Effect of vitamin D3 supplementation in winter on physical performance of university students: a one-month randomized controlled trial.

BACKGROUND: There is epidemiological evidence which suggests an association between 25-hydroxyvitamin D [25(OH)D] levels and bone and muscle function; however, it is unclear whether vitamin D supplementation has an added benefit beyond bone health. Here, we investigated the effects of vitamin D3 supplementation (1 month) on physical performance in Chinese university students in winter. METHODS: One hundred and seventeen eligible subjects with 25(OH)D (19.2 ± 7.8 ng/mL) were randomly assigned to either vitamin D3 supplement (N = 56; 1000 IU/day) or the control (N = 61) group for 1 month. Pre- and post-measurements included: 1) serum levels of 25(OH)D; 2) musculoskeletal and pulmonary function [vertical jump height (VJH) and right handgrip strength (RHS), forced vital capacity (FVC), and forced expiratory volume at 1s (FEV1)]; 3) bone turnover markers [parathyroid hormone (PTH), n-terminal osteocalcin (N-MID), and calcium]; 4) hemoglobin-related parameters [hemoglobin (Hb), hematocrit (HCT), red blood cells (RBC), and red cell distribution width (RDW)]; 5) lipid parameters [total triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)]; 6) Fatigue-related indicators [serum creatine kinase (CK), lactate dehydrogenase (LDH), and total testosterone (T)]. In addition, aerobic capacity was assessed by measuring maximal oxygen uptake (VO2max) at baseline. RESULTS: During wintertime, supplementation with 1000 IU/d of vitamin D3 significantly increased serum 25(OH)D levels (from 18.85 ± 7.04 to 26.98 ± 5.88 ng/mL, p < 0.05), accompanied by a decrease of PTH (p < 0.05). However, vitamin D3 supplementation did not significantly impact the physical performance, serum lipid parameters, and bone turnover markers of students. Furthermore, 25(OH)D was found to be positively correlated with VJH and negatively correlated with PTH and TC at the beginning and end of the study (p < 0.05). In addition, the multiple linear regression analysis showed that 25(OH)D combined with athletic, gender, height, weight, Hb, and FVC could account for 84.0% of the VO2max value. CONCLUSIONS: The study demonstrated that one-month of 1000 IU/d of vitamin D3 supplementation during the winter had beneficial effects on 25(OH)D status and PTH. However, vitamin D3 intervention was not sufficient to improve physical performance. Furthermore, 25(OH)D levels combined with athletic, Hb and FVC could be a predictor of VO2max.

Effects of PEMFs on Osx, Ocn, TRAP, and CTSK gene expression in postmenopausal osteoporosis model mice.

Objective: Ovariectomized mice were used to simulate the symptoms of postmenopausal women with osteoporosis, and observe the effects of PEMF treatment on expression of Osx, Ocn, TRAP, and CTSK in ovariectomized mice. Methods: Thirty-week-old wild-type C57BL/6 mice were randomly divided into three groups (n=10, each group): sham operation group, ovariectomy (OVX) group, and PEMF group. Mice in the sham group underwent sham ovariectomy, while mice in the remaining two groups were ovariectomized. On postoperative day two, mice in the PEMF treatment group received PEMF treatment at a frequency of 8 Hz and an intensity of 3.8 mT for one hour daily for four weeks. At the same time, mice in the remaining two groups were placed in the PEMF treatment area under power-down state daily, similar to that in the PEMF group. After four weeks, all relevant indicators were tested. Results: (1) Compared with mice in the sham group, the number of trabecular bones significantly decreased, the thickness of the trabecular bone became thinner, the number of osteoclasts significantly increased, the gene expression of Osx and Ocn significantly decreased, and the gene expression of TRAP and CTSK significantly increased in the OVX group (P<0.01). (2) Compared with the blank controls without operation, the number of osteoblasts increased in the PEMF group. (3) Compared with the OVX group, the number of osteoclasts significantly decreased, the expression of Osx and Ocn significantly increased, and the gene expression of TRAP and CTSK significantly decreased in the PEMF group (P<0.01). Conclusion: PEMF treatment can significantly promote bone formation, which may be realized through inhibition of osteoclast formation, achieving bone morphological protection. PEMFs can significantly upregulate Osx and Ocn osteogenesis-related genes, which affect bone formation, and downregulate TRAP and CTSK osteoclast-related genes, which affect bone resorption. PEMFs may be used to treat postmenopausal osteoporosis by regulating Osx, Ocn, TRAP, and CTSK gene expression.