158 research outputs found
Associations of serum 25(OH)D levels with physical performance and anabolic hormones in young men
Purpose: The present study examined the association of vitamin D measured by serum 25(OH)D with physical performance outcomes and serum levels of anabolic hormones in young men. Methods: 412 young men (age 19 ± 1 year) entering their compulsory military service volunteered to participate in the study. The study consisted of two groups from two different military bases: Group A was studied in January and group B in July. The groups were first compared with each other and due to statistically significant (p < 0.001 analyzed with independent samples t-test) differences in physical condition (sit-up, push-up, and standing long jump-tests and testosterone levels) between the groups, groups were analyzed separately. The serum levels of 25(OH)D, testosterone (TES), sex hormone binding globulin (SHBG), and insulin-like growth factor-1 (IGF-1) were analyzed by electrochemiluminescence immunoassay. Physical performance tests consisted of muscular fitness (sit-ups, push-ups, standing long jump) and aerobic fitness (12-minute-running) tests. The association of serum 25(OH)D with physical performance tests and anabolic hormones was analyzed using linear regression. Results: After controlling for the group, body mass index, and leisure-time physical activity, serum 25(OH)D level was positively associated with aerobic and muscular fitness (β = 0.15–0.20, all p < 0.05). Also, the participants with sufficient serum 25(OH)D levels (≥75 nmol/L) had better aerobic and muscular fitness and higher TES in group B, and better upper extremity muscular fitness in group A (all p < 0.05). In group A, there were 166 participants with serum levels of 25(OH) D < 75 nmol/L and 18 ≥ 75 nmol/L. In group B, the amounts were 92 (<75 nmol/L) and 136 (≥75 nmol/L), respectively. Conclusion: Serum 25(OH)D was positively associated with both aerobic and muscular fitness and those with sufficient vitamin D levels, had higher levels of TES. Thus, maintaining a sufficient serum 25(OH)D level may be beneficial for physical performance and anabolic state in young men.publishedVersionPeer reviewe
Staphylococcus aureus nasal carriage is associated with serum 25-hydroxyvitamin D levels, gender and smoking status. The Tromsø Staph and Skin Study
Vitamin D induces the expression of antimicrobial peptides with activity against Staphylococcus aureus. Thus, we studied the association between serum 25-hydroxyvitamin D (25(OH)D) and S. aureus nasal colonization and carriage. Nasal swabs, blood samples and clinical data from 2,115 women and 1,674 men, aged 30–87 years, were collected in the Tromsø Staph and Skin Study 2007–08, as part of the population-based sixth Tromsø Study. Multivariate logistic regression analyses were stratified by recognized risk factors for S. aureus carriage: sex, age and smoking. In non-smoking men, we observed a 6.6% and 6.7% decrease in the probability of S. aureus colonization and carriage, respectively, by each 5 nmol/l increase in serum 25(OH)D concentration (P < 0.001 and P = 0.001), and serum 25(OH)D > 59 nmol/l and ≥75 nmol/l as thresholds for ~30% and ~50% reduction in S. aureus colonization and carriage. In non-smoking men aged 44–60 years, the odds ratio for S. aureus colonization was 0.44 (95% confidence interval, 0.28−0.69) in the top tertile of serum 25(OH)D versus the bottom tertile. In women and smokers there were no such associations. Our study supports that serum vitamin D is a determinant of S. aureus colonization and carriage
Peak expiratory flow rate shows a gender-specific association with vitamin D deficiency
Context: To our knowledge, no previous studies examined the longitudinal relationship between vitamin D status and pulmonary function in a population-based sample of older persons. Objective: Our objective was to examine the cross-sectional as well as the longitudinal relationship between vitamin D status and peak expiratory flow rate (PEFR) in a representative sample of the Dutch older population. Design, Setting, and Participants: Participants included men and women in the Longitudinal Aging Study Amsterdam, an ongoing cohort study in older people. Main Outcome Measure: PEFR was measured using the mini-Wright peak flow meter. Results: Men with serum 25-hydroxyvitamin D (25-OHD) levels below 10 ng/ml (25 nmol/liter) had a significantly lower PEFR in the cross-sectional analyses, and men with serum 25-OHD levels below 20 ng/ml (50 nmol/liter) had a significantly lower PEFR in the longitudinal analyses as compared with men with serum 25-OHD levels above 30 ng/ml (75 nmol/liter) (cross-sectional: β = -47.0, P = 0.01 for serum 25-OHD<10 ng/ml; longitudinal: β = -45.0, P<0.01 for serum 25-OHD<10 ng/ml; and β = -20.2, P = 0.03 for serum 25-OHD = 10-20 ng/ml in the fully adjusted models). Physical performance (β = -32.5, P = 0.08 for serum 25-OHD<10 ng/ml) and grip strength (β = -40.0, P = 0.03 for serum 25-OHD <10 ng/ml) partly mediated the cross-sectional associations but not the longitudinal associations. In women, statistically significant associations between 25-OHD and PEFR were observed in the cross-sectional analyses after adjustment for age and season of blood collection but not in the fully adjusted models or in the longitudinal analyses. Conclusions: A strong relationship between serum 25-OHD and PEFR was observed in older men, both in the cross-sectional as well as longitudinal analyses, but not in older women. The association in men could partly be explained by physical performance and muscle strength. Copyright © 2012 by The Endocrine Society
Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
This study was supported by a grant from the National Institute for Health Research (NIHR) under its Health Technology Assessment programme (reference No 13/03/25, to ARM
Vitamin D Supplementation to Prevent Acute Respiratory Tract Infections: Systematic Review and Meta-Analysis Of Individual Participant Data
OBJECTIVES To assess the overall effect of vitamin D supplementation on risk of acute respiratory tract infection, and to identify factors modifying this effect. DESIGN Systematic review and meta-analysis of individual participant data (IPD) from randomised controlled trials. DATA SOURCES Medline, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and the International Standard Randomised Controlled Trials Number registry from inception to December 2015. ELIGIBILITY CRITERIA FOR STUDY SELECTION Randomised, double blind, placebo controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration were eligible for inclusion if they had been approved by a research ethics committee and if data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome. RESULTS 25 eligible randomised controlled trials (total 11 321 participants, aged 0 to 95 years) were identified. IPD were obtained for 10 933 (96.6%) participants. Vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96; P for heterogeneity \u3c0.001). In subgroup analysis, protective effects were seen in those receiving daily or weekly vitamin D without additional bolus doses (adjusted odds ratio 0.81, 0.72 to 0.91) but not in those receiving one or more bolus doses (adjusted odds ratio 0.97, 0.86 to 1.10; P for interaction=0.05). Among those receiving daily or weekly vitamin D, protective effects were stronger in those with baseline 25-hydroxyvitamin D levels \u3c25 nmol/L (adjusted odds ratio 0.30, 0.17 to 0.53) than in those with baseline 25-hydroxyvitamin D levels ≥25 nmol/L (adjusted odds ratio 0.75, 0.60 to 0.95; P for interaction=0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (adjusted odds ratio 0.98, 0.80 to 1.20, P=0.83). The body of evidence contributing to these analyses was assessed as being of high quality. CONCLUSIONS Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit
Shortcomings of Vitamin D-Based Model Simulations of Seasonal Influenza
Seasonal variation in serum concentration of the vitamin D metabolite 25(OH)
vitamin D [25(OH)D], which contributes to host immune function, has
been hypothesized to be the underlying source of observed influenza seasonality
in temperate regions. The objective of this study was to determine whether
observed 25(OH)D levels could be used to simulate observed influenza infection
rates. Data of mean and variance in 25(OH)D serum levels by month were obtained
from the Health Professionals Follow-up Study and used to parameterize an
individual-based model of influenza transmission dynamics in two regions of the
United States. Simulations were compared with observed daily influenza excess
mortality data. Best-fitting simulations could reproduce the observed seasonal
cycle of influenza; however, these best-fit simulations were shown to be highly
sensitive to stochastic processes within the model and were unable consistently
to reproduce observed seasonal patterns. In this respect the simulations with
the vitamin D forced model were inferior to similar modeling efforts using
absolute humidity and the school calendar as seasonal forcing variables. These
model results indicate it is unlikely that seasonal variations in vitamin D
levels principally determine the seasonality of influenza in temperate
regions
Nonclassical Vitamin D Action
It is becoming increasingly clear that vitamin D has a broad range of actions in the human body. Besides its well-known effects on calcium/phosphate homeostasis, vitamin D influences muscle function, cardiovascular homeostasis, nervous function, and the immune response. Vitamin D deficiency/insufficiency has been associated with muscle weakness and a high incidence of various chronic diseases such as cardiovascular disease, cancer, multiple sclerosis, and type 1 and 2 diabetes. Most importantly, low vitamin D status has been found to be an independent predictor of all-cause mortality. Several recent randomized controlled trials support the assumption that vitamin D can improve muscle strength, glucose homeostasis, and cardiovascular risk markers. In addition, vitamin D may reduce cancer incidence and elevated blood pressure. Since the prevalence of vitamin D deficiency/insufficiency is high throughout the world, there is a need to improve vitamin D status in the general adult population. However, the currently recommended daily vitamin D intake of 5-15 µg is too low to achieve an adequate vitamin D status in individuals with only modest skin synthesis. Thus, there is a need to recommend a vitamin D intake that is effective for achieving adequate circulating 25-hydroxyvitamin D concentrations (>75 nmol/L)
VITA-D: Cholecalciferol substitution in vitamin D deficient kidney transplant recipients: A randomized, placebo-controlled study to evaluate the post-transplant outcome
<p>Abstract</p> <p>Background</p> <p>Vitamin D does not only regulate calcium homeostasis but also plays an important role as an immune modulator. It influences the immune system through the induction of immune shifts and regulatory cells resulting in immunologic tolerance. As such, vitamin D is thought to exert beneficial effects within the transplant setting, especially in kidney transplant recipients, considering the high prevalence of vitamin D deficiency in kidney transplant recipients.</p> <p>Methods/Design</p> <p>The VITA-D study, a randomized, placebo-controlled, double-blind study with two parallel groups including a total of 200 kidney transplant recipients, is designed to investigate the immunomodulatory and renoprotective effects of cholecalciferol (vitamin D<sub>3</sub>) within the transplant setting. Kidney transplant recipients found to have vitamin D deficiency defined as 25-hydroxyvitamin D<sub>3 </sub>< 50 nmol per liter will be randomly assigned to receive either oral cholecalciferol therapy or placebo and will be followed for one year. Cholecalciferol will be administered at a dose of 6800 International Units daily over a time period of one year.</p> <p>The objective is to evaluate the influence of vitamin D<sub>3 </sub>substitution in vitamin D deficient kidney transplant recipients on the post-transplant outcome. As a primary endpoint glomerular filtration rate calculated with the MDRD formula (modification of diet in renal disease) one year after kidney transplantation will be evaluated. Incidence of acute rejection episodes, and the number and severity of infections (analyzed by means of C-reactive protein) within the first year after transplantation will be monitored as well. As a secondary endpoint the influence of vitamin D<sub>3 </sub>on bone mineral density within the first year post-transplant will be assessed. Three DXA analyses will be performed, one within the first four weeks post-transplant, one five months and one twelve months after kidney transplantation.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00752401</p
Vitamin D as an Adjunctive Therapy in Asthma. Part 1: A Review of Potential Mechanisms
Vitamin D deficiency (VDD) is highly prevalent worldwide. The classical role for vitamin D is to regulate calcium absorption form the gastrointestinal tract and influence bone health. Recently vitamin D receptors and vitamin D metabolic enzymes have been discovered in numerous sites systemically supporting diverse extra-skeletal roles of vitamin D, for example in asthmatic disease. Further, VDD and asthma share several common risk factors including high latitude, winter season, industrialization, poor diet, obesity, and dark skin pigmentation. Vitamin D has been demonstrated to possess potent immunomodulatory effects, including effects on T cells and B cells as well as increasing production of antimicrobial peptides (e.g. cathelicidin). This immunomodulation may lead to asthma specific clinical benefits in terms of decreased bacterial/viral infections, altered airway smooth muscle-remodeling and efunction as well as modulation of response to standard anti-asthma therapy (e.g. glucocorticoids and immunotherapy). Thus, vitamin D and its deficiency have a number of biological effects that are potentially important in altering the course of disease pathogenesis and severity in asthma. The purpose of this first of a two-part review is to review potential mechanisms whereby altering vitamin D status may influence asthmatic disease
The role of vitamin D in pulmonary disease: COPD, asthma, infection, and cancer
The role of vitamin D (VitD) in calcium and bone homeostasis is well described. In the last years, it has been recognized that in addition to this classical function, VitD modulates a variety of processes and regulatory systems including host defense, inflammation, immunity, and repair. VitD deficiency appears to be frequent in industrialized countries. Especially patients with lung diseases have often low VitD serum levels. Epidemiological data indicate that low levels of serum VitD is associated with impaired pulmonary function, increased incidence of inflammatory, infectious or neoplastic diseases. Several lung diseases, all inflammatory in nature, may be related to activities of VitD including asthma, COPD and cancer. The exact mechanisms underlying these data are unknown, however, VitD appears to impact on the function of inflammatory and structural cells, including dendritic cells, lymphocytes, monocytes, and epithelial cells. This review summarizes the knowledge on the classical and newly discovered functions of VitD, the molecular and cellular mechanism of action and the available data on the relationship between lung disease and VitD status
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