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  • 2020 Influence of vitamin D

    Accepted author manuscript, 600 KB, PDF document

    Embargo ends: 21/01/22

DOI

  • Sophie Harrison
  • Sam Oliver
  • Daniel Kashi
    Liverpool John Moores University
  • Alexander Carswell
    University of East Anglia
  • Jason Edwards
    Liverpool John Moores University
  • Laurel Wentz
    Appalachian State University
  • Ross Roberts
  • Jonathan Tang
    University of East Anglia
  • Rachel Izard
    Army Recruitment and Training DivisionDefence Science and Technology
  • Sarah Jackson
    Army Recruitment and Training Division
  • Donald Allan
    Salford Royal Foundation NHS Trust
  • Lesley Rhodes
    University of Manchester
  • William Fraser
    University of East Anglia
  • Julie Greeves
    University of East Anglia
  • Neil Walsh
    Liverpool John Moores University

PURPOSE: This study aimed to determine the relationship between vitamin D status and upper respiratory tract infection (URTI) of physically active men and women across seasons (study 1) and then to investigate the effects on URTI and mucosal immunity of achieving vitamin D sufficiency (25(OH)D ≥50 nmol·L-1) by a unique comparison of safe, simulated sunlight or oral D3 supplementation in winter (study 2).

METHODS: In study 1, 1644 military recruits were observed across basic military training. In study 2, a randomized controlled trial, 250 men undertaking military training received placebo, simulated sunlight (1.3× standard erythemal dose, three times per week for 4 wk and then once per week for 8 wk), or oral vitamin D3 (1000 IU·d-1 for 4 wk and then 400 IU·d-1 for 8 wk). URTI was diagnosed by a physician (study 1) and by using the Jackson common cold questionnaire (study 2). Serum 25(OH)D, salivary secretory immunoglobulin A (SIgA), and cathelicidin were assessed by liquid chromatography-mass spectrometry LC-MS/MS and enzyme-linked immunosorbent assay.

RESULTS: In study 1, only 21% of recruits were vitamin D sufficient during winter. Vitamin D-sufficient recruits were 40% less likely to suffer URTI than recruits with 25(OH)D <50 nmol·L-1 (OR = 0.6, 95% confidence interval = 0.4-0.9), an association that remained after accounting for sex and smoking. Each URTI caused, on average, three missed training days. In study 2, vitamin D supplementation strategies were similarly effective to achieve vitamin D sufficiency in almost all (≥95%). Compared with placebo, vitamin D supplementation reduced the severity of peak URTI symptoms by 15% and days with URTI by 36% (P < 0.05). These reductions were similar with both vitamin D strategies (P > 0.05). Supplementation did not affect salivary secretory immunoglobulin A or cathelicidin.

CONCLUSION: Vitamin D sufficiency reduced the URTI burden during military training.

Original languageEnglish
Pages (from-to)1505-1516
Number of pages12
JournalMedicine and Science in Sports and Exercise
Volume53
Issue number7
Early online date21 Jan 2021
DOIs
Publication statusPublished - 1 Jul 2021
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