What do we know and do not know about vitamin D?: a causal association between vitamin D receptor genetic polymorphism and hypertension

The policy implemented by the government and the protection effect of PM2.5 decreasing on blood pressure in adolescents: From a quasi-experimental study

BACKGROUND

High particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) exposure levels posed a great risk to human health, but the protection effects of environmental protection on cardiovascular disease have not been systematically evaluated. This study aims to illustrate the effect of the decreased concentration of PM2.5 on blood pressure level in adolescents after enacting the protection measures of environment from a cohort study.

METHODS

A quasi-experimental study including 2415 children from the Chongqing Children's Health Cohort, aged 7.32 ± 0.60 years with normal blood pressure at baseline, with 53.94% males, were analysed. Both the generalised linear regression model (GLM) and Poisson regression model were used to calculate the impact of the declining exposure level of PM2.5 on blood pressure and the incidence of prehypertension and hypertension.

RESULTS

The annual mean PM2.5 concentration in 2014 and in 2019 were 65.01 ± 6.46 µgmes per cubic metre (μg / m3), 42.08 ± 2.04 μg / m3 respectively, and the decreased PM2.5 concentration between 2014 and 2019 was 22.92 ± 4.51 μg / m3. The effect of decreased PM2.5 concentration by 1μg / m3 on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and the difference of blood pressure (BP) indexes between 2014 and 2019 were all significant (P < 0.001). The absolute differences of SBP (-3.598 mmHg; 95% confidence interval (CI) = -4.47,-2.72 mm Hg), DBP (-2.052 mmHg; 95% CI = -2.80,-1.31 mm Hg) and MAP (-2.568 mmHg; 95% CI = -3.27,-1.87 mm Hg) in the group with a decreased level of ≥25.56 μg / m3 were more significant than those in a decreased concentration of PM2.5 for <25.56 μg / m3 (P < 0.001). And the incidence of prehypertension and hypertension for three occasions blood pressure diagnose was 2.21% (95% CI = 1.37%-3.05%, P = 0.001) in children with PM2.5 decreased level ≤25.56 μg / m3 (50%), which was significant higher than its' counterparts 0.89% (95% CI = 0.37%-1.42%, P = 0.001).

CONCLUSIONS

Our study found the etiological relationship between the declining PM2.5 concentration and the BP values and the incidence of prehypertension and hypertension in children and adolescents, suggesting continuous environmental protection measures in China have achieved remarkable health benefits.

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

BACKGROUND AND AIMS

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

METHODS AND RESULTS

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

Effects of Vitamin D Supplementation on Plasma Aldosterone and Renin-A Randomized Placebo-Controlled Trial

Increasing evidence describes a possible interplay between vitamin D insufficiency with increased aldosterone. The authors sought to evaluate the effect of vitamin D supplementation on plasma aldosterone concentration (PAC) in patients with hypertension and 25-hydroxyvitamin D[25(OH)D] insufficiency. The Styrian Vitamin D Hypertension Trial was a single-center, double-blind, placebo-controlled randomized clinical trial conducted from 2011 to 2014. Two hundred patients with arterial hypertension and 25(OH)D levels <30 ng/mL were enrolled. Study participants were randomized to receive either 2800 IU of vitamin D3 or placebo. The present investigation is a post hoc analysis using analysis of covariance adjusting for baseline differences. A total of 188 participants (mean±standard deviation age, 60.1±11.3 years; 47% women; 25(OH)D, 21.2±5.6 ng/mL) completed the trial. Mean differences between baseline and follow-up PAC in the control and intervention arm were +3.3 ng/dL and +0.9 ng/dL, respectively (P=.04). The findings indicate that vitamin D3 supplementation significantly decreases PAC in patients with arterial hypertension and 25(OH)D insufficiency.

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.

The renin-angiotensin-aldosterone system and calcium-regulatory hormones

There is increasing evidence of a clinically relevant interplay between the renin-angiotensin-aldosterone system and calcium-regulatory systems. Classically, the former is considered a key regulator of sodium and volume homeostasis, while the latter is most often associated with skeletal health. However, emerging evidence suggests an overlap in regulatory control. Hyperaldosteronism and hyperparathyroidism represent pathophysiologic conditions that may contribute to or perpetuate each other; aldosterone regulates parathyroid hormone and associates with adverse skeletal complications, and parathyroid hormone regulates aldosterone and associates with adverse cardiovascular complications. As dysregulation in both systems is linked to poor cardiovascular and skeletal health, it is increasingly important to fully characterize how they interact to more precisely understand their impact on human health and potential therapies to modulate these interactions. This review describes the known clinical interactions between these two systems including observational and interventional studies. Specifically, we review studies describing the inhibition of renin activity by calcium and vitamin D, and a potentially bidirectional and stimulatory relationship between aldosterone and parathyroid hormone. Deciphering these relationships might clarify variability in outcomes research, inform the design of future intervention studies and provide insight into the results of prior and ongoing intervention studies. However, before these opportunities can be addressed, more effort must be placed on shifting observational data to the proof of concept phase. This will require reallocation of resources to conduct interventional studies and secure the necessary talent.