title: Effects of vitamin D supplementation in older African American women.
abstract: BACKGROUND
  Serum 25-hydroxyvitamin D (25OHD) is lower in women with darker skin color. Is it due to lower skin production, lower absorption, or different metabolism of vitamin D?
  
  
  OBJECTIVE
  The objective of the study was to measure the effect of vitamin D3 on serum 25OHD and serum PTH in older African American women with vitamin D insufficiency and the serum 25OHD 20 ng/mL or less (<50 nmol/L). The results can be used to estimate the Recommended Dietary Allowance (RDA).
  
  
  METHODS
  This was a randomized, double-blind placebo trial at Creighton University Medical Center and Indiana University Medical Center.
  
  
  METHODS
  Participants were 110 healthy older African American women.
  
  
  METHODS
  The intervention consisted of participants randomly assigned to placebo, vitamin D3 400, 800, 1600, 2400, 3200, 4000, or 4800 IU daily; calcium supplements were given to maintain total calcium intake of 1200-1400 mg/d.
  
  
  METHODS
  Change in serum 25OHD and serum PTH levels at 12 months was measured.
  
  
  RESULTS
  Mean baseline serum 25OHD was 13 ng/mL (33 nmol/L). On 4800 IU, serum 25OHD averaged 50 ng/mL (125 nmol/L) compared with 47 ng/mL (117 nmol/L) in Caucasian women. Serum PTH at 12 months decreased significantly (P = .008) when related to serum 25OHD but not dose. Hypercalcemia occurred in 7% and hypercalciuria in 15%. Events were unrelated to vitamin D dose.
  
  
  CONCLUSIONS
  Vitamin D3 800 IU increased serum 25OHD greater than 20 ng/mL (>50 nmol/L) in 97.5% of the African American women just as it did in the Caucasian women, and therefore, the RDA is the same for both groups. Because absorption and metabolism of oral vitamin D absorption is similar in both groups, lower levels of serum 25OHD in African Americans must be due to lower production of vitamin D in skin.
authors: Bone Metabolism Unit, Creighton University School of Medicine, 601 North 30th Street, Suite 6718, Omaha, Nebraska 68131, USA. jcg@creighton.edu
authors: J Christopher
authors: JC
authors: Gallagher
authors: Munro
authors: M
authors: Peacock
authors: Vinod
authors: V
authors: Yalamanchili
authors: Lynette M
authors: LM
authors: Smith
mesh_terms: D001741:Black or African American; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010919:Placebos; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy* / Q000208:ethnology; D014815:Vitamins / Q000008:administration & dosage* / Q000009:adverse effects; D044465:White People
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D010919:Placebos; D014815:Vitamins; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D
references: J Steroid Biochem Mol Biol. 2010 Jul;121(1-2):176-9
references: 20302938
references: J Clin Endocrinol Metab. 2011 Jan;96(1):53-8
references: 21118827
references: J Clin Endocrinol Metab. 2005 Feb;90(2):635-40
references: 15546897
references: J Bone Miner Res. 2011 Oct;26(10):2378-88
references: 21710614
references: J Clin Endocrinol Metab. 2010 Jun;95(6):2637-45
references: 20332246
references: Ann Intern Med. 2008 Aug 19;149(4):242-50
references: 18711154
references: J Bone Miner Res. 2008 Jan;23(1):143-50
references: 17907920
references: Arch Intern Med. 2005 Jul 25;165(14):1618-23
references: 16043680
references: J Am Geriatr Soc. 2011 Jul;59(7):1165-74
references: 21668915
references: Calcif Tissue Int. 2010 May;86(5):367-74
references: 20349229
references: Am J Clin Nutr. 2008 Jun;87(6):1952-8
references: 18541590
references: Osteoporos Int. 2005 Nov;16(11):1425-31
references: 15744449
references: Ann Intern Med. 2012 Mar 20;156(6):425-37
references: 22431675
references: Am J Clin Nutr. 2007 Dec;86(6):1657-62
references: 18065583
references: J Clin Endocrinol Metab. 2011 Mar;96(3):E436-46
references: 21159838
references: Lancet. 2010 Jul 17;376(9736):180-8
references: 20541252
references: J Nutr. 2010 Mar;140(3):542-50
references: 20053937
references: J Clin Endocrinol Metab. 2010 Nov;95(11):5069-73
references: 20685862