title: Serum 25-hydroxyvitamin D status of adolescents and adults in two seasonal subpopulations from NHANES III.
abstract: Subclinical vitamin D deficiency may be common in certain subgroups in the U.S., but to date vitamin D data from other groups in the population have not been available. We used serum 25-hydroxyvitamin D (25-OHD) data from 18,875 individuals examined in the Third National Health and Nutrition Examination Survey (NHANES III 1988-1994) to assess the vitamin D status of selected groups of the noninstitutionalized U.S. adolescent and adult population. Serum 25-OHD levels were measured by a radioimmunoassay kit (DiaSorin, Inc., Stillwater, MN; normal range 22.5-94 nmol/L). Because physical exams are performed in mobile vans in NHANES, data could not be collected in northern latitudes during the winter; instead data were collected in northern latitudes during summer and in southern latitudes in winter. To address this season-latitude aspect of the NHANES design, we stratified the sample into two seasonal subpopulations (winter/lower latitude and summer/higher latitude) before examining vitamin D status. Less than 1% of the winter/lower latitude subpopulation had vitamin D deficiency (25-OHD <17.5 nmol/L). However, the prevalence of vitamin D insufficiency in this group ranged from 1%-5% with 25-OHD <25 nmol/L to 25%-57% with 25-OHD <62.5 nmol/L, even though the median latitude for this subsample (32 degrees N) was considerably lower than the latitude at which vitamin D is not synthesized during winter months (approximately 42 degrees N). With the exception of elderly women, prevalence rates of vitamin D insufficiency were lower in the summer/higher latitude subpopulation (<1%-3% with 25-OHD <25 nmol/L to 21%-49% with 25-OHD <62.5 nmol/L). Mean 25-OHD levels were highest in non-Hispanic whites, intermediate in Mexican Americans, and lowest in non-Hispanic blacks. Our findings suggest that vitamin D deficiency is unlikely in the two seasonal subpopulations of noninstitutionalized adolescents and adults that can be validly assessed in NHANES III. However, vitamin D insufficiency is more common in these two seasonal subpopulations. Of particular interest is that insufficiency occurred fairly frequently in younger individuals, especially in the winter/lower latitude subsample. Our findings support continued monitoring of this vitamin in the U.S. population.
authors: National Center for Health Statistics, Centers for Disease Control and Prevention, Room 900, 6525 Belcrest Road, Hyattsville, MD 20782, USA. acl1@cdc.gov
authors: Anne C
authors: AC
authors: Looker
authors: B
authors: B
authors: Dawson-Hughes
authors: M S
authors: MS
authors: Calvo
authors: E W
authors: EW
authors: Gunter
authors: N R
authors: NR
authors: Sahyoun
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D012621:Seasons; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000208:ethnology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D