Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Dec;88(6):1519-27.
doi: 10.3945/ajcn.2008.26182.

Serum 25-hydroxyvitamin D Status of the US Population: 1988-1994 Compared With 2000-2004

Affiliations
Free PMC article

Serum 25-hydroxyvitamin D Status of the US Population: 1988-1994 Compared With 2000-2004

Anne C Looker et al. Am J Clin Nutr. .
Free PMC article

Abstract

Background: Changes in serum 25-hydroxyvitamin D [25(OH)D] concentrations in the US population have not been described.

Objective: We used data from the National Health and Nutrition Examination Surveys (NHANES) to compare serum 25(OH)D concentrations in the US population in 2000-2004 with those in 1988-1994 and to identify contributing factors.

Design: Serum 25(OH)D was measured with a radioimmunoassay kit in 20 289 participants in NHANES 2000-2004 and in 18 158 participants in NHANES III (1988-1994). Body mass index (BMI) was calculated from measured height and weight. Milk intake and sun protection were assessed by questionnaire. Assay differences were assessed by re-analyzing 150 stored serum specimens from NHANES III with the current assay.

Results: Age-adjusted mean serum 25(OH)D concentrations were 5-20 nmol/L lower in NHANES 2000-2004 than in NHANES III. After adjustment for assay shifts, age-adjusted means in NHANES 2000-2004 remained significantly lower (by 5-9 nmol/L) in most males, but not in most females. In a study subsample, adjustment for the confounding effects of assay differences changed mean serum 25(OH)D concentrations by approximately 10 nmol/L, and adjustment for changes in the factors likely related to real changes in vitamin D status (ie, BMI, milk intake, and sun protection) changed mean serum 25(OH)D concentrations by 1-1.6 nmol/L.

Conclusions: Overall, mean serum 25(OH)D was lower in 2000-2004 than 1988-1994. Assay changes unrelated to changes in vitamin D status accounted for much of the difference in most population groups. In an adult subgroup, combined changes in BMI, milk intake, and sun protection appeared to contribute to a real decline in vitamin D status.

Figures

Figure 1
Figure 1
Age-standardized mean serum 25OHD by sex and season of blood collection among persons age 12 years and older: NHANES III (as originally assayed and as predicted if current assay used) versus NHANES 2000–2004 NHW = Non-Hispanic white NHB = Non-Hispanic black MA = Mexican * P < 0.05 comparing NHANES III to NHANES 2000-2004 based on t-tests **Comparison for November-March limited to Non-Hispanic whites only due to significant different in proportion of nonwhites between NHANES III and NHANES 2000-2004 for the November-March sample.
Figure 1
Figure 1
Age-standardized mean serum 25OHD by sex and season of blood collection among persons age 12 years and older: NHANES III (as originally assayed and as predicted if current assay used) versus NHANES 2000–2004 NHW = Non-Hispanic white NHB = Non-Hispanic black MA = Mexican * P < 0.05 comparing NHANES III to NHANES 2000-2004 based on t-tests **Comparison for November-March limited to Non-Hispanic whites only due to significant different in proportion of nonwhites between NHANES III and NHANES 2000-2004 for the November-March sample.
Figure 2
Figure 2
Mean age- and sex-adjusted serum 25OHD by selected variables for non-Hispanic whites ages 20–59 years: NHANES 2003–2004 P values from overall F test for variable from linear regression.
Figure 3
Figure 3
Observed and predicted age-standardized mean serum 25OHD by sex among non-Hispanic whites age 20–59 years examined in April-October: NHANES III (1988–1994) versus NHANES 2003–2004 * Calculated as NHANES III mean minus NHANES 2003-04 mean ** Mean predicted for NHANES III 1988-1994 if current RIA was used. *** Mean predicted for NHANES III 1988-1994 assuming current RIA was used and mean predicted for NHANES 2003-2004 if mean BMI and milk consumption rates from NHANES III and sun protective behavior rates from 1992 NHIS applied.
Figure 3
Figure 3
Observed and predicted age-standardized mean serum 25OHD by sex among non-Hispanic whites age 20–59 years examined in April-October: NHANES III (1988–1994) versus NHANES 2003–2004 * Calculated as NHANES III mean minus NHANES 2003-04 mean ** Mean predicted for NHANES III 1988-1994 if current RIA was used. *** Mean predicted for NHANES III 1988-1994 assuming current RIA was used and mean predicted for NHANES 2003-2004 if mean BMI and milk consumption rates from NHANES III and sun protective behavior rates from 1992 NHIS applied.
Figure 3
Figure 3
Observed and predicted age-standardized mean serum 25OHD by sex among non-Hispanic whites age 20–59 years examined in April-October: NHANES III (1988–1994) versus NHANES 2003–2004 * Calculated as NHANES III mean minus NHANES 2003-04 mean ** Mean predicted for NHANES III 1988-1994 if current RIA was used. *** Mean predicted for NHANES III 1988-1994 assuming current RIA was used and mean predicted for NHANES 2003-2004 if mean BMI and milk consumption rates from NHANES III and sun protective behavior rates from 1992 NHIS applied.

Comment in

Similar articles

See all similar articles

Cited by 210 articles

See all "Cited by" articles

MeSH terms

Feedback