Recently published data indicated that the Food and Nutrition Board (FNB) made a statistical error when arriving at the recommended dietary allowance (RDA) for vitamin D in 2010. Dr. Cannell covered this paper in a blog.
The statisticians estimated that 8,895 IU daily of vitamin D is needed to get 97.5% of the population above 20 ng/ml, or the level considered sufficient by the FNB. However, the analysis possessed a major limitation: there was no available data on individuals receiving over 2,400 IU daily.
In a letter to the statisticians, Dr. Heaney and colleagues confirmed that higher supplementation is needed to reach healthy vitamin D levels in 97.5% of the population by using data from the GrassrootsHealth Study (GRH).
GRH has compiled data from 3,657 individuals with vitamin D intakes ranging from zero to above 10,000 IU daily. Heaney and colleagues found that 3,875 IU, 6,201 IU, and 9,122 IU daily of vitamin D corresponded to vitamin D levels of 20 ng/ml, 30 ng/ml, and 40 ng/ml, respectively.
The vitamin D dosages only accounted for supplements, and excluded vitamin D intake from the sun and food. The researchers estimated that the intake from the sun and food amount to be around 3000 IU daily.
“Since an RDA, by definition, relates to intake from all sources, it is clear that total intake required to achieve 20 ng/mL in 97.5% of the cohort must be close to 7000 IU per day, not substantially different from that calculated by Veugelers and Ekwaru.”