The effect of 14 weeks of vitamin D₃ supplementation on antimicrobial peptides and proteins in athletes

Abstract

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D 3 supplementation (5000 IU/ day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immunoglobulin A (SIgA), cathelicidin, lactoferrin and lysozyme in athletes during a winter training period. Blood and saliva were obtained at the start of the study from 39 healthy men who were randomly allocated to vitamin D 3 supplement or placebo. Blood samples were also collected at the end of the study; saliva samples were collected after 7 and 14 weeks. Plasma total 25(OH)D concentration increased by 130% in the vitamin D 3 group and decreased by 43% in the placebo group (both P = 0.001). The percentage change of plasma cathelicidin concentration in the vitamin D 3 group was higher than in the placebo group (P = 0.025). Only in the vitamin D 3 group, the saliva SIgA and cathelicidin secretion rates increased over time (both P = 0.03). A daily 5000 IU vitamin D 3 supplement has a beneficial effect in up-regulating the expression of SIgA and cathelicidin in athletes during a winter training period, which could improve resistance to respiratory infections.

Oral spray wintertime vitamin D3 supplementation has no impact on inflammation in Gaelic footballers

“…Whilst total 25(OH)D cut‐offs for bone heath are well‐established (Ross et al., ), no consensus has been met over what constitutes an “optimal” total 25(OH)D concentration for extra‐skeletal outcomes such as inflammation. Although it has been suggested that a total 25(OH)D concentration in excess of 75 nmol/L may be necessary in order to achieve immune‐related benefits (Laird et al., ; He et al., ), these thresholds are currently speculative owing to inconsistent results from randomized controlled trials (Barnes et al., ; Das et al., ; He et al., ). Furthermore, it is not uncommon for cytokines to fall below the LLOD of a multiplex assay when samples are derived from healthy adults (Kleiner et al., ).…”

“…Furthermore, it is not uncommon for cytokines to fall below the LLOD of a multiplex assay when samples are derived from healthy adults (Kleiner et al., ). A wealth of in vitro data lends support to an immunoregulatory role of 1,25(OH) 2 D (Cantorna et al., ); although few have investigated the impact of vitamin D supplementation on inflammation in athletes in vivo (Lewis et al., ; He et al., ). Despite 93% of the cohort in the present study presenting with total 25(OH)D concentrations below 75 nmol/L at baseline and an endpoint mean total 25(OH)D concentration of 84 nmol/L, supplementation with vitamin D 3 did not impact measures of inflammation including peripheral cytokine or antimicrobial peptide concentrations.…”

“…To our knowledge only two RCTs have examined the effects of vitamin D supplementation on inflammation in athletes and little is known regarding the effect of vitamin D supplementation on inflammation in athletes that compete in interval sports such as Gaelic football (Lewis et al., ; He et al., ). Previously studied cohorts were vitamin D sufficient (>50 nmol/L) at baseline and reported mixed findings, however, the response to supplementation may be greater in those who present with vitamin D insufficiency/deficiency (<50 nmol/L) (Didriksen et al., ).…”

Immunological aspects of sport nutrition

“…Low vitamin D status in athletes low vitamin D status is associated with low saliva IgA secretion, low pro-inflammatory cytokine production by antigen-stimulated blood mononuclear cells and increased respiratory infection risk with longer lasting illness symptoms 16 . Oral vitamin D3 supplements of around 4 000 IU per day can elevate vitamin D status from deficient levels to adequate or high levels within a matter of weeks and can significantly elevate saliva IgA and defensin secretion rates in athletes 31 . Oral vitamin D3 supplements of around 1 000 IU per day can maintain adequate vitamin D status throughout the winter months if status is adequate at the end of summer.…”

“…16 Oral vitamin D3 supplements of~4000 IU per day can elevate vitamin D status from deficient levels to adequate or high levels within a matter of weeks and can significantly elevate saliva IgA and defensin secretion rates in athletes. 31 Oral vitamin D3 supplements of around 1000 IU per day can maintain adequate vitamin D status throughout the winter months if status is adequate at the end of summer. Several large-scale studies in the general population indicate that vitamin D3 supplements reduce the number of common cold episodes and reduce the use of antibiotics 17 so there is a likely benefit for athletes who have low vitamin D status.…”