Very interesting stuff. Thanks!

This is rather old research you are citing on vitamin D. We used to believe that doses in the range of 3000-5000 IU were producing elevated levels in serum, but that was before the range for normal was adjusted from 20 being the low normal to 32 being the low normal. Some recent medical studies are now using 50 and the low normal. When we redefine what we consider to be normal values for a nutrient like this, the levels needed on a daily basis to keep an average number of people in the population healthy changes dramatically. Emerging research is starting to support levels of 2000 to even 10,000 IU of D3 daily as not only safe but possible necessary to keep people healthy based on this new definition.

I am the original blogger. The key question is not what happens to serum vitamin D as intake increases; rather, it is clinical consequences. And benefits and risks can coexist at the same intake. Admittedly, the hypercalcemia study
referred to in the 1997 UL determination for vitamin D was conducted in 1984. Hathcock [Am J Clin Nutr 2007;85:6-18] more recently admirably reviewed the literature and recommended a UL of 10,000 IU/day. I personally expect the IOM report in 2010 will raise the Adequate Intake to 1000 IU but be more conservative in raising the UL from the current 2000 IU, if at all. Maybe to 3000 IU. The suspected risks include renal stones and calcification of arteries and other soft tissues. Regardless, the point of the blog was that right now 5000 IU products are “outside the pale” and subject to regulatory warnings.