title: 25-hydroxyvitamin D levels in African American and Nigerian women.
abstract: OBJECTIVE
  African Americans (AA) have substantially lower levels of circulating 25-hydroxyvitamin D (25(OH)D) than whites. We compared population-based samples of 25(OH)D in women of African descent from Nigeria and metropolitan Chicago.
  
  
  METHODS
  One hundred women of Yoruba ethnicity from southwest Nigeria and 94 African American women from metropolitan Chicago were recruited and compared using a standardized survey protocol and the same laboratory assay for 25(OH)D.
  
  
  RESULTS
  Mean 25(OH)D levels were 64 nmol/l among the Nigerians and 29 nmol/l among the AA. Only 10% of the values were shared in common between the groups, and 76% of the Nigerians were above the currently defined threshold for adequate circulating 25(OH)D compared to 5% of the AA. Modest associations were seen between 25(OH)D and measures of obesity, although adjustment for these traits did not materially affect the group differences.
  
  
  CONCLUSIONS
  These data support the presumption that skin color is an adaptive trait which has evolved in part to regulate 25(OH)D. It remains undetermined, however, whether lower values observed in AA have negative health consequences.
authors.affiliation: Department of Public Health Sciences, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA.
authors.forename: Ramon A
authors.initials: RA
authors.lastname: Durazo-Arvizu
authors.forename: John F
authors.initials: JF
authors.lastname: Aloia
authors.forename: Lara R
authors.initials: LR
authors.lastname: Dugas
authors.forename: Bamidele O
authors.initials: BO
authors.lastname: Tayo
authors.forename: David A
authors.initials: DA
authors.lastname: Shoham
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Bertino
authors.forename: James K
authors.initials: JK
authors.lastname: Yeh
authors.forename: Richard S
authors.initials: RS
authors.lastname: Cooper
authors.forename: Amy
authors.initials: A
authors.lastname: Luke
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D001786:Blood Glucose; D001794:Blood Pressure; D001837:Body Weights and Measures; D005260:Female; D006801:Humans; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D012424:Rural Population; D012641:Selection, Genetic; D014481:United States / Q000453:epidemiology; D014505:Urban Population; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000208:ethnology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D014807:Vitamin D
references.citation: Obesity (Silver Spring). 2008 Sep;16(9):2148-54
references.pmid: 19186335
references.citation: Cancer Epidemiol Biomarkers Prev. 2010 Sep;19(9):2325-31
references.pmid: 20647395
references.citation: Arch Intern Med. 2008 Aug 11;168(15):1629-37
references.pmid: 18695076
references.citation: Mol Nutr Food Res. 2011 Jan;55(1):96-108
references.pmid: 20824663
references.citation: NCHS Data Brief. 2011 Mar;(59):1-8
references.pmid: 21592422
references.citation: Future Cardiol. 2009 Jan;5(1):15-8
references.pmid: 19371198
references.citation: J Am Soc Nephrol. 2009 Dec;20(12):2631-9
references.pmid: 19875805
references.citation: Am J Clin Nutr. 2009 Jan;89(1):169-76
references.pmid: 19056567
references.citation: Circulation. 2008 Jan 29;117(4):503-11
references.pmid: 18180395
references.citation: J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):467-71
references.pmid: 15225822
references.citation: Am J Clin Nutr. 2008 Aug;88(2):545S-550S
references.pmid: 18689399
references.citation: Nat Rev Cardiol. 2009 Oct;6(10):621-30
references.pmid: 19687790
references.citation: Diabetes Metab. 2005 Sep;31(4 Pt 1):318-25
references.pmid: 16369193