Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004.
Level 4 - case-series / case-control
Repeated cross-sectional population surveys (NHANES)
PubMed 19307527 · doi:10.1001/archinternmed.2008.604
What was done
Researchers compared serum 25-hydroxyvitamin D (25[OH]D) concentrations from two nationally representative US cohorts: NHANES III (1988–1994, n = 18,883) and NHANES 2001–2004 (n = 13,369) to evaluate population trends and demographic disparities in vitamin D insufficiency.
What was found
Mean serum 25(OH)D dropped from 30 ng/mL (95% CI, 29–30) during NHANES III to 24 ng/mL (95% CI, 23–25) during NHANES 2001–2004. The prevalence of 25(OH)D <10 ng/mL increased from 2% (95% CI, 2%–2%) to 6% (95% CI, 5%–8%), while levels ≥30 ng/mL decreased from 45% (95% CI, 43%–47%) to 23% (95% CI, 20%–26%). Among non-Hispanic Black participants, 25(OH)D <10 ng/mL rose from 9% to 29%, and levels ≥30 ng/mL fell from 12% to 3%. Differences across age strata (28–32 ng/mL) and between sexes (28 ng/mL in women vs 32 ng/mL in men) observed in NHANES III equalized to 24 ng/mL in NHANES 2001–2004.
Why it matters
This study documented substantial population-level declines in circulating vitamin D status across the US over a 16-year period, highlighting pronounced and widening racial disparities.
Limits
The study is based on repeated cross-sectional surveys rather than longitudinal follow-up of individuals. The abstract reports no adjustment for laboratory assay drift or method changes between survey waves, nor data on seasonal sampling, sun exposure, body mass index, or dietary and supplement intake.
Cited by
- supports Approximately 70% of the US population has inadequate vitamin D levels, defined as less than 30 ng/mL.