Seasonal Vitamin D Status in Polish Elite Athletes in Relation to Sun Exposure and Oral Supplementation

Abstract

Vitamin D does not only influence the musculoskeletal health and mineral homeostasis but it also affects cardiovascular, endocrine, nervous, immune and mental functions, thus it is of considerable importance for both physically active people and elite athletes. However, vitamin D deficiency is common worldwide and results from inadequate endogenous skin synthesis (insufficient ultraviolet B exposure) and diet. To improve the vitamin D status elite athletes often travel to lower latitude during winter. The aim of the study was to evaluate the seasonal vitamin D status in Polish elite athletes according to the sun exposure and oral supplementation. Serum concentration of 25-hydroxyvitamin D (25(OH)D) was measured in the years 2010–2014 in 409 elite athletes, who were divided into the following groups: OUTD—outdoor sports, represented by track and field athletes, who trained in Poland; IND—weightlifters, handball and volleyball players who trained indoors in Poland; SUN—track and field athletes who trained during Polish winter in lower latitude with high sunshine exposure; SUPL—track and field athletes who trained in Poland, had an inadequate vitamin D status (25(OH)D < 30 ng/ml) and were supplemented orally. Inadequate Vitamin D status was observed in 80% of OUTD and 84% of IND athletes in winter, whereas in summer the values amounted to 42% and 83%, respectively. The athletes exposed to sun in winter had significantly higher vitamin D concentration than OUTD group. Oral supplementation improved vitamin D concentration by 45%, whereas winter sun exposure caused its increase by 85%. Except for a few summer months an inadequate status of vitamin D was found in the majority of Polish elite athletes, with the deficiency level being similar to the one observed in non-athletic population. The most serious deficiency was observed in indoor disciplines. Adequate vitamin D status can be achieved by both increased sun exposure, especially in winter, and oral supplementation. Athletes should therefore routinely assess their vitamin D status and be educated how to approach their sunlight exposure, diet and supplementation.

The effect of vitamin D supplementation on serum total 25(OH) levels and biochemical markers of skeletal muscles in runners

“…Most studies supported the benefits of dietary supplementation with vitamin D in healthy untrained adults and people diagnosed with 25-hydroxyvitamin D insufficiency (< 30 ng/ml) [25,35,36]. Contrarily, a recent metaanalysis involving 532 athletes found no improvement in measures of physical performance despite the inclusion of vitamin D deficient athletes at baseline and improvements in vitamin D levels over mean 12 weeks of follow-up [5]. Previous results revealed a positive effect of vitamin D supplementation on global muscle strength, power and muscle fatigue risk factors [15,16,18,37].…”

“…In a recent study, a prevalence of vitamin D deficiency in extreme endurance athletes, and an association between a delayed physical performance and a deficiency in vitamin D were observed during regular training [2][3][4]. These physiological responses in skeletal muscles were influenced by exercise-induced mechanisms and were probably affected by the nutritional athletic status and a limitation of sun exposure [5][6][7].…”

Health-related quality of life in young women starting hormonal contraception: a pilot study

“…Vitamin D metabolism also seems to be related to stress [26]. Vitamin D deficiency is common, especially in Nordic countries, and results from inadequate endogenous skin synthesis (insufficient exposure to ultraviolet B rays) and diet [13,[27][28][29]. At our latitude in Uppsala of 59…”

Concerning the vitamin D reference range: pre-analytical and analytical variability of vitamin D measurement

“…However, vitamin D deficiency has become increasingly common also among populations living at lower latitudes owing to the changes brought about by the adoption of modern lifestyle habits ( e.g. , less outdoor activity, greater usage of sunscreens) often associated with not meeting daily UVB requirements ( 14 - 16 ). Physical activity seems to be another important factor in the determination of vitamin D concentrations, as documented by the surprisingly high prevalence of vitamin D insufficiency, and even deficiency, in professional athletes regardless of amounts of the sunlight exposure during indoor or outdoor activities ( 17 - 19 ).…”