Serum 25-hydroxyvitamin D fluctuations in military personnel during 6-month summer operational deployments in Afghanistan

Abstract

Soldier operational performance is determined by their fitness, nutritional status, quality of rest/recovery, and remaining injury/illness free. Understanding large fluctuations in nutritional status during operations is critical to safeguarding health and well-being. There are limited data world-wide describing the effect of extreme climate change on nutrient profiles. This study investigated the effect of hot-dry deployments on vitamin D status (assessed from 25-hydroxyvitamin D (25(OH)D) concentration) of young, male, military volunteers. Two data sets are presented (pilot study, n 37; main study, n 98), examining serum 25(OH)D concentrations before and during 6-month summer operational deployments to Afghanistan (March to October/November). Body mass, percentage of body fat, dietary intake and serum 25(OH)D concentrations were measured. In addition, parathyroid hormone (PTH), adjusted Ca and albumin concentrations were measured in the main study to better understand 25(OH)D fluctuations. Body mass and fat mass (FM) losses were greater for early (pre- to mid-) deployment compared with late (mid- to post-) deployment (P<0·05). Dietary intake was well-maintained despite high rates of energy expenditure. A pronounced increase in 25(OH)D was observed between pre- (March) and mid-deployment (June) (pilot study: 51 (sd 20) v. 212 (sd 85) nmol/l, P<0·05; main study: 55 (sd 22) v. 167 (sd 71) nmol/l, P<0·05) and remained elevated post-deployment (October/November). In contrast, PTH was highest pre-deployment, decreasing thereafter (main study: 4·45 (sd 2·20) v. 3·79 (sd 1·50) pmol/l, P<0·05). The typical seasonal cycling of vitamin D appeared exaggerated in this active male population undertaking an arduous summer deployment. Further research is warranted, where such large seasonal vitamin D fluctuations may be detrimental to bone health in the longer-term.

Dietary Assessment Methods in Military and Veteran Populations: A Scoping Review

“…A range of dietary intake methodologies were used with studies incorporating one dietary assessment method (n = 76, 85%) [2,[6][7][8]20,[22][23][24][25]28,29,32,[34][35][36][37][38][39][40][42][43][44][45][46][47][48][49][50][51]53,[55][56][57][58][59][60][61][62][63][64][65][66]70,94,[97][98][99][100][101][102][103]…”

“…There was one (1%) of each study design for longitudinal cohort [21], validation study [71], cohort study [88], and retrospective cross-sectional study [29]. Twenty-one of the studies were interventions including eight (9%) randomised control trials [7,36,39,51,53,89,94,103], four (4%) pre-post design studies [21,48,49,62], three (3%) non-randomised control trials [40,84,86], two (2%) case-control trials [65,104], and two (2%) non-controlled trial [32,56]. There was one (1%) of each study design for retrospective case-control trial [38] and randomised trial [54].…”

“…The year of publication of studies ranged from 1973-2019, with 63 (71%) of the studies being published from 2000 onwards [2,[6][7][8][20][21][22][23][24][25]29,30,32,[34][35][36][37]39,40,43,[46][47][48]51,53,56,[62][63][64][65][66][70][71][72][73][74][75][76][77][78]81,82,[84][85][86][88][89][90]92,94,[96]…”

“…One study did not report on participant numbers [45]. Forty-five of the 89 studies included male personnel (51%) [ The military population most frequently studied, in descending order, was the army with n = 48 (54%) [2,6,7,[21][22][23][24][29][30][31][32]34,35,[37][38][39][40][43][44][45][46][47][48][50][51][52][53][56][57][58][59][60][61][62]66,[70][71][72][73]76,77,82,84,88,89], followed by veterans n = 18 (20%) [20,[90][91]…”

“…The population types that included intervention studies were army (n = 9) [7,21,32,38,51,53,56,84,89], air force (n = 3) [36,49,54], veterans (n = 1) [103], National Guard (n = 1) [86], and Navy Marines (n = 1) [39]. The most commonly studied type of military personnel in included studies were soldiers (n = 28, 31%) [6,7,22,24,29,32,35,37,38,45,46,48,50,51,53,56,57,59,62,[70][71][72][73][74]76,88] followed by veterans (n = 14, 16%) [20,[94][95][96][97][98][99][100]…”