countries, including Canada, use nanomoles per liter. The panel also expressed concerns about current vitamin D blood testing, including standardization of methodology and cut-off points for results.
As for calcium, the new IOM guidelines say adolescents age 9 through 18 need the most: 1300 mg per day. They also worry that adolescent girls, in particular, might not be getting enough. For men and women age 19 through 50, the recommended dietary allowance of calcium is 1000 mg. Women should increase intake to 1200 mg starting at age 51, while men should increase calcium intake to 1200 mg starting at age 71. The panel also warned that postmenopausal women may be taking in too much, thus increasing risk for kidney stones.
How much is too much? The panel set limits. For vitamin D, intake should be no more than 4000 IU daily and for calcium, no more than 2000 mg daily. The new IOM recommendations for vitamin D and calcium for bone health are thoughtful, cautious, and conservative as expected from this esteemed blue-ribbon panel.
Meanwhile, the vitamin D story continues to unfold as new studies emerge about its possible role in other diseases.
References
http://www.medscape.com/viewarticle/735575?src=ptalk
