Should hypertensive patients take vitamin D?

Older Age Is Associated with Decreased Levels of VDR, CYP27B1, and CYP24A1 and Increased Levels of PTH in Human Parathyroid Glands

Parathyroid glands contain the vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), which catalyze the production and degradation of 1,25-dihydroxyvitamin D [1,25(OH)₂D], respectively. Previous studies have shown that the serum level of intact parathyroid hormone (iPTH) increases with age. We hypothesized that the expression of CYP27B1 or VDR in parathyroid glands decreases with age, which might account for the increased serum levels of iPTH due to decreased suppression of parathyroid hormone (PTH) secretion by 1,25(OH)₂D in older people. To test this hypothesis, we examined relative expression levels of VDR, CYP27B1, CYP24A1, and PTH in specimens from parathyroid glands unintentionally removed during thyroidectomy for 70 patients varying in age from 10 to 70 years. The results showed that there was an inverse correlation between age and VDR, CYP27B1, and CYP24A1 expression (p < 0.05). A significant positive correlation between PTH expression levels and age was also observed (p < 0.05). These data indicate that older age is associated with decreased levels of VDR, CYP27B1, and CYP24A1 and increased levels of PTH in human parathyroid glands.

Vitamin D deficiency and risk of cardiovascular diseases: a narrative review

Vitamin D, a fat-soluble prohormone, has wide-ranging roles in the regulation of many physiological processes through their interactions with the vitamin D receptors (VDR). It plays a major role in bones and calcium metabolism. Vitamin D deficiency is not uncommon and it has been associated with many health-related issues, including skeletal and non-skeletal complications. The association of low vitamin D and cardiovascular diseases and risk factors has been explored in both animal and human studies. However, studies and trials on the effect of vitamin D supplementation on cardiovascular risk factors and hypertension are conflicting with inconsistent results. Therefore, large, well-powered randomized controlled trials are warranted. If successful, supplementation with easy and low-cost vitamin D can impact our health positively. Here, we summarized the evidence for the association of vitamin D, cardiovascular diseases and risk factors, including coronary artery diseases, stroke, and hypertension, and mortality, with special consideration to resistant hypertension.

Sequence analysis of four vitamin D family genes (VDR, CYP24A1, CYP27B1 and CYP2R1) in Vogt-Koyanagi-Harada (VKH) patients: identification of a potentially pathogenic variant in CYP2R1

BACKGROUND

VKH is a rare autoimmune disease. Decreased level of vitamin D has recently been found to be involved in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease. This study was designed to screen the vitamin D pathway genes for pathogenic mutations, if any, in VKH patients.

METHODS

Genomic DNA was extracted from blood samples collected from patients with VKH disease and healthy controls. Entire coding region, exon-intron junctions of four genes were sequenced in DNA from 39 Saudi VKH patients and 50 ethnically matched healthy individuals. All patients and controls were unrelated.

RESULTS

Vitamin D levels in VKH patients were found either insufficient (21-29 ng/mL) or deficient (<20 ng/mL). Sequencing analysis of the VDR, CYP24A1, CYP27B1 and CYP2R1 detected twelve nucleotide changes in these genes in our cohort of 39 patients; 4 of which were non-coding, 6 were synonymous coding and 2 were non-synonymous coding sequence changes. All synonymous coding variants were benign polymorphisms with no apparent clinical significance. A non-synonymous coding sequence variant (c.2 T > C; p.1Met?) found in VDR is an initiation coding change and was detected in control individuals as well, while another variant (c.852G > A; p.284 M > I) found in CYP2R1 is predicted to be disease causing by mutationtaster software. This potentially pathogenic variant was found in 17 out of 39 VKH patients.

CONCLUSIONS

Screening of four Vitamin D pathway genes in 39 VKH patients shows that a potentially pathogenic sequence variant in CYP2R1 may cause VKH in a subset of patients. These findings support the previous observation that low vitamin D levels might play a role in VKH pathogenesis and mutations in genes involved in vitamin D anabolism and catabolism might be of importance in VKH pathobiology.

Vitamin D status is associated with early markers of cardiovascular disease in prepubertal children

BACKGROUND

The associations of 25-hydroxyvitamin D [25(OH)D], non-high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL), and related markers of early cardiovascular disease (CVD) are unclear in prepubertal children.

OBJECTIVE

To investigate the association of 25(OH)D with markers of CVD. The hypothesis was that 25(OH)D would vary inversely with non-HDL-C.

SUBJECTS AND METHODS

A prospective cross-sectional study of children (n=45; 26 males, 19 females) of mean age 8.3 ± 2.5 years to investigate the relationships between 25(OH)D and glucose, insulin, high-sensitivity C-reactive protein, and lipids. Vitamin D deficiency was defined as 25(OH)D <20 ng/mL; overweight as body mass index (BMI) ≥ 85 th but <95th percentile; and obesity as BMI >95th percentile.

RESULTS

Twenty subjects (44.4%) had BMI <85%, and 25 had BMI of ≥ 85%. Eleven participants (24.4%) had 25(OH)D of <20 ng/mL, and 10 (22.2%) had 25(OH)D of >30 ng/mL. Patients with 25(OH)D of <20 ng/mL had significantly elevated non-HDL-C (136.08 ± 44.66 vs. 109.88 ± 28.25, p=0.025), total cholesterol (TC)/HDL ratio (3.89 ± 1.20 vs. 3.21 ± 0.83, p=0.042), and triglycerides (TG) (117.09 ± 71.27 vs. 73.39 ± 46.53, p=0.024), while those with 25(OH)D of >30 ng/mL had significantly lower non-HDL-C, TC/HDL, TG, and LDL (82.40 ± 18.03 vs. 105.15 ± 28.38, p=0.006). Multivariate analysis showed significant inverse correlations between 25(OH)D and non-HDL cholesterol (β=-0.337, p=0.043), and TC/HDL ratio (β=-0.339, p=0.028), and LDL (β=-0.359, p=0.016), after adjusting for age, race, sex, BMI, and seasonality.

CONCLUSIONS

Vitamin D varied inversely with non-HDL, TC/HDL, and LDL. A 25(OH)D level of 30 ng/mL is associated with optimal cardioprotection in children.