title: 25-Hydroxyvitamin D and blood pressure: a plateau effect in adults with African ancestry living at different latitudes.
abstract: This study examined the association of 25-hydroxyvitamin D [25(OH)D] levels and blood pressure above and below 25(OH)D levels of 20 ng/ml in young adults with African ancestry.
  
  
  
  This cross-sectional analysis utilized data from a pooled sample of 2242 adults with African ancestry from five different latitudes (403 in the United States, 474 in South Africa, 479 in Ghana, 448 in Jamaica, and 438 in Seychelles). Piecewise linear regression models with a single knot were fitted to determine above and below a 25(OH)D level of 20 ng/ml the slope of SBP and DBP while adjusting for covariates including calcium intake and site.
  
  
  
  The mean age was 34.4 (6.1) years, and 46.3% were men. Mean SBP and DBP were 118.1 (15.6) and 73.2 (12.2) mmHg, respectively, and were significantly higher among the United States vs Ghana, Jamaica, and Seychelles groups (P < 0.001 for all comparisons). 25(OH)D levels were significantly lower in the United States vs all other sites (P < 0.001 for all comparisons). When 25(OH)D levels were less than 20 ng/ml, slopes of SBP [-0.33 (95% confidence interval (CI) -0.57, -0.07)] and DBP [-0.21 (95% CI -0.40, -0.02)] were negative and significantly different from zero after adjustment for covariates. In contrast, with 25(OH)D levels above 20 ng/ml, the slopes of SBP [-0.03 (95% CI -0.13, 0.06)] and DBP [-0.04 (-0.11, 0.03)] did not differ significantly from zero.
  
  
  
  The cross-sectional association of 25(OH)D with blood pressure is strongest when 25(OH)D levels are less than 20 ng/ml in young adults with African ancestry.
authors.affiliation: aDepartment of Public Health Sciences bDivision of Nephrology and Hypertension, Department of Medicine cDivision of Endocrinology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois dBone Mineral Research Center, Winthrop University Hospital, Mineola, New York, USA eInstitute of Social & Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland fMinistry of Health, Victoria, Republic of Seychelles gDepartment of Physiology, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana hTropical Medicine Research Institute, University of the West Indies, Kingston, Jamaica iDepartment of Human Biology, Division of Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa.
authors.forename: Daniel
authors.initials: D
authors.lastname: Chiang
authors.forename: Holly
authors.initials: H
authors.lastname: Kramer
authors.forename: Amy
authors.initials: A
authors.lastname: Luke
authors.forename: Richard
authors.initials: R
authors.lastname: Cooper
authors.forename: John
authors.initials: J
authors.lastname: Aloia
authors.forename: Pascal
authors.initials: P
authors.lastname: Bovet
authors.forename: Jacob
authors.initials: J
authors.lastname: Plange-Rhule
authors.forename: Terrence
authors.initials: T
authors.lastname: Forrester
authors.forename: Vickie
authors.initials: V
authors.lastname: Lambert
authors.forename: Pauline
authors.initials: P
authors.lastname: Camacho
authors.forename: Lara
authors.initials: L
authors.lastname: Dugas
authors.forename: Ramon
authors.initials: R
authors.lastname: Durazo-Arvizu
mesh_terms: D000328:Adult; D044383:Black People; D001794:Blood Pressure; D003430:Cross-Sectional Studies; D005260:Female; D005869:Ghana; D006801:Humans; D007563:Jamaica; D016014:Linear Models; D008297:Male; D012750:Seychelles; D013019:South Africa; D014481:United States; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000503:physiopathology; D001741:Black or African American
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D