Effects of vitamin d on muscle function and performance: a review of evidence from randomized controlled trials

Randomized Trial to Improve Body Composition and Micronutrient Status Among South African Children

INTRODUCTION

Physical activity (PA) promotion combined with multimicronutrient supplementation (MMNS) among school-age children may reduce fat mass accrual and increase muscle mass through different mechanisms and so benefit child health. This study determined the efficacy of combined interventions on body composition among South African schoolchildren and determined if micronutrients mediate these effects.

STUDY DESIGN

Longitudinal cluster randomized controlled trial of children followed from 2019 to 2021. Statistical analyses carried from 2022 to 2023.

SETTING/PARTICIPANTS

A total of 1,304 children 6-12 years of age recruited from public schools in Gqeberha, South Africa.

INTERVENTION

Children were randomized by classes to either: (a) a physical activity group (PA); (b) a MMNS group; (c) a physical activity + multimicronutrient supplementation group (PA + MMNS); and (d) a placebo control group.

MAIN OUTCOME MEASURES

Trajectories of overall and truncal fat free mass (FFM) and fat mass (FM) estimates in modeled at 9 and 21 months using latent growth curve models (LGCM). Changes in micronutrient concentrations at 9 months from baseline.

RESULTS

An increased FFM trajectory was found among children in the MMNS arm at 9 months (Beta 0.16, 95% CI = 0.12, 0.31). The PA and MMNS arms both had positive indirect effects on this trajectory at 9 months (Beta 0.66, 95% CI = 0.44, 0.88 and Beta 0.32 95% CI = 0.1 0.5, respectively) and similarly at 21 months when mediated by zinc concentration changes. A reduced FM trajectory was found among children in the PA promotion arm at 9 months when using this collection point as the referent intercept. This arm was inversely associated with the FM trajectory at 9 months when mediated by zinc changes.

CONCLUSIONS

PA and MMNS promotion in school-based interventions directly contributed to reductions in FM and increased FFM among South African children and indirectly through changes in micronutrient status.

TRIAL REGISTRATION

ISRCTN, ISRCTN29534081. Registered on August 9, 2018 Institutional review board: Ethikkommission Nordwest- und Zentralschweiz" (EKNZ, project number: Req-2018-00608). Date of approval: 2018.

Vitamin D as an intervention for improving quadriceps muscle strength in patients after anterior cruciate ligament reconstruction: study protocol for a randomized double-blinded, placebo-controlled clinical trial

BACKGROUND

The goal of anterior cruciate ligament reconstruction (ACLR) is to restore the preinjury level of knee function to return to play (RTP). However, even after completing the rehabilitation programme, some patients may have persistent quadriceps muscle weakness affecting knee function which ultimately leads to a failure in returning to play. Vitamin D has been long recognized for its musculoskeletal effects. Vitamin D deficiency may impair muscle strength recovery after ACLR. Correcting vitamin D levels may improve muscle strength.

METHODS

This is a double-blinded, randomized controlled trial to investigate the effects of vitamin D supplementation during the post-operative period on quadriceps muscle strength in anterior cruciate ligament (ACL)-injured patients. Patients aged 18-50 with serum vitamin D < 20 ng/ml, unilateral ACL injury, > 90% deficit in total quadriceps muscle volume on the involved leg compared with uninvolved leg, Tegner score 7 + , and no previous knee injury/surgery will be recruited. To assess patient improvement, we will perform isokinetic and isometric muscle assessments, ultrasound imaging for quadriceps thickness, self-reported outcomes, KT-1000 for knee laxity, biomechanical analysis, and Xtreme CT for bone mineral density. To investigate the effect of vitamin D status on quadriceps strength, blood serum samples will be taken before and after intervention.

DISCUSSION

Patients with low vitamin D levels had greater quadriceps fibre cross-sectional area loss and impaired muscle strength recovery after ACL. The proposed study will provide scientific support for using vitamin D supplementation to improve quadriceps strength recovery after ACLR.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05174611. Registered on 28 November 2021.

Vitamin D Deficiency Leads to Poorer Health Outcomes and Greater Length of Stay After Total Knee Arthroplasty and Supplementation Improves Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Vitamin D deficiency is increasingly identified as a predictor of poorer outcomes in musculoskeletal disease affecting as many as 1 in 4 people. This study aimed to evaluate the effect of vitamin D supplementation on outcomes after primary total knee arthroplasty (TKA).

METHODS

A targeted search of terms related to vitamin D and TKA outcomes was performed in PubMed, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, American Academy of Orthopaedic Surgeons, and British Orthopaedic Association databases. The results were analyzed using forest plots with I2 heterogeneity statistics and pooled effects with 95% confidence intervals (CIs) and p values. A p < 0.05 was considered statistically significant.

RESULTS

A total of 146,054 patients with 150,107 TKRs were analyzed in 10 studies that complied with the inclusion criteria, of which 3 were suitable for meta-analysis. Of these, 4 of the 10 studies showed that vitamin D deficiency resulted in poorer functional outcome scores (Western Ontario and McMasters Universities Osteoarthritis Index, Knee Society Scoring System, and American Knee Society scores), as well as increased risk of revision surgery, incidence of joint infection, and postoperative stiffness. Meta-analysis of length of hospital stay (LOS) demonstrated a significant increase in LOS in patients with vitamin D deficiency (standardized mean difference, -0.54, 95% CI, -0.69 to -0.38, p < 0.00001). Furthermore, outcomes were improved with vitamin D supplementation in 6 of 10 studies.

CONCLUSION

Vitamin D deficiency results in poorer outcomes of primary TKA, with improved outcomes after supplementation. Further studies should examine the role of preoperative vitamin D screening and/or perioperative supplementation in primary TKA and standardize outcome measures to assess their effect.

LEVEL OF EVIDENCE

Level I/II. See Instructions for Authors for a complete description of levels of evidence.

Vitamin D and Calcium and Bioavailability of Calcium in Various Calcium Salts

Introduction

The active form of vitamin D, 1,25D3, plays an important function in the metabolism of calcium. The recommended daily INTAKE of Calcium varies from 1300 mg/day during adolescence to 1200 mg/day after the age of 50 years. Similarly, for vitamin D, the recommended daily intake varies from 400 IU/day during adolescence to 1000 IU/day after the age of 70 years. There is an intricate inter-play of homeostasis of calcium led by vitamin D and PTH at various sites like intestine, kidney, and bones. The increased fracture risk due to bone loss and osteoporosis creates a burden on the patient, healthcare provider as well as the health system. As the population grows old worldwide gradually, the long-term sequelae like pain, loss of independence, and institutionalized care will become more pervasive. Behavioral change to incorporate a healthy lifestyle, including optimal calcium and vitamin D intake and physical exercise in adolescence, form the important foundation in the program for osteoporosis prevention.

Conclusion

Increased emphasis on lifestyle modification and nutrition should be given during times of increased bone loss in old age and after menopause.

Differences Between 25-hydroxyvitamin D Levels in Patients with Pelvic Organ Prolapse and Non-Pelvic Organ Prolapse: A Systematic Review

OBJECTIVES

Treatment options for cases of pelvic organ prolapse still lead to the use of a pessary rather than a surgical method. Additional therapy is needed to help treat or prevent pelvic organ prolapse. Vitamin D deficiency has consistently been associated with decreased muscle function, so it is assumed that it will affect the pelvic floor muscles. This paper systematically explores the differences between 25-hydroxyvitamin D levels in patients with pelvic organ prolapse and non-pelvic organ prolapse.

STUDY DESIGN

A systematic review was conducted through the PubMed, Google Scholar, Cochrane Library, and ScienceDirect databases using relevant keywords. Articles published in the last 10 years-from 2012 to 2022-that were written in English, that discuss the status or effect of vitamin D on pelvic organ prolapse, and that focus on 25 OH-vitamin D were included in the review.

RESULTS

In total, 717 articles were filtered but 8 articles met the criteria. A total of 1339 women with prolapse and without prolapse with ages ranging from 20 years to 78 years were included in the study. The studies found did not use the same standard threshold in determining deficiency status. Most studies have found that there are lower levels of vitamin D in women who have had pelvic organ prolapse. A total of 7 of 8 studies confirmed the comparison of vitamin D-25OH levels in women with pelvic organ prolapse and without pelvic organ prolapse at P < 0.05.

CONCLUSIONS

There are differences between 25-hydroxyvitamin D levels in patients with pelvic organ prolapse and non-pelvic organ prolapse.

Current Research on Vitamin D Supplementation against Sarcopenia: A Review of Clinical Trials

Vitamin D plays an important role in skeletal muscle function and metabolism. The aim of this review was A) to discuss the clinical evidence of vitamin D supplementation either alone or combined with other strategies in the prevention of sarcopenia in non-sarcopenic individuals and B) to critically discuss the clinical evidence on the effect of vitamin D combined with other strategies on muscle strength, mass and function in sarcopenic individuals without vitamin D deficiency. Sparse clinical data on non-sarcopenic individuals indicate that vitamin D alone has a subtle beneficial effect on knee extensor strength at doses 880-1600 IU/day without improving handgrip strength or muscle mass. When co-administered with other supplements such as protein, mixed effects appear to prevent the decline of muscle mass, possibly delaying the onset of sarcopenia in non-sarcopenic individuals, at doses of 800-1,000 IU/day over 6-12 weeks. In sarcopenic individuals, vitamin D 100-1,000 IU/day co-supplementation with protein results in increased handgrip strength between 9.8-40.5%. However, there is no strong clinical evidence that vitamin D dosage correlates with changes in muscle strength or mass. Potential sources of discrepancy among studies are discussed. Future studies with appropriate experimental design are essential to dissect the net effect of vitamin D on sarcopenia.

The pathogenesis of post-stroke osteoporosis and the role oxidative stress plays in its development

Cardiovascular disease and osteoporotic fractures (OF) are the main diseases affecting the health of middle-aged and elderly people. With the gradual increase of population aging in China and even the world, the incidence of the two and the prevalence of high-risk groups are also showing a continuous upward trend. The relationship between the two, especially the impact of cardiovascular disease on the risk and prognosis of OF, has attracted more and more attention. Therefore, it is of great significance to fully understand the pathogenesis of cardiovascular and cerebrovascular diseases and the resulting osteoporosis and to provide targeted interventions to prevent the occurrence of diseases and fractures. This article reviews the relationship between one of the Cardiovascular disease-stroke and related therapeutic drugs and the risk of OF, and the role of oxidative stress in its pathophysiological mechanism by reviewing relevant domestic and foreign literature in recent years, in order to gain a more comprehensive understanding of the association between stroke and OF, and then provide a basis and reference for screening high-risk groups of fractures and reducing the burden on the health system caused by the disease.

Gastric Cancer with Sarcopenia: an Area Worth Focusing On

OPINION STATEMENT

Gastric cancer (GC) is the fifth most common cancer and the third leading cause of cancer death worldwide, which seriously endangers human health. A number of studies have shown that sarcopenia occurs more frequently in patients with gastric cancer than in the general population and can significantly affect the disease status and survival of patients, which is of great significance in predicting the prognosis of gastric cancer. Patients with gastric cancer may suffer sarcopenia no matter before or after surgery, and the pathogenesis is complex. Abnormal nutrient metabolism and reduced exercise are the leading causes. In addition, surgical treatment and chemotherapy for gastric cancer might participate in the physiological and pathological mechanism of sarcopenia. Generally speaking, exercise and nutritional therapy are the main prevention and treatment methods for sarcopenia. But more prospective evidence is needed to establish reasonable interventions, and other drug treatments are in their infancy. For the diagnostic criteria of sarcopenia, the cut-off values of the skeletal muscle mass index obtained from CT images vary widely and need to be standardized and unified. We also need to explore simple predictors to facilitate sarcopenia risk assessment. More research is needed to formulate more appropriate treatments for gastric cancer patients with sarcopenia.

The Sunlight-Vitamin D Connection: Implications for Patient Outcomes in the Surgical Intensive Care Unit

This review delves into the intricate relationship between Vitamin D and patient outcomes in the Surgical Intensive Care Unit (SICU). Vitamin D, known for its multifaceted roles in immune modulation, inflammation regulation, and maintenance of calcium homeostasis, emerges as a pivotal factor in the care of critically ill patients. Our exploration reveals a high prevalence of Vitamin D deficiency in the SICU, primarily attributable to limited sunlight exposure, comorbidities, and medication use. Importantly, Vitamin D status impacts infection rates, mortality, and length of stay in the SICU, making it a clinically relevant consideration. Mechanistic insights into the immunomodulatory and anti-inflammatory effects of Vitamin D shed light on its potential benefits in critical care. However, challenges, including accurate assessment, individualised supplementation, and ethical considerations regarding sunlight exposure, are evident. The prospect of personalised Vitamin D supplementation strategies offers promise for optimising patient care. In conclusion, the Sunlight-Vitamin D Connection holds significant potential to improve outcomes in the SICU, emphasising the importance of further research and tailored approaches for the well-being of critically ill individuals.

Vitamin D3 supplementation improves spatial memory, muscle function, pain score, and modulates different functional physiological biomarkers in vitamin D3 deficiency diet (VDD)-induced rats model

BACKGROUND

Vitamin D Deficiency is recognized as a pandemic, which is associated with high mortality. An inadequate level of vitamin D is associated with autoimmune diseases, hypertension, and cancer. The study was aimed to assess the pharmacological effects of chronic vitamin D3 supplementation on the manipulation diet regiment of deprived cholecalciferol (vitamin D3 deficient diet, VDD) rats.

METHODS

Memory performance (Y-maze task), muscular function (muscle grip strength), and pain score (pressure application measurement meter) were measured. Functional biomarkers were measured using ELISA method in different matrix viz. in serum (parathyroid hormone; PTH, calcitonin, thyroxine, and C-reactive protein; CRP, 25-OH Vit D3), and in CSF (klotho and β-endorphin). 25-OH Vit D3 was also estimated in liver and kidney homogenate using ELISA. Vitamin D receptor (VDR) was measured spectrophotometrically in liver and adipose tissue.

RESULTS

VDD-induced rats showed a decrease in number of entries and time spent in the novel arm and spontaneous alternations in the Y-maze task. Significant improvements of neuromuscular function and pain score after addition of vitamin D3. In comparison to the VDD group, VDR expression (liver) and active metabolites of vitamin D3 (25-OH vit.D3) in serum were significantly higher by 48.23% and 280%, respectively. The PTH and CRP levels were significantly reduced by 32.5% and 35.27%, respectively, whereas calcitonin was increased by 36.67% compared with the VDD group. Klotho and β-endorphin expressions in cerebrospinal fluid were significantly elevated by 19.67% and 133.59%, respectively, compared to VDD group.

CONCLUSIONS

Overall, the results indicate that supplementation of cholecalciferol significantly improved spatial memory impairment, VDR expression, and may provide an opportunity to manage vitamin D deficiencies.

Systematic review and meta-analysis: Associations of vitamin D with pulmonary function in children and young people with cystic fibrosis

BACKGROUND

Increasing evidence suggests that vitamin D is associated with pulmonary health, which may benefit children and young people diagnosed with Cystic Fibrosis (cypCF). Therefore, the aim of this systematic review was to evaluate primary research to establish associations between 25OHD and pulmonary health in cypCF.

METHODS

Electronic databases were searched with keywords related to CF, vitamin D, children/young people and pulmonary function. Included studies were cypCF (aged ≤21 years) treated in a paediatric setting. The primary outcome was lung function [forced expiratory volume in 1 s (FEV₁% predicted)] and secondary outcomes were rate of pulmonary exacerbations, 25OHD status and growth. Evidence was appraised for risk of bias using the CASP tool, and quality using the EPHPP tool. A Meta-analysis was performed.

RESULTS

Twenty-one studies were included with mixed quality ratings and heterogeneity of reported outcomes. The Meta-analysis including 5 studies showed a significantly higher FEV₁% predicted in the 25OHD sufficiency compared to the deficiency group [FEV₁% predicted mean difference (95% CI) was 7.71 (1.69-13.74) %; p = 0.01]. The mean ± SD FEV₁% predicted for the sufficient (≥75 nmol/L) vs. deficient (<50 nmol/L) group was 94.7 ± 31.9% vs. 86.9 ± 13.2%; I² = 0%; χ² = 0.5; df = 4). Five studies (5/21) found significantly higher rate of pulmonary exacerbations in those who were 25OHD deficient when compared to the sufficient group and negative associations between 25OHD and FEV% predicted. The effects of vitamin D supplementation dosages on 25OHD status (10/21) varied across studies and no study (12/21) showed associations between 25OHD concentration and growth.

CONCLUSION

This systematic review suggests that 25OHD concentration is positively associated with lung function and a concentration of >75 nmol/L is associated with reduced frequency of pulmonary exacerbations, which may slow lung function decline in cypCF. Future randomised clinical trials and mechanistic studies are warranted.

Does an Association among Sarcopenia and Metabolic Risk Factors Exist in People Older Than 65 Years? A Systematic Review and Meta-Analysis of Observational Studies

Sarcopenia is defined as the generalized and progressive loss of skeletal muscle strength and mass that may be affected by metabolic factors, although this relationship has been poorly studied. The aim of this review and meta-analysis was to analyze the relationship among the different metabolic risk factors and sarcopenia in people older than 65 years. Following the PRISMA 2020 guide, we searched for articles that studied the relationship among sarcopenia and metabolic risk factors in adults over 65 years of age, published between 2012 and 2022 in four databases: PubMed, Web of Science, Cochrane Plus, and CINAHL. A total of 370 articles were identified in the initial search, of which 13 articles were selected for inclusion in this review. It was observed that metabolic risk factors such as Body Mass Index, systolic and diastolic blood pressure, glucose, cholesterol, or triglycerides had a significant association with sarcopenia. There is evidence of the association of different metabolic risk factors with sarcopenia in adults over 65 years of age, so it is necessary to carry out studies that investigate different strategies that reduce the appearance of sarcopenia, and with it, the incidence of metabolic diseases.

Evaluation of the Association of VDR rs2228570 Polymorphism with Elite Track and Field Athletes' Competitive Performance

The present study aimed to examine the vitamin D receptor (VDR), rs2228570 polymorphism, and its effect on elite athletes' performance. A total of 60 elite athletes (31 sprint/power and 29 endurance) and 20 control/ physically inactive, aged 18-35, voluntarily participated in the study. The International Association of Athletics Federations (IAAF) score scale was used to determine the performance levels of the athletes' personal best (PB). Whole exome sequencing (WES) was performed by the genomic DNA isolated from the peripheral blood of the participants. Sports type, sex, and competitive performance were chosen as the parameters to compare within and between the groups by linear regression models. The results showed no statistically significant difference between the CC, TC, and TT genotypes within and between the groups (p > 0.05). Additionally, our results underlined that there were no statistically significant differences for the association of rs2228570 polymorphism with PBs within the groups of the (p > 0.05) athletes. The genetic profile in the selected gene was similar in elite endurance, sprint athletes, and in controls, suggesting that rs2228570 polymorphism does not determine competitive performance in the analyzed athlete cohort.

Impact of Vitamin D Level on Sarcopenia in Elderly People: A Critical Review

Vitamin D insufficiency is a widespread health issue globally, particularly among the elderly. Vitamin D controls and affects the metabolism and functionality of several human systems, including muscle tissue. The action of vitamin D on muscles has been extensively studied, with evidence indicating that this vitamin can increase the osteogenic differentiation of muscle fibers, hence preserving and enhancing muscular strength and athletic performance. Low hormone levels are more common in older people as a result of poor food intake and decreased skin ultraviolet irradiation. As a result, elderly persons who are deficient in vitamin D may be at risk of developing sarcopenia, a geriatric condition defined by gradual loss of skeletal muscle mass and strength that is frequently accompanied by adverse events such as falls, incapacity hospitalization, and mortality. As a result, these activities are seen to be crucial in illuminating the underlying functional condition of the aged, and functional mobility is employed as a technique for assessing fall risk and frailty. Several randomized controlled studies have been done to explore the efficacy of oral treatment in elderly people to prevent or cure sarcopenia; however, the results are still debatable. We describe the biochemical, clinical, and epidemiological data supporting the idea of a causal relationship between vitamin D insufficiency and a higher likelihood of sarcopenia in elderly adults in this narrative review. The muscular system, the biggest organ in the body, contributing to around 40% of body composition, is vital in exercising and glycogen depletion. Sarcopenia, a steady deterioration in muscle mass and strength, and function in the aged can result in prolonged circumstances, wheelchair confinement, and a reduction in quality of life. Diagnosis and control of muscle wasting are vital for improving health and quality of life in industrialized nations with aging populations. Vitamin D, a fat-soluble vitamin, has gained popularity in recent years because of its relevance in sarcopenia. The role of vitamin D deficiency and fortification on muscle wasting will be the focus of this review.

The Effect of Vitamin D Supplementation for Bone Healing in Fracture Patients: A Systematic Review

While most literature on vitamin D supplementation in fracture patients focuses on fracture prevention, the effect of vitamin D on bone healing is a much less studied concept. The primary aim of this systematic review was to assess whether vitamin D supplementation in fracture patients improves clinical or radiological union complications. The secondary aims were to assess supplementation effect on patient functional outcome scores and bone mineral density (BMD). A systematic search of all relevant articles was performed using the following databases: MEDLINE, Embase, Google Scholar, and Web of Science. The population selection included human patients with a fresh fracture treated conservatively or operatively. The intervention included any form of vitamin D supplementation, compared to no supplementation or a placebo. The primary outcomes assessed were clinical or radiological union rates or complications arising from the nonunion. The secondary outcomes assessed were functional outcome scores, BMD scores after treatment, and pain scores. A total of fourteen studies, assessing a total of 2734 patients, were included. Eight studies assessed the effect of vitamin D on clinical or radiological union. Five studies reported no significant difference in complication rates when supplementing fracture patients. Alternatively, three studies reported a positive effect with supplementation between the groups. One of these studies found a difference only for early orthopaedic complications (<30 days), but no differences in late complications. The other two studies found significant differences in clinical union; however, no changes were observed in radiological union. Six studies investigated functional outcome scores after supplementation. Four of these studies found no significant differences between most functional outcome scores. Only three studies reported BMD outcomes, one of which found limited effect on total hip BMD. The overall findings are that vitamin D alone does little to influence fracture healing and subsequent union rates or functional outcome. The studies suggestive of a positive effect were generally of a lower quality. Further high quality RCTs are needed to justify routine supplementation at the time of fracture.

Identification of Agents That Ameliorate Hyperphosphatemia-Suppressed Myogenin Expression Involved in the Nrf2/p62 Pathway in C2C12 Skeletal Muscle Cells

Hyperphosphatemia can occur as a result of reduced phosphate (P_i) excretion in cases of kidney dysfunction, which can induce muscle wasting and suppress myogenic differentiation. Higher P_i suppresses myogenic differentiation and promotes muscle atrophy through canonical (oxidative stress-mediated) and noncanonical (p62-mediated) activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. However, the crosstalk between myogenin and Nrf2/p62 and potential drug(s) for the regulation of myogenin expression needed to be addressed. In this study, we further identified that myogenin may negatively regulate Nrf2 and p62 protein levels in the mouse C2C12 muscle cell line. In the drug screening analysis, we identified N-acetylcysteine, metformin, phenformin, berberine, 4-chloro-3-ethylphenol, cilostazol, and cilomilast as ameliorating the induction of Nrf2 and p62 expression and reduction in myogenin expression that occur due to high P_i. We further elucidated that doxorubicin and hydrogen peroxide reduced the amount of myogenin protein mediated through the Kelch-like ECH-associated protein 1/Nrf2 pathway, differently from the mechanism of high Pi. The dual functional roles of L-ascorbic acid (L-AA) were found to be dependent on the working concentration, where concentrations below 1 mM L-AA reversed the effect of high P_i on myogenin and those above 1 mM L-AA had a similar effect of high P_i on myogenin when used alone. L-AA exacerbated the effect of hydrogen peroxide on myogenin protein and had no further effect of doxorubicin on myogenin protein. In summary, our results further our understanding of the crosstalk between myogenin and Nrf2, with the identification and verification of several potential drugs that can be applied in rescuing the decline of myogenin due to high P_i in muscle cells.

The effect of vitamin D level on cardiac rehabilitation in patients with Coronary Artery Disease

BACKGROUND

25-hydroxy vitamin D (25OHD) deficiency is associated with cardiovascular disease and poor physical performance.

OBJECTIVE

To assign the effect of 25OHD level on cardiac rehabilitation (CR) in patients with coronary artery disease (CAD).

METHODS

One-hundred-thirty-five patients with CAD who underwent a CR programme were enrolled in this retrospective study. Patients were divided into two-group according to 25OHD level (Group 1: < 20 ng/dl; Group 2: ⩾ 20 ng/dl). All patients received CR for 30 sessions. Each participant performed 40 minutes of aerobic exercise with a cycloergometer followed by muscle strengthening exercises. The patients were evaluated before and after CR by a pulmonary function test (PFT) and a cardiopulmonary exercise test (CPET).

RESULTS

There were 77 (57%) patients in Group 1 and 58 patients (43%) in Group 2. Demographic characteristics between the groups were similar. Pre- and post-rehabilitation CPET parameters were lower in Group 1 (p< 0.05). Both groups had significant improvement in CPET (p< 0.05). Post-rehabilitation PFT parameters (FEV1, FVC) were higher in Group 2 (p< 0.05). There was a positive correlation between the 25OHD-level and the CPET-PFT parameters (p< 0.05).

CONCLUSION

25OHD deficiency in patients with CAD reduces the response to CR. It also affects respiratory function according to the FEV1, FVC parameters. In patients scheduled for CR, 25OHD-levels should be evaluated, and any deficiency corrected.

Vitamin D supplementation and increased dairy protein intake do not affect muscle strength or physical function in healthy 6-8-year-old children: the D-pro randomized trial

PURPOSE

To investigate separate and combined effects of vitamin D supplementation during the extended winter and increased dairy protein intake on muscle strength and physical function in children, and furthermore to explore potential sex differences.

METHODS

In a 2 × 2-factorial, randomized winter trial, 183 healthy, 6-8-year-old children received blinded tablets with 20 µg/day vitamin D3 or placebo, and substituted 260 g/day dairy with yogurts with high (HP, 10 g protein/100 g) or normal protein content (NP, 3.5 g protein/100 g) for 24 weeks during winter at 55° N. We measured maximal isometric handgrip and leg press strength, and physical function by jump tests and a 30 s sit-to-stand test. Physical activity was measured by 7-day accelerometry.

RESULTS

Baseline (mean ± SD) serum 25-hydroxyvitamin D was 80.8 ± 17.2 nmol/L, which increased to 88.7 ± 17.6 nmol/L with vitamin D supplementation and decreased to 48.4 ± 19.2 nmol/L with placebo. Baseline protein intake was 15.5 ± 2.4 E%, which increased to 18.4 ± 3.4 E% with HP and was unchanged with NP. We found no separate or combined effects of vitamin D supplementation and/or increased dairy protein intake on muscle strength or physical function (all P > 0.20). There was an interaction on the sit-to-stand test (Pvitamin×yogurt = 0.02), which however disappeared after adjusting for physical activity (P = 0.16). Further, vitamin D supplementation increased leg press strength relatively more in girls compared to boys (mean [95% CI] 158 [17, 299] N; Pvitamin×sex = 0.047).

CONCLUSION

Overall, vitamin D and dairy protein supplementation during the extended winter did not affect muscle strength or physical function in healthy children. Potential sex differences of vitamin D supplementation should be investigated further. REGISTERED AT CLINICALTRIALS.GOV: NCT0395673.

The Relationship of Falls With Achieved 25-Hydroxyvitamin D Levels From Vitamin D Supplementation: The STURDY Trial

Context

The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a randomized trial enrolling older adults with low 25-hydroxyvitamin D [25(OH)D], demonstrated vitamin D supplementation ≥ 1000 IU/day did not prevent falls compared with 200 IU/day, with doses ≥ 2000 IU/day potentially showing safety concerns.

Objective

To examine associations of achieved and change in 25(OH)D concentrations after 3 months of vitamin D supplementation with fall risk.

Design

Observational analysis of trial data.

Setting

General community.

Participants

A total of 637 adults aged ≥ 70 with baseline 25(OH)D concentrations 10 to 29 ng/mL and elevated fall risk. Three-month on-treatment absolute 25(OH)D; absolute and relative changes from baseline.

Main Outcome Measures

Incident first fall (primary) and first consequential fall (injury or sought medical care) up to 24 months. Cox models were adjusted for sociodemographics, season, Short Physical Performance Battery, and body mass index.

Results

At baseline, mean (SD) age was 77.1 (5.4) years and 25(OH)D was 22.1 (5.1) ng/mL; 43.0% were women and 21.5% non-White. A total of 395 participants experienced ≥ 1 fall; 294 experienced ≥ 1 consequential fall. There was no association between absolute achieved 25(OH)D and incident first fall (30-39 vs < 30 ng/mL hazard ratio [HR], 0.93; 95% CI, 0.74-1.16; ≥40 vs < 30 ng/mL HR, 1.09; 95% CI, 0.82-1.46; adjusted overall P = 0.67), nor absolute or relative change in 25(OH)D. For incident consequential first fall, the HR (95% CI) comparing absolute 25(OH)D ≥ 40 vs < 30 ng/mL was 1.38 (0.99-1.90).

Conclusion

Achieved 25(OH)D concentration after supplementation was not associated with reduction in falls. Risk of consequential falls may be increased with achieved concentrations ≥ 40 ng/mL.

Trial Registration

ClinicalTrials.gov: NCT02166333.

Effect of Daily Vitamin D3 Supplementation on Muscle Health: An Individual Participant Meta-analysis

BACKGROUND

The role of vitamin D on muscle health is debated.

METHODS

An individual participant metanalysis of 4 randomized placebo-controlled trials, investigating short-term (3-9months) effects of vitamin D3 in moderate (2800 IU) to high (7000 IU) daily oral doses on muscle health and quality of life (QoL). Inclusion criteria were either obesity (n = 52), newly diagnosed primary hyperparathyroidism (n = 41), Graves' disease (n = 86), or secondary hyperparathyroidism (n = 81).

RESULTS

Overall (n = 260) as well as in a subgroup analysis including only vitamin D insufficient [25(OH)D < 50 nmol/L] individuals (n = 176), vitamin D supplementation did not affect measures of muscle health (isometric muscle strength, Timed Up and Go test, chair rising test, body composition, and balance) or QoL. However, a beneficial effect was present on QoL (physical component score) in vitamin D deficient [25(OH)D < 25 nmol/L] individuals (n = 34). Overall, relative changes in 25(OH)D inversely affected maximum muscle strength in a dose-response manner. Stratified into body mass index </> 30 kg/m2, vitamin D supplementation had divergent effects on isometric muscle strength, with beneficial effects in obese individuals (n = 93) at knee flexion 90° (P = 0.04), and adverse effects in nonobese individuals (n = 167) at handgrip (P = 0.02), knee extension 60° (P = 0.03) and knee flexion 60° (P < 0.01).

CONCLUSION

Overall, short-term treatment with moderate to high daily doses of vitamin D did not affect muscle health or QoL. A potential beneficial effect was present on muscle strength in severely obese individuals and on QoL in vitamin D deficient individuals. Subgroup analyses, however, suggested negative effects of large relative increases in p-25(OH)D.

The effects of vitamin D supplementation on frailty in older adults at risk for falls

Background

Low serum 25-hydroxyvitamin D [25(OH)D] level is associated with a greater risk of frailty, but the effects of daily vitamin D supplementation on frailty are uncertain. This secondary analysis aimed to examine the effects of vitamin D supplementation on frailty using data from the Study To Understand Fall Reduction and Vitamin D in You (STURDY).

Methods

The STURDY trial, a two-stage Bayesian, response-adaptive, randomized controlled trial, enrolled 688 community-dwelling adults aged ≥ 70 years with a low serum 25(OH)D level (10–29 ng/mL) and elevated fall risk. Participants were initially randomized to 200 IU/d (control dose; n = 339) or a higher dose (1000 IU/d, 2000 IU/d, or 4000 IU/d; n = 349) of vitamin D3. Once the 1000 IU/d was selected as the best higher dose, other higher dose groups were reassigned to the 1000 IU/d group and new enrollees were randomized 1:1 to 1000 IU/d or control group. Data were collected at baseline, 3, 12, and 24 months. Frailty phenotype was based on number of the following conditions: unintentional weight loss, exhaustion, slowness, low activity, and weakness (≥ 3 conditions as frail, 1 or 2 as pre-frail, and 0 as robust). Cox proportional hazard models estimated the risk of developing frailty, or improving or worsening frailty status at follow-up. All models were adjusted for demographics, health conditions, and further stratified by baseline serum 25(OH)D level (insufficiency (20–29 ng/mL) vs. deficiency (10–19 ng/mL)).

Results

Among 687 participants (mean age 77.1 ± 5.4, 44% women) with frailty assessment at baseline, 208 (30%) were robust, 402 (59%) were pre-frail, and 77 (11%) were frail. Overall, there was no significant difference in risk of frailty outcomes comparing the pooled higher doses (PHD; ≥ 1000 IU/d) vs. 200 IU/d. When comparing each higher dose vs. 200 IU/d, the 2000 IU/d group had nearly double the risk of worsening frailty status (HR = 1.89, 95% CI: 1.13–3.16), while the 4000 IU/d group had a lower risk of developing frailty (HR = 0.22, 95% CI: 0.05–0.97). There were no significant associations between vitamin D doses and frailty status in the analyses stratified by baseline serum 25(OH)D level.

Conclusions

High dose vitamin D supplementation did not prevent frailty. Significant subgroup findings might be the results of type 1 error.

Trial registration

ClinicalTrials.gov: NCT02166333.

The Biological Role of Vitamins in Athletes’ Muscle, Heart and Microbiota

Physical activity, combined with adequate nutrition, is considered a protective factor against cardiovascular disease, musculoskeletal disorders, and intestinal dysbiosis. Achieving optimal performance requires a significantly high energy expenditure, which must be correctly supplied to avoid the occurrence of diseases such as muscle injuries, oxidative stress, and heart pathologies, and a decrease in physical performance during competition. Moreover, in sports activities, the replenishment of water, vitamins, and minerals consumed during training is essential for safeguarding athletes’ health. In this scenario, vitamins play a pivotal role in numerous metabolic reactions and some muscle biochemical adaptation processes induced by sports activity. Vitamins are introduced to the diet because the human body is unable to produce these micronutrients. The aim of this review is to highlight the fundamental role of vitamin supplementation in physical activity. Above all, we focus on the roles of vitamins A, B6, D, E, and K in the prevention and treatment of cardiovascular disorders, muscle injuries, and regulation of the microbiome.

Challenges Ahead for a Rational Analysis of Vitamin D in Athletes

Vitamin D is an essential vitamin for the normal formation of bones and calcium absorption. It is synthesized into our body through sunlight exposure and obtained by consuming foods rich in vitamin D (e.g., fatty fish, eggs yolk, dairy products). Its benefits on the health and performance of athletes are well documented. This article outlines some analytical challenges concerning the analytical quantification of vitamin D for its optimal intake, namely, a comprehensive study of the variability of the assay before categorizing any method as the golden standard, assurance of sample comparability to draw meaningful correlations, revision of the intake guidance based on appropriate statistical power analysis, and the implementation of rational strategies for preventing the underlying mechanism of preanalytical factors. Addressing these challenges will enable the effective management of vitamin D in the sports sector.

Changes in Fitness of Rural Primary School Students from Southwest China after Two-Year's Nutrition Intervention

Children in China’s poor rural areas often have insufficient protein and micronutrient intake. There is little research about the effect of milk and egg supplementation published on these children. A prospective randomized controlled trial was applied to evaluate the effect of milk and egg supplementation on the growth and fitness of poor rural primary school students in southwest China whose physical development was below national averages. A total of 955 healthy students aged 6–13 years old were recruited. The intervention group (538) received 200 g milk and 50 g braised egg at each school day, while the control group (417) kept their normal diet and received no extra supplementation. Serum vitamin D levels were measured by an enzyme-linked immunosorbent assay. A mixed linear model with repeated measures was performed to analyze the efficacy of the supplementation. Statistically significant interactions between groups and time were seen in weight in boys, but not in girls. Significant improvement in vitamin D levels, the broad jump, and the 8 × 50 m shuttle run were observed in both genders. Therefore, the supplementation of egg and milk for two years might have a positive effect on growth and physical fitness and decreasing vitamin D deficiency in poor rural Chinese children.

Vitamin D and Rheumatic Diseases: A Review of Clinical Evidence

Vitamin D plays an important role in maintaining a healthy mineralized skeleton. It is also considered an immunomodulatory agent that regulates innate and adaptive immune systems. The aim of this narrative review is to provide general concepts of vitamin D for the skeletal and immune health, and to summarize the mechanistic, epidemiological, and clinical evidence on the relationship between vitamin D and rheumatic diseases. Multiple observational studies have demonstrated the association between a low level of serum 25-hydroxyvitamin D [25(OH)D] and the presence and severity of several rheumatic diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), spondyloarthropathies, and osteoarthritis (OA). Nevertheless, the specific benefits of vitamin D supplements for the treatment and prevention of rheumatic diseases are less accepted as the results from randomized clinical trials are inconsistent, although some conceivable benefits of vitamin D for the improvement of disease activity of RA, SLE, and OA have been demonstrated in meta-analyses. It is also possible that some individuals might benefit from vitamin D differently than others, as inter-individual difference in responsiveness to vitamin D supplementation has been observed in genomic studies. Although the optimal level of serum 25(OH)D is still debatable, it is advisable it is advisable that patients with rheumatic diseases should maintain a serum 25(OH)D level of at least 30 ng/mL (75 nmol/L) to prevent osteomalacia, secondary osteoporosis, and fracture, and possibly 40–60 ng/mL (100–150 nmol/L) to achieve maximal benefit from vitamin D for immune health and overall health.

The Role of Vitamins in Neurodegenerative Disease: An Update

Acquiring the recommended daily allowance of vitamins is crucial for maintaining homeostatic balance in humans and other animals. A deficiency in or dysregulation of vitamins adversely affects the neuronal metabolism, which may lead to neurodegenerative diseases. In this article, we discuss how novel vitamin-based approaches aid in attenuating abnormal neuronal functioning in neurodegeneration-based brain diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and Prion disease. Vitamins show their therapeutic activity in Parkinson's disease by antioxidative and anti-inflammatory activity. In addition, different water- and lipid-soluble vitamins have also prevented amyloid beta and tau pathology. On the other hand, some results also show no correlation between vitamin action and the prevention of neurodegenerative diseases. Some vitamins also exhibit toxic activity too. This review discusses both the beneficial and null effects of vitamin supplementation for neurological disorders. The detailed mechanism of action of both water- and lipid-soluble vitamins is addressed in the manuscript. Hormesis is also an essential factor that is very helpful to determine the effective dose of vitamins. PubMed, Google Scholar, Web of Science, and Scopus were employed to conduct the literature search of original articles, review articles, and meta-analyses.

The effects of vitamin D supplementation in carpal tunnel syndrome treatment outcomes: a systematic review

PURPOSE

Vitamin D deficiency is related to carpal tunnel syndrome symptoms. Correcting vitamin D levels by supplementation was supposed to improve carpel tunnel symptoms, though there is a lack of aggregated data about treatment outcomes. This study aimed to examine whether vitamin D supplementation could improve the treatment outcomes in carpal tunnel syndrome patients.

METHODS

A comprehensive search of the PubMed, Cochrane Library, Scopus, and Web of Science databases for articles on vitamin D and carpel tunnel syndrome from January 2000 to March 2021 was performed. The article screening and data extraction were performed by two investigators independently with blinding to decisions on selected studies. All included studies had assessed the quality of evidence using the Methodological Index for Non-Randomized Studies (MINORS) scoring system.

RESULTS

We retrieved four studies that met the eligibility criteria. The treatment outcomes were evaluated by visual analog scale (124 wrists), functional scores (176 patients), muscle strength (84 patients), and nerve conduction velocity (216 wrists). After vitamin D supplementation, two studies reported improved pain scores and nerve conduction velocity, and three studies showed enhancement of functional status.

CONCLUSION

Vitamin D administration could offer favorable outcomes in pain improvement, better functional status, and increased sensory conduction velocity in carpal tunnel syndrome. However, there is to date no recommendations concerning a standardized dose or duration of vitamin D administration in carpal tunnel syndrome; prescribing vitamin D at the usual appropriate dose is suggested as an additional treatment in patients with mild to moderate carpel tunnel symptoms.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Vitamin D and Muscle Health: A Systematic Review and Meta-analysis of Randomized Placebo-Controlled Trials

The objective of this study was to investigate the effects of vitamin D supplementation versus placebo on muscle health. For this systematic review and trial-level meta-analysis of placebo-controlled trials, a systematic search of randomized controlled trials published until October 2020 was performed in Medline, Embase, and Google Scholar. We included studies in humans (except athletes) on supplementation with vitamin D2 or D3 versus placebo, regardless of administration form (daily, bolus, and duration) with or without calcium co-supplementation. The predefined endpoints were physical performance reported as timed up and go test (TUG; seconds), chair rising test (seconds), 6-minute walking distance (m), and Short Physical Performance Battery (SPPB; points). Furthermore, endpoints were maximum muscle strength (Newton) measured at handgrip, elbow flexion, elbow extension, knee flexion, and knee extension, as well as muscle (lean tissue) mass (kg). Falls were not included in the analysis. Cochrane Review Manager (version 5.4.1.) calculating mean difference (MD) using a random effect model was used. In total, 54 randomized controlled trials involving 8747 individuals were included. Vitamin D versus placebo was associated with a significantly longer time spent performing the TUG (MD 0.15 [95% confidence interval (CI) 0.03 to 0.26] seconds, N = 19 studies, I²  = 0%, n = 5223 participants) and a significant lower maximum knee flexion strength (MD -3.3 [-6.63 to -0.03] Newton, N = 12 studies, I²  = 0%, n = 765 participants). Total score in the SPPB showed a tendency toward worsening in response to vitamin D compared with placebo (MD -0.18 [-0.37 to 0.01] points, N = 8 studies, I²  = 0%, n = 856 participants). Other measures of muscle health did not show between-group differences. In subgroup analyses, including studies with low vitamin D levels, effects of vitamin D supplementation did not differ from placebo. Available evidence does not support a beneficial effect of vitamin D supplementation on muscle health. Vitamin D may have adverse effects on muscle health, which needs to be considered when recommending vitamin D supplementation. © 2021 American Society for Bone and Mineral Research (ASBMR).

The Effect of ACTN3 and VDR Polymorphisms on Skeletal Muscle Performance in Axial Spondyloarthropathies

Background

Spondyloarthritis (SpA) are the most common group of chronic inflammatory rheumatic diseases affecting about 1.5% of the adult Caucasian population. Low back pain is the most common symptom. The aetiopathogenesis of SpA is multifactorial, with well-known genetic and environmental contributions. Furthermore, muscle properties might also be involved in the pathophysiological process and these could be modulated by the genetic background. Alpha-actinin-3 (ACTN3) and Vitamin D receptor (VDR) genes are well-known genes related with muscle performance. Our aim was to analyze four SNPs of these genes and to evaluate their influence in axial SpA (axSpA) susceptibility, phenotype and muscle properties.

Methods

We performed a pilot study based on case-control approach involving 56 participants: 28 axSpA patients and 28 healthy controls matched by age, gender and levels of physical activity. Clinical, epidemiological and muscle characterization data—muscle physical properties (stiffness, tone, and elasticity), strength, mass, and performance, were collected. Two different muscles were considered for analysis, the Multifidus and Gastrocnemius. Four SNPs of ACTN3 (rs1815739) and VDR (rs2228570, rs731236, and rs7975232), were selected, analyzed and correlated with clinical, epidemiological and muscle characterization data.

Results

In total, 51 individuals (27 axSpA patients and 24 matched controls) were eligible for further genetic analysis, 66.7% being male and with a mean age of 36 years. Muscle physical properties, muscle strength and muscle mass were similar in both groups; however, axSpA patients showed a decrease in muscle performance. None of the studied SNPs were associated with disease susceptibility/phenotype, muscle physical properties, muscle strength or muscle mass. However, ACTN3 rs1815739 and VDR rs2228570 were shown to be associated with muscle performance.

Conclusion

Our results suggest an association between ACTN3 and VDR polymorphisms and muscle performance in axSpA.

A longitudinal histologic evaluation of vitamin D receptor expression in the skeletal muscles of patients with a distal radius fracture

We investigated the effect of vitamin D supplementation on the expression of muscle vitamin D receptor (VDR) and cross-sectional area (CSA) in patients with a distal radius fracture (DRF). Significant increases in VDR expression and CSA were observed, especially in vitamin D-deficient patients.

PURPOSE

Vitamin D supplementation is known to enhance muscle mass and function, but whether the VDR is essential in this process remains unknown. We evaluated the change in VDR expression and CSA in the forearm muscles following vitamin D supplementation in patients with a DRF.

METHODS

We prospectively recruited 18 women with a median age of 63.5 years who have a DRF. We obtained two biopsies of the forearm muscle, first at the time of fracture repair and then during hardware removal. We supplemented 1000 IU of vitamin D per day during a median interval of 8 months. We examined the changes in VDR expression and CSA by immunohistochemistry.

RESULTS

The median serum 25-hydroxyvitamin D [25(OH)D] increased from 14.3 to 32.1 ng/mL (P = 0.001). The median VDR expression increased from 0.72 to 0.78 (P = 0.002), and the median CSA increased from 1290.0 to 1685.8 μm² (P = 0.022). Significant increases in VDR expression and CSA were observed in vitamin D-deficient patients [25(OH)D] < 20 ng/mL, but not in vitamin D-non-deficient patients. The changes in VDR expression and CSA were in the same direction in 13 patients, but in the opposite direction in 5 patients.

CONCLUSION

Vitamin D supplementation may increase muscle VDR expression and CSA in patients with a DRF, especially in vitamin D-deficient patients. The increase in CSA without an increase in VDR expression in some patients indicates that the effect of vitamin D supplementation on muscle mass could be mediated by indirect effect of serum vitamin D restoration and by VDR.

Vitamin D3 supplementation does not enhance the effects of resistance training in older adults

BACKGROUND

Lifestyle therapy with resistance training is a potent measure to counteract age-related loss in muscle strength and mass. Unfortunately, many individuals fail to respond in the expected manner. This phenomenon is particularly common among older adults and those with chronic diseases (e.g. chronic obstructive pulmonary disease, COPD) and may involve endocrine variables such as vitamin D. At present, the effects of vitamin D supplementation on responses to resistance training remain largely unexplored.

METHODS

Ninety-five male and female participants (healthy, n = 71; COPD, n = 24; age 68 ± 5 years) were randomly assigned to receive either vitamin D3 or placebo supplementation for 28 weeks in a double-blinded manner (latitude 61°N, September-May). Seventy-eight participants completed the RCT, which was initiated by 12 weeks of supplementation-only (two weeks with 10 000 IU/day, followed by 2000 IU/day), followed by 13 weeks of combined supplementation (2000 IU/day) and supervised whole-body resistance training (twice weekly), interspersed with testing and measurements. Outcome measures included multiple assessments of muscle strength (nvariables  = 7), endurance performance (n = 6), and muscle mass (n = 3, legs, primary), as well as muscle quality (legs), muscle biology (m. vastus lateralis; muscle fibre characteristics, transcriptome), and health-related variables (e.g. visceral fat mass and blood lipid profile). For main outcome domains such as muscle strength and muscle mass, weighted combined factors were calculated from the range of singular assessments.

RESULTS

Overall, 13 weeks of resistance training increased muscle strength (13% ± 8%), muscle mass (9% ± 8%), and endurance performance (one-legged, 23% ± 15%; whole-body, 8% ± 7%), assessed as weighted combined factors, and were associated with changes in health variables (e.g. visceral fat, -6% ± 21%; [LDL]serum , -4% ± 14%) and muscle tissue characteristics such as fibre type proportions (e.g. IIX, -3% points), myonuclei per fibre (30% ± 65%), total RNA/rRNA abundances (15%/6-19%), and transcriptome profiles (e.g. 312 differentially expressed genes). Vitamin D3 supplementation did not affect training-associated changes for any of the main outcome domains, despite robust increases in [25(OH)D]serum (∆49% vs. placebo). No conditional effects were observed for COPD vs. healthy or pre-RCT [25(OH)D]serum . In secondary analyses, vitamin D3 affected expression of gene sets involved in vascular functions in muscle tissue and strength gains in participants with high fat mass, which advocates further study.

CONCLUSIONS

Vitamin D3 supplementation did not affect muscular responses to resistance training in older adults with or without COPD.

Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis

BACKGROUND

Evidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients.

METHODS

This is a secondary cross-sectional analysis of previously published interventional study, with in vitro follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3 mL/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n = 20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors.

RESULTS

In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with V̇O_2Peak was seen with total vitamin D (25OHD). in vitro, 1α,25(OH)₂D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter.

CONCLUSIONS

Vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.

The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: A multicentre retrospective study

BACKGROUND

A 25-hydroxyvitamin D (25OHD) may exert immunomodulatory effects on respiratory health, which may translate to improvements in exercise physiology. Thus, we aimed to investigate whether plasma 25OHD is associated with lung function and aerobic fitness in people with cystic fibrosis (pwCF).

METHODS

A multicentre retrospective review of pwCF (> 9 years old) attending the Royal Hospital for Sick Children (Edinburgh) or Wessex CF-Unit (Southampton) was performed between July 2017 and October 2019. Demographic and clinical data were collected. Plasma 25OHD measured closest in time to clinical cardiopulmonary exercise testing and/or spirometry [forced expiratory volume (FEV₁ )% predicted] was recorded. Pancreatic insufficiency was diagnosed based on faecal elastase of < 100 µg g^-1 . We performed multiple-regression analysis with aerobic fitness outcomes [peak oxygen uptake (VO_2 peak )] and FEV₁ % predicted as primary outcomes.

RESULTS

Ninety pwCF [mean ± SD age: 19.1 ± 8.6 years, 54 (60%) children, 48 (53%) males and 88 (98%) Caucasian] were included. 25OHD deficiency and insufficiency was 15 (17%) and 44 (49%), respectively. 25OHD deficiency and insufficiency was significantly associated with pancreatic insufficiency (χ²  = 4.8, p = 0.02). Plasma 25OHD was not significantly associated with FEV₁ % predicted (r²  = 0.06, p = 0.42, 95% CI = -0.09 to 0.19) or VO_2 peak (r²  = 0.04, p = 0.07, 95% CI = -011 to 0.005) in all pwCF. However, 25OHD was significantly associated with both FEV₁ % (r²  = 0.15, p = 0.02, 95% CI = 1.99-2.64) and VO_2 peak (r²  = 0.13, p = 0.05, 95% CI = -0.26 to -0.005) in the paediatric cohort.

CONCLUSIONS

We showed that 25OHD is associated with improved lung function and aerobic fitness in children and adolescents with CF. Mechanistic and high-quality prospective studies including both lung function and aerobic fitness as primary outcomes are now warranted.

New Therapeutic Approaches and Biomarkers for Increased Healthspan

Healthcare costs have increased in developing countries over the last few decades, mostly due to the escalation in average life expectancy and the concomitant increase in age-related disorders. To address this issue, widespread research is now being undertaken across the globe with the aim of finding a way of increasing healthy aging. A number of potential interventions have already shown promise, including lifestyle changes and the use of natural products or pharmaceuticals that may delay the onset of diseases associated with the aging process. In parallel, a number of potential biomarkers have already been identified that can be used for assessing risk of developing age-associated disorders and for monitoring response to therapeutic interventions. This review describes the most recent advances towards the goal of achieving healthier aging with fewer disabilities that may lead to enhanced quality of life and reduced healthcare costs around the world.

Outcomes of a Physical Therapist-Led, Statewide, Community-Based Fall Risk Screening

BACKGROUND AND PURPOSE

Falls are the leading cause of morbidity and mortality among US older adults and result in considerable medical and social consequences. Community-based screenings are a type of intervention that provides accessible fall risk screening and education at no cost to the participants. However, little is known about whether or how participants change behavior after screening events. Therefore, the purpose of this study was to quantify and characterize participant risk-reducing behaviors after community-based fall risk screenings.

METHODS

Participants were recruited during 22 community-based fall risk screening events in 2017 led by physical therapists. The screenings were conducted using a modified version of the Centers for Disease Control and Prevention Stopping Elderly Accidents, Deaths, and Injuries (CDC STEADI) toolkit. Screenings included risk reduction education via group format and individual recommendations tailored to fall risk classification based on the screening outcomes. For the study, questionnaires were used at baseline to collect demographics and screening results and at 1-month and 5-month follow-up to assess risk reduction behavior change. Descriptive statistics characterized behavior change and assessed outcome differences by baseline fall risk level. Logistic regression analyses examined factors impacting behavior change after screening.

RESULTS AND DISCUSSION

At baseline, 123 participants enrolled and 104 (84.6%) responded at 1- and 5-month follow-up. By 1 month, 50.0% of participants had adopted at least 1 fall risk-reducing behavior, which increased to 64.9% by 5 months. Moderate or high fall risk was significantly associated with adopting a new behavior change by 5 months compared with those with low fall risk (P = .04). The odds of adopting a fall risk reduction strategy by 5 months increased with higher education (odds ratio: 2.5, 95% confidence interval: 1.0-6.0) and moderate/high fall risk (odds ratio: 3.0, 95% confidence interval: 1.3-7.2) in a logistic regression model adjusted by age and sex.

CONCLUSIONS

Screening and education using the STEADI toolkit during community-based screenings result in short- and long-term behavior change to reduce fall risk among older adults, particularly those with moderate to high fall risk. Further research is needed to identify barriers and incentives among participants who do not make fall-related behavioral changes after screening.

Age-Related Skeletal Muscle Dysfunction Is Aggravated by Obesity: An Investigation of Contractile Function, Implications and Treatment

Obesity is a global epidemic and coupled with the unprecedented growth of the world's older adult population, a growing number of individuals are both old and obese. Whilst both ageing and obesity are associated with an increased prevalence of chronic health conditions and a substantial economic burden, evidence suggests that the coincident effects exacerbate negative health outcomes. A significant contributor to such detrimental effects may be the reduction in the contractile performance of skeletal muscle, given that poor muscle function is related to chronic disease, poor quality of life and all-cause mortality. Whilst the effects of ageing and obesity independently on skeletal muscle function have been investigated, the combined effects are yet to be thoroughly explored. Given the importance of skeletal muscle to whole-body health and physical function, the present study sought to provide a review of the literature to: (1) summarise the effect of obesity on the age-induced reduction in skeletal muscle contractile function; (2) understand whether obesity effects on skeletal muscle are similar in young and old muscle; (3) consider the consequences of these changes to whole-body functional performance; (4) outline important future work along with the potential for targeted intervention strategies to mitigate potential detrimental effects.

Effects of Different Vitamin D Supplementation Schemes in Post-Menopausal Women: A Monocentric Open-Label Randomized Study

BACKGROUND

The improvement of muscular strength is a well-known extra-skeletal effect of Vitamin D. The aim of the study was to evaluate the effectiveness of the calcifediol supplementation compared to various cholecalciferol administration schedules in increasing 25(OH)D serum levels and improving muscular function.

METHODS

107 post-menopausal women with hypovitaminosis D were assigned to receive Vitamin D supplementation according to four different regimens: colecalciferol single, monthly, or weekly oral dose and calcifediol weekly oral dose. Serum levels of 25(OH)D and muscular function of lower limbs (Sit-to-Stand test and Timed-Up-and-Go test) were evaluated at baseline and during 6 months follow-up.

RESULTS

Calcifediol and weekly cholecalciferol induced a greater and faster increase of serum 25(OH)D, compared to monthly or single-dose cholecalciferol administration. The 25(OH)D increase was associated with an improvement of muscle function of lower limbs. The larger increase of serum 25(OH)D observed with calcifediol and with weekly cholecalciferol was associated with a concomitant greater improvement of muscle strength.

CONCLUSIONS

Supplementation with calcifediol is more effective and faster compared to cholecalciferol in increasing 25(OH)D serum levels and is associated with a greater improvement of muscular function, thus representing a therapeutic alternative for treatment of hypovitaminosis D.

Vitmamin D supplementation with Cardiac Rehabilitation reduces the number of RVOT Premature

Introduction. Vitamin D deficiency is a quite common pathology in European countries. Serum vitamin D levels are closely linked to physical fitness and lesser response to cardiac rehabilitation in various categories of patients with heart disease. Vitamin D is also involved in the function of heart cells via a vitamin D receptors found in cardiomyocytes. We present the case of a patient with vitamin D deficiency and symptomatic premature ventricular contractions (PVCs), in whom cardiac rehabilitation decreased PVC number, but association with vitamin D supplements led to a significant decrease in PVCs and complete disappearance of symptoms. Keywords: cardiac rehabilitation, vitamin D, ventricular premature contractions, physical activity,

Individualised physical exercise training and enhanced protein intake in older citizens during municipality-based rehabilitation: protocol for a randomised controlled trial

INTRODUCTION

Successful rehabilitation of the growing number of older citizens receiving healthcare services can lead to preservation of functional independence and improvement in quality of life. Adequate intake of dietary protein and physical training are key factors in counteracting the age-related decline in strength performance and physical function. However, during rehabilitation, many older people/persons have insufficient protein intake, and difficulties in performing exercise training with sufficient intensity and volume. The primary aim of this trial is to investigate if individualised physical exercise training programmes combined with increased protein intake (IPET+P) can improve measures on all International Classification of Functioning, Disability and Health levels, such as strength, gait speed and health-related quality of life, when compared with care as usual in municipality-based rehabilitation alone (usual care, UC) or care as usual in combination with increased protein intake (UC+P). Further, the trial investigates whether UC+P will potentiate more significant improvements in outcome measures than UC.

METHODS AND ANALYSIS

The trial is a three-armed multicentre, block-randomised controlled trial consisting of a 12-week intervention period with a 1-year follow-up. Citizens above 65 years referred to rehabilitation in the municipality without restricting comorbidities are eligible. Participants are randomised to either a UC group, a UC group with protein supplementation receiving 27.5 g protein/day (UC+P), or an IPET+P supplementation of 27.5 g protein/day. The Short Musculoskeletal Function Assessment questionnaire is the primary outcome.

ETHICS AND DISSEMINATION

Approvals from The Ethics Committee in Region Zealand, Denmark (SJ-758), and the General Data Protection Regulation at the University of Southern Denmark, Odense (10.330) have been obtained.

TRIAL REGISTRATION NUMBER

NCT04091308.

Vitamin D ameliorates adipose browning in chronic kidney disease cachexia

Patients with chronic kidney disease (CKD) are often 25(OH)D3 and 1,25(OH)2D3 insufficient. We studied whether vitamin D repletion could correct aberrant adipose tissue and muscle metabolism in a mouse model of CKD-associated cachexia. Intraperitoneal administration of 25(OH)D3 and 1,25(OH)2D3 (75 μg/kg/day and 60 ng/kg/day respectively for 6 weeks) normalized serum concentrations of 25(OH)D3 and 1,25(OH)2D3 in CKD mice. Vitamin D repletion stimulated appetite, normalized weight gain, and improved fat and lean mass content in CKD mice. Vitamin D supplementation attenuated expression of key molecules involved in adipose tissue browning and ameliorated expression of thermogenic genes in adipose tissue and skeletal muscle in CKD mice. Furthermore, repletion of vitamin D improved skeletal muscle fiber size and in vivo muscle function, normalized muscle collagen content and attenuated muscle fat infiltration as well as pathogenetic molecular pathways related to muscle mass regulation in CKD mice. RNAseq analysis was performed on the gastrocnemius muscle. Ingenuity Pathway Analysis revealed that the top 12 differentially expressed genes in CKD were correlated with impaired muscle and neuron regeneration, enhanced muscle thermogenesis and fibrosis. Importantly, vitamin D repletion normalized the expression of those 12 genes in CKD mice. Vitamin D repletion may be an effective therapeutic strategy for adipose tissue browning and muscle wasting in CKD patients.

Low Vitamin D Levels and Frailty Status in Older Adults: A Systematic Review and Meta-Analysis

Serum vitamin D deficiency is widespread among older adults and is a potential modifiable risk factor for frailty. Moreover, frailty has been suggested as an intermediate step in the association between low levels of vitamin D and mortality. Hence, we conducted a systematic review of the literature and meta-analysis to test the possible association of low concentrations of serum 25-hydroxyvitamin D (25(OH)D), a marker of vitamin D status, with frailty in later life. We reviewed cross-sectional or longitudinal studies evaluating populations of older adults and identifying frailty by a currently validated scale. Meta-analyses were restricted to cross-sectional data from studies using Fried’s phenotype to identify frailty. Twenty-six studies were considered in the qualitative synthesis, and thirteen studies were included in the meta-analyses. Quantitative analyses showed significant differences in the comparisons of frail (standardized mean difference (SMD)—1.31, 95% confidence interval (CI) (−2.47, −0.15), p = 0.0271) and pre-frail (SMD—0.79, 95% CI (−1.58, −0.003), p = 0.0491) subjects vs. non-frail subjects. Sensitivity analyses reduced heterogeneity, resulting in a smaller but still highly significant between-groups difference. Results obtained indicate that lower 25(OH)D levels are significantly associated with increasing frailty severity. Future challenges include interventional studies testing the possible benefits of vitamin D supplementation in older adults to prevent/palliate frailty and its associated outcomes.

Effects of sunlight exposure and vitamin D supplementation on HIV patients

Unlike many vitamins derived predominantly from food sources, vitamin D is produced endogenously in the skin upon exposure to sunlight. Ethnicity, skin pigmentation, socioeconomic status, geographic location, climate and sunscreen; all of these factors contribute to the amount of insolation for any given individual. Insufficient insolation creates the prerequisites for vitamin D deficiency. This is particularly true in HIV-infected individuals, who are highly vulnerable to vitamin D insufficiency/deficiency, as it plays a huge role in the musculoskeletal and cardiovascular systems. Antiretroviral therapy may also be a factor in vitamin D deficiency. Today, as the issues of preventing common skeletal and non-skeletal diseases with HIV-infected people are becoming highly relevant, the maintenance of vitamin D levels through exposure to sunlight or supplementation appears to be an effective and safe solution. This review focuses on studies concerning the potential role of vitamin D supplementation through adequate sunlight exposure or dietary intake in HIV-infected people. The biology and epidemiology of HIV infection, as well as the issues related to vitamin D deficiency, its status on immune function, the effect of vitamin D against HIV disease progression and other health aspects of this vitamin, are briefly explained.

Is vitamin D status reflected by testosterone concentration in elite athletes?

Vitamin D is a nutrient whose active form affects tissues as a hormone and possibly enhances performance. One plausible mechanism is by increasing testosterone concentration, which is established as an important factor for athletic performance. Therefore the aim of the study was to examine the relationship between plasma concentration of 25(OH)D and testosterone in Polish elite track and field athletes depending on vitamin D status, season, training period, body composition, sex, type of training, sun exposure and vitamin D supplementation. Plasma concentrations of 25(OH)D and testosterone were measured in all seasons within two years in athletes (70 females, 79 males) who represent strength (n = 103) and endurance (n = 46) kinds of sports, in the preparatorycompetitive season and transition period. There were no differences in 25(OH)D concentration between male and female athletes, insufficiency [25(OH)D < 30 ng/ml] was observed in 32.9%, whereas deficiency [25(OH)D < 20 ng/ ml] in 3.2%. Circannual rhythm was noted for vitamin D but not for testosterone concentration; no correlations between them were found either in strength or endurance athletes or between 25(OH)D and body composition. Testosterone concentration was higher in the transition period than in the preparatory-competition period only in male athletes. Higher 25(OH)D was observed in athletes who trained during winter in Africa (higher sun exposure) or used oral supplementation, whereas the respective testosterone levels were unchanged. In athletes, testosterone concentration did not reflect vitamin D status. The widespread of inadequate vitamin D status among athletes, makes it vital to recommend them the regular monitoring of 25(OH)D concentration and use of reasonable supplementation.

Vitamin D repletion ameliorates adipose tissue browning and muscle wasting in infantile nephropathic cystinosis-associated cachexia

BACKGROUND

Ctns-/- mice, a mouse model of infantile nephropathic cystinosis, exhibit hypermetabolism with adipose tissue browning and profound muscle wasting. Ctns-/- mice are 25(OH)D3 and 1,25(OH)2 D3 insufficient. We investigated whether vitamin D repletion could ameliorate adipose tissue browning and muscle wasting in Ctns-/- mice.

METHODS

Twelve-month-old Ctns-/- mice and wild-type controls were treated with 25(OH)D3 and 1,25(OH)2 D3 (75 μg/kg/day and 60 ng/kg/day, respectively) or an ethylene glycol vehicle for 6 weeks. Serum chemistry and parameters of energy homeostasis were measured. We quantitated total fat mass and studied expression of molecules regulating adipose tissue browning, energy metabolism, and inflammation. We measured lean mass content, skeletal muscle fibre size, in vivo muscle function (grip strength and rotarod activity), and expression of molecules regulating muscle metabolism. We also analysed the transcriptome of skeletal muscle in Ctns-/- mice using RNAseq.

RESULTS

Supplementation of 25(OH)D3 and 1,25(OH)2 D3 normalized serum concentration of 25(OH)D3 and 1,25(OH)2 D3 in Ctns-/- mice, respectively. Repletion of vitamin D partially or fully normalized food intake, weight gain, gain of fat, and lean mass, improved energy homeostasis, and attenuated perturbations of uncoupling proteins and adenosine triphosphate content in adipose tissue and muscle in Ctns-/- mice. Vitamin D repletion attenuated elevated expression of beige adipose cell biomarkers (UCP-1, CD137, Tmem26, and Tbx1) as well as aberrant expression of molecules implicated in adipose tissue browning (Cox2, Pgf2α, and NF-κB pathway) in inguinal white adipose tissue in Ctns-/- mice. Vitamin D repletion normalized skeletal muscle fibre size and improved in vivo muscle function in Ctns-/- mice. This was accompanied by correcting the increased muscle catabolic signalling (increased protein contents of IL-1β, IL-6, and TNF-α as well as an increased gene expression of Murf-2, atrogin-1, and myostatin) and promoting the decreased muscle regeneration and myogenesis process (decreased gene expression of Igf1, Pax7, and MyoD) in skeletal muscles of Ctns-/- mice. Muscle RNAseq analysis revealed aberrant gene expression profiles associated with reduced muscle and neuron regeneration, increased energy metabolism, and fibrosis in Ctns-/- mice. Importantly, repletion of 25(OH)D3 and 1,25(OH)2 D3 normalized the top 20 differentially expressed genes in Ctns-/- mice.

CONCLUSIONS

We report the novel findings that correction of 25(OH)D3 and 1,25(OH)2 D3 insufficiency reverses cachexia and may improve quality of life by restoring muscle function in an animal model of infantile nephropathic cystinosis. Mechanistically, vitamin D repletion attenuates adipose tissue browning and muscle wasting in Ctns-/- mice via multiple cellular and molecular mechanisms.

Supplemental vitamin D3 does not affect musculoskeletal or psychomotor performance in college aged males

The experiment examined the effects 4 weeks of vitamin D (Vit D) supplementation versus placebo on musculoskeletal and psychomotor performance. Thirty-two college age males (Age: 22 ± 4 y, Height: 177.7 ± 8.3 cm, Weight: 81.5 ± 14.6 kg, BF%: 19.6 ± 7.9, Vit D: 20.0 ± 7.2 ng/ml). Participants were assigned to group (Vit D vs placebo) and remained blind throughout the study. The treatments were 4000 IU of Vit D3 or placebo (dextrose) administered daily for 4 weeks. The participants underwent baseline testing for isometric strength, explosive ability and psychomotor performance, which was repeated at week 2 and week 4. Isometric tests consisted of an Isometric Mid Thigh Pull on a Force Plate (IMTP) and an upper body isometric test (UBIST) using a load cell. Peak force during a countermovement jump (CMJ) was also determined via force plate. A psychomotor vigilance test (PVT) was used to measure sustained reaction time. Analysis of the UBIST data did not reveal a significant group × time interaction (p = 0.14; Vit D pre: 553.7 ± 168.3 N, post: 585.5 ± 150.2 N; Placebo pre: 677.7 ± 182.3 N, post: 649.8 ± 236.9 N). For IMTP no significant group × time interaction (p = 0.83; Vit D pre: 2596.4 ± 342.3 N, post: 2606.9 ± 378.3 N; Placebo pre: 2684.0 ± 432.9 N, post: 2762.6 ± 440.4 N) was found. CMJ analysis did not reveal interaction effects for group × time (p = 0.21; Vit D pre: 4429.7 ± 1619.0 N, post: 4938.5 ± 2374.8 N; Placebo pre: 5537.3 ± 3027.0 N, post: 6266.9 ± 4577.3 N). For PVT (mean reaction time) there was no significant interaction effects for group × time (p = 0.35; Vit D pre: 0.304 ± 0.041 sec, post: 0.301 ± 0.053 sec; Placebo pre: 0.295 ± 0.044 sec, post: 0.284 ± 0.029 sec). In conclusion, four weeks of Vit D supplementation was not effective in increasing musculoskeletal or psychomotor performance.

The Role of Nutrition in Attenuating Age-Related Skeletal Muscle Atrophy

The elderly population is increasing rapidly worldwide, and we are faced with the significant challenge for maintaining or improving physical activity, independence, and quality of life. Sarcopenia, the age-related decline of skeletal muscle mass, is characterized by loss of muscle quantity and quality resulting to a gradual slowing of movement, a decrease in strength and power, elevated risk of fall-related injury, and often frailty. Supplemental, hormonal, and pharmacological approaches have been attempted to attenuate sarcopenia but these have not achieved outstanding results. In this review, we summarize the current knowledge of nutrition-based therapies for counteracting sarcopenia.

Effect of vitamin D fortified foods on bone markers and muscle strength in women of Pakistani and Danish origin living in Denmark: a randomised controlled trial

BACKGROUND

Deficient and insufficient vitamin D status (defined as serum 25(OH)D < 30 nmol/L and > 50 nmol/L) is prevalent worldwide and associated with decreased muscle strength and poor bone health. We aimed to investigate the effect of vitamin D fortification on bone markers and muscle strength among younger adult women at risk of vitamin D deficiency.

METHODS

A 12-week randomised double-blinded placebo-controlled winter intervention trial, providing 30 μg vitamin D₃/day through fortified yoghurt, cheese, eggs and crisp-bread or similar placebo products. Participants were 143 women of Danish and Pakistani origin 18-50 years of age, living in Denmark, randomised into four groups stratified by ethnicity. Serum 25-hydroxyvitamin D (25(OH)D) by LC-MS/MS and the secondary endpoints: four specific bone markers (osteocalcin (OC), Bone specific Alkaline Phosphatase (BALP), Procollagen type 1 amino-terminal propeptide (P1NP), C-terminal crosslinked telopeptide of type 1 collagen (CTX)) and three muscle strength measures (handgrip, knee extension strength, chair-standing), were assessed using one-way ANOVA, Tukey HSD and subsequent linear ANCOVA models, adjusted for relevant covariates.

RESULTS

Significantly increased serum 25(OH)D concentration from 53.3 (17) to 77.8 (14) nmol/L and from 44.5 (21) to 54.7 (18) nmol/L among Danish and Pakistani women in the fortified groups, respectively (P <  0.05). The bone turnover markers OC, BALP, P1NP and CTX did not change significantly. Muscle strength by handgrip, knee extension and chair-standing test did not change significantly following the intervention.

CONCLUSIONS

Consumption of vitamin D fortified foods for 12 weeks did not result in significant changes of the bone turnover markers OC, BALP, P1NP and CTX. Muscle strength measured as hand grip strength, knee extension strength and chair-standing did not change significantly following the intervention.

The effects of vitamin D supplementation on muscle function among postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

The loss of muscle mass and its strength is one of the most critical changes in aging which is associated with an increased risk of falls, osteoporotic fractures and mobility disability. Vitamin D, with its extra-skeletal benefits, might improve muscle function in elderly. The current systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize available relevant data and determine the effect of vitamin D supplementation on muscle function among postmenopausal women. We reached databases including; Cochrane library, Embase, PubMed, and Web of Science database until the end of May 2018 to identify relevant published RCTs. Heterogeneity among included studies was assessed using Q-test and I² statistics. Random-effect model was applied to pool data and weighted mean difference (WMD) was calculated representing summary effect size. Outcomes of interest included the effects of vitamin D supplementation on hand grip strength (HGS), back muscle strength (BMS), and Timed Up and Go (TUG). Twelve RCTs out of 1739 potential reports were included in our meta-analysis. The pooled findings showed that vitamin D supplementation had no significant effect on HGS (WMD -0.03 kilogram (Kg); 95 % CI, -0.26, 0.20; P=0.78), BMS (WMD 7.21 newton (N); 95 % CI, -5.98, 20.40; P=0.28), and TUG (WMD 0.01 second (S); 95 % CI, -0.17, 0.18; P=0.93) in postmenopausal women. Overall, the current meta-analysis showed that taking vitamin D supplementation by postmenopausal women did not affect markers of muscle function. Further studies are required to confirm the effect of vitamin D supplementation on markers of muscle function.

No effect of monthly supplementation with 12000 IU, 24000 IU or 48000 IU vitamin D3 for one year on muscle function: The vitamin D in older people study

Vitamin D plays a role in muscle function through genomic and non-genomic processes. The objective of this RCT was to determine the effect of monthly supplemental vitamin D3 onmuscle function in 70+ years old adults. Participants (n = 379) were randomized to receive, 12,000 IU, 24,000 IU or 48,000 IU of vitamin D3 monthly for 12 months. Standardized Hand Grip Strength (GS) and Timed-Up and Go (TUG) were measured before and after vitamin D3 supplementation. Fasting total plasma 25 hydroxyvitamin D (25OHD) and Parathyroid Hormone (PTH) concentrations were measured by Liquid Chromatography Tandem Mass Spectrometry (LC-MSMS) and immunoassay, respectively. Baseline plasma 25OHD concentrations were 41.3 (SD 19.9), 39.5 (SD 20.6), 38.9 (SD 19.7) nmol/L; GS values were 28.5 (SD 13.4), 28.8 (SD 13.0) and 28.1 (SD 12.1) kg and TUG test values were 10.8 (SD 2.5), 11.6 (SD 2.9) and 11.9 (SD 3.6) s for the 12,000 IU, 24,000 IU and 48,000 IU dose groups, respectively. Baseline plasma 25OHD concentration < 25 nmol/L was associated with lower GS (P = 0.003). Post-interventional plasma 25OHD concentrations increased to 55.9 (SD 15.6), 64.6 (SD15.3) and 79.0 (SD 15.1) nmol/L in the 12,000 IU, 24,000 IU and 48,000 IU dose groups, respectively and there was a significant dose-related response in post-interventional plasma 25OHD concentration (p<0.0001). Post-interventional GS values were 24.1 (SD 10.1), 26.2 (SD10.6) and 25.7 (SD 9.4) kg and TUG test values were 11.5 (SD 2.6), 12.0 (SD 3.7) and 11.9 (SD 3.2) s for 12,000 IU, 24,000 IU and 48,000 IU dose groups, respectively. The change (Δ) in GS and TUG from pre to post-intervention was not different between treatment groups before and after the adjustment for confounders, suggesting no effect of the intervention. Plasma 25OHD concentration was not associated with GS and TUG test after supplementation. In conclusion, plasma 25OHD concentration < 25 nmol/L was associated with lower GS at baseline. However, monthly vitamin D3 supplementation with 12,000 IU, 24,000 IU and 48,000 IU, for 12 months had no effect on muscle function in older adults aged 70+ years. Trial Registration : EudraCT 2011-004890-10 and ISRCTN35648481.