Seasonal changes in free 25-(OH)D and vitamin D metabolite ratios and their relationship with psychophysical stress markers in male professional football players

Anna Książek; Aleksandra Zagrodna; Giovanni Lombardi; Małgorzata Słowińska-Lisowska

doi:10.3389/fphys.2023.1258678

Seasonal changes in free 25-(OH)D and vitamin D metabolite ratios and their relationship with psychophysical stress markers in male professional football players

Front Physiol. 2023 Oct 16:14:1258678. doi: 10.3389/fphys.2023.1258678. eCollection 2023.

Authors

Anna Książek¹, Aleksandra Zagrodna¹, Giovanni Lombardi^{2

3}, Małgorzata Słowińska-Lisowska¹

Affiliations

¹ Department of Biological and Medical Basis of Sport, Faculty of Physical Education and Sports, Wroclaw University of Health and Sport Sciences, Wroclaw, Poland.
² Laboratory of Experimental Biochemistry and Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Milan, Italy.
³ Department of Athletics, Strength and Conditioning, Poznań University of Physical Education, Poznań, Poland.

Abstract

Introduction: Novel markers of vitamin D status are currently being investigated, including free 25-(OH)D (25-(OH)D_F) and the vitamin D metabolite ratio (24,25-(OH)₂D₃:25-(OH)D₃; VMR). The VMR may provide additional functional information on vitamin D metabolism in athletes. Therefore, the main objective of the current study was to evaluate 25-(OH)D_F, bioavailable 25-(OH)D (25-(OH)D_B), VMR, and psychophysical stress markers during different training periods over a half-season. The second aim was to assess the association between vitamin D binding protein (VDBP), total and free 25-(OH)D, VMRs, and psychophysical stress markers in professional football players. Moreover, we examined the relationship between 25-(OH)D₃ and vitamin D metabolites (24,25-(OH)₂D₃, 3-epi-25-(OH)D₃) to determine if training loads in different training periods influenced the vitamin D metabolome. Methods: Twenty professional football players were tested at six different time points across half a year (V1-June; V2-July; V3-August; V4-October; V5-December; V6-January). Results: Analyses indicated a significant seasonal rhythm for VDBP, and total 25-(OH)D (25-(OH)D_T), 25-(OH)D_B, 24,25-(OH)₂D₃, 3-epi-25-(OH)D₃, 25-(OH)D₃:24,25-(OH)₂D₃, and 24,25-(OH)₂D₃:25-(OH)D₃ VMRs throughout the training period. No correlation was detected between 25-(OH)D_T, 25-(OH)D_B, 25-(OH)D_F, vitamin D metabolites, VMRs, VDBP, and ferritin, liver enzymes (aspartate transaminase [AST] and alanine transaminase [ALT]), creatine kinase (CK), cortisol, testosterone, and testosterone-to-cortisol ratio (T/C) in each period (V1-V6). However, there was a strong statistically significant correlation between 25-(OH)D₃ and 24,25-(OH)D₃ in each training period. Conclusion: In conclusion, a seasonal rhythm was present for VDBP, 25-(OH)D_T, 25-(OH)D_B, vitamin D metabolites (24,25-(OH)₂D₃, 3-epi-25-(OH)D₃), and VMRs (25-(OH)D₃:24,25-(OH)₂D₃, 25-(OH)D₃:3-epi-25-(OH)D₃). However, no rhythm was detected for 25-(OH)D_F and markers of psychophysical stress (ferritin, liver enzymes, CK, testosterone, cortisol, and T/C ratio). Moreover, the relationships between free and total 25-(OH)D with psychophysical stress markers did not demonstrate the superiority of free over total measurements. Furthermore, training loads in different training periods did not affect resting vitamin D metabolite concentrations in football players.

Keywords: 24; 25-(OH)2D3; VMR; athletes; seasonal variation; training load; vitamin D.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was supported financially by the Wroclaw University of Health and Sport Sciences, Poland.