Independent associations of vitamin D metabolites with anemia in patients referred to coronary angiography: the LURIC study

Etiology of Anemia in Older Mexican Adults: The Role of Hepcidin, Vitamin A and Vitamin D

Anemia in older adults is a growing public health issue in Mexico; however, its etiology remains largely unknown. Vitamin A deficiency (VAD) and vitamin D deficiency (VDD) have been implicated in the development of anemia, though by different mechanisms. The aim of this study is to analyze the etiology of anemia and anemia-related factors in older Mexican adults. This is a cross-sectional study of 803 older adults from the southern region of Mexico in 2015. The anemia etiologies analyzed were chronic kidney disease (CKD), nutritional deficiencies (ND), anemia of inflammation (AI), anemia of multiple causes (AMC) and unexplained anemia (UEA). VAD was considered to be s-retinol ≤ 20 μg/dL, and VDD if 25(OH)D < 50 nmol/L. IL-6 and hepcidin were also measured. Multinomial regression models were generated and adjusted for confounders. Anemia was present in 35.7% of OA, independent of sex. UEA, CKD, AI and ND were confirmed in 45%, 29.3%, 14.6% and 7% of older adults with anemia, respectively. Hepcidin and log IL-6 were associated with AI (p < 0.05) and CKD (p < 0.001). VAD was associated with AI (p < 0.001), and VDD with ND and AMC (p < 0.05). Log-IL6 was associated with UEA (p < 0.001). In conclusion, anemia in older adults has an inflammatory component. VAD was associated to AI and VDD with ND and AMC.

The association between iron and vitamin D status in Arab adolescents

OBJECTIVE

Both vitamin D and Fe micronutrient deficiencies are common in Saudi Arabia but the association between them is unclear. The present study aimed to determine whether Fe indices are associated with vitamin D status and other metabolic markers in Arab adolescents.

DESIGN

Single-centre, cross-sectional study gathering anthropometrics, glucose and lipid profile. Serum 25-hydroxyvitamin D (25(OH)D), Fe, total iron-binding capacity (TIBC), transferrin saturation (%) and other parameters were measured.

SETTING

Vitamin D School Project Database, King Saud University (2014-2016).

PARTICIPANTS

Arab adolescents aged 10-17 years randomly selected from the Vitamin D School Project Database (170 Saudi students; 100 girls, seventy boys).

RESULTS

Among Fe indices, only TIBC was found to be significantly and inversely associated with 25(OH)D (r = -0·20; P < 0·01) and only in girls (r = -0·20; P < 0·05). Among cardiometabolic parameters, serum Fe was associated with TAG in boys (r = 0·36; P < 0·01) and inversely associated with HDL-cholesterol in girls (r = -0·29; P < 0·05). Age was the most significant predictor of serum Fe for all participants, accounting for 5 % (R2 = 0·05; P = 0·004) of variance perceived. Serum 25(OH)D and age, on the other hand, were the most significant predictors for TIBC, accounting for 10·1 % (R2 = 0·10; P < 0·001) of variance perceived.

CONCLUSIONS

Among healthy Arab adolescents, the association between vitamin D and Fe indices, particularly TIBC, is modest, inverse and sex-dependent. Larger studies with inclusion of markers such as hepcidin and ferritin, vitamin D metabolites and endogenous sex hormones may provide a clearer view of this complex association.

Vitamin D deficiency and anemia is highly prevalent and dependent on the etiology of heart failure: A pilot study

BACKGROUND

Anemia and vitamin D deficiency are common factors in chronic heart failure (CHF). The aim of this study was to assess vitamin D levels as well as its binding protein and anemia in relation to a cause of CHF: coronary heart disease, valvular disease and cardiomyopathy.

METHODS

One hundred and sixteen consecutive patients (36 females and 80 males) with CHF were admitted for percutaneous coronary interventions (PCI). Hemoglobin concentration, serum creatinine, B-type natriuretic peptide (BNP), 25-hydroxyvitamin D [25(OH)D] and its binding protein-VDBP were measured.

RESULTS

The prevalence of anemia was 22%. BNP was the highest in the group with coronary artery disease. Ejection fraction was the lowest in cardiomyopathy group. 25(OH)D was lowest in valvular disease group, significantly lower than in the coronary artery group. A similar pattern of change showed vitamin D binding protein. The prevalence of vitamin D deficiency (level below 20 ng/mL) in the whole group was 95%, in 49% of the patients 25(OH)D was below 10 ng/mL. In univariate analysis 25(OH)D correlated with hemoglobin, red blood cell count, hematocrit, mean corpuscular volume and BNP in patients with CHF in the whole group. In multiple regression analysis, predictors of 25(OH)D were estimated, glomerular filtration rate, BNP and valvular disease.

CONCLUSIONS

25(OH)D deficiency is common in CHF patients. Valvular disease is associated the most severe vitamin D deficiency and worsened kidney function. A higher prevalence of anemia in CHF due to coronary heart disease may be associated with wider use of angiotensin converting enzyme inhibitors and acetylsalicylic acid. Heart and kidney function are predictors of 25(OH)D level in the patients of this study.

Vitamin D Supplementation Modestly Reduces Serum Iron Indices of Healthy Arab Adolescents

Vitamin D deficiency has been shown to affect iron status via decreased calcitriol production, translating to decreased erythropoiesis. The present study aimed to determine for the first time whether vitamin D supplementation can affect iron levels among Arab adolescents. A total of 125 out of the initial 200 Saudi adolescents with vitamin D deficiency (serum 25(OH)D < 50 nmol/L) were selected from the Vitamin D-School Project of King Saud University in Riyadh, Saudi Arabia. Cluster randomization was done in schools, and students received either vitamin D tablets (1000 IU/day) (N = 53, mean age 14.1 ± 1.0 years) or vitamin D-fortified milk (40IU/200mL) (N = 72, mean age 14.8 ± 1.4 years). Both groups received nutritional counseling. Anthropometrics, glucose, lipids, iron indices, and 25(OH)D were measured at baseline and after six months. Within group analysis showed that post-intervention, serum 25(OH)D significantly increased by as much as 50%, and a parallel decrease of −42% (p-values <0.001 and 0.002, respectively) was observed in serum iron in the tablet group. These changes were not observed in the control group. Between-group analysis showed a clinically significant increase in serum 25(OH)D (p = 0.001) and decrease in iron (p < 0.001) in the tablet group. The present findings suggest a possible inhibitory role of vitamin D supplementation in the iron indices of healthy adolescents whose 25(OH)D levels are sub-optimal but not severely deficient, implying that the causal relationship between both micronutrients may be dependent on the severity of deficiency, type of iron disorder, and other vascular conditions that are known to affect hematologic indices. Well-designed, randomized trials are needed to confirm the present findings.

The Association between Iron and Vitamin D Status in Female Elite Athletes

Vitamin D may influence iron metabolism and erythropoiesis, whereas iron is essential for vitamin D synthesis. We examined whether vitamin D deficiencies (VDD) are associated with reduced iron status and whether progressive iron deficiency (ID) is accompanied by inferior vitamin D status. The study included 219 healthy female (14–34 years old) athletes. VDD was defined as a 25(OH)D concentration < 75 nmol/L. ID was classified based on ferritin, soluble transferrin receptor (sTfR), total iron binding capacity (TIBC) and blood morphology indices. The percentage of ID subjects was higher (32%) in the VDD group than in the 25(OH)D sufficient group (11%) (χ² = 10.6; p = 0.001). The percentage of VDD subjects was higher (75%) in the ID than in the normal iron status group (48%) (χ² = 15.6; p = 0.001). The odds ratios (ORs) for VDD increased from 1.75 (95% CI 1.02–2.99; p = 0.040) to 4.6 (95% CI 1.81–11.65; p = 0.001) with progressing iron deficiency. ID was dependent on VDD in both VDD groups (25(OH)D < 75 and < 50 nmol/L). The ID group had a lower 25(OH)D concentration (p = 0.000). The VDD group had lower ferritin (p = 0.043) and iron (p = 0.004) concentrations and higher values of TIBC (p = 0.016) and sTfR (p = 0.001). The current results confirm the association between vitamin D and iron status in female athletes, although it is difficult to assess exactly which of these nutrients exerts a stronger influence over the other.

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.

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.

Altered microRNAs expression in T cells of patients with SLE involved in the lack of vitamin D

Vitamin D has been recognized as a potent immunomodulator and its deficiency is common in different population groups including patients with SLE. As miRNAs regulation plays a significant role in SLE, the present study aimed to evaluate the association between vitamin D status and miRNAs levels in patients with SLE. The serum concentrations of vitamin D (25-hydroxyvitamin D) and the levels of six miRNAs in T cells from patients with SLE were measured in 42 SLE cases and 48 healthy controls. Vitamin D treatment was also performed in isolated and cultured T cells from SLE patients in different times and doses. Vitamin D insufficiency (25-hydroxyvitamin D concentration <20 ng/ml) was more common in cases than in controls. Although age and BMI were similar, cases had significantly lower concentrations of miRNA-377, miRNA-342, miRNA-10a, miRNA-374b, miRNA-125a, and miRNA-410 than controls. Furthermore, a significant positive correlation was also observed between 25-hydroxyvitamin D concentrations and measured miRNAs levels. A significant difference in observed miRNAs levels was also observed in patients with 25-hydroxyvitamin D insufficiency compared with patients with 25-hydroxyvitamin D concentration ≥20 ng/ml. And 1α,25(OH)₂D₃ differentially regulated miRNAs expression in dose- and time- manner in vitro. Lower expressions of miRNA-377, miRNA-342, miRNA-10a, miRNA-374b, miRNA-125a, and miRNA-410 were found in SLE patients. And severe vitamin D deficiency is associated with decreased observed miRNAs levels in SLE patients. A 25-hydroxyvitamin D concentration value <20 ng/ml is suggested as the “cut-off” for such immunological alterations in patients with SLE.

Serum 25-hydroxyvitamin D but not dietary vitamin D intake is associated with hemoglobin in women of reproductive age in rural northern Vietnam

BACKGROUND AND OBJECTIVES

Hypovitaminosis D and anemia are both prevalent in Vietnam, and low vitamin D status may be a risk factor for anemia. This study aimed to 1) describe vitamin D intake and its determinants, and 2) examine the associations of vitamin D intake and serum 25(OH)D concentrations with hemoglobin and anemia.

METHODS AND STUDY DESIGN

We used data from the baseline survey of a pre-conceptual micronutrient supplementation trial in women of reproductive age (WRA) in Thai Nguyen, Vietnam (N = 4961). Vitamin D intake was estimated using a semi-quantitative food frequency questionnaire (FFQ). Multivariable regression models were used for the analyses.

RESULTS

Median vitamin D intake was 0.2 µg/d (8.0 IU) [IQR: 0.4]. Age, being a farmer, food insecurity, and body mass index (BMI) were inversely associated with vitamin D intake, while socioeconomic status (SES), total energy intake, and education were positively associated with vitamin D intake. Vitamin D intake was not associated with hemoglobin concentration or anemia after adjusting for age, BMI, total energy intake, transferrin receptor, C-reactive protein, α1-acid glycoprotein, SES, occupation, education, ethnicity, and food insecurity (P = 0.56 and P = 0.65 for hemoglobin and anemia, respectively). Controlling for the same covariates, 25(OH)D <50 nmol/L (vs. ≥50 nmol/L) was associated with decreased hemoglobin concentrations (β = -0.91 (SE:0.42), P = 0.03), but not with anemia (P = 0.11).

CONCLUSIONS

Low vitamin D status may be linked to reduced hemoglobin concentrations, but the role of diet in this association was not evident in this population of WRA in Vietnam where dietary vitamin D intake was very low.