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2000 IU daily raised vitamin D levels by 5 nanograms while on submarine patrol – July 2014

The Efficacy of Vitamin D Supplementation During a Prolonged Submarine Patrol

Calcified Tissue International
Heath G. Gasier heath.gasier at dm.duke.edu (1)
Erin Gaffney-Stomberg erin.g.stomberg.civ at mail.mil (2)
Colin R. Young colin.young at med.navy.mil (1)
Douglas C. McAdams douglas.c.mcadams.mil at health.mil (3)
Laura J. Lutz laura.j.lutz2.civ at mail.mil (2)
James P. McClung james.p.mcclung8.civ at mail.mil (2)
Author Affiliations
1. Department of Submarine Medicine & Survival Systems, Naval Submarine Medical Research Laboratory, Groton, CT, USA
2. Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, USA
3. Submarine Group Nine, Silverdale, WA, USA

Submariners spend prolonged periods submerged without sunlight exposure and may benefit from vitamin D supplementation to maintain vitamin D status. The primary objective of this study was to determine the efficacy of daily vitamin D supplementation on maintenance of 25-hydroxyvitamin D (25(OH)D) during a 3-month submarine patrol. Submariners were randomly divided into three groups: placebo (n = 16), 1,000 IU/day (n = 20), or 2,000 IU/day (n = 17). Anthropometrics, self-reported dietary calcium and vitamin D intake, serum markers of vitamin D and bone metabolism, and peripheral quantitative computed tomography (pQCT) parameters of the tibia were determined before and after the patrol. Prior to departure, 49 % of the subjects were vitamin D insufficient (<50 nmol/L). Following the patrol, 25(OH)D increased in all groups (p < 0.001):

  • 3.3 ± 13.1 (placebo),
  • 4.6 ± 11.3 (1,000 IU/day), and
  • 13 ± 14 nmol/L (2,000 IU/day).

The changes in 25(OH)D levels were dependent upon the baseline concentration of 25(OH)D and body mass (p < 0.001). Osteocalcin increased by 38 % (p < 0.01), and pQCT analyses revealed small, yet significant increases in indices of tibial structure and strength (p < 0.05) that were independent of supplementation. These data suggest that vitamin D status was low prior to the patrol, and the subsequent changes in vitamin D status were dependent on the baseline 25(OH)D levels and body mass. Furthermore, short-term skeletal health does not appear to be negatively affected by 3 months of submergence in spite of a suboptimal response to vitamin D supplementation.

See also VitaminDWiki

Seems like the following photo of the UK submariners was just an experiment, not an on-going practice
UVB submariners WWII.jpg