title: Changes in vitamin D and matrix metalloproteinase-9 in submariners during a submerged patrol.
abstract: OBJECTIVE
  To quantify changes in vitamin D and matrix metalloproteinase-9 (MMP9) in submariners over a single long patrol and compare the data to a group of non-deploying servicemen from their base port.
  
  
  METHODS
  A prospective time-series analysis was performed. Blood samples were taken from 49 submariners deploying on patrol and 43 shore-side controls from the base port (naval officers from base or non-deploying submariners), following a winter ashore at latitude 56° north. Samples were drawn immediately before the submarine sailed, in January, and again in the final week of patrol 85 days later. Paired pre-patrol and late samples from each individual were assayed together and changes in vitamin D and MMP9 were assessed.
  
  
  RESULTS
  Mean pre-patrol vitamin D concentrations were 58 and 49 nmol/L for the controls and submariners, respectively. Mean vitamin D concentrations increased in controls as expected (mean increase 12.6 nmol/L), but not in the submariners (mean decrease 1.6 nmol/L). MMP9 levels were significantly higher in submariners pre-patrol, and increased significantly during the patrol. There was a significant inverse correlation between MMP9 and vitamin D levels (r=-0.41, p=0.01).
  
  
  CONCLUSIONS
  This is the first study to quantify vitamin D and MMP levels in submariners. Circulating vitamin D concentrations on board were insufficient to prevent a rise in MMP. This has potential for adverse health effects and requires further study.
authors.affiliation: Institute of Naval Medicine, Alverstoke, Hampshire, UK.
authors.forename: A
authors.initials: A
authors.lastname: Baker
authors.forename: C L
authors.initials: CL
authors.lastname: Wood
authors.forename: A M
authors.initials: AM
authors.lastname: Wood
authors.forename: P
authors.initials: P
authors.lastname: Timms
authors.forename: A J
authors.initials: AJ
authors.lastname: Allsopp
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D008889:Military Personnel; D011446:Prospective Studies; D013366:Submarine Medicine; D013997:Time Factors; D014807:Vitamin D / Q000097:blood*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D020780:Matrix Metalloproteinase 9