Vitamin D Supplementation and Hemoglobin Levels in Hypertensive Patients: A Randomized Controlled Trial

Association Between Serum 25-Hydroxyvitamin D Level and Risk of Anemia: An Observational and Mendelian Randomization Study

Introduction

Anemia, characterized by low hemoglobin or erythrocyte levels, is a significant global health issue with severe implications for public health. Recent studies have explored the potential link between anemia and 25-hydroxyvitamin D [25(OH)D], yet the precise mechanisms remain unclear. This study aims to clarify the possible causal relationship between 25(OH)D levels and anemia risk.

Methods

We conducted a comprehensive investigation combining observational and Mendelian randomization (MR) analyses. The observational study included detailed demographic, comorbidities, and laboratory data collected from 7160 hospitalized patients in China. For the MR analysis, genetic polymorphisms were utilized to assess causal effects.

Results

Observational analysis revealed an inverse relationship between 25(OH)D levels and the risk of anemia, with stratified analysis indicating a nonlinear association and a threshold of 48.716 nmol/L. The MR analysis confirmed a protective causal relationship between higher 25(OH)D levels and a reduced risk of anemia. Bidirectional MR analysis found no evidence that anemia influences 25(OH)D levels.

Discussion

This study provides strong evidence of a causal link between increased 25(OH)D levels and a lower incidence of anemia. The findings highlight the potential role of vitamin D in anemia prevention, supporting the need for further research into vitamin D supplementation as a strategy to reduce anemia risk.

Conclusion

Our findings support the hypothesis that higher 25(OH)D levels are causally associated with a reduced risk of anemia, suggesting vitamin D's potential role in anemia prevention and public health strategies.

An 8-Week Vitamin D3-Fortified Fruit Drink Supplementation Increases Serum Ferritin Concentration: A Randomized Controlled Trial in Malaysian Women With Low Iron Stores

BACKGROUND

There is limited randomized controlled trial evidence to support the association between vitamin D deficiency and anemia risk, highlighting the necessity for further investigations into the role of vitamin D in influencing iron status.

OBJECTIVE

The aim of this study was to determine the effect of vitamin D3-fortified fruit drink consumption (4,000 IU) on vitamin D and iron status biomarkers among iron-deficient women (serum ferritin of <20 μg/L [to convert μg/L ferritin to ng/mL, multiply by 1]).

DESIGN

An 8-week double-blind randomized controlled trial was conducted.

SUBJECTS/SETTING

A total of 45 healthy, nonpregnant, nonlactating subjects aged 18 through 40 years (mean [SD] 25.3 [4.6] years) were included in the study, excluding those who donated blood 6 months prior, regularly consumed nutritional supplements, or had gastrointestinal or iron metabolic disorders.

INTERVENTION

Subjects were randomly assigned to receive either vitamin D3-fortified fruit drink or a placebo.

MAIN OUTCOME MEASURES

Measurements of 25-hydroxyvitamin D (25[OH]D), serum ferritin, high-sensitivity C-reactive protein, and full blood count concentrations were obtained at baseline, interim, and post intervention.

STATISTICAL ANALYSES

A mixed model, repeated measures analysis of variance was used to analyze the intervention effect.

RESULTS

Attrition rate for the study was 13%, with 6 dropouts, and 39 subjects completed the study. Daily consumption of vitamin D3-fortified fruit drink in the intervention group resulted in significant increases in 25(OH)D and serum ferritin concentrations compared with the placebo group. The intervention group showed significantly higher mean (SD) changes (Δ) in both 25(OH)D (Δ 76.4 [30.2] nmol/L [to convert nmol/L 25(OH)D to ng/mL, multiply by .4] vs Δ -1.3 [10.7] nmol/L; P = .001) and serum ferritin concentrations (Δ 2.2 [4.2] μg/L vs Δ -0.3 [3.4] μg/L; P = .048) between baseline and post intervention. The other iron status biomarkers were not affected by the intervention.

CONCLUSIONS

Our study found that daily vitamin D3-fortified fruit drink supplementation for 8 weeks effectively improved 25(OH)D and iron stores, indicated by increased serum ferritin concentrations, in iron-deficient women. Further research is needed to evaluate its safety, efficacy, feasibility, and optimal food fortification in diverse populations.

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

BACKGROUND

There is epidemiological evidence which suggests an association between 25-hydroxyvitamin D [25(OH)D] levels and bone and muscle function; however, it is unclear whether vitamin D supplementation has an added benefit beyond bone health. Here, we investigated the effects of vitamin D3 supplementation (1 month) on physical performance in Chinese university students in winter.

METHODS

One hundred and seventeen eligible subjects with 25(OH)D (19.2 ± 7.8 ng/mL) were randomly assigned to either vitamin D3 supplement (N = 56; 1000 IU/day) or the control (N = 61) group for 1 month. Pre- and post-measurements included: 1) serum levels of 25(OH)D; 2) musculoskeletal and pulmonary function [vertical jump height (VJH) and right handgrip strength (RHS), forced vital capacity (FVC), and forced expiratory volume at 1s (FEV1)]; 3) bone turnover markers [parathyroid hormone (PTH), n-terminal osteocalcin (N-MID), and calcium]; 4) hemoglobin-related parameters [hemoglobin (Hb), hematocrit (HCT), red blood cells (RBC), and red cell distribution width (RDW)]; 5) lipid parameters [total triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)]; 6) Fatigue-related indicators [serum creatine kinase (CK), lactate dehydrogenase (LDH), and total testosterone (T)]. In addition, aerobic capacity was assessed by measuring maximal oxygen uptake (VO2max) at baseline.

RESULTS

During wintertime, supplementation with 1000 IU/d of vitamin D3 significantly increased serum 25(OH)D levels (from 18.85 ± 7.04 to 26.98 ± 5.88 ng/mL, p < 0.05), accompanied by a decrease of PTH (p < 0.05). However, vitamin D3 supplementation did not significantly impact the physical performance, serum lipid parameters, and bone turnover markers of students. Furthermore, 25(OH)D was found to be positively correlated with VJH and negatively correlated with PTH and TC at the beginning and end of the study (p < 0.05). In addition, the multiple linear regression analysis showed that 25(OH)D combined with athletic, gender, height, weight, Hb, and FVC could account for 84.0% of the VO2max value.

CONCLUSIONS

The study demonstrated that one-month of 1000 IU/d of vitamin D3 supplementation during the winter had beneficial effects on 25(OH)D status and PTH. However, vitamin D3 intervention was not sufficient to improve physical performance. Furthermore, 25(OH)D levels combined with athletic, Hb and FVC could be a predictor of VO2max.

Improvement of vitamin D status through consumption of either fortified food products or supplement pills increased hemoglobin concentration in adult subjects: Analysis of pooled data from two randomized clinical trials

Background: It is documented that vitamin D may have a role in erythropoiesis as its deficiency is accompanied by an increased risk of anemia. Aim: This study aimed to examine whether improvement of vitamin D status through daily consumption of either fortified foods or supplements could impinge on certain hematologic parameters in adults. Methods: We pooled data from our two separate clinical trials and made five experimental groups. As part of their usual diet, one group consumed 500 mL/day of yogurt drink fortified with 1000 IU of vitamin D (D-yogurt, n = 27) whereas one group consumed 500 mL/day of the plain yogurt drink (P-yogurt, n = 27). In addition three other groups consumed either 50 g/day bread fortified with 1000 IU of vitamin D (D-bread) or supplement containing 1000 IU vitamin D (D-supplement, n = 27) or placebo (placebo, n = 27). Biochemical measurements were performed before and after the intervention. Results: In all three vitamin D-supplemented groups, serum 25(OH)D concentration increased after the intervention period, which was interestingly accompanied by a significant increment of hemoglobin (D-yogurt, p < 0.001, D-bread, p = 0.003, D-supplement, p < 0.001). Analyses indicated that among participants in vitamin D-intervention groups, being in D-yogurt group was more favourable predictor of improvement in hemoglobin concentrations compared with the placebo (p < 0.001), D-bread (p = 0.045) and P-yogurt (p = 0.001). Conclusion: Improvement of vitamin D status via regular intake of either vitamin D-fortified food products or supplements can result in a significant increment of hemoglobin in adult subjects. This finding has very important clinical as well as public health implications.

The effect of high-dose vitamin D supplementation on hepcidin-25 and erythropoiesis in patients with chronic kidney disease

BACKGROUND

Hepcidin is considered to play a central role in the pathophysiology of renal anemia. Recent studies in healthy individuals have demonstrated a suppressive effect of vitamin D (VD) on the expression of hepcidin. In this post-hoc analysis based on a randomized controlled study, we evaluated the effect of supplementing chronic kidney disease (CKD) patients (stage G3-G4) with a high daily dose of native VD on serum levels of hepcidin-25, the hepcidin/ferritin ratio, as well as on markers of erythropoiesis.

METHODS

Patients with CKD stage G3-G4 included in a double blind, randomized, placebo (PBO) controlled study with available hepcidin measurements were analyzed. Study subjects received either 8000 international units (IU) of cholecalciferol daily or PBO for 12 weeks. We evaluated the change in markers of hepcidin expression, erythropoiesis, and iron status from baseline to week 12 and compared the change between the groups.

RESULTS

Eighty five patients completed the study. Calcitriol, but not 25-hydroxyvitamin D (25(OH) D), was inversely correlated with serum levels of hepcidin-25 (rho = -0,38; p =  < 0, 01 and rho = -0,02; p = 0, 89, respectively) at baseline. Supplementation with VD significantly raised the serum concentration of serum 25(OH)D in the treatment group (from 54 (39-71) to 156 (120-190) nmol/L; p =  < 0, 01)) but had no effect on any of the markers of hepcidin, erythropoiesis, or iron status in the entire cohort. However, we did observe an increase in hemoglobin (HB) levels and transferrin saturation (TSAT) as compared to the PBO group in a subgroup of patients with low baseline 25(OH)D levels (< 56 nmol/L). In contrast, in patients with high baseline 25(OH)D values (≥ 56 nmol/L), VD supplementation associated with a decrease in HB levels and TSAT (p = 0,056) within the VD group in addition to a decrease in hepcidin levels as compared to the PBO group.

CONCLUSION

High-dose VD supplementation had no discernible effect on markers of hepcidin or erythropoiesis in the entire study cohort. However, in patients with low baseline 25(OH)D levels, high-dose VD supplementation associated with beneficial effects on erythropoiesis and iron availability. In contrast, in patients with elevated baseline 25(OH)D levels, high-dose VD supplementation resulted in a decrease in hepcidin levels, most likely due to a deterioration in iron status.

The Level of Selected Blood Parameters in Young Soccer Players in Relation to the Concentration of 25(OH)D at the Beginning and End of Autumn

This study aimed to demonstrate the changes of selected blood parameters in relation to 25(OH)D concentration during the autumn period in young soccer players. A total of 35 participants’ results (age: 17.5 ± 0.6 years, body mass 71.3 ± 6.9 kg) were tested twice: in mid-September and in mid-December and divided into subgroups with regard to two criteria. First, according to the initial level of the 25(OH)D concentration (optimal group—ODG, suboptimal group—SDG), second, according to drops in 25(OH)D concentration (high drop group—HDG, low drop group—LDG). A significant decrease (p < 0.001) in the 25(OH)D concentration was reported in the total group (TGr) and in all subgroups. Blood parameters such as white blood cells, red blood cells, haemoglobin and haematocrit increased significantly (p < 0.05) in TGr during the analysed period of time. The analysis of changes in the lipid profile did not expose significant differences except triglycerides. The asparagine amino transferase and creatine kinase activity decreased significantly after autumn in all analysed groups. The declining level of 25(OH)D concentration should be compensated (e.g., with vitamin D supplementation) during autumn. Applied training loads could also influence the blood parameters variability in young soccer players. Regular measurements of 25(OH)D concentration are helpful in identifying potential drops and allows for the preparation of individual supplementation plans for the players.

Manan N, Mohamad Alwi MN. Effect of vitamin D3-fortified fruit juice supplementation of 4000 IU daily on the recovery of iron status in childbearing-aged women with marginally low iron stores: Protocol for an 8-week, parallel group, double-blind randomized controlled trial

BACKGROUND

In recent years, emerging evidence has highlighted the role of vitamin D as an iron absorption enhancer by suppressing hepcidin concentration, albeit with an unclear underlying mechanism. Dietary-based approach in improving iron status has been widely practised, however, there is a scarcity in randomized controlled trials (RCT) to elucidate the effect of vitamin D-fortified juice on iron status recovery. Therefore, this study aims to investigate the effect of an 8-week vitamin D3-fortified fruit juice supplementation on iron status indicators in childbearing-aged women with marginally low iron stores.

METHODS

In a placebo-controlled, double-blind, RCT, a total of 120 women aged between 19-40 with serum ferritin < 20 μg/l and fulfilled the eligibility criteria will be randomized into consuming either vitamin D3-fortified fruit juices containing 4000 IU (100 mcg) (vitamin D) or placebo-fruit juices (placebo) daily for eight weeks. At every 4-week interval, 10 ml fasting blood sample, information on dietary habit and anthropometric measurement will be collected. A mixed model repeated-measures analysis of variance will be performed to determine the effect of the intervention and the interaction with time points for all iron and vitamin D status blood biomarkers.

DISCUSSION

Vitamin D supplementation in food fortification as a novel iron absorption enhancer might be a future and relevant alternative management of iron deficiency as opposed to the oral iron therapy that has poor adherence.

TRIAL REGISTRATION

Clinicaltrials.gov: registration number NCT04618289, registration date October 28, 2020, protocol ID JKEUPM-2020-033.

Vitamin D epimers are associated with circulating haemoglobin levels independently of C-reactive protein

Vitamin D deficiency has been shown to be associated with anaemia. Circulating 25(OH)D consists of both epimeric and nonepimeric forms. However, the relative roles of epimeric and nonepimeric vitamin D in regulating anaemia and haemoglobin levels remain unknown. Therefore, in this study, we examined the effect of vitamin D, including its epimers, on haemoglobin levels, independently of its effect on circulating high-sensitivity C-reactive protein (hsCRP). This was a cross-sectional study of 1655 subjects from a long-term follow-up cohort at the Electricity Generating Authority of Thailand. Venous blood sample were collected for determination of vitamin D [25(OH)D₂, 25(OH)D₃, 3'-epi-25(OH)D₂, and 3'-epi-25(OH)D₃], haemoglobin, and hsCRP levels. Data are presented as mean ± standard deviation. Age, sex, and body mass index (BMI) were significantly associated with circulating haemoglobin levels, while no association was found between total serum 25(OH)D and haemoglobin levels. However, when total 25(OH)D was separated into 3'-epimeric and non-3'-epimeric forms, 3'-epi-25(OH)D was significantly associated with haemoglobin levels, independently of age, sex, and BMI (P < 0.01). No association was found between non-3'-epi-25(OH)D and haemoglobin. When hsCRP was added to the model, the effect 3'-epi-25(OH)D on haemoglobin levels remained significant (P < 0.01). In conclusion, vitamin D epimers are associated with circulating haemoglobin levels, which supports the role of vitamin D in red blood cell and iron physiology.

The effect of vitamin D supplementation on hemoglobin concentration: a systematic review and meta-analysis

AIMS

The purpose of this review was to investigate the effect of vitamin D supplements on hemoglobin concentration in subjects aged 17.5-68 years old; using randomized controlled trials (RCTs).

METHODS

Relevant RCT studies were identified from January 2000 to January 2019 by using MeSH terms in PubMed, Embase, Cochrane Library, Clinical trials, Scopus databases and gray literature. The studies were reviewed systematically, and quality assessments were evaluated by the guidelines of the Cochrane risk of bias. The effect of vitamin D supplements (n = 14) on hemoglobin concentration was considered as primary outcome, while its effects on the levels of ferritin, transferrin saturation and iron status were derived as secondary outcomes. In total, 1385 subjects with age range of 17.5 to 68 years old were examined for 3 h to 6 months; Mean (standard deviation) or median interquartile changes in the hemoglobin concentration in each treatment group was recorded for meta-analysis.

RESULTS

Fourteen RCTs met the inclusion criteria. Current study findings propose that vitamin D supplementation leads to a non-significant reduction in hemoglobin levels in subjects (17.5-68 years old) [std. mean difference (SMD): 0.01; 95% CI: - 0.28, 0.29; P = 0.95], also it has no significant effect on ferritin concentrations [std. mean difference (SMD): -0.01; 95% CI: [- 0.20, 0.18; P = 0.91]. However, vitamin D supplementation demonstrated positive effects on transferrin saturation [mean difference (MD): 1.54; 95% CI: 0.31, 2.76; P = 0.01] and iron status [std. mean difference (SMD): 0.24; 95% CI: - 0.09, 0.39; P = 0.002].

CONCLUSION

Current review concluded that supplementation with vitamin D had no significant effect on hemoglobin and ferritin levels while positive effects on transferrin saturation and iron status were observed. Further clinical studies are required to determine the actual effect of this intervention on hemoglobin levels.

A systematic review and meta-analysis of the response of serum 25-hydroxyvitamin D concentration to vitamin D supplementation from RCTs from around the globe

BACKGROUND/OBJECTIVES

Optimal doses of vitamin D (VitD) supplement in different populations are unclear. We aim to evaluate the relationship between VitD supplementation and post-intervention serum 25-hydroxyvitamin D [25(OH)D] concentration, to provide a recommended dosage of VitD for achieving an optimal 25(OH)D concentration for different populations.

SUBJECTS/METHODS

Literature search was conducted in Embase, etc. Randomized controlled trials about VitD supplemental intakes and their effect on 25(OH)D concentration were enrolled. The effect on 25(OH)D concentration between different supplementation doses in each population group was compared by meta-analysis. Multivariate meta-regression model is utilized to establish reference intake dosage of VitD.

RESULTS

A total of 136 articles were included about children (3-17 years), adults (18-64 years), postmenopausal women, the elderly ( >64 years), pregnant, or lactating women. Overall, intervention groups obtained higher 25(OH)D concentration than controls and there was obvious dose-response effect between intake dose and 25(OH)D concentration. Baseline 25(OH)D concentration and age were significant indicators for 25(OH)D concentration. To reach sufficient 25(OH)D concentration (75 nmol/L), the recommended VitD supplemental intakes was 1340 and 2250 IU/day for children and pregnant women, 2519 and 797 IU/day for European adults aged 18-64 and 65-85 years, 729, 2026, and 1229 IU/day for adults in North America, Asia and Middle East and Africa, respectively.

CONCLUSIONS

Regional- and age-specific recommended dosages of VitD supplements for population to achieve optimal 25(OH)D concentrations have been suggested.

Vitamin D3 supplementation for 8 weeks leads to improved haematological status following the consumption of an iron-fortified breakfast cereal: a double-blind randomised controlled trial in iron-deficient women

The effect of 38 µg (1500 IU) daily vitamin D3 supplementation, consumed with an Fe-fortified breakfast cereal for 8 weeks, on haematological indicators in Fe-deficient female subjects was investigated. Fifty Fe-deficient subjects (plasma ferritin concentration &lt;20 µg/l; mean age: 27·4 (sd 9·4) years) were randomised to consume an Fe-fortified breakfast cereal containing 9 mg of Fe daily, with either a vitamin D3 supplement or placebo. Blood samples were collected at baseline, interim (4 weeks) and post-intervention (8 weeks) for measurement of Fe and vitamin D status biomarkers. The effect of intervention was analysed using mixed-model repeated-measures ANOVA. Significant increases were observed in two main haematological indices: Hb concentration and haematocrit level from baseline to post-intervention in the vitamin D group but not in the placebo group. The increase from baseline to post-intervention in Hb concentration in the vitamin D group (135 (sd 11) to 138 (sd 10) g/l) was significantly higher compared with the placebo group (131 (sd 15) to 128 (sd 13) g/l) (P=0·037). The increase in haematocrit level from baseline to post-intervention was also significantly higher in the vitamin D group (42·0 (sd 3·0) to 43·8 (sd 3·4) %) compared with the placebo group (41·2 (sd 4·3) to 40·7 (sd 3·6) %) (P=0·032). Despite the non-significant changes in plasma ferritin concentration, this study demonstrates that 38 µg supplemental vitamin D, consumed daily, with Fe-fortified breakfast cereal led to improvement in Hb concentration and haematocrit levels in women with low Fe stores. These findings may have therapeutic implications in the recovery of Fe status in Fe-deficient populations at a healthcare level.

High-Dose Vitamin D3 Administration Is Associated With Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Anemia and vitamin D deficiency are highly prevalent in critical illness, and vitamin D status has been associated with hemoglobin concentrations in epidemiologic studies. We examined the effect of high-dose vitamin D therapy on hemoglobin and hepcidin concentrations in critically ill adults.

MATERIALS AND METHODS

Mechanically ventilated critically ill adults (N = 30) enrolled in a pilot double-blind, randomized, placebo-controlled trial of high-dose vitamin D3 (D3 ) were included in this analysis. Participants were randomized to receive placebo, 50,000 IU D3 , or 100,000 IU D3 daily for 5 days (totaling 250,000 IU D3 and 500,000 IU D3 , respectively). Blood was drawn weekly throughout hospitalization for up to 4 weeks. Linear mixed-effects models were used to assess change in hemoglobin and hepcidin concentrations by treatment group over time.

RESULTS

At enrollment, >75% of participants in all groups had plasma 25-hydroxyvitamin D (25(OH)D) concentrations <30 ng/mL, and >85% of participants across groups were anemic. In the 500,000-IU D3 group, hemoglobin concentrations increased significantly over time (Pgroup × time = .01) compared with placebo but did not change in the 250,000-IU D3 group (Pgroup × time = 0.59). Hepcidin concentrations decreased acutely in the 500,000-IU D3 group relative to placebo after 1 week (P = .007). Hepcidin did not change significantly in the 250,000-IU D3 group.

CONCLUSION

In these critically ill adults, treatment with 500,000 IU D3 was associated with increased hemoglobin concentrations over time and acutely reduced serum hepcidin concentrations. These findings suggest that high-dose vitamin D may improve iron metabolism in critical illness and should be confirmed in larger studies.

Effects of Vitamin D3 on asymmetric- and symmetric dimethylarginine in arterial hypertension

BACKGROUND AND AIMS

Accumulating evidence has proposed a correlation between vitamin D (25(OH)D) insufficiency and cardiovascular (CV) disease. Vitamin D associated effects on endothelial function have been suggested to be a possible culprit. The present study investigated the association of vitamin D3 treatment on markers of endothelial dysfunction in patients with arterial hypertension.

METHODS AND RESULTS

The Styrian Vitamin D Hypertension Trial is a double-blind, placebo-controlled, single-centre study conducted at the Medical University of Graz, Austria. A total of 200 study participants with arterial hypertension and 25(OH)D levels below 30ng/mL were enrolled. The study participants were randomized to receive 2800 IU of vitamin D3 per day as oily drops (n=100) or placebo (n=100) for a duration of eight weeks. The present study uses an analysis of covariance (ANCOVA) to investigate the effect of vitamin D3 treatment on symmetric (SDMA) and asymmetric dimethylarginine (ADMA). A total of 187 participants (mean [SD] age 60.0 [11.3] years; 47% women; 25(OH)D 21.2 [5.6]ng/mL; mean systolic blood pressure of 131.4 [8.9] mmHg on a median of 2 antihypertensive drugs) completed the trial. Mean treatment effect was -0.004 (95%CI [-0.03 to 0.04]; P=0.819) on ADMA and 0.001 (95%CI [-0.05 to 0.05]; P=0.850) on SDMA. In the subgroup analysis patients with a 25(OH)D concentration <20ng/mL had a significant increase in their log l-arginine/ADMA ratio (mean treatment effect 18.4 95%CI [1.84-34.9]μmol/L/μmol/L; P=0.030). ClinicalTrials.gov Identifier: NCT02136771 EudraCT number: 2009-018125-70 CONCLUSIONS: Vitamin D3 supplementation in hypertensive patients with low 25-hydroxyvitamin D has no significant effect on ADMA and SDMA.

Vitamin D Status Is Associated with Hepcidin and Hemoglobin Concentrations in Children with Inflammatory Bowel Disease

BACKGROUND

Anemia, iron deficiency, and hypovitaminosis D are well-known comorbidities in inflammatory bowel disease (IBD). Epidemiologic studies have linked vitamin D deficiency with increased risk of anemia, and in vitro studies suggest that vitamin D may improve iron recycling through downregulatory effects on hepcidin and proinflammatory cytokines.

METHODS

We aimed to investigate the association of vitamin D status with inflammation, iron biomarkers, and anemia in pediatric IBD. Cross-sectional data were obtained from N = 69 patients with IBD aged 5 to <19 years. Iron biomarkers (ferritin, soluble transferrin receptor), and 25-hydroxyvitamin D (25(OH)D), inflammatory biomarkers (C-reactive protein and α-1-acid glycoprotein), hepcidin, and hemoglobin were collected. Iron biomarkers were regression corrected for inflammation. Multivariable logistic/linear models were used to examine the associations of 25(OH)D with inflammation, iron status, hepcidin, and anemia.

RESULTS

Approximately 50% of subjects were inflamed (C-reactive protein >5 mg/L or α-1-acid glycoprotein >1 g/L). Iron deficiency prevalence (inflammation-corrected ferritin <15 μg/L or soluble transferrin receptor >8.3 mg/L) was 67%; anemia was 36%, and vitamin D insufficiency (25(OH)D <30 ng/mL) was 77%. In linear regression models, vitamin D insufficiency was associated with increased hepcidin levels (β [SE] = 0.6 [0.2], P = 0.01) and reduced hemoglobin (β [SE] = -0.9 [0.5], P = 0.046), controlling for age, sex, race, insurance status, body mass index for age, inflammation, disease diagnosis (ulcerative colitis versus Crohn's disease), and disease duration, compared with 25(OH)D ≥30 ng/mL.

CONCLUSIONS

Our results suggest that concentrations of 25(OH)D ≥30 ng/mL are associated with lower hepcidin and higher hemoglobin levels. Further research is needed to clarify the association of vitamin D with inflammation, iron status, and anemia in pediatric IBD.

Randomized supplementation of 4000 IU vitamin D3 daily vs placebo on the prevalence of anemia in advanced heart failure: the EVITA trial

Background

Low 25-hydroxyvitamin D (25OHD) levels (< 75 nmol/l) are inversely associated with anemia prevalence. Since anemia and low 25OHD levels are common in patients with heart failure (HF), we aimed to investigate whether vitamin D supplementation can reduce anemia prevalence in advanced HF.

Methods

EVITA (Effect of Vitamin D on Mortality in Heart Failure) is a randomized, placebo-controlled clinical trial in patients with initial 25OHD levels < 75 nmol/l. Participants received either 4000 IU vitamin D₃ daily or a matching placebo for 36 months. A total of 172 patients (vitamin D group: n = 85; placebo group: n = 87) were investigated in this pre-specified secondary data analysis. Hemoglobin (Hb) and other hematological parameters were measured at baseline and study termination. Assessment of between-group differences in anemia prevalence and Hb concentrations was performed at study termination, while adjusting for baseline differences.

Results

In the vitamin D and placebo group, baseline proportions of patients with anemia (Hb < 12.0 g/dL in females and < 13.0 g/dL in males) were 17.2% and 10.6%, respectively (P = 0.19). At study termination, the proportion of patients with anemia in the vitamin D and placebo groups was 32.2% and 31.8%, respectively (P > 0.99). There was no between-group difference in change in the Hb concentrations (− 0.04 g/dL [95%CI:-0.53 to 0.45 g/dL]; P = 0.87). Results regarding anemia risk and Hb concentrations were similar in the subgroup of patients with chronic kidney disease (vitamin D group: n = 26; placebo group: n = 23). Moreover, results did not differ substantially when data analysis was restricted to patients with deficient baseline 25OHD levels.

Conclusions

A daily vitamin D supplement of 4000 IU did not reduce anemia prevalence in patients with advanced HF. Data challenge the clinical relevance of vitamin D supplementation to increase Hb levels.

Trial registration

The study was registered at EudraCT (No. 2010–020793-42) and clinicaltrials.gov (NCT01326650).

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-017-0270-5) contains supplementary material, which is available to authorized users.

High-dose vitamin D3 reduces circulating hepcidin concentrations: A pilot, randomized, double-blind, placebo-controlled trial in healthy adults

BACKGROUND & AIMS

In vitro studies suggest that vitamin D may reduce hepcidin expression and pro-inflammatory cytokine release from monocytes. However, data assessing the vitamin D-mediated effects on iron recycling in healthy individuals are lacking. We aimed to examine the effect of high-dose vitamin D₃ on plasma hepcidin, inflammatory cytokine, and ferritin concentrations in healthy adults.

METHODS

This was a pilot, double-blind, placebo-controlled trial in healthy adults (N = 28) randomized to receive a one-time oral dose of 250,000 IU of vitamin D₃ or placebo. Between- and within-group differences in plasma hepcidin, pro-inflammatory cytokine [interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1)], and ferritin concentrations at baseline and 1 week were determined using two-sample and paired t-tests, respectively.

RESULTS

At baseline, plasma 25-hydroxyvitamin D [25(OH)D], hepcidin, pro-inflammatory cytokine, and ferritin concentrations did not differ between the two groups, and greater than 70% of subjects in both groups were vitamin D deficient (25(OH)D < 20 ng/mL). After 1 week, plasma hepcidin concentrations decreased by 73% from baseline in those who received vitamin D₃ (geometric mean ratio [GMR] = 0.27 (95% CI: 0.11-0.62); P = 0.005); there was no significant change in the placebo group (GMR = 0.73 (95% CI: 0.49-1.09); P = 0.11). Plasma cytokine and ferritin concentrations did not change significantly in either group.

CONCLUSIONS

High-dose vitamin D₃ significantly reduced plasma hepcidin concentrations in healthy adults 1 week post-dosing, without a change in plasma pro-inflammatory cytokine or ferritin concentrations. These data suggest that vitamin D may have a role in regulating iron recycling by acting independently of changes in pro-inflammatory markers.