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Int J Environ Res Public Health. 2018 Sep 14;15(9). pii: E2003. doi: 10.3390/ijerph15092003.

Vitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled Trial.

Author information

1
Department of Kinesiology, College of Health Sciences, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA. jung@ulm.edu.
2
Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea. smilly1004@khu.ac.kr.
3
Department of Counseling, Health, and Kinesiology, College of Education and Human Development, Texas A&M University-San Antonio, One University Way, San Antonio, TX 78224, USA. slee@tamusa.edu.
4
Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea. kswrha@khu.ac.kr.
5
Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea. jksong@khu.ac.kr.

Abstract

Vitamin D insufficiency may be associated with increased risk of upper respiratory tract infection (URTI) in athletes. This study examined the effects of vitamin D₃ supplementation on salivary immune functions and symptoms of URTI in vitamin D-insufficient taekwondo athletes. Twenty-five male taekwondo athletes, aged 19⁻22 years with vitamin D insufficiency [serum 25-hydroxyvitamin-D concentrations (25(OH)D, 31.3 ± 1.39 nmol/L)], participated in this study. They were randomized to receive 5000 IU/day of vitamin D₃ (n = 13) or placebo capsule (n = 12) during 4 weeks of winter training. Blood samples were collected two times (pre- and post-tests) for analyzing serum 25(OH)D concentration while salivary samples were obtained three times (pre-, mid-, and post-tests) for secretory immunoglobulin A (SIgA) and lactoferrin analyses. The symptoms of URTI were reported daily during the intervention. Serum 25(OH)D concentration significantly increased by 255.6% in the vitamin D group, whereas in the placebo group it did not change (p < 0.001). While the significant increase in SIgA was observed in both groups (p < 0.001), elevated salivary lactoferrin level in response to winter training was found only in the placebo group (p = 0.011). The change in serum 25(OH)D concentration was negatively associated with total URTI symptoms (r = -0.435, p = 0.015). Vitamin D₃ supplementation may be effective in reducing the symptoms of URTI during winter training in vitamin D-insufficient taekwondo athletes.

KEYWORDS:

high-intensity training; respiratory immune function; secretory immunoglobulin; vitamin D

PMID:
30223447
PMCID:
PMC6164435
DOI:
10.3390/ijerph15092003
[Indexed for MEDLINE]
Free PMC Article

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