Influence of vitamin D supplementation by simulated sunlight or oral D3 on respiratory infection during military training

Harrison, Sophie, Oliver, Samuel J., Kashi, Daniel S., Carswell, Alexander, Edwards, Jason P., Wentz, Laurel M., Roberts, Ross, Tang, Jonathan C. Y. ORCID:, Izard, Rachel M., Jackson, Sarah, Allan, Donald, Rhodes, Lesley E., Fraser, William, Greeves, Julie and Walsh, Neil P. (2021) Influence of vitamin D supplementation by simulated sunlight or oral D3 on respiratory infection during military training. Medicine and Science in Sports and Exercise, 53 (7). pp. 1505-1516. ISSN 0195-9131

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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.

Item Type: Article
Faculty \ School: Faculty of Medicine and Health Sciences > School of Health Sciences
Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: LivePure Connector
Date Deposited: 13 Jan 2021 00:54
Last Modified: 21 Apr 2023 14:30
DOI: 10.1249/MSS.0000000000002604

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