scholarly journals Efficacy of vitamin D supplementation in combination with conventional antiviral therapy in patients with chronic hepatitis C infection: a meta-analysis of randomised controlled trials

2017 ◽  
Vol 31 (2) ◽  
pp. 168-177 ◽  
Author(s):  
H.-B. Kim ◽  
S.-K. Myung ◽  
Y.-J. Lee ◽  
B.-J. Park ◽  
Keyword(s):  
Vitamin D ◽  
Chronic Hepatitis ◽  
Hepatitis C ◽  
Antiviral Therapy ◽  
Randomised Controlled Trials ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Controlled Trials ◽  
Hepatitis C Infection ◽  
Randomised Controlled

scholarly journals The Effect of Vitamin D Supplementation on Glycaemic Control in Women with Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

2019 ◽  
Vol 16 (10) ◽  
pp. 1716 ◽  
Author(s):  
Omorogieva Ojo ◽  
Sharon M. Weldon ◽  
Trevor Thompson ◽  
Elisabeth J. Vargo
Keyword(s):  
Diabetes Mellitus ◽  
Vitamin D ◽  
Glycaemic Control ◽  
Gestational Diabetes ◽  
Randomised Controlled Trials ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Risk Of Bias ◽  
Controlled Trials ◽  
Randomised Controlled

Vitamin D deficiency is highly prevalent amongst pregnant women and is linked to a range of adverse complications, including gestational diabetes. However, there is no consensus among researchers regarding the impact of vitamin D supplementation in alleviating adverse effects in gestational diabetes. The objective of this systematic review and meta-analysis was to determine whether supplementation of vitamin D given to women with gestational diabetes can promote glycaemic control. EMBASE and PubMed were searched up to November, 2018. The selection criteria included randomised controlled trials of the effect of vitamin D supplementation (1000–4762 IU/day) on pregnant women with gestational diabetes mellitus. Study data and outcome measures (fasting blood glucose, glycated haemoglobin and serum insulin) were extracted from included studies. Random-effects models were used for meta-analyses. Heterogeneity tests, and analysis of the risk of bias were conducted. Most of the studies were graded as having either low risk or moderate risk of bias although two studies had a high risk of bias in the areas of blinding of participants and personnel, and incomplete outcome data. On the other hand, the heterogeneity statistic (I2) ranged from 0–41% in the studies included. Five randomised controlled trials were selected for this review and meta-analysis (involving a total of 173 participants supplemented with vitamin D and 153 participants as control drawn from the studies). Vitamin D supplementation was associated with a decrease in fasting blood glucose by a mean of 0.46 mmol/L (−0.68, −0.25) (p < 0.001), glycated haemoglobin by a mean of 0.37% (−0.65, −0.08) (p < 0.01) and serum insulin concentration by mean of 4.10 µIU/mL (−5.50, −2.71) (p < 0.001) compared to controls. This review shows evidence that vitamin D supplementation has the potential to promote glycaemic control in women with Gestational Diabetes Mellitus (GDM). However, due to the limited number of studies in the meta-analysis, the conclusion should be interpreted with caution. Further studies are needed to fully understand the exact mechanism by which vitamin D influences glucose metabolism.

scholarly journals Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of aggregate data from randomised controlled trials

2020 ◽  
Author(s):  
David A Jolliffe ◽  
Carlos A Camargo ◽  
John D Sluyter ◽  
Mary Aglipay ◽  
John F Aloia ◽  
...  
Keyword(s):  
Vitamin D ◽  
Randomised Controlled Trials ◽  
Respiratory Infections ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Controlled Trials ◽  
Acute Respiratory Infections ◽  
Dosing Regimen ◽  
Randomised Controlled ◽  
Reduced Risk

AbstractBackgroundA 2017 meta-analysis of data from 25 randomised controlled trials of vitamin D supplementation for the prevention of acute respiratory infections revealed a protective effect of the intervention. Since then, 20 new RCTs have been completed.MethodsSystematic review and meta-analysis of data from randomised controlled trials (RCTs) of vitamin D for ARI prevention using a random effects model. Pre-specified sub-group analyses were done to determine whether effects of vitamin D on risk of ARI varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration or dosing regimen. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science and the ClinicalTrials.gov registry from inception to 1st May 2020. Double-blind RCTs of supplementation with vitamin D or calcidiol, of any duration, were eligible if they were approved by a Research Ethics Committee and if ARI incidence was collected prospectively and pre-specified as an efficacy outcome. Aggregate data, stratified by baseline 25(OH)D concentration, were obtained from study authors. The study was registered with PROSPERO (no. CRD42020190633).FindingsWe identified 45 eligible RCTs (total 73,384 participants). Data were obtained for 46,331 (98.0%) of 47,262 participants in 42 studies, aged 0 to 95 years. For the primary comparison of vitamin D supplementation vs. placebo, the intervention reduced risk of ARI overall (Odds Ratio [OR] 0.91, 95% CI 0.84 to 0.99; P for heterogeneity 0.01). No statistically significant effect of vitamin D was seen for any of the sub-groups defined by baseline 25(OH)D concentration. However, protective effects were seen for trials in which vitamin D was given using a daily dosing regimen (OR 0.75, 95% CI 0.61 to 0.93); at daily dose equivalents of 400-1000 IU (OR 0.70, 95% CI 0.55 to 0.89); and for a duration of ≤12 months (OR 0.82, 95% CI 0.72 to 0.93). No significant interaction was seen between allocation to vitamin D vs. placebo and dose frequency, dose size, or study duration. Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (OR 0.97, 95% CI 0.86 to 1.09). Risk of bias within individual studies was assessed as being low for all but three trials. A funnel plot showed left-sided asymmetry (P=0.008, Egger’s test).InterpretationVitamin D supplementation was safe and reduced risk of ARI, despite evidence of significant heterogeneity across trials. Protection was associated with administration of daily doses of 400-1000 IU vitamin D for up to 12 months. The relevance of these findings to COVID-19 is not known and requires investigation.FundingNone

scholarly journals Determinants of parathyroid hormone response to vitamin D supplementation: a systematic review and meta-analysis of randomised controlled trials

2015 ◽  
Vol 114 (9) ◽  
pp. 1360-1374 ◽  
Author(s):  
Nazanin Moslehi ◽  
Sakineh Shab-Bidar ◽  
Parvin Mirmiran ◽  
Farhad Hosseinpanah ◽  
Fereidoun Azizi
Keyword(s):  
Systematic Review ◽  
Vitamin D ◽  
Parathyroid Hormone ◽  
Randomised Controlled Trials ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Controlled Trials ◽  
Significant Heterogeneity ◽  
Randomised Controlled ◽  
Pth Level

AbstractThis systematic review aimed to assess the determinants of the parathyroid hormone (PTH) level response to vitamin D supplementation. We searched Medline, Google Scholar and the reference lists of previous reviews. All randomised controlled trials (RCT) on vitamin D supplementation that involved apparently healthy human subjects with a report of PTH were selected. Potential studies were screened independently and in duplicate. Results are summarised as mean differences with 95 % confidence intervals. Quality assessment, subgroup analysis, meta-analysis and meta-regression analysis were carried out. Thirty-three vitamin D supplementation RCT were included. Vitamin D supplementation significantly raised circulating 25-hydroxyvitamin D (25(OH)D) with significant heterogeneity among studies with a pooled mean difference (PMD) of 15.5 ng/ml (test for heterogeneity: P<0·001 and I2=97·3 %). Vitamin D supplementation significantly reduced PTH level with PMD of −8·0 pg/ml, with significant heterogeneity ((test for heterogeneity: P<0·001) and the I2 value was 97·3 %). In the subgroup analyses, the optimum treatment effect for PTH was observed with Ca doses of 600–1200 mg/d (−22·48 pg/ml), after the duration of a >12-month trial (−18·36 pg/ml), with low baseline 25(OH)D concentration of <20 ng/ml (−16·70 pg/ml) and in those who were overweight and obese (−18·11 pg/ml). Despite the present meta-analysis being hindered by some limitations, it provided some interesting evidence, suggesting that suppression of PTH level needs higher vitamin D intake (75 μg/d) than the current recommendations and longer durations (12 months), which should be taken into account for nutritional recommendations.

scholarly journals Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysis

2019 ◽  
Vol 23 (2) ◽  
pp. 1-44 ◽  
Author(s):  
Adrian R Martineau ◽  
David A Jolliffe ◽  
Lauren Greenberg ◽  
John F Aloia ◽  
Peter Bergman ◽  
...  
Keyword(s):  
Vitamin D ◽  
Randomised Controlled Trials ◽  
Respiratory Infections ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Controlled Trials ◽  
Acute Respiratory Infections ◽  
Protective Effects ◽  
Individual Participant ◽  
Randomised Controlled

Background Randomised controlled trials (RCTs) exploring the potential of vitamin D to prevent acute respiratory infections have yielded mixed results. Individual participant data (IPD) meta-analysis has the potential to identify factors that may explain this heterogeneity. Objectives To assess the overall effect of vitamin D supplementation on the risk of acute respiratory infections (ARIs) and to identify factors modifying this effect. Data sources MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, ClinicalTrials.gov and the International Standard Randomised Controlled Trials Number (ISRCTN) registry. Study selection Randomised, double-blind, placebo-controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration having incidence of acute respiratory infection as a prespecified efficacy outcome were selected. Study appraisal Study quality was assessed using the Cochrane Collaboration Risk of Bias tool to assess sequence generation, allocation concealment, blinding of participants, personnel and outcome assessors, completeness of outcome data, evidence of selective outcome reporting and other potential threats to validity. Results We identified 25 eligible RCTs (a total of 11,321 participants, aged from 0 to 95 years). IPD were obtained for 10,933 out of 11,321 (96.6%) participants. Vitamin D supplementation reduced the risk of ARI among all participants [adjusted odds ratio (aOR) 0.88, 95% confidence interval (CI) 0.81 to 0.96; heterogeneity p < 0.001]. Subgroup analysis revealed that protective effects were seen in individuals receiving daily or weekly vitamin D without additional bolus doses (aOR 0.81, 95% CI 0.72 to 0.91), but not in those receiving one or more bolus doses (aOR 0.97, 95% CI 0.86 to 1.10; p = 0.05). Among those receiving daily or weekly vitamin D, protective effects of vitamin D were stronger in individuals with a baseline 25-hydroxyvitamin D [25(OH)D] concentration of < 25 nmol/l (aOR 0.30, 95% CI 0.17 to 0.53) than in those with a baseline 25(OH)D concentration of ≥ 25 nmol/l (aOR 0.75, 95% CI 0.60 to 0.95; p = 0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (aOR 0.98, 95% CI 0.80 to 1.20; p = 0.83). The body of evidence contributing to these analyses was assessed as being of high quality. Limitations Our study had limited power to detect the effects of vitamin D supplementation on the risk of upper versus lower respiratory infection, analysed separately. Conclusions Vitamin D supplementation was safe, and it protected against ARIs overall. Very deficient individuals and those not receiving bolus doses experienced the benefit. Incorporation of additional IPD from ongoing trials in the field has the potential to increase statistical power for analyses of secondary outcomes. Study registration This study is registered as PROSPERO CRD42014013953. Funding The National Institute for Health Research Health Technology Assessment programme.

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