Витамин D, децата, майките, възрастните и зимата...8

The error originated with the Institute of Medicine (IOM) , now the National Academy of Medicine, when it set the RDA for vitamin D at 600 IU/day for most adults.

The goal was to set an intake level that would ensure 97.5% of the population reached a minimum healthy blood level of 20 ng/mL (50 nmol/L).

The core mistake, as identified by researchers, was in the statistical method. Instead of analyzing individual participant data, the IOM averaged results at the study level—an "average of averages" approach. This method smoothed out natural biological variation between individuals, leading to a significant underestimation of the intake required to protect nearly everyone in a population, not just the average person.
The Corrected Calculation

The corrected analysis was published in 2014 by researchers Paul Veugelers and John Paul Ekwaru from the University of Alberta. Using the exact same dataset as the IOM, they re-ran the statistical models correctly.

Their conclusion was that to ensure 97.5% of individuals achieve the target blood level, the daily intake would need to be 8,895 IU—more than ten times the official recommendation.
Key Sources and Context

This finding has been discussed in several publications and analyses:

    "The Big Vitamin D Mistake" (2017): A paper by Dimitrios T. Papadimitriou explicitly states that a statistical error was discovered and that a correct analysis found 8895 IU/d was needed for 97.5% of individuals to achieve the target level.

    GrassrootsHealth: This nonprofit research organization has extensively covered the error. They explain that the mistake was confusing population averages with individual requirements and confirm the corrected figure of 8,895 IU/day.

    Medical Commentary: Dr. Caroline Fife, M.D., has also written about the error, noting that the IOM's calculation was flawed and that the requirement to get 97.5% of the population to a sufficient level would be 8,895 IU per day.

    National Academies Response: The National Academies has published responses acknowledging the claims of mathematical errors in its 2011 report, indicating the issue has been formally raised.