by James Lyons-Weiler, PhD, Popular Rationalism, ©2026
(May 20, 2026) — Public health failures do not always begin with corruption. Sometimes they begin with a spreadsheet.
For more than a decade, the United States has operated under vitamin D intake recommendations that many researchers now believe substantially underestimate the intake required for much of the population to achieve adequate vitamin D status. The dispute is not fringe speculation. It emerged from a published statistical critique of the Institute of Medicine’s (IOM) own methodology—a critique that has never been fully resolved at the policy level despite broad acknowledgment that the criticism raised legitimate concerns. (MDPI)
The result is one of the most consequential unresolved disputes in modern nutritional science: whether millions of Americans—including pregnant women, children, the elderly, darker-skinned individuals living in northern latitudes, and heavily indoor populations—have been systematically underdosed because policymakers confused averages with individuals.
The story begins with the 2011 IOM report Dietary Reference Intakes for Calcium and Vitamin D. That report established the now-familiar recommendations of 600 IU/day for most adults, 800 IU/day for older adults, and a tolerable upper intake limit (UL) of 4,000 IU/day. The committee concluded that these intakes would place 97.5% of the population above a serum 25-hydroxyvitamin D [25(OH)D] level of 50 nmol/L (20 ng/mL), the threshold associated with bone health sufficiency.
The problem is that the mathematics used to derive that conclusion appears to have been wrong.
In 2014, University of Alberta researchers Paul Veugelers and John Paul Ekwaru published A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Their criticism was devastatingly simple: the IOM had interpreted prediction intervals around study averages as though they described individual people.
That may sound technical. It is not.
To help explain the problem, imagine a transportation engineer trying to determine how high a bridge must be so that 97.5% of trucks can pass underneath safely.
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