Vitamin D is being rediscovered. Mainstream views that have dominated nutritional science over the past several decades focus on vitamin D’s role in calcium metabolism and bone health. The recommended vitamin D intakes for adults have been from 200 to 600 IU per day. And reference values for blood levels of circulating vitamin D (indicating adequate vitamin D status) stand at 30-40 ng/ml. But all of this is being revised.
Recent research shows that our conventional wisdom concerning vitamin D is far too narrow and limiting. We now know that, in addition to maintaining bone health, sound vitamin D nutrition plays important roles in supporting cardiovascular health, preventing some cancers, promoting robust and balanced immune function, maintaining sound muscle function, normalizing glucose levels, and more. In my opinion the scientific evidence clearly indicates that the optimal range for circulating vitamin D is 40-80 ng/ml, far higher than the current reference range. Moreover, it is becoming clear that vitamin D intakes in the neighborhood of 2,000 IU per day (and up to 4,000-5,000 IU per day during winter months) are needed to maintain these concentrations.
Unfortunately, this news comes late for many of us. The conventional wisdom has not served us well. Very high percentages of people around the world, particularly those living in temperate climates, are chronically deficient for vitamin D, and their health has suffered because of it. Up to 40% of the U.S. population is vitamin D deficient, and certain groups, such as the elderly, have even higher rates. In the weeks ahead, I will be sharing with you my thoughts on what each of us needs to do to get the amounts of vitamin D we truly need. Stay tuned.