The effect of vitamin D3 supplementation on markers of cardiovascular health in hyperparathyroid, vitamin D insufficient women: a randomized placebo-controlled trial

Effect of Vitamin D Supplementation on Blood Pressure: A Systematic Review

Hypertension is a major risk factor for cardiovascular disease and mortality. Emerging evidence suggests a potential role of vitamin D in blood pressure regulation through its influence on the renin-angiotensin-aldosterone system, endothelial function, and inflammation. However, findings from interventional studies remain inconsistent. This systematic review aims to evaluate the effect of vitamin D supplementation on systolic and diastolic blood pressure across various populations. A comprehensive literature search was conducted in PubMed, Cochrane Central, and ScienceDirect to identify randomized controlled trials and cohort studies investigating the impact of vitamin D on hypertension. Data extraction and risk of bias assessments were performed independently by two reviewers. The primary outcome was the change in systolic and diastolic blood pressure before and after vitamin D supplementation. In total, 12 studies met the inclusion criteria, with sample sizes ranging from 35 to 3,788 participants. The highest reduction in systolic blood pressure (-28.44 mmHg) and diastolic blood pressure (-7.38 mmHg) was observed in one study with 50,000 IU/week supplementation. Other studies reported reductions ranging from -0.5 to -4.5 mmHg for systolic blood pressure and -1 to -5 mmHg for diastolic blood pressure, with variability influenced by dosage and duration. Vitamin D supplementation demonstrates potential benefits in reducing blood pressure, particularly with higher doses over shorter durations. However, heterogeneity across studies warrants further research to establish optimal dosing strategies for hypertensive patients.

Effect of Vitamin D Supplementation on Lipid Profile in Overweight or Obese Women: A Meta-analysis and Systematic Review of Randomized Controlled Trials

CONTEXT

Previous studies have explored the relationship between vitamin D and lipid profile in individuals with obesity or overweight women, but the results have been inconsistent.

OBJECTIVE

This meta-analysis and systematic review of randomized controlled trials (RCTs) was conducted to assess the effect of vitamin D on lipid profile in women who are overweight or obese.

DATA SOURCES

A meticulous search strategy was used across the Scopus, PubMed/Medline, Web of Science, and Embase databases up to June 2024.

DATA EXTRACTION

RCT studies administering vitamin D to overweight or obese women were extracted. A random-effects model was applied to compute the weighted mean difference (WMD) and 95% CIs of the intervention on each variable.

DATA ANALYSES

Thirteen eligible publications with 16 arms focused on low-density-lipoprotein cholesterol (LDL-C), 16 arms on high-density-lipoprotein cholesterol (HDL-C), 18 arms on total cholesterol (TC), and 18 arms on triglycerides (TG) were included in the final quantitative analysis. Vitamin D supplementation resulted in significant reductions in TG (WMD: -6.13 mg/dL; 95% CI: -8.99 to -3.28; P = .000) and TC (WMD: -4.45 mg/dL; 95% CI: -7.06 to -1.83; P = .001), as well as a significant increase in HDL-C concentrations (WMD: 1.54 mg/dL; 95% CI: 0.57 to 2.52; P = .002). Stratified analysis indicated a greater reduction in TG levels in studies with a mean baseline TG concentration ≥150 mg/dL (WMD: -23.58 mg/dL) and when vitamin D was administered for ≤26 weeks (WMD: -11.44 mg/dL).

CONCLUSION

According to our findings, vitamin D has a significant effect on hypertriglyceridemia in individuals who are overweight or obese. However, vitamin D has no significant effect on LDL-C concentrations in this population.

Vitamin D supplementation in primary hyperparathyroidism: effects on 1,25(OH)2 vitamin D and FGF23 levels

PURPOSE

In patients with Primary Hyperparathyroidism (PHPT) vitamin D deficiency has been associated with more severe presentations. Our aim was to investigate the effects of Vitamin D supplementation on mineral homeostasis and related hormones in individuals with and without PHPT.

METHODS

Individuals with and without PHPT (CTRL) received 14,000 IU/week of oral vitamin D3 for 12 weeks. At baseline and endpoint, blood samples were collected to measure 1,25(OH)2vitamin D (1,25(OH)2D), intact Fibroblast Growth Factor 23 (FGF23), 25OHD, Parathormone, and other biochemical markers. The 1,25(OH)2D measurement was performed using liquid chromatography and mass spectrometry (LC-MS/MS).

RESULTS

70 PHPT patients and 75 CTRL were included, and 55 PHPT and 64 CTRL completed the 12-week protocol. After the intervention, there were significant increases in the FGF23 levels (PHPT: 47.9 ± 27.1 to 76.3 ± 33.3; CTRL: 40.5 ± 13.9 to 59.8 ± 19.8 pg/mL, p < 0.001), and significant decreases in 1,25(OH)2D levels (PHPT: 94.8 ± 34.6 to 68.9 ± 25.3; CTRL: 68.7 ± 23.5 to 56.4 ± 20.7 pg/mL, p < 0.001). The reduction of 1,25(OH)2D was inversely associated with the increase of FGF23 in both the PHPT (r = -0.302, p = 0.028) and CTRL (r = -0.278, p = 0.027). No changes in plasmatic or uninary calcium concentrations were observed in both groups.

CONCLUSION

The weekly administration of 14,000 IU of Vitamin D3 was safe and efficient to increase in 25OHD levels in both groups. However, a paradoxical decrease in 1,25(OH)2D levels measured by LC-MS/MS was associated with a significant increase in FGF23 levels in both groups. This phenomenon might represent a defense against hypercalcemia after vitamin D supplementation and paves the way for new studies in this regard.

Effect of Vitamin D Supplementation According to Daily Dietary Levels on Biochemical Parameters in 25-Hydroxyvitamin D Deficiency of Women with Obesity

Objectives

This study examined how vitamin D supplementation based on daily dietary intake affects biomarkers in obese women with 25-hydroxyvitamin D deficiency.

Materials and Methods

Group D (n= 14) used vitamin D supplements daily for 2 months, and Group C (n= 16) did not receive supplements. Three blood samples were collected from the volunteers during the initial phase of the study. In this study, blood was collected from the volunteers: first measurement (M1), second measurement (M2), and third measurement (M3).

Results

Compared with Group C, Group D had lower high-density lipoprotein (HDL) levels at M2 and fasting serum glucose (FSG) levels at M3 (p < 0.05), and lower HDL levels at M2 and FSG levels in normal-weight individuals at M3 (p < 0.05). In addition, 25-hydroxyvitamin D levels were higher in normal-weight women than in obese women according to M3 (p= 0.043). There was a higher negative correlation between HDL-C in M1 and FSG in Group D (r= -0.710, p= 0.004). 25-hydroxyvitamin D was moderately positively correlated with dietary vitamin D in M2 in Group D (r= 0.559, p= 0.038). Significant positive correlations were observed between iodine intake and triiodothyronine (T3) levels, whereas no significant difference was observed between thyroid-stimulating hormone and T3 levels.

Conclusion

Vitamin D intake improves HDL levels in normal-weight individuals and causes an effect on FSG to be at the desired low level, whereas in individuals with obesity, although serum 25-hydroxyvitamin D levels increased in the last measurement, no effect was observed. Women with normal vitamin D levels have higher serum 25-hydroxyvitamin D levels than those who are obese.

Physiology of Vitamin D-Focusing on Disease Prevention

Vitamin D is a crucial micronutrient, critical to human health, and influences many physiological processes. Oral and skin-derived vitamin D is hydroxylated to form calcifediol (25(OH)D) in the liver, then to 1,25(OH)2D (calcitriol) in the kidney. Alongside the parathyroid hormone, calcitriol regulates neuro-musculoskeletal activities by tightly controlling blood-ionized calcium concentrations through intestinal calcium absorption, renal tubular reabsorption, and skeletal mineralization. Beyond its classical roles, evidence underscores the impact of vitamin D on the prevention and reduction of the severity of diverse conditions such as cardiovascular and metabolic diseases, autoimmune disorders, infection, and cancer. Peripheral target cells, like immune cells, obtain vitamin D and 25(OH)D through concentration-dependent diffusion from the circulation. Calcitriol is synthesized intracellularly in these cells from these precursors, which is crucial for their protective physiological actions. Its deficiency exacerbates inflammation, oxidative stress, and increased susceptibility to metabolic disorders and infections; deficiency also causes premature deaths. Thus, maintaining optimal serum levels above 40 ng/mL is vital for health and disease prevention. However, achieving it requires several times more than the government's recommended vitamin D doses. Despite extensive published research, recommended daily intake and therapeutic serum 25(OH)D concentrations have lagged and are outdated, preventing people from benefiting. Evidence suggests that maintaining the 25(OH)D concentrations above 40 ng/mL with a range of 40-80 ng/mL in the population is optimal for disease prevention and reducing morbidities and mortality without adverse effects. The recommendation for individuals is to maintain serum 25(OH)D concentrations above 50 ng/mL (125 nmol/L) for optimal clinical outcomes. Insights from metabolomics, transcriptomics, and epigenetics offer promise for better clinical outcomes from vitamin D sufficiency. Given its broader positive impact on human health with minimal cost and little adverse effects, proactively integrating vitamin D assessment and supplementation into clinical practice promises significant benefits, including reduced healthcare costs. This review synthesized recent novel findings related to the physiology of vitamin D that have significant implications for disease prevention.

The Effects of Vitamin D Supplementation on C-Reactive Protein and Systolic and Diastolic Blood Pressure in Postmenopausal Women: A Meta-Analysis and Systematic Review of Randomized Controlled Trials

BACKGROUND

An inverse relationship between vitamin D supplementation and C-reactive protein (CRP) and hypertension has been reported, mostly through observational data. This inverse relationship, however, has not been confirmed in randomized controlled trials (RCTs). A meta-analysis of RCTs is needed to provide more robust evidence.

OBJECTIVE

This systematic review of RCTs was conducted to assess the effect of vitamin D supplementation on CRP, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in postmenopausal women.

METHODS

Four databases (PubMed, Web of Science, Embase, and Scopus) were systemically searched to identify relevant RCTs published in international scientific journals up to January 2023. Changes from baseline and SDs of CRP, SBP, and DBP were compared between postmenopausal women who received vitamin D supplementation and those who did not (controls). These parameters were applied to compute the overall effect sizes using the random-effects model. Data were summarized as mean difference (MD) with 95% CI. Heterogeneity among arms was scrutinized using the Cochrane's Q test and I2 statistic. Publication bias was judged by means of funnel plots and Egger's test.

RESULTS

Seven studies with 6 arms on CRP, 6 arms on SBP, and 6 arms on DBP were included in the meta-analysis. Combined effect sizes suggested a significant effect of vitamin D supplementation on CRP (MD = -0.65 mg/L; 95% CI -0.93 to -0.37 mg/L; P < .001). In addition, CRP concentrations were significantly reduced after vitamin D supplementation in studies with a duration of more than 3 months (MD = -0.91 mg/L; 95% CI -1.37 to -0.45 mg/L; P < .001) and studies involving doses of ≤1,000 IU/d (MD = -2.10 mg/L; 95% CI -2.51 to -1.68 mg/L; P < .001). Vitamin D supplementation did not reduce SBP significantly (MD = -1.06 mm Hg; 95% CI -2.43 to 0.30 mm Hg; P = .127) and DBP (MD = 0.003 mm Hg; 95% CI -0.86 to 0.86 mm Hg; P = .994) levels compared with control groups.

CONCLUSIONS

This meta-analysis concluded that vitamin D supplementation is associated with reduced CRP concentrations among postmenopausal women.

Evaluating the effect of vitamin D supplementation on serum levels of 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D, parathyroid hormone and renin-angiotensin-aldosterone system: a systematic review and meta-analysis of clinical trials

BACKGROUND

Vitamin D, one of the most essential micronutrients, is crucial in various health outcomes. However, previous studies showed conflicting results and uncertainty about vitamin D supplementation's optimal dosage and duration. In this study, we aimed to evaluate the vitamin D supplements efficiency on serum levels of 25-hydroxy vitamin D (25(OH)D), 1,25-dihdroxy vitamin D (1,25(OH)2D), parathyroid hormone (PTH) and renin-angiotensin-aldosterone system (RAAS) in adults.

METHODS

A systematic analysis of eligible and relevant randomized-controlled trials (RCT) published before April 2023 assessing the effect of vitamin D supplementations applied. The studies were identified by searching several databases, including Pubmed, Scopus, Web of Science, ProQuest, and Cochrane Register of controlled trials.

RESULTS

Five eligible RCTs with 346 participants in the intervention and 352 participants in the control group were assessed in our project. According to the results, there was a substantial change in 25(OH)D (SMD: 2.2, I2: 92.3, 95% Confidence Interval (CI): 1.38-3.02, P-value: 0.048) and 1,25(OH)2D (SMD:1.23, I2: 86.3, 95% CI: 0.01- 2.44, P-value < 0.010) affected by vitamin D intervention. Regarding Parathyroid hormone (PTH), however, vitamin D intervention showed a remarkable decrease (SMD: -0.75, I2: 82.4, 95% CI: (-1.3)-(-0.18), P-value < 0.010). Moreover, sensitivity analysis showed significant publication bias in terms of 25(OH)D.

CONCLUSION

Vitamin D supplements significantly increase the serum levels of 25(OH)D and 1,25(OH)2D and decrease PTH levels. While some studies reported decreasing effect of vitamin D supplements on RAAS activity, some reported no changes.

The Effects of Vitamin D on Markers of Glucose and Obesity in Postmenopausal Women: A Meta-analysis of Randomized Controlled Trials

PURPOSE

The effect of vitamin D effect on glucose markers and obesity in postmenopausal women remains controversial. The current literature contains little information on vitamin D dosage and duration for optimal efficacy in postmenopausal women. This meta-analysis was undertaken to assess the impact of vitamin D on glucose markers and obesity in postmenopausal women.

METHODS

A number of databases were used dated up to January 5, 2023, with no language restrictions (PubMed/MEDLINE, Web of Science, EMBASE, and Scopus). Treatment response from baseline was estimated from the mean within-group analysis, and SDs were used to calculate the treatment response.

FINDINGS

Nine eligible articles with 12 comparisons qualified for the final quantitative analysis. An overall decrease was noted in fasting blood glucose (weighted mean difference [WMD], -3.56 mg/dL; 95% CI, -5.49 to -1.64; P < 0.001), homeostatic model assessment for insulin resistance (WMD, -1.168 mm; 95% CI, -2.001 to -0.33; P = 0.006), insulin (WMD, -2.26 units; 95% CI, -4.35 to -0.18; P = 0.033), and glycosylated hemoglobin (WMD, -0.41%; 95% CI, -0.54 to -0.29; P < 0.001) after vitamin D administration in postmenopausal women. In subgroup analyses, a notable decrease in fasting blood glucose was detected when the intervention course was ˃6 months and dosage ≤1000 IU/d (WMD, -3.48 mg/dL). The present study showed that vitamin D was not associated with body mass index, body weight, or waist circumference in postmenopausal women.

IMPLICATIONS

Vitamin D is beneficial for glucose markers but not obesity in postmenopausal women. An individualized dosage regimen of vitamin D should be followed depending on the clinical outcome target of postmenopausal women.

The effect of vitamin D on the lipid profile as a risk factor for coronary heart disease in postmenopausal women: a meta-analysis and systematic review of randomized controlled trials

BACKGROUND AND AIM

The exact effect of vitamin D administration on the lipid profile in postmenopausal women is unknown. However, as dyslipidemia is a recognized risk factor for coronary heart disease (CHD) in this population, the lipid-lowering effects of vitamin D need to be explored Thus, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) that evaluated the impact of vitamin D use on triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) as a risk factor for coronary heart disease (CHD) in postmenopausal women.

METHODS

We developed a search strategy for multiple databases (PubMed/Medline, Scopus, Embase, and Web of Science) to identify relevant RCTs whose results were published until June 1st, 2021. We combined the results using a random effects model (the DerSimonian and Laird random effects model). Lipid profile outcomes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CIs) between intervention and comparator groups.

RESULTS

Supplementation with vitamin D decreased TG (WMD: -3.55 mg/dL, 95% CI: -5.34 to -1.76, P < 0.001) in postmenopausal females versus controls. In the subgroup analyses, vitamin D increased TC when the treatment duration was ˂26 weeks (WMD: 6.56 mg/dL, 95% CI: 0.78 to 12.35, P = 0.02) as compared to ≥26 weeks (WMD: -2.06 mg/dL, 95% CI: -5.49, 1.36, P = 0.23) and in the participants with a BMI ≥30 kg/m2 (WMD: 3.65 mg/dL, 95% CI: 0.09, 7.22, P = 0.044). Moreover, vitamin D increased HDL-C when the treatment duration was ˂26 weeks (WMD: 2.67 mg/dL, 95% CI: 0.66 to 4.68, P = 0.009). In addition, vitamin D decreased LDL-C when the vitamin D dose was ˃400 IU/day (WMD: -1.89 mg/dL, 95% CI: -2.47 to -1.31, P < 0.001) as compared to ≤400 IU/day (WMD: 2.50 mg/dL, 95% CI: -2.50, 7.52, P = 0.327).

CONCLUSIONS

Vitamin D administration on the lipid profile as a risk factor for CHD in postmenopausal women reduces TG. Its effects to lower LDL-C and increase HDL-C and TC levels are clinically negligible but should be investigated in future research. In addition, supplementation with vitamin D results in a clinically significant reduction in TG, particularly in postmenopausal females with hypertriglyceridemia at baseline.

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 effect of cholecalciferol supplementation on allograft function in incident kidney transplant recipients: A randomized controlled study

It is unknown whether cholecalciferol supplementation improves allograft outcomes in kidney transplant recipients (KTRs). We conducted a single-center randomized, double-blind, placebo-controlled trial of daily 4000 IU cholecalciferol supplementation in KTRs at 1-month posttransplant. The primary endpoint was the change in eGFR from baseline to 12-month posttransplant. Secondary endpoints included severity of interstitial fibrosis and tubular atrophy (IFTA) at 12-month posttransplant and changes in urinary biomarkers. Of 193 randomized patients, 180 participants completed the study. Changes in eGFR were 1.2 mL/min/1.73 m² (95% CI; -0.7 to 3.1) in the cholecalciferol group and 1.8 mL/min/1.73 m² (95% CI, -0.02 to 3.7) in the placebo group, with no significant between-group difference (-0.7 mL/min/1.73 m² [95% CI; -3.3 to 2.0], p = 0.63). Subgroup analyses showed detrimental effects of cholecalciferol in patients with eGFR <45 mL/min/1.73 m² (P_interaction <0.05, between-group difference; -4.3 mL/min/1.73 m² [95% CI; -7.3 to -1.3]). The degree of IFTA, changes in urine albumin-to-creatinine ratio, or adverse events including hypercalcemia and infections requiring hospitalization did not differ between groups. In conclusion, cholecalciferol supplementation did not affect eGFR change compared to placebo among incident KTRs. These findings do not support cholecalciferol supplementation for improving allograft function in incident KTRs. Clinical trial registry: This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as UMIN000020597 (please refer to the links below). UMIN-CTR: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000023776.

Effect of 1-year oral cholecalciferol on a metabolic profile and blood pressure in poor-controlled type 2 diabetes mellitus: an open-label randomized controlled pilot study

PURPOSE

Hypovitaminosis D has been associated with many cardio-metabolic disorders, although their pathogenetic link still remains unclear. Our aim was to evaluate whether 1-year vitamin D (D) supplementation could improve glycemic control, lipid profile, systolic (SBP) and diastolic (DBP) blood pressure levels and body composition.

METHODS

In an open-label randomized-controlled pilot study, thirty poor-controlled (HbA1c > 59 mmol/mol) type 2 diabetic patients (age 71.5 ± 3.2 years, M/F 21/9, BMI 29.8 ± 3.6 kg/m²) with hypovitaminosis D (25OHD 22.0 ± 11.3 nmol/l) were randomized to cholecalciferol supplementation (500 UI/kg p.o. weekly, + D) or observation (- D) for one year. Changes in parameters of glucose, lipid and blood pressure control at 3, 6, 9 and 12 months vs. baseline were assessed.

RESULTS

One-year D supplementation restored D status and had a beneficial effect on fasting glucose (FG, mean percentage changes ± SD, - 1.8% ± 23.1 vs. + 18.8% ± 30.0), glycosylated haemoglobin (HbA1c, - 13.7% ± 14.5 vs. - 4.2% ± 14.1), SBP (- 13.4% ± 8.5 vs. - 2.4% ± 12.6) and HDL-cholesterol levels (- 2.1% ± 14.0 vs. - 10.9% ± 12.9; p < 0.05 for all comparisons) in + D vs. - D patients, respectively. In the former, a reduction in HBA1c, SBP and DBP levels, BMI, fat mass index (FMI) and ratio (FMR) was observed after 1 year (p < 0.05 for all comparisons vs. baseline). We noticed a relationship between 1-year mean percentage changes of serum 25OHD and SBP levels (R = - 0.36, p < 0.05).

CONCLUSION

One-year cholecalciferol supplementation, able to restore D status, significantly improves FG, HbA1c, SBP and HDL-cholesterol levels in patients with poor-controlled type 2 diabetes mellitus and D deficiency.

Serum 25-Hydroxyvitamin D Concentrations and Cardiometabolic Biomarkers in Chinese Rural Population

There is a paucity of data on the relation between serum 25-hydroxyvitamin D [25(OH)D] concentration and cardiometabolic biomarkers in the Chinese population. To comprehensively and quantitatively examine the association of 25(OH)D and cardiometabolic traits, we conducted a cross-sectional study in the Chinese rural population. Serum 25(OH)D and eight cardiometabolic biomarkers were measured in 1714 individuals from Henan province, China. Scatter plot was used to visualize the distribution and correlation of 25(OH)D and cardiometabolic indicators. Moreover, multivariate linear regressions and restricted cubic spline (RCS) functions were performed to examine the quantitative association between the serum 25(OH)D and cardiometabolic parameters. The median serum 25(OH)D level was 19.94 ng/ml in all participants, with an estimated 50.12% presenting vitamin D deficiency. Serum 25(OH)D level showed significantly modest association with cardiometabolic parameters (p<0.05) except for diastolic blood pressure (r=0.03, p=0.22). Multiple linear regression models showed that 25(OH)D concentration was positively associated with high-density lipoprotein cholesterol (HDL-C) and negatively associated with low-density lipoprotein cholesterol (LDL-C) and fasting serum glucose (GLU). The results of restricted cubic spline models indicated a positively linear association of 25(OH)D with HDL-C (p for overall<0.001, p for nonlinearity=0.191) and a negatively linear association with GLU (p for overall=0.024, p for nonlinearity=0.095). Overall, vitamin D deficiency was very common among Chinese rural population living near the 34 degrees north latitude. Besides, there were significant association between 25(OH)D concentrations and cardiometabolic biomarkers including HDL-C and GLU levels. Future longitudinal studies and randomized trials are warranted to clarify the causal relationship.

Vitamin D and Lipid Profiles in Postmenopausal Women: A Meta-Analysis and Systematic Review of Randomized Controlled Trials

Background and Aim: It is known that hyperlipidemia and low vitamin D level are risk factors associated with cardiovascular disease (CVD). However, the effect of vitamin D administration on lipid profiles in postmenopausal women remains unclear. This study aims to evaluate the effect of vitamin D on lipid profiles in postmenopausal women based on meta-analysis and systemic review. Methods: The literature search was performed in multiple databases (Scopus, PubMed/Medline, Web of Science, and Embase) from 1997 to 2021. The statistical analysis was performed using the Stata software version 14 (Stata Corp. College Station, Texas, United States). The effects of vitamin D administration of the lipid profiles, including Triacylglycerol (TG), LDL-Cholesterol (LDL-C), HDL-Cholesterol (HDL-C), and Total Cholesterol (TC) were evaluated by the Der Simonian and Laird random effects model. The weighted mean difference (WMD) and 95% confidence intervals (CI) were calculated. Results: The level of TG changed significantly by -3.76 mg/dl (CI: -6.12 to -1.39, p = 0.004) and HDL-C by 0.48 mg/dl (CI: -0.80 to -0.15, p = 0.004) in vitamin D administration group [11 eligible trials (placebo = 505 participants, vitamin D intervention = 604 participants)] compared to the control group in the postmenopausal women. Taking into account this comparison between groups, in contrast, the level of LDL-Cholesterol (LDL-C) (WMD: 0.73 mg/dl, 95% CI: -1.88, 3.36, p = 0.583) and TC (WMD: 0.689 mg/dl, CI: -3.059 to 4.438, p = 0.719) did not change significantly. Conclusion: In conclusion, the vitamin D administration in postmenopausal women, decreased the concentrations of TG, and HDL-C, but have no effects on LDL-C and TC.

Circulating Levels of Muscle-Related Metabolites Increase in Response to a Daily Moderately High Dose of a Vitamin D3 Supplement in Women with Vitamin D Insufficiency-Secondary Analysis of a Randomized Placebo-Controlled Trial

Recently, we demonstrated negative effects of vitamin D supplementation on muscle strength and physical performance in women with vitamin D insufficiency. The underlying mechanism behind these findings remains unknown. In a secondary analysis of the randomized placebo-controlled trial designed to investigate cardiovascular and musculoskeletal health, we employed NMR-based metabolomics to assess the effect of a daily supplement of vitamin D3 (70 µg) or an identically administered placebo, during wintertime. We assessed the serum metabolome of 76 postmenopausal, otherwise healthy, women with vitamin D (25(OH)D) insufficiency (25(OH)D < 50 nmol/L), with mean levels of 25(OH)D of 33 ± 9 nmol/L. Compared to the placebo, vitamin D3 treatment significantly increased the levels of 25(OH)D (−5 vs. 59 nmol/L, respectively, p < 0.00001) and 1,25(OH)₂D (−10 vs. 59 pmol/L, respectively, p < 0.00001), whereas parathyroid hormone (PTH) levels were reduced (0.3 vs. −0.7 pmol/L, respectively, p < 0.00001). Analysis of the serum metabolome revealed a significant increase of carnitine, choline, and urea and a tendency to increase for trimethylamine-N-oxide (TMAO) and urinary excretion of creatinine, without any effect on renal function. The increase in carnitine, choline, creatinine, and urea negatively correlated with muscle health and physical performance. Combined with previous clinical findings reporting negative effects of vitamin D on muscle strength and physical performance, this secondary analysis suggests a direct detrimental effect on skeletal muscle of moderately high daily doses of vitamin D supplements.

Effect of Vitamin D on Blood Pressure and Hypertension in the General Population: An Update Meta-Analysis of Cohort Studies and Randomized Controlled Trials

Background

The effect of vitamin D supplementation on blood pressure has been explored in previous meta-analyses, but whether the association is causal in the general population is still unknown. We evaluated the association comprehensively and quantitatively.

Methods

We searched PubMed and Embase for relevant cohort studies and randomized controlled trials (RCTs). We used a 2-step generalized least-squares method to assess the dose–response association of circulating 25-hydroxyvitamin D (25[OH]D) and hypertension and a fixed-effects model to pool the weighted mean differences (WMDs) and corresponding 95% confidence intervals (95% CIs) of blood pressure across RCTs.

Results

We identified 11 cohort studies and 27 RCTs, with 43,320 and 3,810 participants, respectively. The dose–response relationship between circulating 25(OH)D levels and hypertension risk was approximately L-shaped (P_nonlinearity = .04), suggesting that the risk of hypertension increased substantially below 75 nmol/L as 25(OH)D decreased, but it remained significant over the range of 75–130 nmol/L. However, pooled results of RCTs showed that there was no significant reduction in systolic blood pressure (WMD, −0.00 mm Hg; 95% CI, −0.71 to 0.71) or diastolic blood pressure (WMD, 0.19 mm Hg; 95% CI, −0.29 to 0.67) after vitamin D intervention.

Conclusions

The results of this meta-analysis indicate that supplementation with vitamin D does not lower blood pressure in the general population. RCTs with long-term interventions and a sufficient number of participants who have low levels of vitamin D are needed to validate these findings.

Effects of Elevated Parathyroid Hormone Levels on Muscle Health, Postural Stability and Quality of Life in Vitamin D-Insufficient Healthy Women: A Cross-Sectional Study

Independently of plasma 25-hydroxyvitamin D (P-25(OH)D) levels, elevated parathyroid hormone (PTH) levels may exert an adverse effect on muscle health, postural stability, well-being, and quality of life. Using a cross-sectional design, we investigated 104 healthy postmenopausal women with low P-25(OH)D (< 50 nmol/l) levels, who had either secondary hyperparathyroidism (SHPT) with elevated PTH levels (> 6.9 pmol/l, n = 52) or normal PTH levels (n = 52). The average PTH value in women with SHPT was 8.5 (interquartile range 7.5-9.7) pmol/l and 5.3 (4.4-6.3) pmol/l in women with normal PTH (p < 0.001). Plasma phosphate was significantly lower in women with SHPT than in women with normal PTH (1.01 ± 0.14 vs. 1.09 ± 0.13 mmol/l; p < 0.01). In the total cohort, average level of 25(OH)D were 38 (31-45) nmol/l, with no differences between groups. SHPT was associated with impaired muscle strength as assessed by both maximum muscle strength and maximum force production at knee flexion with the knee fixed at 60° and 90° (p_all < 0.05). Postural stability was impaired during semi tandem standing (p = 0.001). However, the two groups did not differ in terms of self-reported physical activity, muscle-related symptoms, quality of life, or lean muscle mass as assessed by dual-energy X-ray absorptiometry. Independently of 25(OH)D levels, mild to moderately elevated PTH levels are associated with adverse effects on muscle strength and postural stability. Why some individuals respond to vitamin D insufficiency with an elevated PTH and others do not need further elucidation, but elevated PTH itself seems to affect muscle function and postural stability.

Effect of vitamin D supplementation on endothelial function - An updated systematic review with meta-analysis and meta-regression

BACKGROUND AND AIMS

Atherogenesis and endothelial dysfunction contribute to cardiovascular risk and vitamin D has been implemented in endothelial repair. This systematic review, meta-analysis and meta-regression aims to establish the effect of vitamin D supplementation on endothelial function.

METHODS AND RESULTS

To conduct the systematic review we searched the Cochrane Library of Controlled Trials, PubMed, ProQuest and EMBASE for randomized controlled trials that investigated the effects of vitamin D supplementation on flow-mediated dilation (FMD%), pulse wave velocity (PWV), and central augmentation index (AIx). Meta-analysis was based on a random effects model and inverse-variance methods to calculate either mean difference (MD) or standardized mean difference (SMD) as effects sizes. This was followed by meta-regression investigating the effect of baseline vitamin D concentrations, vitamin D dosing and study duration. Risk of bias was assessed using the JADAD scale and funnel plots. We identified 1056 studies of which 26 studies met inclusion criteria for quantitative analysis. Forty-two percent of the 2808 participants had either deficient or insufficient levels of vitamin D. FMD% (MD 1.17% (95% CI -0.20, 2.54), p = 0.095), PWV (SMD -0.09 m/s (95% CI -0.24, 0.07), p = 0.275) and AIx (SMD 0.05% (95% CI -0.1, 0.19), p = 0.52) showed no improvement with vitamin D supplementation. Sub-analysis and meta-regression revealed a tendency for AIx and FMD% to increase as weekly vitamin doses increased; no other significant relationships were identified.

CONCLUSIONS

Vitamin D supplementation showed no improvement in endothelial function. More evidence is required before recommendations for management of endothelial dysfunction can be made.

Effect of 9 months of vitamin D supplementation on arterial stiffness and blood pressure in Graves' disease: a randomized clinical trial

PURPOSE

Risk of cardiovascular disease (CVD) is increased in Graves' disease (GD). CVD is predicted by increased pulse wave velocity (PWV) and blood pressure (BP). GD and these risk factors are all associated with lower levels of vitamin D. We aimed to assess the effect of supplemental vitamin D on PWV and BP in GD.

METHODS

In a double-blinded trial, newly diagnosed GD patients were randomized to vitamin D3 70 µg/day (n = 44) or placebo (n = 42) as add-on to anti-thyroid medication. At baseline, 3 and 9 months PWV, BP and wave analysis were performed in office and 24 h setting. Between-group differences in change at 9 months were analyzed using linear mixed modelling. In subanalysis, effect of intervention in regard to baseline vitamin D insufficiency (25(OH)D < 50 nmol/L) was investigated. (The DAGMAR study, clinicaltrials.gov ID NCT02384668).

RESULTS

PWV was unaffected by intervention in main analysis. However in the subanalysis, comparing the response to intervention in the vitamin D insufficient (n = 28) and the vitamin D replete patients, supplemental vitamin D induced a significant decrease in office PWV of 1.2 (95% CI: -2.3; -0.1) m/s compared to placebo. Of notice, baseline PWV was non-significantly higher among the vitamin D insufficient as compared to the replete participants. In response to vitamin D, office central systolic BP (-3.9 (95% CI: -7.5; -0.3) and brachial mean BP (-3.3 (95% CI: -6.5; -0.3) declined whereas 24 h measurements were unaffected.

CONCLUSIONS

High-dose vitamin D supplementation did not affect PWV. We observed significant reduction in office but not 24 h BP. Subanalysis showed a clinically relevant PWV reduction among vitamin D insufficient participants, although regression towards the mean might contribute to findings. Further studies on supplemental vitamin D in GD should focus on patients with vitamin D insufficiency.

Bone Microstructure in Response to Vitamin D3 Supplementation: A Randomized Placebo-Controlled Trial

Vitamin D supplementation is often used in the prevention and treatment of osteoporosis, but the role of vitamin D has lately been questioned. We aimed to investigate the effect of 3 months of daily vitamin D3 supplementation (70 µg [2800 IU] vs. placebo) initiated in winter months on bone health. This study is a double-blinded placebo-controlled randomized trial. Bone health was assessed by bone turnover markers, DXA, HRpQCT, and QCT scans. The participants were 81 healthy postmenopausal women with low 25(OH)D (< 50 nmol/l) and high PTH levels (> 6.9 pmol/l) at screening. Vitamin D3 supplementation significantly increased levels of 25(OH)D and 1,25(OH)₂D by 59 nmol/l and 19 pmol/l, respectively, whereas PTH was reduced by 0.7 pmol/l (all p < 0.0001). Compared with placebo, vitamin D3 did not affect bone turnover markers, aBMD by DXA or trabecular bone score. Vitamin D3 increased trabecular vBMD (QCT scans) in the trochanter region (0.4 vs. - 0.7 g/cm³) and the femoral neck (2.1 vs. - 1.8 g/cm³) p_all < 0.05. HRpQCT scans of the distal tibia showed reduced trabecular number (- 0.03 vs. 0.05 mm^-1) and increased trabecular thickness (0.001 vs. - 0.005 mm), as well as an improved estimated bone strength as assessed by failure load (0.1 vs. - 0.1 kN), and stiffness (2.3 vs. - 3.1 kN/mm p_all ≤ 0.01). Changes in 25(OH)D correlated significantly with changes in trabecular thickness, stiffness, and failure load. Three months of vitamin D3 supplementation improved bone strength and trabecular thickness in tibia, vBMD in the trochanter and femoral neck, but did not affect aBMD.

Parathyroid Hormone Causes Endothelial Dysfunction by Inducing Mitochondrial ROS and Specific Oxidative Signal Transduction Modifications

Vitamin D deficiency contributes to cardiovascular risk (CVR), with hyperparathyroidism advocated as a putative mechanism. Indeed, mounting evidence supports the hypothesis that parathyroid hormone (PTH) impairs endothelial function, even though mechanisms are not fully elucidated. The present study was designed to verify in vitro the ability of sustained exposure to PTH to cause endothelial dysfunction, exploring the underlying mechanisms. In bovine aortic endothelial cells (BAECs), we evaluated the effects of PTH exposure (0.1 nM–24 hours) on both endothelial response to vasodilators, such as bradykinin (Bk (30 nM)) and acetylcholine (Ach (1 μM)), and angiogenic competence. Pretreatment with PTH impaired endothelial response to Bk but not to Ach, in terms of cytosolic calcium fluxes and NO production. In order to explore the underlying mechanisms, we assessed the production of total and mitochondrial ROS (tROS and mROS, respectively) in response to PTH (at 1 and 3 hours). PTH increased ROS generation, to an extent high enough to determine oxidation of Bk receptor B2. Conversely, the oxidation levels of M1 and M3 Ach receptors were not affected by PTH. A mROS selective scavenger (MitoTEMPO (5 μM)) restored the endothelial responsiveness to Bk while the well-known antioxidant properties of vitamin D (100 nM) failed to counteract PTH-mediated oxidative stress. PTH determined mitochondrial calcium fluxes ([Ca²⁺]_mt) and the mitochondrial calcium uniporter inhibitor Ru360 (10 μM) reduced mROS production and prevented the PTH-mediated endothelial dysfunction. Angiogenic competence was evaluated as tubular formations in the endothelial Matrigel assay and showed a significant impairment in PTH-pretreated cells (0.1 nM–24 hours), despite the increase in VEGF transcriptional levels. VEGFR2 oxidation occurred in response to PTH, suggesting that even the impairment of angiogenesis was due to the ROS surge. These results indicate that PTH affects endothelial function through ROS production, driven by mitochondrial calcium overload. PTH-induced oxidative stress might act as signaling modifiers, altering specific pathways (Bk and VEGF) and preserving others (Ach).