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Vitamin D levels dropped after training for white, but not black females April 2010

Changes in vitamin D status of female Soldiers during basic combat training

Nancy Ellen Andersen1, J. Philip Karl1, Jennifer E Diaz1, Sonya J Cable2, Kelly W Williams2, Jennifer C Rood3, Andrew J Young1, Harris R Lieberman1 and James P McClung1
FASEB (Federation of American Societies of Experimental Biology) Journal Vol 24 April 2010 917.5
1 Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA
2 Experimentation and Analysis Element, Directorate of Basic Combat Training, Ft. Jackson, SC
3 Pennington Biomedical Research Center, Baton Rouge, LA

Vitamin D is an essential nutrient for maintaining bone health. Recent data suggest that changes in vitamin D status might influence stress fracture prevalence. Although stress fracture is considered a health risk for Soldiers undergoing military training, no study has documented vitamin D status in that population. This longitudinal study aimed to determine the effects of basic combat training (BCT) on 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) levels in female Soldiers. Serum 25(OH)D and PTH were measured in 74 fasted Soldier volunteers before and after a 9 wk BCT course between August and October in Columbia, SC. In the total study population, 25(OH)D levels decreased (72.9 ± 30.0 vs 63.3 ± 19.8 nmol/L, p<0.05) and PTH levels increased ([mean ± SD] 36.2 ± 15.8 vs 47.5 ± 21.2 pg/mL, p<0.05) during BCT.

Ethnicity affected changes in vitamin D status (group-by-time interaction, p<0.05); 25(OH)D decreased by

  • 10 ± 27% (89.23 ± 29.3 vs 74.87 ± 17.0, p<0.05) in non-Hispanic whites,
  • 15 ± 18% (74.07 ± 15.1 vs 63.27 ± 14.2, p<0.05) in Hispanic whites,
  • but did not change in non-Hispanic blacks.

Ethnicity did not affect BCT-induced changes in PTH. These data indicate that vitamin D status in female Soldiers may decline during military training. Future studies should ascertain whether this decline affects bone health. Research supported by MRMC.
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Summary by VitaminDWiki:
    Due to training: -10 ng non-Hispanic whites, -15 ng Hispanic whites, 0 ng change blacks

Possible reasons for the racial differences include

  1. the whites and Hispanics wore sunscreen
  2. the blacks already had very low levels of vitamin D (the abstract does not indicate the vitamin D levels of blacks)

See also VitaminDWiki