Tufts University Confirms That Vitamin A Protects Against Vitamin D Toxicity by Curbing Excess Production of Vitamin K-Dependent Proteins
Tufts University confirmed my hypothesis that vitamin A protects against vitamin D's induction of renal calcification (kidney stones) by normalizing the production of vitamin K-dependent proteins in December, 2008, without citing my hypothesis or telling me they had confirmed it. I am, of course, very grateful that they thought it significant enough to investigate.
Estimation of the dietary requirement for vitamin D in free-living adults >=64 y of age.
Cashman KD, Wallace JM, Horigan G, Hill TR, Barnes MS, Lucey AJ, Bonham MP, Taylor N, Duffy EM, Seamans K, Muldowney S, Fitzgerald AP, Flynn A, Strain JJ, Kiely M.
Am J Clin Nutr. 2009 May;89(5):1366-74. Epub 2009 Mar 18.
PMID: 19297462
doi:10.3945/ajcn.2008.27334
Conclusion: To ensure that the vitamin D requirement is met by the vast majority (>97.5%) of adults aged ≥64 y during winter, between 7.9 and 42.8 µg vitamin D/d is required, depending on summer sun exposure and the threshold of adequacy of 25(OH)D. .