1 On his Vitamin D Council web site, Cannell now recommends blood levels of
calcidiol between 50 and 80 ng / mL53 and supplementation of 1,000 IU for every 25 pounds of bodyweight.2 For someone weighing between 150 and 175 pounds, he thus recommends between 6,000 and 7,000 IU per day from all sources.