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Controlled Clinical Trial
. 2023 Dec;20(1):2206802.
doi: 10.1080/15502783.2023.2206802.

Can the supplementation of vitamin D, sun exposure, and isolation during the COVID-19 pandemic affect the seasonal concentration of 25(OH)D and selected blood parameters among young soccer players in a one-year training season?

Joanna Jastrzębska  1 , Maria Skalska  1 , Łukasz Radzimiński  2 , Guillermo F López Sánchez  3 , Lee Hill  4 , Katja Weiss  5 , Beat Knechtle  5   6
Affiliations
Controlled Clinical Trial

Can the supplementation of vitamin D, sun exposure, and isolation during the COVID-19 pandemic affect the seasonal concentration of 25(OH)D and selected blood parameters among young soccer players in a one-year training season?

Joanna Jastrzębska et al. J Int Soc Sports Nutr. 2023 Dec.

Abstract

Objective: This study examined the effect of vitamin D supplementation, sunlight radiationradiation, and home isolation during the COVID-19 pandemic on the seasonal changes in 25(OH)D concentration and selected biomarkers in young soccer players along a one-year training cycle.

Method: Forty elite young soccer players (age: 17.2 ± 1.16 years, body mass: 70.2 ± 5.84, and body height: 179.1 ± 4.26 cm) participated in the research. Only 24 players completed the measurements during all four time- points (T1-: September 2019, T2-: December 2019, T3-: May 2020, and T4-: August 2020) and were divided into two subgroups: supplemented group (GS) and placebo group (GP). Players from GS received 5,000 IU of vitamin D for 8 weeks (January-MarchJanuary-March 2020). Several biomarkers such as 25(OH)D, white blood cells (WBC), red blood cells (RBC), hemoglobin (HGB), muscle damage markersmarkers, and lipid profile were measured.

Results: AnalysisThe analysis of the total group demonstrated significant seasonal changes in 25(OH)D, HGB, asparagine aminotransferaseaminotransferase, and creatine kinase along the one1-year training cycle. The level of 25(OH)D concentrationinconcentration in T4 was significantly (p < 0.001, pη [ = 0.82) higher in both subgroups in comparison to T2 and T3. Moreover, the significant (p = 0.023) but poor (r = -0.23) correlation between 25(OH)D and WBC was calculated.

Conclusion: Current research confirmed the significant seasonal changes in 25(OH)D concentration during four seasons. 8-weekEight-week vitamin D supplementation had no extended effect on the level of 25(OH)D concentration.

Keywords: COVID-19; Supplementation; football; home-based training.

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Conflict of interest statement

No potential conflict of interest was reported by the author(s).

Figures

Figure 1.
Figure 1.
The study timeline and flowchart of the participants.
Figure 2.
Figure 2.
The scope of the UV index for the city of Gdynia (Poland) during the project [33].
Figure 3.
Figure 3.
Correlations between 25(OH)D concentration and white blood cells in young soccer players (n = 24) during a one1-year training cycle.
See this image and copyright information in PMC

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