title: Vitamin D supplementation in underway submariners.
abstract: BACKGROUND
  We assessed the efficacy of vitamin D supplementation in maintaining normal calcium and bone homeostasis in underway submariners deprived of sunlight.
  
  
  METHODS
  Serum 25-hydroxycholecalciferol (25(OH)D), 1,25-dihydroxycholecalciferol (1,25(OH)2D), calcium, parathyroid hormone (PTH), phosphate, osteocalcin, bone specific alkaline phosphatase, and urinary levels of N-telopeptide were examined in 51 subjects aboard a submarine. These levels were obtained prior to a 76-d deployment, before and after a 6-d liberty period (deployment day 49 and 55), and on return to homeport. There were 26 subjects who received 400-lU of vitamin D daily supplementation, and 25 who received placebo.
  
  
  RESULTS
  Both groups exhibited significant reductions in 25(OH)D levels in the initial submergence (a decrease from 28.3 +/- 15 ng x ml(-1) to 24.1 +/- 10 ng x ml(-1) in the experimental group and 26.3 +/- 10 ng x ml(-1) to 20.7 +/- 9 ng x ml(-1) in the controls), an increase in 25(OH)D levels not significantly different from baseline during the liberty period, and decrements in 25(OH)D on repeat submergence (22.8 +/- 10 ng x ml(-1) in experimental and 21.4 +/- 10 ng x ml(-1) in controls). Both groups exhibited an increase in post-liberty osteocalcin (20.4 +/- 6 ng x ml(-1) to 24.5 +/- 5 ng x ml(-1) for experimental and 18.3 +/- 6 to 23.5 +/- 7 ng x ml(-1) for controls), and stable serum calcium levels throughout the patrol.
  
  
  CONCLUSIONS
  400-IU daily vitamin D supplementation was insufficient in maintaining serum vitamin D levels in underway submariners, engendering biochemical evidence of bone resorption and turnover. Six d sunlight exposure compensated for 49 d sunlight absence, supporting the enormous capacity of UV-B mediated vitamin D production.
authors.affiliation: Naval Submarine Medical Research Laboratory, Groton, CT 06349, USA. Duplessis@nsmrl.navy.mil
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Duplessis
authors.forename: Eric B
authors.initials: EB
authors.lastname: Harris
authors.forename: Donald E
authors.initials: DE
authors.lastname: Watenpaugh
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Horn
mesh_terms: D000328:Adult; D001862:Bone Resorption; D019587:Dietary Supplements; D006801:Humans; D008297:Male; D009326:Naval Medicine; D011446:Prospective Studies; D013366:Submarine Medicine; D013997:Time Factors; D014481:United States; D014807:Vitamin D / Q000031:analogs & derivatives / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D014807:Vitamin D