Vitamin D status in professional ballet dancers: Winter vs. summer

The Influence of Hormonal Contraception on Vitamin D Supplementation on Serum 25(OH)D3 Status in Premenopausal Women: A Prospective Double-Blind Placebo Random Controlled Trial

“…This study supports the observations of previous cross-sectional and longitudinal observation studies that oral contraception has a positive effect on serum 25(OH)D levels [10,14]. Our study also showed those taking the estrogen-containing oral contraceptive had 11% higher baseline 25(OH)D but this did not reach statistical significance.…”

“…Wolman et al [10] noted a significant decrease in PTH for those on oral contraception that was association with a significant increase in serum 25(OH)D above the levels reported for those not taking oral contraception. The study was limited by low numbers of participants on contraception [5] and therefore the results cannot be generalized further.…”

“…Deficiency is associated with a range of medical disorders including metabolic bone disease [3,5], type 2 diabetes [2], cancer and impaired immune function [6,7]. It is also associated with muscle weakness, which has been linked to the increased risk of falls in the elderly [5,8] and to impaired athletic performance [9][10][11].…”

“…Palaniswamy et al [13] reported that gender, season, diet, obesity and physical activity were all associated with low 25(OH)D concentrations. A number of cross-sectional studies have reported that estrogen-containing hormonal contraception enhances serum 25(OH)D levels in women [10,13,14]. Harris and Dawson-Hughes [14] reported that women on contraception had 39% higher serum 25(OH)D levels compared with non-users.…”

Acute Effects of Vitamin D3 Supplementation on Muscle Strength in Judoka Athletes

“…Serum concentrations of 25(OH)D 3 constitute a storage facility similar to other steroid hormones. 3 Serum vitamin D insufficiency has been defined when values are between 10 and 30 ng/mL and deficiency for levels below 10 ng/mL [4][5][6] Holick and Chen 4 highlighted in their review that the increases in worldwide vitamin D (25(OH) D 3 ) deficiency are due to the use of sunblock and skin coverings to reduce the risk of skin cancer; this is exacerbated for indoor athletes, 5 and dancers 6,7 have been shown to be at risk of deficiency mainly because of decreased sunlight exposure. 8 Birge and Haddad 9 were the first to confirm the link between muscle function and 25(OH)D 3 .…”