41.6 percent of US adults counted as deficient at one cutoff
Measured against 20 nanograms per millilitre, 41.6 percent of US adults counted as deficient, rising to 82.1 percent of Black adults. Move the line to 12 and the count falls.
What the study found
Four in ten US adults fall below a line nobody agrees on
Measured against 20 nanograms per millilitre, 41.6 percent of US adults counted as deficient, rising to 82.1 percent of Black adults and 69.2 percent of Hispanic adults. Move the line to 12 and the count falls sharply. That line was never built to diagnose anyone.
The caveat · Race stands in for sun, skin, diet
This is a snapshot of blood levels taken in 2005 and 2006, so it shows who sits below a line and never what being below it does to them. Race here stands in for skin pigmentation, sun exposure, diet and income all at once, rather than for anything measured biologically. Black Americans measure lowest without correspondingly worse bone density or fracture rates, which is the part the number does not explain.
What we don't know
This is a snapshot of blood levels taken in 2005 and 2006, so it shows who sits below a line and never what being below it does to them. Race here stands in for skin pigmentation, sun exposure, diet and income all at once, rather than for anything measured biologically. Black Americans measure lowest without correspondingly worse bone density or fracture rates, which is the part the number does not explain.