A prospective study of plasma vitamin D metabolites, vitamin D receptor gene polymorphisms, and risk of hypertension in men

Interplay between vitamin D status, vitamin D receptor gene variants and preeclampsia risk in Ghanaian women: A case-control study

BACKGROUND AND AIM

Preeclampsia (PE) is characterized by hypertension and proteinuria mostly after 20 weeks of gestation. It affects 2-8% of pregnancies worldwide, with detrimental consequences for both mother and foetus. Evidence, suggests that genetic factors, including vitamin D receptor (VDR) gene polymorphisms, could contribute to PE complexity. However, their role in the Ghanaian population remains underexplored. We assessed the interplay between Vitamin D, VDR gene variants and preeclampsia risk in Ghanaian women.

METHODS

This unmatched case-control study was conducted at Kumasi South Hospital, Ghana, from June to November 2022. A total of 162 participants consisting of 62 PE cases and 100 normotensive controls were enrolled. Clinical and obstetric data were collected. Blood samples were also collected for DNA extraction and vitamin D assay. Genotyping of VDR Fok1 and Bsm1 gene variants was performed using Polymerase Chain Reaction (PCR) and Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analysis whereas Vitamin D levels were estimated using sandwich ELISA. Statistical analyses were computed with SPSS version 25 and GraphPad prism version 8.0. A p-value of < 0.05 was considered statistically significant.

RESULTS

Vitamin D concentration were significantly lower in the PE group (p < 0.0001). Vitamin D deficiency (aOR = 3.311, 95% CI: 1.584-6.921, p = 0.0010) was significantly associated with a three-fold increase in preeclampsia risk, whilst VDR gene variants, particularly the "bb" genotype (cOR = 0.227, 95% CI: 0.055-0.944, p = 0.0410) was associated with reduced risk of PE. There was no association between the distribution of Fok1 genotypes and PE.

CONCLUSION

This study highlights a significant association between vitamin D deficiency and an increased risk of PE among Ghanaian women. However, the VDR gene variant, "bb", genotype, for Bsm1 reduces the risk of PE.

Vitamin D deficiency and the vitamin D receptor (VDR) gene polymorphism rs2228570 (FokI) are associated with an increased susceptibility to hypertension among the Bangladeshi population

Vitamin D receptor (VDR) gene is implicated in hypertension vulnerability due to its role in regulating the renin-angiotensin system (RAS) and blood pressure. In this case-control study, a carefully selected cohort of 111 hypertensive individuals and 100 healthy controls underwent serum analysis using HPLC to measure 25-hydroxy vitamin D levels. Polymorphic variations in the VDR gene were detected and characterized using the PCR-RFLP method. At first, lower 25-hydroxy vitamin D levels were observed in hypertensive individuals compared to controls (p<0.001). The genotype frequency of the VDR gene TaqI showed no significant difference between cases and controls (p>0.05). Similarly, no significant difference was found in the VDR gene BsmI genotype frequency between hypertensive patients and controls (p>0.05). However, a statistically significant distinction was observed in the VDR gene FokI genotype frequency between cases and controls (p<0.01). The odds ratios for FokI genotypes (CC, CT, TT, and CT+TT) were 1.0, 0.590, 1.566, and 0.963, respectively. Furthermore, serum 25-hydroxy vitamin D levels were significantly higher in control subjects compared to hypertensive patients across all genotypes of VDR (p<0.001). Hypertensive patients, excluding those with the FokI VDR gene CC genotype, exhibited significantly higher systolic blood pressure levels compared to the control group (p<0.05). Similarly, hypertensive subjects displayed elevated diastolic blood pressure levels compared to the control group (p<0.001). Overall, the results suggest the presence of a potential inverse correlation between serum 25-hydroxy vitamin D levels and hypertension. The association analysis conducted indicated that there is no significant association between TaqI and bsmI genotypic variants and the risk of developing hypertension. However, it was observed that VDR gene polymorphisms do have a clear association with hypertension susceptibility, as evidenced by the significantly higher occurrence of FokI genotypic variants in hypertensive patients. Our study therefore introduces the possibility of utilizing 25-hydroxy vitamin D deficiency and VDR gene polymorphisms as a biomarker for hypertension.

Vitamin D receptor gene rs2228570 (FOKI) polymorphism associated with essential hypertension in Iraqi patients

OBJECTIVE

Aim: To understand how vitamin D receptor gene polymorphism (VDR rs2228570) affects blood pressure in Iraqi patients with essential hypertension in Al Diwaniya province.

PATIENTS AND METHODS

Materials and Methods: This is a single-center observational cross-sectional descriptive study of 90 patients with essential hypertension. Using the PCRTETRA ARM technique, blood samples were genotyped and examined for the polymorphisms of FOKI (rs2228570) gene.

RESULTS

Results: The most frequent allele was A (121, 67%) while the most frequent genotype was AG (55, 61%). There was no statistical difference between the actual and expected frequency distribution, according to Hardy-Weinberg equilibrium. The effect of VDR polymorphism rs 2228570 on blood pressure indicates (the mean systolic blood pressure in AA, AG, and GG carrier patients was 149, 150 and 166 respectively, P=0.29. On the other hand, the mean diastolic blood pressure in AA, AG, and GG carrier patients was 89, 89, and 94 respectively P=0.6) there was no statistically significant effect on systolic and diastolic blood pressure.

CONCLUSION

Conclusions: there is no statistically significant effect of VDR rs2228570 on SBP and DBP (p = 0.6), vitamin D receptor gene polymorphism rs2228570 was related to vitamin D level.

Vitamin D: An Overview of Gene Regulation, Ranging from Metabolism to Genomic Effects

Vitamin D is a pro-hormone characterized by an intricate metabolism and regulation. It is well known for its role in calcium and phosphate metabolism, and in bone health. However, several studies have assessed a huge number of extra-skeletal functions, ranging from cell proliferation in some oncogenic pathways to antioxidant and immunomodulatory functions. Vitamin D exerts its role by binding to VDRs (vitamin D receptors), which are located in many different tissues. Moreover, VDRs are able to bind hundreds of genomic loci, modulating the expression of various primary target genes. Interestingly, plenty of gene polymorphisms regarding VDRs are described, each one carrying a potential influence against gene expression, with relapses in several chronic diseases and metabolic complications. In this review, we provide an overview of the genetic aspects of vitamin D and VDR, emphasizing the gene regulation of vitamin D, and the genetic modulation of VDR target genes. In addition, we briefly summarize the rare genetic disease linked to vitamin D metabolism.

Differences in Chronic Low-Grade Inflammation and Metabolic Disturbances between VDR Genotypes in an Ethnically Homogenous Postmenopausal Female Population from Poland

(1) Vitamin D deficiency and changes in the endocrine system may stimulate systemic inflammation. VDR expression and the vitamin D concentration decrease with age, which is important in postmenopausal women for whom estrogen deficiency causes rapid bone loss. This group is, moreover, particularly at risk of developing atherosclerosis and its adverse consequences, such as chronic inflammation. The aim of this study was to assess the differentiation by the VDR genotype of the risk factors for so-called chronic low-grade inflammation and metabolic disorders. (2) We studied the differences between the anthropometric, metabolic, and inflammation parameters of VDR genotypes for Apa-I, Bsm-I, Fok-I, and Taq-I in a sample of 321 women aged 50-60 from an ethnically homogeneous urban population in Poland. (3) The TT Taq-I genotype presented a significantly higher rate of insulin resistance (HOMA) and lower serum levels of adiponectin than the other two genotypes. The AA genotype of the Bsm-I polymorphism was associated with a more atherogenic serum profile and significantly higher LDL and LDL/HDL values and Castelli Index. (4) Chronic low-grade inflammation was associated with the TT Taq-I genotype and presented a higher rate of insulin resistance. The AA genotype of the Bsm-I polymorphism presented a more atherogenic serum lipid profile and, therefore, a higher risk of developing cardiovascular disease.

Fok I and Bsm I gene polymorphism of vitamin D receptor and essential hypertension: a mechanistic link

The vitamin D receptor (VDR) gene serves as a good candidate gene for susceptibility to essential hypertension. The gene regulates the renin angiotensin system by influencing blood pressure regulation. Around 3% of the human genome is regulated by the vitamin D endocrine system. Several studies have reported mixed results with respect to relationship of VDR gene and hypertension. Observational evidence supports the concept that vitamin D plays a role in the pathogenesis of cardiovascular disease and arterial hypertension which is further supported by meta-analysis and case control studies reporting how VDR polymorphism leads to the onset and development of hypertension. In this review, we summarize the existing literature on the link between VDR and hypertension, including mechanistic studies, observational data, and clinical trials showing relationship of vitamin D level and hypertension with a focus on recent findings related to genetic studies that showed the relationship of VDR gene polymorphism with vitamin D level in hypertensive and normotensive groups. As a result, determining the association of VDR polymorphisms with essential hypertension is expected to aid in the risk assessment for the condition.

Association of CYP2R1 and VDR Polymorphisms with Metabolic Syndrome Components in Non-Diabetic Brazilian Adolescents

Associations between vitamin D deficiency and metabolic syndrome (MS) have been reported; however, the underlying biological mechanisms remain controversial. The aim of this study was to investigate the associations of CYP2R1 and VDR variants with MS and MS components in non-diabetic Brazilian adolescents. This cross-sectional study included 174 adolescents who were classified as overweight/obese. Three CYP2R1 variants and four VDR variants were identified by allelic discrimination. The CYP2R1 polymorphisms, rs12794714 (GG genotype) (odds ratio [OR] = 3.54, 95% confidence interval [CI] = 1.24–10.14, p = 0.023) and rs10741657 (recessive model—GG genotype) (OR = 3.90, 95%CI = 1.18–12.92, p = 0.026) were significantly associated with an increased risk of MS and hyperglycemia, respectively. The AG + GG genotype (dominant model) of the rs2060793 CYP2R1 polymorphism was associated with hyperglycemia protection (OR = 0.28, 95%CI = 0.08–0.92, p = 0.037). Furthermore, the CC genotype (recessive model) of the rs7975232 VDR polymorphism was significantly associated with a risk of hypertension (OR = 5.91, 95%CI = 1.91–18.32, p = 0.002). In conclusion, the CYP2R1 rs12794714 polymorphism could be considered a possible new molecular marker for predicting the risk of MS; CYP2R1 rs10741657 polymorphism and VDR rs7975232 polymorphism are associated with an increased risk of diabetes and hypertension in adolescents with overweight/obesity.

Current Evidence and Future Perspectives of the Best Supplements for Cardioprotection: Have We Reached the Final Chapter for Vitamins?

Cardiovascular disease (CVD), a broad-spectrum term comprising coronary artery disease, stroke, hypertension, and heart failure, presents as one of the most significant strains on global healthcare systems. Coronary artery disease, caused by atherosclerosis, has various modifiable risk factors such as dietary changes and exercise. Since these risk factors are found to be linked to oxidative stress and inflammations, the dietary supplementation with vitamins' role in treating and preventing the diseases has been of much debate. With various vitamins having anti-inflammatory and antioxidative properties, studies have explored their correlation with cardiovascular health. Therefore, this narrative review explores and evaluates the benefits and risks of all vitamin supplementations in patients with CVD and provides future recommendations.

Evidence of a casual relationship between vitamin D deficiency and hypertension: a family-based study

An association between vitamin D deficiency and hypertension has been observed in numerous studies. However, blood pressure improvements resulting from supplementation with vitamin D have been inconsistent. The causal relationship between vitamin D deficiency and hypertension is still unclear and was investigated in this family-based study. A total of 1370 individuals from both vitamin D deficiency and hypertension families were included. First, the heritability of vitamin D deficiency was estimated by the Falconer method. Second, SNPs (single nucleotide polymorphisms) of vitamin D metabolic and functional pathway genes associated with vitamin D deficiency were screened by a family-based association test, and the findings were further verified in nuclear families with vitamin D deficiency. Finally, a family-based association test was applied to investigate the association between selected SNPs associated with vitamin D deficiency and hypertension. The heritability of vitamin D deficiency was 50.4% in this family-based study. Allele C of rs3847987 was a risk factor for vitamin D deficiency (OR: 1.639, 95% CI: 1.170-2.297, P = 0.004). Furthermore, a family-based association of rs3847987 with hypertension was found in both additive and recessive models (P < 0.05). In addition, vitamin D deficiency was associated with hypertension (OR: 1.317, 95% CI: 1.022-1.698, P = 0.033). In conclusion, rs3847987 in the VDR gene was associated with both vitamin D deficiency and hypertension. Therefore, vitamin D deficiency may be a causal factor for hypertension.

Circulating 25-hydroxyvitamin D levels and hypertension risk after adjusting for publication bias

BACKGROUND

Previous systematic reviews reported that serum vitamin D deficiency was associated with risk of hypertension. The aim was to conduct a meta-epidemiological analysis for evaluating the potential effects of publication bias.

METHODS

The selection criterion was defined as a follow-up study for evaluating the association between circulating 25-hydroxyvitam D level and hypertension risk in adults. A funnel plot and Egger's test were used to detect a publication bias. If a publication bias was identified, trim-and-fill analysis (TFA) with linear estimator was performed to estimate a summary relative risk (sRR).

RESULTS

The meta-analysis of 13 cohorts resulted in the lower the vitamin D, the higher the risk of hypertension statistically significant (sRR, 1.22; 95% confidence interval [CI], 1.05 to 1.41). But The P-value of Egger's test (=0.015) and asymmetry of the funnel plot showed that there was a publication bias. TFA resulted in that statistical significance disappeared in the association between vitamin D level and hypertension risk in total cohorts (filled sRR, 1.03; 95% CI, 0.89 to 1.18) as well as men and women cohorts.

CONCLUSIONS

The publication bias-adjusted results by TFA had no statistically significant association between vitamin D levels and the risk of hypertension. The significant results in previous systematic reviews might be interpreted as due to publication bias.

Dietary Intake and Genetic Background Influence Vitamin Needs during Pregnancy

Numerous approaches demonstrate how nutritional intake can be sufficient to ensure the necessary supply of vitamins. However, it is evident that not all vitamins are contained in all foods, so it is necessary either to combine different food groups or to use a vitamin supplement to be well-fed. During pregnancy, deficiencies are often exacerbated due to increased energy and nutritional demands, causing adverse outcomes in mother and child. Micronutrient supplementation could lead to optimal pregnancy outcomes being essential for proper metabolic activities that are involved in tissue growth and functioning in the developing fetus. In order to establish adequate vitamin supplementation, various conditions should be considered, such as metabolism, nutrition and genetic elements. This review accurately evaluated vitamin requirements and possible toxic effects during pregnancy. Much attention was given to investigate the mechanisms of cell response and risk assessment of practical applications to improve quality of life. Importantly, genetic studies suggest that common allelic variants and polymorphisms may play an important role in vitamin metabolism during pregnancy. Changes in gene expression of different proteins involved in micronutrients’ metabolism may influence the physiological needs of the pregnant woman.

Vitamin D receptor gene polymorphism in Madura pregnant women with hypertension: a case control study

Background

Genetic factors are important considerations in the etiology of preeclampsia and gestational hypertension. Several previous studies have shown an association of Vitamin D receptor (VDR) gene polymorphisms with hypertension in pregnancy. However, the number of studies is still very limited and the results differ from one another.

Aim of the study

This study aimed to analyze the polymorphisms of rs2228570 and rs731236 of the VDR gene in subjects with hypertension and non-hypertension in pregnancy in Madura ethnicity.

Subjects and methods

The researchers conducted tests for two polymorphisms in the VDR gene among 210 subjects consisting of 105 pregnant women with hypertension and 105 non-hypertension pregnant women from Madura ethnicity. The rs2228570 (T>C) and rs731236 (C>T) polymorphisms were detected by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism. All data were analyzed by T-tests and Chi-Square tests.

Results

The TT genotype frequency of rs2228570 (15.2%) in the hypertension group was higher than in the control group (6.7%) (p = 0.047). Subjects with the TT genotype at rs2228570 showed a 3.048 times greater risk of developing hypertension than the CC genotype (OR = 3.048: 1.135–8.183, p = 0.023). The T allele frequency of rs2228570 (40.5%) in the hypertension group was higher than in the control group (30.5%) (p = 0.032). Subjects with the T allele had 1.551 times greater risk of developing hypertension. There was no significant difference in genotype and allele of rs731236 between hypertension subjects and controls.

Conclusion

The TT genotype and T allele of rs2228570 in the hypertension group were risk factors for hypertension in this study. While the TT genotype and T allele at rs731236 were not risk factors for hypertension in pregnancy. Genotyping of VDR gene polymorphisms in pregnant women is expected to be useful in strategies for treating hypertension in pregnancy.

Serum Vitamin D Levels in Relation to Hypertension and Pre-hypertension in Adults: A Systematic Review and Dose–Response Meta-Analysis of Epidemiologic Studies

Background

Findings of observational studies that evaluated the association of serum vitamin D status and high blood pressure were contradictory. This meta-analysis of epidemiologic studies assessed the relation of serum vitamin D levels to hypertension (HTN) and pre-hypertension in adults.

Methods

We conducted a systematic search of all published articles up to March 2021, in four electronic databases (MEDLINE (PubMed), Web of Science (ISI), Embase and Scopus), and Google scholar. Seventy epidemiologic studies (10 prospective cohort, one nested case–control, and 59 cross-sectional investigations) that reported relative risks (RRs), odds ratios (ORs), hazard ratios, or prevalence ratios with 95% CIs for HTN or pre-hypertension in relation to serum vitamin D concentrations in adults were included in the analysis.

Results

In prospective studies, a 16% decrease in risk of hypertension was observed in participants with high levels of serum vitamin D compared to low levels (RR: 0.84; 95%CI: 0.73, 0.96; 12 effect sizes). Dose–response analysis in prospective studies revealed that each 25 nmol/L increase in serum vitamin D concentrations resulted in 5% reduced risk of HTN (RR: 0.95; 95% CI: 0.90, 1.00). Also, a significant nonlinear relationship between serum vitamin D levels and HTN was found (P_nonlinearity < 0.001). In cross-sectional investigations, highest vs. lowest level of serum vitamin D was related to reduced odds of HTN (OR: 0.84; 95%CI: 0.79, 0.90; 66 effect sizes) and pre-hypertension (OR: 0.75; 0.95%CI: 0.68, 0.83; 9 effect sizes). Dose–response analysis in these studies showed that each 25 nmol/L increase in serum vitamin D levels was related to a significant 6% reduction in odds of hypertension in all populations (RR: 0.94; 95%CI: 0.90, 0.99) and 3% in studies with representative populations (RR: 0.97; 95%CI: 0.95, 0.99).

Conclusion

This meta-analysis of epidemiologic studies disclosed that serum vitamin D concentrations were inversely related to the risk of HTN in adults, in a dose–response manner in both prospective cohort and cross-sectional studies.

Systematic Review Registration:http://www.crd.york.ac.uk/Prospero, identifier: CRD42021251513.

The Significance of VDR Genetic Polymorphisms in the Etiology of Preeclampsia in Pregnant Polish Women

For the first time in the Polish population, we aimed to investigate associations between the VDR gene single-nucleotide polymorphisms (SNPs) BsmI (rs15444410), ApaI (rs7975232), FokI (rs19735810), and TaqI (rs731236) and the development of preeclampsia (PE). A case-control study surveyed 122 preeclamptic and 184 normotensive pregnant women. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed to examine the maternal VDR FokI, BsmI, TaqI, and ApaI polymorphisms. The VDR BsmIAA homozygous genotype was statistically significantly more frequent in preeclamptic women compared to the control group (p = 0.0263), which was also associated with a 2-fold increased risk of PE (OR = 2.06, p = 0.012). A correlation between the VDR BsmI polymorphism with systolic and diastolic blood hypertension was noted. Furthermore, 3-marker haplotype CTA (TaqI/ApaI/BsmI) was associated with significantly higher systolic (p = 0.0075) and diastolic (p = 0.0072) blood pressure. Association and haplotype analysis indicated that the VDR BsmI A allele could play a significant role in the PE pathomechanism and hence could be a risk factor for PE development in pregnant Polish women. These results indicate the importance of the VDR BsmI polymorphism and reveal that this variant is closely associated with a higher predisposition to hypertension.

Vitamin D: Not Just Bone Metabolism but a Key Player in Cardiovascular Diseases

Vitamin D is the first item of drug expenditure for the treatment of osteoporosis. Its deficiency is a condition that affects not only older individuals but also young people. Recently, the scientific community has focused its attention on the possible role of vitamin D in the development of several chronic diseases such as cardiovascular and metabolic diseases. This review aims to highlight the possible role of vitamin D in cardiovascular and metabolic diseases. In particular, here we examine (1) the role of vitamin D in diabetes mellitus, metabolic syndrome, and obesity, and its influence on insulin secretion; (2) its role in atherosclerosis, in which chronic vitamin D deficiency, lower than 20 ng/mL (50 nmol/L), has emerged among the new risk factors; (3) the role of vitamin D in essential hypertension, in which low plasma levels of vitamin D have been associated with both an increase in the prevalence of hypertension and diastolic hypertension; (4) the role of vitamin D in peripheral arteriopathies and aneurysmal pathology, reporting that patients with peripheral artery diseases had lower vitamin D values than non-suffering PAD controls; (5) the genetic and epigenetic role of vitamin D, highlighting its transcriptional regulation capacity; and (6) the role of vitamin D in cardiac remodeling and disease. Despite the many observational studies and meta-analyses supporting the critical role of vitamin D in cardiovascular physiopathology, clinical trials designed to evaluate the specific role of vitamin D in cardiovascular disease are scarce. The characterization of the importance of vitamin D as a marker of pathology should represent a future research challenge.

Examining chronic inflammatory markers on blood pressure measures in the presence of vitamin D insufficiency among indigenous cree adults: results from the cross-sectional Multi-Community Environment-and-Health Study in Eeyou Istchee, Quebec, Canada

OBJECTIVE

High blood pressure (BP) is a risk factor for cardiovascular disease. Examining the role of inflammatory mediators on BP is important since vitamin D (VD) is a modifiable risk factor, which possibly modulates inflammatory cytokines. This study simulated what are known as average 'controlled direct effects (CDE)' of inflammatory markers, C reactive protein (CRP), tumour necrosis factor-α (TNF-α), and interlukin-6 (IL-6) on continuous BP measures, while fixing VD, an intermediate variable to specific level.

DESIGN

Cross-sectional study.

SETTING

We analysed data from the Multi-Community Environment-and-Health Study, 2005-2009, conducted in Eeyou Istchee, Quebec, Canada.

PARTICIPANTS

This study recruited 1425 study Indigenous Cree participants from seven Cree communities. Only adults with serum VD levels, inflammatory markers and BP measures were included in this data analysis.

PRIMARY AND SECONDARY OUTCOMES MEASURES

Inflammatory markers examined the top 25th exposure percentiles. VD 'insufficiency' (ie, 25-hydroxyvitamin-D levels<50 nmol/L) defined by the Institute of Medicine. CDE for each inflammatory marker in the presence and absence of population VD insufficiency simulated the average direct effect change for systolic and diastolic BP (SBP and DBP) measures. All models were adjusted for exposure-and-mediator outcome relationship.

RESULTS

Among 161 participants, 97 (60 %) were female. The prevalence of VD insufficiency was 32%. CDE estimates show in the presence and absence of population vitamin D insufficiency, inflammatory markers have a slightly different association on BP. TNF-α significantly and inversely associated with SBP in the presence of vitamin D insufficiency, fully adjusted model β = -13.61 (95% CI -24.42 to -2.80); however, TNF-α was not associated with SBP in the absence of vitamin D insufficiency. CRP, IL-6 were also not significantly associated with BP measures, although the magnitude of association was greater for those with elevated inflammation and VD insufficiency.

CONCLUSION

This novel analysis shows in the presence of VD insufficiency, inflammation (particularly TNF-α) may affect SBP. Additional research is needed to elucidate these findings, and the temporal relationship between these variables.

Association of AGTR1 (rs5186), VDR (rs2228570) genes polymorphism with blood pressure elevation in patients with essential arterial hypertension

Essential arterial hypertension (EAH) is a polygenic disease due to environmental, genetic, and epigenomic factors. The study aimed to establish the association of single nucleotide polymorphism (SNP) of AGTR1 (rs5186) and VDR (rs2228570) genes with the blood pressure (BP) elevation in EAH patients. 100 EAH subjects with hypertensive-mediated organ damaging (2^nd stage), moderate, high, or very high cardiovascular risk were recruited into the case-control study. There were 70.83% females and 29.17% males, mean age 57.86±7.81 y.o. The control group included 60 healthy individuals of relevant age and gender distribution. Estimation of AGTR1 (rs5186) and VDR (rs2228570) gene polymorphism was performed by Real-Time Polymerase Chain Reaction. In EAH patients, the AGTR1 gene (rs5186) mutation occurs with a frequency of 2.78% in the absence of such among healthy individuals. The VDR (rs2228570) gene mutation occurs with a frequency of 23% cases. The C-allele carriers’ (AGTR1 gene) numbers with 2^nd and 3^rd BP values degree dominate over AA-genotype patients by 25.32% (_χ2=4.52; p=0.033). VDR gene (rs2228570) polymorphic variants do not link to BP elevation values. Thus, the C-allele of the AGTR1 gene (rs5186) is associated with BP elevation in hypertensive patients. BP values do not depend on VDR gene (rs2228570) polymorphic variants.

Role of Vitamin-D Receptor (VDR) single nucleotide polymorphisms in gestational hypertension development: A case-control study

Background

Recent literature data have highlighted the important role of hypovitaminosis D in pregnancy complications and prenatal/perinatal health. Vitamin D action takes place through vitamin D receptor (VDR) activation. Two single nucleotide polymorphisms of VDR gene, FokI and BsmI, have been reported to affect VDR molecular signaling and be associated with several disorders, including hypertension.

Methods

We carried out a case-control study aimed to assess vitamin D serum levels together with the distribution of VDR FokI and BsmI in a population of 116 pregnant women with gestational hypertension (GH) and 69 normotensive pregnant women (CTR).

Results

Hypovitaminosis D was largely prevalent both in GH (81%) and CTR (69%) pregnant women. Vitamin D insufficiency (10–30 ng/ml) had a similar frequency in both cohorts (GH 60% vs CTR 58%), while vitamin D deficiency (<10 ng/ml) was more frequent in GH cohort than in CTR one (21% vs 11%). Regression analysis showed that GH was significantly (p = 0.031) linked to vitamin D status. Vitamin D deficiency was associated with a threefold-increased risk of developing GH, while a normal vitamin D status was protective against this pregnancy disorder. The VDR FF/bB haplotype was the most frequent in GH cohort, and resulted to increase by two folds the risk for GH. Notably, hypovitaminosis D was found in 92% of FF/bB GH pregnant women, 27% of which had deficient vitamin D levels compared with 11% of their normotensive counterparts.

Conclusions

Despite being preliminary, these findings suggest that genotyping of pregnant women for VDR polymorphisms may be useful for a tailored vitamin D supplementation strategy.

Vitamin D Receptor Gene Polymorphisms and the Risk of Metabolic Syndrome (MetS): A Meta-Analysis

BACKGROUND

Several studies have assessed the association between the vitamin D receptor (VDR) polymorphism and the risk of metabolic syndrome (MetS). However, the results were inconsistent and inconclusive. Therefore, we conducted a meta-analysis to clarify the exact association between the vitamin D receptor (VDR) polymorphisms and the risk of MetS.

METHODS

All accessible studies reporting the association between the FokI (rs2228570) or/and TaqI (rs731236) or/and BsmI (rs1544410) or/and ApaI (rs7975232 polymorphisms of the Vitamin D Receptor and susceptibility to MetS published prior to February 2019 were systematically searched in Web of Science, Scopus, and PubMed. After that, Odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated to evaluate the strength of the association in five genetic models.

RESULTS

A total of 9 articles based on four gene variations, and comprising 3348 participants with 1779 metabolic syndrome patients were included. The overall results suggested a significant association between BsmI (rs1544410) polymorphism and MetS susceptibility in recessive model (OR, 0.72, 95% CI, 0.55-0.95, fixed effect model), allelic model (OR, 0.83, 95% CI, 0.72-0.95, fixed effect model), and bb vs BB (OR, 0.65, 95% CI, 0.46-0.93, fixed effect). However, no significant association was identified between TaqI (rs731236) polymorphism, ApaI (rs7975232) polymorphism, and FokI (rs2228570) polymorphism and MetS.

CONCLUSION

This meta-analysis suggested an association between the BsmI (rs1544410) polymorphism and MetS. Indeed, BsmI (rs1544410) acts as a protective factor in the MetS. As a result, the VDR gene could be regarded as a promising pharmacological and physiological target in the prevention or treatment of the MetS.

Meta-Analysis of the Association Between the rs228570 Vitamin D Receptor Gene Polymorphism and Arterial Hypertension Risk

The association between FokI polymorphism in the vitamin D receptor (VDR) gene and susceptibility to arterial hypertension (HT) is controversial. Thus, we evaluated the relation between FokI and HT according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using MEDLINE® (Medical Literature Analysis and Retrieval System Online)/PubMed, Scopus, and Cochrane Library CENTRAL databases. Data from case-control studies, including the number of participants, age, 25-hydroxyvitamin D concentrations, systolic and diastolic blood pressure values, FokI allele, and genotype frequency were extracted by 2 independent authors and OR was calculated with the 95% CI to assess the strength of the association between the FokI variant and odds of HT. In general and subgroup analyses, we used allelic (f compared with F), common (ff compared with FF + Ff), risk (ff + Ff compared with FF), and additive (ff compared with FF) models. Six case-control studies including 3140 cases and 3882 controls were reviewed in the meta-analysis. Global assessment revealed a correlation between FokI and reduced odds of HT in the additive/homozygote model (ff compared with FF; OR: 0.65; 95% CI: 0.45-0.94) and common/recessive model (ff compared with FF + Ff; OR: 0.75; 95% CI: 0.57-0.99). In Asian subjects, there was a significant reduction in the odds of HT in additive (ff compared with FF; OR: 0.84; 95% CI: 0.73-0.98) and risk models (ff + Ff compared with FF; OR: 0.87, 95% CI: 0.78-0.97), in particular, for Indians (South). In Africans, the statistically significant association occurred in the additive and common models. Allele f in the FokI polymorphism of the VDR gene was associated with reduced odds of HT in the general population based on the risk model. Thus, nutritional genomics can help understand the influence of nutrition on metabolic homeostasis pathways and the clinical consequences of hypertension. This study shows the need for healthy, anti-inflammatory, and antioxidant compounds to prevent or treat chronic complications.

Serum 25-hydroxyvitamin D and hypertension in premenopausal and postmenopausal women: National Health and Nutrition Examination Surveys 2007-2010

OBJECTIVE

A recent meta-analysis suggested that the association between vitamin D and risk of hypertension was markedly stronger in women aged <55 years in observational data, while the association became null in women aged ≥55 years. We therefore hypothesized that this difference in associations might potentially be caused by the change in oestrogen around menopause. Our objective was to investigate associations between vitamin D status and hypertension risk and to evaluate those associations as they may differ according to menopausal status.

DESIGN

A cross-sectional population survey conducted by the US Centers for Disease Control and Prevention, National Center for Health Statistics.

SETTING

The National Health and Nutrition Examination Surveys (NHANES) 2007-2010 formed the setting for the present study.

PARTICIPANTS

We analysed data from 2098 premenopausal women and 2298 postmenopausal women.

RESULTS

After adjustment for sociodemographic, behavioural and dietary factors, higher concentrations both of serum total 25-hydroxyvitamin D (25(OH)D) and serum 25-hydroxycholecalciferol (25(OH)D3) revealed significant dose-dependent trends with lower risk of hypertension (Ptrend = 0·005 and 0·014, respectively) in premenopausal women. In those women, 25(OH)D ≥ 50 nmol/l (sufficient; in contrast to deficient, vitamin D < 30 nmol/l) appeared to have a protective effect against hypertension (OR = 0·64, 95 % CI 0·39, 1·02 for total 25(OH)D and OR = 0·60, 95 % CI 0·36, 1·00 for 25(OH)D3). Neither association with hypertension was observed in postmenopausal women.

CONCLUSIONS

Serum 25(OH)D concentrations were associated with lower risk of hypertension in premenopausal women, but not in postmenopausal women.

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.

Low serum 25-hydroxyvitamin D levels may increase the detrimental effect of VDR variants on the risk of essential hypertension

BACKGROUND/OBJECTIVES

The present cross-sectional study evaluated the association of vitamin D receptor (VDR) variants with serum 25(OH)D₃ levels and their interaction on essential hypertension (EH) risk.

SUBJECTS/METHODS

1539 patients were eligible in the study population. Two loci in VDR gene (rs2239179, rs2189480) were genotyped by TaqMan probe assays. Logistic regression, Kruskal-Wallis rank test and Chi-square test were used to determine the association among VDR polymorphisms, serum vitamin D metabolites, and the risk of EH. Interaction plots were performed to explain the interaction effects of circulating 25(OH)D₃ levels and VDR variants on EH susceptibility.

RESULTS

After potential confounding adjustment, we observed that the mutations of VDR (rs2239179/rs2189480) were associated with the increased risk of EH (P < 0.05). Moreover, plasma 25(OH)D₃ levels were inversely associated with EH, However, we did not find the association between serum 25(OH)D₃ and VDR variants. When comparing with wild-type homozygous and heterozygous genotype carriers with vitamin D sufficiency, hypovitaminosis D and insufficient participants carrying homozygous variant genotype of rs2239179 showed a higher risk of EH, increased by 113% (OR = 2.13, 95% CI: 1.20, 3.80); Notably, the detrimental effect of rs2239179 homozygous variant on EH became stronger in the case of serum 25(OH)D₃ <30 ng/ml. However, we did not find the interaction effect between rs2189480 variants and serum 25(OH)D₃ levels on the risk of EH.

CONCLUSIONS

Our results suggested that the mutations of VDR may accelerate the progression of EH etiology, especially when suffering hypovitaminnosis D and insufficiency.

Vitamin D as A Protector of Arterial Health: Potential Role in Peripheral Arterial Disease Formation

Atherosclerotic occlusive diseases and aneurysms that affect large and medium-sized arteries outside the cardiac and cerebral circulation are collectively known as peripheral arterial disease (PAD). With a rise in the rate of aging population worldwide, the number of people diagnosed with PAD is rapidly increasing. The micronutrient vitamin D is an important steroid hormone that acts on many crucial cellular mechanisms. Experimental studies suggest that optimal levels of vitamin D have beneficial effects on the heart and blood vessels; however, high vitamin D concentrations have been implicated in promoting vascular calcification and arterial stiffness. Observations from various clinical studies shows that deficiency of vitamin D has been associated with a greater risk of PAD. Epidemiological studies have often reported an inverse relation between circulating vitamin D status measured in terms of 25-hydroxivitamin D [25(OH)D] levels and increased cardiovascular disease risk; however, randomized controlled trials did not show a consistent positive effect of vitamin D supplementation on cardiovascular disease risk or events. Even though PAD shares all the major risk factors with cardiovascular diseases, the effect of vitamin D deficiency in PAD is not clear. Current evidence suggests a strong role of vitamin D in promoting genomic and epigenomic changes. This review summarises the current literature that supports the notion that vitamin D deficiency may promote PAD formation. A better understanding of underlying pathological mechanisms will open up new therapeutic possibilities which is the main unmet need in PAD management. Furthermore, epigenetic evidence shows that a more holistic approach towards PAD prevention that incorporates a healthy lifestyle, adequate exercise and optimal nutrition may be more effective in protecting the genome and maintaining a healthy vasculature.

The possible role of maternal and placental vitamin D receptor polymorphisms and haplotypes in pathogenesis of preeclampsia

Purpose: Vitamin D deficiency may be a main causative agent in the pathogenesis of preeclampsia (PE). The actions of the active form of vitamin D are mediated via the vitamin D receptor (VDR), which is expressed in numerous organs including placenta. Therefore, we evaluated the potential relationship between maternal and placental VDR polymorphisms and the predisposition to PE in an Iranian population.Methods: This case-control study surveyed 152 PE and 160 normotensive pregnant women. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed to examine the maternal and placental VDR Fok1 rs2228570, Bsm1 rs1544410, Taq1 rs731236, and Apa1 rs7975232 polymorphisms.Results: The maternal but not placental VDR FokI Ff genotype, was significantly lower in PE women (P = .02 and P = .06, respectively). The maternal and placental VDR FokI polymorphism was associated with lower PE risk in the dominant model (Ff+ff vs. FF) and these genotypes could decrease PE risk (OR, 0.5 [95% CI, 0.3-0.8], P = .007 and OR, 0.5 [95% CI, 0.3-0.9], P = .02, respectively). The haplotype analysis revealed that the maternal and placental TABf haplotype may lead to decreased risk of PE. In addition, the placental TABF haplotype was associated with higher risk of PE. No relationship was observed between PE susceptibility and the maternal and placental VDR Bsm1, Taq1 and Apa1 polymorphisms. There was also no relationship between the maternal and placental VDR polymorphisms and PE severity.Conclusions: the maternal and placental VDR FokI variant was associated with decreased risk of PE in the dominant model.

Obesity and hypovitaminosis D: causality or casualty?

Epidemiological studies reported that vitamin D deficiency represents an increasingly widespread phenomenon in various populations. Vitamin D deficiency is considered a clinical syndrome determined by low circulating levels of 25-hydroxyvitamin D (25(OH)D), which is the biologically-inactive intermediate and represents the predominant circulating form. Different mechanisms have been hypothesized to explain the association between hypovitaminosis D and obesity, including lower dietary intake of vitamin D, lesser skin exposure to sunlight, due to less outdoor physical activity, decreased intestinal absorption, impaired hydroxylation in adipose tissue and 25(OH)D accumulation in fat. However, several studies speculated that vitamin D deficiency itself could cause obesity or prevent weight loss. The fat-solubility of vitamin D leads to the hypothesis that a sequestration process occurs in body fat depots, resulting in a lower bioavailability in the obese state. After investigating the clinical aspects of vitamin D deficiency and the proposed mechanisms for low 25(OH)D in obesity, in this manuscript we discuss the possible role of vitamin D replacement treatment, with different formulations, to restore normal levels in individuals affected by obesity, and evaluate potential positive effects on obesity itself and its metabolic consequences. Food-based prevention strategies for enhancement of vitamin D status and, therefore, lowering skeletal and extra-skeletal diseases risk have been widely proposed in the past decades; however pharmacological supplementation, namely cholecalciferol and calcifediol, is required in the treatment of vitamin D insufficiency and its comorbidities. In individuals affected by obesity, high doses of vitamin D are required to normalize serum vitamin D levels, but the different liposolubility of different supplements should be taken into account. Although the results are inconsistent, some studies reported that vitamin D supplementation may have some beneficial effects in people with obesity.

Platelet Surface CD62p and Serum Vitamin D Levels are Associated with Clopidogrel Resistance in Chinese Patients with Ischemic Stroke

BACKGROUND

To explore the association of platelet activation markers, vitamin D, and antiplatelet drugs resistance in ischemic stroke patients.

METHODS

A total of 230 patients with ischemic stroke were enrolled in this study. Platelet aggregation, platelet activation marker (CD62p), and vitamin D were measured after 7-14 days of dual antiplatelet treatment (aspirin + clopidogrel). All individuals were divided into a drug resistance group and a drug sensitive group according to the platelet maximum aggregation rate induced by antagonist adenosine diphosphate or arachidonic acid.

RESULTS

In this study, the prevalence of aspirin resistance was low (1.2%), while the prevalence of clopidogrel resistance (CR) was 24.8%, so we focused on CR. The percentage of CD62p on activated platelet [(25.74 ± 4.61) versus (12.41 ± 3.93), P < .001] and the prevalence of hypertension [93.0% (53) versus 79.8% (138), P = .021] in CR group were significantly higher than those in clopidogrel sensitive (CS) group, while the vitamin D concentration [(8.96 ± 4.41) versus (13.9 ± 4.84) ng/mL, P = .003] in CR group was significantly lower compared with the CS group. No significant difference was found in soluble P-selectin between these 2 groups [(56.2 ± 16.13) versus (54.2 ± 14.87) ng/mL, P = .258], neither in calcium [(2.29 ± .12) versus (2.33 ± .13) mmol/L, P = .821]. Logistic regression analysis showed that hypertension (odds ratio [OR] = 5.348, 95% confidence intervals [CI] 1.184-23.350, P = .026), expression of platelet CD62p (OR = 1.095, 95% CI 1.052-1.201, P = .018) and vitamin D level (OR = .832, 95% CI .763-.934, P = .005) were associated with CR in ischemic stroke patients.

CONCLUSIONS

CR in ischemic stroke patients is associated with several independent predictors, including increased platelet activation marker CD62p, decreased vitamin D level, and hypertension.

New Insights on Low Vitamin D Plasma Concentration as a Potential Cardiovascular Risk Factor

The role of Vitamin D hormone in human health and disease is still debated. Recently, growing attention has been paid to its putative role in cardiovascular system homeostasis with several studies that suggested a correlation between low vitamin D levels and increased cardiovascular risk. Several mechanisms are involved in the development of cardiovascular diseases: systemic inflammation, endothelial dysfunction, arterial hypertension and insulin resistance. In the present paper, we have revised the current literature supporting a role for vitamin D in the development of these pathogenetic processes. Finally, we have evaluated the current evidence linking vitamin D to atherosclerosis and its natural consequence, cardiovascular diseases.

The Association of Vitamin A and Vitamin D with Hypertension in Children: A Case-Control Study

BACKGROUND

The prevalence of hypertension in children increases rapidly. This paper is to investigate the association of vitamin A and serum 25(OH)D level with hypertension and to explore the risk factors of hypertension in children.

METHODS

164 children (age: 6-12 years, females: 49.39%) were included in this case-control study. The serum vitamin A and serum 25(OH)D level, the transcription level of RARs and RXRs, 25(OH)D receptor, and the retinol acyltransferase (LRAT), an indicator of vitamin A storage function, were measured.

RESULTS

The serum vitamin A level in hypertensive subjects was not significantly different compared to control, but the serum 25(OH)D level was significantly lower in hypertensive subjects compared to control (38.22±12.00umol/L vs. 43.28±12.33 umol/L, P=0.02). The transcription levels of RARα, RARβ, and RARγ were not significantly different between the two groups; but the LRAT was lower in the hypertensive group than that in the control (P<0.001). Compared with control group, the level of 25(OH)D receptor was lower in hypertension children (P=0.003). Logistic regression model showed that LRAT, HDL, and breastfed duration were negatively associated with blood pressure, and waist circumference was positively associated with blood pressure.

CONCLUSIONS

The LRAT, serum 25(OH)D, and 25(OH)D receptor were significantly associated with blood pressure level, and both breastfed and HDL-C were independent protective factors of blood pressure level in children.

A comprehensive overview on osteoporosis and its risk factors

Osteoporosis is a bone disorder with remarkable changes in bone biologic material and consequent bone structural distraction, affecting millions of people around the world from different ethnic groups. Bone fragility is the worse outcome of the disease, which needs long term therapy and medical management, especially in the elderly. Many involved genes including environmental factors have been introduced as the disease risk factors so far, of which genes should be considered as effective early diagnosis biomarkers, especially for the individuals from high-risk families. In this review, a number of important criteria involved in osteoporosis are addressed and discussed.

Vitamin D Deficiency, Supplementation, and Cardiovascular Health

Vitamin D has been traditionally recognized as a vitamin quintessential for bone-mineral health. In the past 2 decades, numerous experimental and observational studies have highlighted the role of vitamin D in immunity, metabolic syndrome (obesity and diabetes), cancers, renal disease, memory, and neurological dysfunction. In this article, we review important studies that focused on the impact of vitamin D on blood pressure, myocardial infarction, peripheral arterial disease, heart failure, and statin intolerance. Amidst the current pool of ambiguous evidence, we intend to discuss the role of vitamin D in "high-value cardiovascular health care".

Association of Vitamin D deficiency with peripheral arterial disease: a meta-analysis of literature studies

CONTEXT

Vitamin D deficiency patients have an increased cardiovascular (CV) morbidity and mortality. Contrasting data are available about the association between peripheral arterial disease (PAD) and Vitamin D status.

OBJECTIVE

To perform a meta-analysis of studies evaluating the association between Vitamin D status and PAD.

DATA SOURCES

Studies were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases.

RESULTS

Ten studies with data on Vitamin D levels in 2,079 PAD patients and 18,233 non-PAD controls and 6 studies on the prevalence of PAD in 23,171 subjects with Vitamin D deficiency (<20 ng/ml), 48,311 subjects with Vitamin D insufficiency (20-30 ng/ml) and 27,910 with normal Vitamin D levels (>30 ng/ml) were included. Compared to controls, PAD patients showed significantly lower Vitamin D levels (MD: -2.24 ng/ml; 95%CI: -3.38, -1.10; p<0.001, I2=86.5%; p<0.001). Moreover, a higher prevalence of PAD was found both in subjects with Vitamin D insufficiency (OR: 1.098, 95%CI: 1.010-1.195, p=0.029, I2: 0%, p=0,600) and in subjects with Vitamin D deficiency (OR: 1.484, 95%CI: 1.348-1.635, p<0.001, I2: 7.65%, p=0,367) compared with controls with normal Vitamin D levels. Sensitivity analyses and the analysis of data on the cumulative risk of PAD according to Vitamin D levels derived from multivariate analysis consistently confirmed results.

CONCLUSIONS

PAD patients have lower vitamin D levels than controls and both Vitamin D deficiency and Vitamin D insufficiency are significantly associated with PAD. Reduced Vitamin D levels might represent an independent risk factor for PAD and, in turn, for CV events.

Association of Vitamin D receptor gene polymorphisms with metabolic syndrome and its components among adult Arabs from the United Arab Emirates

AIMS

The aim was to investigate relationships of Vitamin D receptor gene (VDR) polymorphisms to the components of MetS among Arabs adult residing in the United Arab Emirates.

METHODS

A cross-sectional study of 198 Arabs adult (50 males and 148 females). Serum levels of glucose, vitamin D, HDL-C, and TG, and blood pressure were measured. FokI, BsmI & TaqI genotyping of VDR were investigated using PCR-RFLP technique.

RESULTS

Age of the participants was 21(9) years with a BMI of 26.8(7.8) kg/m². About 15% had MetS with serum vitamin D levels of 25.5(18.2) nmol/L. VDR genotyping yielded: FokI: 57.1% FF and 38.9% Ff, BsmI: 29.8% bb and 51.5% Bb, while TaqI showed 39.4% TT and 43.4% Tt. The ff carriers had higher total cholesterol [174(12.4) mg/dl] than FF and Ff genotypes. Bb carriers showed higher BMI and LDL-C than BB and bb genotypes. In females, FokI VDR polymorphism showed significant association with systolic blood pressure (SBP) and F allele carriers were at higher risk of developing high SBP [x²=4.4, df1, OR=0.29 (95%CI: 0.087-0.98), p=0.035].

CONCLUSION

VDR gene polymorphisms were not associated with MetS, yet it may affect the severity of some of components of MetS, namely the association of BsmI with obesity, FokI and BsmI with dyslipidemia and FokI with SBP.

Role of Placental VDR Expression and Function in Common Late Pregnancy Disorders

Vitamin D, besides its classical role in bone metabolism, plays a distinct role in multiple pathways of the feto-maternal unit. Calcitriol is the major active ligand of the nuclear vitamin D receptor (VDR). The vitamin D receptor (VDR) is expressed in different uteroplacental parts and exerts a variety of functions in physiologic pregnancy. It regulates decidualisation and implantation, influences hormone secretion and placental immune modulations. This review highlights the role of the vitamin D receptor in physiologic and disturbed pregnancy, as preeclampsia, fetal growth restriction, gestational diabetes and preterm birth. We discuss the existing literature regarding common VDR polymorphisms in these pregnancy disorders.

Impact of Vitamin D deficiency on subclinical carotid atherosclerosis: a pooled analysis of cohort studies

CONTEXT

Vitamin D deficiency patients have an increased cardiovascular (CV) morbidity and mortality. Carotid intima-media thickness (IMT) and carotid plaques are markers of subclinical atherosclerosis and predictors of CV events.

OBJECTIVE

To perform a meta-analysis of studies evaluating the impact of Vitamin D deficiency on common carotid artery IMT (CCA-IMT) and on the prevalence of carotid plaques.

DATA SOURCES

Studies were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases.

RESULTS

Twenty-one studies (3,777 Vitamin D deficiency patients and 4,792 controls) with data on CCA-IMT and 6 studies (1,889 Vitamin D deficiency patients and 2,883 controls) on the prevalence of carotid plaques were included. Compared to controls, Vitamin D deficiency patients showed a significantly higher CCA-IMT (mean difference [MD]: 0.043 mm; 95%CI: 0.030, 0.056; P<0.001), and an increased prevalence of carotid plaques (Odds Ratio [OR]: 2.29, 95%CI: 1.03-5.11; P=0.043) with an attributable risk of 35.9%. When selecting studies specifically including patients with diabetes, the prevalence of carotid plaques in Vitamin D deficiency patients than in controls resulted higher (OR: 3.27; 95%CI: 1,62-6.62; P=0.001). A significant difference in CCA-IMT was confirmed when comparing patients with Vitamin D insufficiency to controls (MD: 0.011; 95%CI: 0.010-0.012, P<0.001). Sensitivity analyses substantially confirmed results and regression models showed that with the exception of LDL-cholesterol, HDL-cholesterol, triglycerides and the prevalence of hypercholesterolemia, all the other clinical and demographic co-variates significantly impacted on the difference in CCA-IMT between Vitamin D deficiency patients and controls.

CONCLUSIONS

Both Vitamin D deficiency and Vitamin D insufficiency are associated with subclinical atherosclerosis, potentially suggesting an increased CV risk in these clinical settings.

Risk of Deficiency in Multiple Concurrent Micronutrients in Children and Adults in the United States

Certain population sub-groups in the United States are vulnerable to micronutrient malnutrition. Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) describing the biochemical status of vitamins A, B6, B12, C, D, E, folate, and anemia, were aggregated to determine the overall risk of multiple concurrent deficiencies in U.S. children and adults (n = 15,030) aged >9 years. The prevalence of deficiency risk according to socio-demographic, life-stage, dietary supplement use, and dietary adequacy categories was investigated. Thirty-one percent of the U.S. population was at risk of at least one vitamin deficiency or anemia, with 23%, 6.3%, and 1.7% of the U.S. population at risk of deficiency in 1, 2, or 3-5 vitamins or anemia, respectively. A significantly higher deficiency risk was seen in women (37%), non-Hispanic blacks (55%), individuals from low income households (40%), or without a high school diploma (42%), and underweight (42%) or obese individuals (39%). A deficiency risk was most common in women 19-50 years (41%), and pregnant or breastfeeding women (47%). Dietary supplement non-users had the highest risk of any deficiency (40%), compared to users of full-spectrum multivitamin-multimineral supplements (14%) and other dietary supplement users (28%). Individuals consuming an adequate diet based on the Estimated Average Requirement had a lower risk of any deficiency (16%) than those with an inadequate diet (57%). Nearly one-third of the U.S. population is at risk of deficiency in at least one vitamin, or has anemia.

Effect of vitamin D on isoprenaline-induced myocardial infarction in rats: possible role of peroxisome proliferator-activated receptor-γ

Infarct-like lesion induced by isoprenaline is a well-known model to study myocardial infarction (MI). Vitamin D has been shown to have anti-inflammatory and antioxidant effects. Recent studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study was designed to investigate the effect of pretreatment with vitamin D on the isoprenaline-induced infarct-like lesion in rats and the role of PPAR-γ as a novel mechanism in vitamin-D-mediated cardioprotective effect. Markers chosen to assess cardiac damage included serum level of creatine kinase (CK), lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Cardiac contents of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH) were also assessed. Furthermore, ECG monitoring and measurement of injury extension were carried out. Isoprenaline increased the level of cardiac enzymes, as well as inflammatory and oxidative stress biomarkers. In addition, it produced ST-segment elevation. Pretreatment with vitamin D significantly improved previous parameters. The prior treatment with bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist, significantly attenuated the protective effect of vitamin D. In conclusion, vitamin D can be demonstrated as a promising cardioprotective agent in MI and PPAR-γ significantly contributes toward vitamin-D-mediated protection.

Vitamin D and hypertension: Prospective study and meta-analysis

OBJECTIVES

The study sought to determine the link between vitamin D concentrations and incident hypertension in prospective study and meta-analysis.

METHODS

The study was embedded in the Kailuan Study, a population-based cohort of adults that contains underground miners. In 2012, we studied 2,456 men and women free of prevalent hypertension, age 21 to 67 at baseline. Serum 25-hydroxyvitamin D was measured from previously frozen baseline samples using ELISA (Enzyme-Linked ImmunoadSorbent Assay). We use the logistic regression analysis to estimate the odd radio (ORs) 95% confidence intervals (CIs) for 25-hydroxyvitamin D [25(OH)D] concentrations with incident hypertension. To help place our new data in context, we conducted a systemic review and meta-analysis of previous prospective reports of vitamin D and hypertension.

RESULTS

During a median follow-up of 2 years, 42.6% of the cohort (n = 1047) developed hypertension. Compared with the 25-hydroxyvitamin D >30ng/ml, 25-hydroxyvitamin D <20 ng/ml was associated with a greater hypertension risk (OR: 1.225 [95% CI: 1.010 to 1.485] p = 0.04), although the association was attenuated and not statistically significant after adjusting for potential confounders (OR: 1.092 [95% CI: 0.866 to 1.377] p = 0.456). This meta-analysis included seven prospective studies for 53,375 participants using adjusted HR founded a significant association between vitamin D deficiencies and incident hypertension (HRs = 1.235 (95% CI: 1.083 to 1.409, p = 0.002)).

CONCLUSION

Lower serum 25-hydroxyvitamin D concentrations were not associated with a greater risk of incident hypertension. More research is needed to further determine the role of 25-hydroxyvitamin D in hypertension prevention and therapy.

The effect of vitamin D supplementation on hypertension in non-CKD populations: A systemic review and meta-analysis

OBJECTIVES

To investigate the vitamin D supplementation on blood pressure control by a systemic review and meta-analysis.

METHODS

Randomized controlled clinical trials were analyzed, which date from eight studies in databases including MEDLINE, EMBASE, Clinical trials, China Integrated Knowledge Resources Database and the Cochrane library.

RESULTS

Total 917 patients from eight randomized controlled trials (RCTs), treatment with vitamin D for more than 3months were analyzed. Meta-analysis showed that vitamin D supplementation slightly reduced the systolic blood pressure (SBP) by 1.964mmHg (95% CI, 0.362-3.566; P=0.016), but not lowered diastolic blood pressure (SMD: -0.087, 95% CI, -0.208-0.033; P=0.155). Subgroup analysis also showed that sBP lowering by vitamin D supplementation was not dose-dependent. Comparison to placebo, there is also no statistical difference in SBP lowering by vitamin D supplementation.

CONCLUSIONS

This meta-analysis indicated that vitamin D is not an antihypertensive agent although it has a moderate SBP lowering effect. More RCTs are required to observe the role of vitamin D plus other antihypertensive drugs in blood pressure control, and define the optimum dose, dosing interval, and type of vitamin D to administer.

SNP rs11185644 of RXRA gene is identified for dose-response variability to vitamin D3 supplementation: a randomized clinical trial

The level of serum 25-Hydroxyvitamin D [25(OH)D] has high heritability, suggesting that genes may contribute to variations in serum 25(OH)D level and vitamin D dose-response. As vitamin D deficiency has been linked to numerous diseases, understanding how genetic variation contributes to vitamin D dose-response is important for personalized vitamin D treatment and cost-effective disease prevention. To identify genetic variants responsible for vitamin D status and dose-response, we performed two vitamin D3 and calcium clinical supplementation trials in 2,207 postmenopausal Caucasian women. We examined the association of 291 SNPs with baseline serum 25(OH)D levels and 25(OH)D dose-response. Five SNPs, rs10500804 (P = 4.93 × 10⁻⁷), rs2060793 (P = 6.63 × 10⁻⁷), rs10741657 (P = 1.49 × 10⁻⁶), rs10766197 (P = 1.05 × 10⁻⁵) and rs11023380 (P = 7.67 × 10⁻⁵) in the CYP2R1 gene, as well as 6 SNPs, rs4588 (P = 7.86 × 10⁻⁷), rs2298850 (P = 1.94 × 10⁻⁶), rs1155563 (P = 6.39 × 10⁻⁶), rs705119 (P = 2.80 × 10⁻⁵), rs705120 (P = 1.08 × 10⁻⁴) and rs222040 (P = 1.59 × 10⁻⁴) in the GC gene were associated with baseline serum 25(OH)D levels. SNP rs11185644 near the RXRA was significantly associated with 25(OH)D dose-response (P = 1.01 × 10⁻⁴). Our data suggest that polymorphisms in the CYP2R1 and GC gene may contribute to variation in baseline serum 25(OH)D concentration, and that polymorphism rs11185644 may contribute to variation in 25(OH)D dose-response in healthy postmenopausal Caucasian women.

Vitamin D Receptor Gene Polymorphisms Are Associated with Abdominal Visceral Adipose Tissue Volume and Serum Adipokine Concentrations but Not with Body Mass Index or Waist Circumference in African Americans: The Jackson Heart Study

BACKGROUND

The biological actions of vitamin D are mediated through the vitamin D receptor (VDR). Single-nucleotide polymorphisms (SNPs) in the VDR gene have been previously associated with adiposity traits. However, to our knowledge, few studies have included direct measures of adiposity and adipokine concentrations.

OBJECTIVE

We examined the association of tagging SNPs in the VDR gene with multiple adiposity measures, including waist circumference (WC), body mass index (BMI), body fat percentage, subcutaneous and visceral adipose tissue (VAT) volume, and serum adipokine (adiponectin and leptin) concentrations in adult African Americans (AAs).

METHODS

Data from 3020 participants (61.9% women; mean age, 54.6 y) from the Jackson Heart Study were used for this analysis. Forty-five tag SNPs were chosen with the use of genotype data from the International HapMap project. We used linear regression to test the associations of imputed VDR SNPs with each of the traits, adjusted for age, sex, educational status, physical activity, smoking, alcohol intake, serum vitamin D concentration, European ancestry, and multiple testing.

RESULTS

The G allele of the SNP rs4328262 remained associated with increased VAT volume after multiple testing correction (β = 45.7; P < 0.001). The A allele of another SNP (rs11574070) was nominally associated with body fat percentage (β = 0.96; P = 0.002). None of the VDR SNPs analyzed showed any link with WC or BMI. The A allele of rs2228570 (β = 0.08; P = 0.001) for men and the T allele of rs2853563 (β = 0.04; P < 0.001) for women remained positively associated with serum adiponectin concentrations after multiple testing correction.

CONCLUSION

Although we did not find any association for anthropometric measures, we did observe associations of VDR variants with serum adipokines and with the more metabolically active fat, VAT. Therefore, our findings demonstrate a possible role of VDR variants in regulating adipose tissue activity and adiposity among AAs.

25-Hydroxyvitamin D insufficiency discriminates cardiovascular risk factors accumulation in peri-pubertal boys undergoing overweight screening

The aim of this study was to evaluate the possible association between cardiometabolic risk factors accumulation and vitamin D status in a cohort of Italian normal weight and overweight male children. 108 boys enrolled in an andrological health prevention project underwent physical examination, anthropometric measurements, and fasting blood sampling. Serum blood glucose, HDL-cholesterol, triglycerides, parathyroid hormone, and 25-hydroxyvitamin D (25(OH)D) were measured. Cardiovascular risk factors were defined according to the National Cholesterol Education Program Adult Treatment Panel III modified for age. Lean and overweight subjects differed in terms of waist circumference (P < 0.001), HDL-cholesterol (P = 0.001), triglycerides (P = 0.001), systolic blood pressure (P < 0.001) and diastolic blood pressure (P = 0.002). Both groups had similar mean 25(OH)D levels (P = 0.160) and were below the sufficiency threshold: indeed only 24 % of normal weight had 25(OH)D ≥30 ng/ml, and even less in the overweight/obese group (8 %, P = 0.03 vs. normal weight). A significant accumulation of risk factors in course of 25(OH)D insufficiency was detected in both the whole cohort and in the normal weight group (P = 0.003 and P = 0.04, respectively) with odd ratios of 1.31 (1.16-1.49 95%CI) and 1.41 (1.18-1.69 95%CI), respectively. In course of vitamin D deficiency, the odd ratios were 2.24 (1.34-3.77 95%CI, P = 0.003) in the whole cohort and 2.40 (1.27-4.82 95%CI, P = 0.03) in lean subjects. We reported a considerable occurrence of cardiovascular risk factors in course of hypovitaminosis D in overweight/obese boys and even in lean subjects, which normally would not have been further evaluated by considering the sole BMI-related parameters. In this regard, 25(OH)D levels appear as a potential discriminating parameter able to identify male children at higher health risk.

Interaction effect of serum 25-hydroxyvitamin D levels and CYP1A1, CYP1B1 polymorphisms on blood pressure in an elderly population

OBJECTIVE

Hypertension and vitamin D deficiency are prevalent worldwide, especially in the elderly. Considering the possibility of gene-environment contributions to disease development, we evaluated the influence of certain cytochrome P450 polymorphisms and vitamin D levels on blood pressure (BP).

METHODS

We measured serum 25-hydroxyvitamin D levels [25(OH)D] and BP in 535 individuals over 60 years old and identified single-nucleotide polymorphisms (SNPs) of CYP1A1 and CYP1B1 in lymphocyte DNA. Repeated measure analyses were used to determine the statistical association.

RESULTS

The relationship between 25(OH)D and SBP or DBP was inversely significant, and influence of several CYP1A1 and CYP1B1 SNPs on BP was found across different genotypes. Estimated effect of 25(OH)D levels on BP in the group with higher risky genotype scores of selected SNPs (rs4646421, rs2551188, and rs1056836) was greater (β = -2.841, P = 0.004 for SBP; β = -2.035, P = 0.001 for DBP) than the group with lower genotype score (β = -0.878, P = 0.347 for SBP; β = 0.037, P = 0.947 for DBP), and synergistic interaction between vitamin D levels and genotype variations was observed (P-interaction = 0.081 for SBP and 0.008 for DBP). When stratified by the hypertension medication status, interaction effect was found only in individuals taking medication (P-interaction = 0.004 for SBP and 0.001 for DBP).

CONCLUSION

Genetic variations in CYP1A1 and CYP1B1 and the serum levels of 25(OH)D showed synergistic effect on BP, especially in individuals currently in treatment for hypertension.

Vitamin D deficiency and essential hypertension

Essential hypertension (EH) results when the balance between vasoconstriction and vasodilation is shifted in favor of vasoconstriction. This balance is controlled by the interaction of genetic and epigenetic factors. When there is an unstable balance, vitamin D deficiency as an epigenetic factor triggers a shift to the side of vasoconstriction. In this article, we critically analyze clinical findings on the effect of vitamin D on blood pressure, combined with progress in molecular mechanisms. We find that vitamin D repletion exerts a clinically significant antihypertensive effect in vitamin D-deficient EH patients. Of note, a few trials reported no antihypertensive effect from vitamin D due to suboptimal study design. Short-term vitamin D supplementation has no effect on blood pressure in normotensive subjects. This could explain the mixed results and may provide a theoretical basis for future trials to identify beneficial effects of vitamin D in intervention for EH.

Association of VDR gene polymorphisms with heart disease in chronic kidney disease patients

OBJECTIVES

It has been postulated that VDR polymorphisms influence mortality in CKD by directly modifying VDR protein levels or VDR sensitivity in target organs. Here we aimed at evaluating the possible association of VDR FokI and BsmI gene polymorphisms with co-morbid conditions of CKD at different stages.

DESIGN AND METHODS

The patients included in this study were a Sicilian cohort of 171 subjects, at CKD stage 1-2 (n=49), stage 3 (n=34), stage 4-5 (n=34), and hemodialysis (HD) (n=54). Almost 70% of patients were also suffering from heart disease, with/without diabetes and/or hypertension, and 40% were also suffering of hypertension, with/without diabetes and/or heart disease; only around 20% had no co-morbid conditions.

RESULTS

A highly significant association was found between the BsmI B minor allele and heart disease in all CKD stages. Indeed, the odds ratio calculation showed that patients bearing either the bB or BB genotype had, respectively, a seven-fold and around twelve-fold increased risk for heart disease. Instead, the presence of bb wild-type genotype was associated with a fifty-fold reduced risk for heart disease, suggesting that the b allele may display a protective effect. No association was found for FokI genotypes with the different co-morbid conditions.

CONCLUSIONS

We first demonstrated that the VDR BsmI B allele may be considered as a genetic determinant for heart disease and hypertension in CKD, independently from disease stage. Thus, the screening for VDR variants should be regarded as a way to better address preventive strategies and improving the management of CKD co-morbid conditions.

Interplay of vitamin D, erythropoiesis, and the renin-angiotensin system

For many years deficiency of vitamin D was merely identified and assimilated to the presence of bone rickets. It is now clear that suboptimal vitamin D status may be correlated with several disorders and that the expression of 1-α-hydroxylase in tissues other than the kidney is widespread and of clinical relevance. Recently, evidence has been collected to suggest that, beyond the traditional involvement in mineral metabolism, vitamin D may interact with other kidney hormones such as renin and erythropoietin. This interaction would be responsible for some of the systemic and renal effects evoked for the therapy with vitamin D. The administration of analogues of vitamin D has been associated with an improvement of anaemia and reduction in ESA requirements. Moreover, vitamin D deficiency could contribute to an inappropriately activated or unsuppressed RAS, as a mechanism for progression of CKD and/or cardiovascular disease. Experimental data on the anti-RAS and anti-inflammatory effects treatment with active vitamin D analogues suggest a therapeutic option particularly in proteinuric CKD patients. This option should be considered for those subjects that are intolerant to anti-RAS agents or, as add-on therapy, in those already treated with anti-RAS but not reaching the safe threshold level of proteinuria.

Links between Vitamin D Deficiency and Cardiovascular Diseases

The aim of the present paper was to review the most important mechanisms explaining the possible association of vitamin D deficiency and cardiovascular diseases, focusing on recent experimental and clinical data. Low vitamin D levels favor atherosclerosis enabling vascular inflammation, endothelial dysfunction, formation of foam cells, and proliferation of smooth muscle cells. The antihypertensive properties of vitamin D include suppression of the renin-angiotensin-aldosterone system, renoprotective effects, direct effects on endothelial cells and calcium metabolism, inhibition of growth of vascular smooth muscle cells, prevention of secondary hyperparathyroidism, and beneficial effects on cardiovascular risk factors. Vitamin D is also involved in glycemic control, lipid metabolism, insulin secretion, and sensitivity, explaining the association between vitamin D deficiency and metabolic syndrome. Vitamin D deficit was associated in some studies with the number of affected coronary arteries, postinfarction complications, inflammatory cytokines and cardiac remodeling in patients with myocardial infarction, direct electromechanical effects and inflammation in atrial fibrillation, and neuroprotective effects in stroke. In peripheral arterial disease, vitamin D status was related to the decline of the functional performance, severity, atherosclerosis and inflammatory markers, arterial stiffness, vascular calcifications, and arterial aging. Vitamin D supplementation should further consider additional factors, such as phosphates, parathormone, renin, and fibroblast growth factor 23 levels.