Vitamin D 3 Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled Trial

Hyun Chul Jung, Myong-Won Seo, Sukho Lee, Sung Woo Kim and Jong Kook Song
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Hyun Chul Jung: Department of Kinesiology, College of Health Sciences, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA
Myong-Won Seo: Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea
Sukho Lee: 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
Sung Woo Kim: Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea
Jong Kook Song: Department of Taekwondo, College of Physical Education, Kyung Hee University, 1732 Deokyoungdaero, Giheung-gu, Yongin-si, Gyeonggi-do 17014, Korea

IJERPH, 2018, vol. 15, issue 9, 1-12

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 D 3 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 D 3 ( 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 D 3 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 (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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