title: Vitamin D status indicators in indigenous populations in East Africa.
abstract: OBJECTIVE
  Sufficient vitamin D status may be defined as the evolutionary established circulating 25-hydroxyvitamin D [25(OH)D] matching our Paleolithic genome.
  
  
  METHODS
  We studied serum 25(OH)D [defined as 25(OH)D₂ + 25(OH)D₃] and its determinants in 5 East African ethnical groups across the life cycle: Maasai (MA) and Hadzabe (HA) with traditional life styles and low fish intakes, and people from Same (SA; intermediate fish), Sengerema (SE; high fish), and Ukerewe (UK; high fish). Samples derived from non-pregnant adults (MA, HA, SE), pregnant women (MA, SA, SE), mother-infant couples at delivery (UK), infants at delivery and their lactating mothers at 3 days (MA, SA, SE), and lactating mothers at 3 months postpartum (SA, SE). Erythrocyte docosahexaenoic acid (RBC-DHA) was determined as a proxy for fish intake.
  
  
  RESULTS
  The mean ± SD 25(OH)D of non-pregnant adults and cord serum were 106.8 ± 28.4 and 79.9 ± 26.4 nmol/L, respectively. Pregnancy, delivery, ethnicity (which we used as a proxy for sunlight exposure), RBC-DHA, and age were the determinants of 25(OH)D. 25(OH)D increased slightly with age. RBC-DHA was positively related to 25(OH)D, notably 25(OH)D₂. Pregnant MA (147.7 vs. 118.3) and SE (141.9 vs. 89.0) had higher 25(OH)D than non-pregnant counterparts (MA, SE). Infant 25(OH)D at delivery in Ukerewe was about 65 % of maternal 25(OH)D.
  
  
  CONCLUSIONS
  Our ancient 25(OH)D amounted to about 115 nmol/L and sunlight exposure, rather than fish intake, was the principal determinant. The fetoplacental unit was exposed to high 25(OH)D, possibly by maternal vitamin D mobilization from adipose tissue, reduced insulin sensitivity, trapping by vitamin D-binding protein, diminished deactivation, or some combination.
authors.affiliation: Laboratory Medicine, Room Y 3.181, University Medical Center Groningen (UMCG), P.O. Box 30.001, 9700 RB, Groningen, The Netherlands. mfluxwolda@hotmail.com
authors.forename: Martine F
authors.initials: MF
authors.lastname: Luxwolda
authors.forename: Remko S
authors.initials: RS
authors.lastname: Kuipers
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
authors.forename: E
authors.initials: E
authors.lastname: van der Veer
authors.forename: D A Janneke
authors.initials: DA
authors.lastname: Dijck-Brouwer
authors.forename: Frits A J
authors.initials: FA
authors.lastname: Muskiet
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000097:blood; D044383:Black People; D002112:Calcifediol / Q000097:blood*; D004032:Diet / Q000009:adverse effects* / Q000208:ethnology; D004781:Environmental Exposure; D005260:Female; D005312:Fetal Blood; D006801:Humans; D007231:Infant, Newborn; D007774:Lactation / Q000097:blood; D008019:Life Style / Q000208:ethnology; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena; D009752:Nutritional Status / Q000208:ethnology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000208:ethnology / Q000209:etiology; D013472:Sunlight; D013636:Tanzania; D014808:Vitamin D Deficiency / Q000097:blood* / Q000208:ethnology / Q000209:etiology / Q000517:prevention & control
chemical_list: D015415:Biomarkers; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol