by Helen Thompson October 25, 2012 (NPR)
Researchers largely agree that about half of Americans are probably not getting enough vitamin D from the places we’ve traditionally gotten it: food and sunlight. And that’s a problem because vitamin D keeps calcium from leaking out of our bones; too little vitamin D can also be a factor in kidney disease and skeletal problems.
Public health institutions have debated how much is enough, and when to add supplements to the diet. Two years ago, the IOM reported that having about 20 nanograms per milliliter (ng/mL) of vitamin D in your bloodstream was sufficient (about 600 units per day). Meanwhile hormone specialists at the Endocrine Society have told consumers to stick with the old cut off: 30 ng/mL. Doctors aren’t sure whose rules to follow.
A new study supports the IOM guidelines for a lower minimum vitamin D requirement vitamin D supplements. The study, led by Holly Kramer, a nephrologist at Loyola University Medical Center, found that mortality rates don’t change much whether you have levels of 20 ng/ML or 40 ng/ML in your bloodstream on a daily basis…