Physiological and pathophysiological role of magnesium in the cardiovascular system: implications in hypertension

Review Article on Molecular Mechanism of Regulation of Hypertension by Macro-elements (Na, K, Ca and Mg), Micro-elements/Trace Metals (Zn and Cu) and Toxic Elements (Pb and As)

Hypertension (HT) is a medical condition arising due to increase in blood pressure (BP) prevalent worldwide. The balanced dietary intakes of macro-elements and micro-elements including Na, K, Ca, Mg, Zn, and Cu have been described to maintain BP in humans by regulating the osmolarity of blood, cells/tissues, prevention of generation of oxidative and nitrosative stress (OANS), and endothelial damage through their functioning as important components of renin-angiotensin-aldosterone system (RAAS), antioxidant enzyme defense system, and maintenance of blood vascular-endothelial and vascular smooth muscle cell (VSMC) functions. However, inadequate/excess dietary intakes of Na/K, Ca/Mg, and Zn/Cu along with higher Pb and As exposures recognized to induce HT through common mechanisms including the followings: endothelial dysfunctions due to impairment of vasodilatation, increased vasoconstriction and arterial stiffness, blood clotting, inflammation, modification of sympathetic activity and higher catecholamine release, increased peripheral vascular resistance, and cardiac output; increased OANS due to reduced and elevated activities of extracellular superoxide dismutase and NAD(P)H oxidase, less nitric oxide bioavailability, decrease in cGMP and guanylate cyclase activity, increase in intracellular Ca2+ ions in VSMCs, and higher pro-inflammatory cytokines; higher parathyroid and calcitriol hormones; activation/suppression of RAAS resulting imbalance in blood Na+, K+, and water regulated by renin, angiotensin II, and aldosterone through affecting natriuresis/kaliuresis/diuresis; elevation in serum cholesterol and LDL cholesterol, decrease in HDL cholesterol due to defect in lipoprotein metabolism. The present study recommends the need to review simple dietary mineral intervention studies/supplementation trials before keeping their individual dietary excess intakes/exposures in consideration because their interactions lead to elevation and fall of their concentrations in body affecting onset of HT.

Beyond Ion Homeostasis: Hypomagnesemia, Transient Receptor Potential Melastatin Channel 7, Mitochondrial Function, and Inflammation

As the second most abundant intracellular divalent cation, magnesium (Mg2+) is essential for cell functions, such as ATP production, protein/DNA synthesis, protein activity, and mitochondrial function. Mg2+ plays a critical role in heart rhythm, muscle contraction, and blood pressure. A significant decline in Mg2+ intake has been reported in developed countries because of the increased consumption of processed food and filtered/deionized water, which can lead to hypomagnesemia (HypoMg). HypoMg is commonly observed in cardiovascular diseases, such as heart failure, hypertension, arrhythmias, and diabetic cardiomyopathy, and HypoMg is a predictor for cardiovascular and all-cause mortality. On the other hand, Mg2+ supplementation has shown significant therapeutic effects in cardiovascular diseases. Some of the effects of HypoMg have been ascribed to changes in Mg2+ participation in enzyme activity, ATP stabilization, enzyme kinetics, and alterations in Ca2+, Na+, and other cations. In this manuscript, we discuss new insights into the pathogenic mechanisms of HypoMg that surpass previously described effects. HypoMg causes mitochondrial dysfunction, oxidative stress, and inflammation. Many of these effects can be attributed to the HypoMg-induced upregulation of a Mg2+ transporter transient receptor potential melastatin 7 channel (TRMP7) that is also a kinase. An increase in kinase signaling mediated by HypoMg-induced TRPM7 transcriptional upregulation, independently of any change in Mg2+ transport function, likely seems responsible for many of the effects of HypoMg. Therefore, Mg2+ supplementation and TRPM7 kinase inhibition may work to treat the sequelae of HypoMg by preventing increased TRPM7 kinase activity rather than just altering ion homeostasis. Since many diseases are characterized by oxidative stress or inflammation, Mg2+ supplementation and TRPM7 kinase inhibition may have wider implications for other diseases by acting to reduce oxidative stress and inflammation.

A Rare Association of Hypomagnesemia and Posterior Reversible Encephalopathy Syndrome (PRES)

Posterior reversible encephalopathy syndrome (PRES) is a rare neurologic disorder that presents with variable symptoms and symmetrical abnormal white matter signaling most commonly of the occipital and parietal lobes on magnetic resonance imaging (MRI). PRES, also known as reversible posterior leukoencephalopathy syndrome (RPLS) is commonly associated with hypertension. Hypomagnesemia's association with PRES has been rarely reported. Here, we report a patient with severe hypomagnesemia that presented with PRES syndrome that improved with magnesium replacement. Hypomagnesemia should be considered an underlying etiology in patients presenting with PRES syndrome and should be promptly treated. The presentation can often be concerning for acute cerebrovascular accidents with symptoms of dysarthria and upper motor neuron symptoms, such as facial droop, dysarthria, and gait instability. Differential diagnosis of PRES often includes rostral brainstem infarction, transient ischemic attack, infectious encephalopathy, and metabolic/toxic encephalopathy, which is evaluated in the description of the case. The most common presentation of RPLS/PRES includes altered mental status, drowsiness, seizure, vomiting, alterations in speech including dysarthria, and visual disturbance. The first signs noted are commonly lethargy and somnolence. In this case, the patient presented notably with initial symptoms of dysarthria of speech and facial droop, with serum hypomagnesemia in which symptoms corrected rapidly with the administration of intravenous magnesium sulfate.

Circulating Magnesium and Risk of Major Adverse Cardiac Events among Patients with Atrial Fibrillation in the ARIC Cohort

Background: Serum magnesium (Mg) has been reported to be inversely associated with the risk of atrial fibrillation (AF), coronary artery disease (CAD), and major adverse cardiovascular events (MACE). The association between serum Mg and the risk of MACE, heart failure (HF), stroke, and all-cause mortality among patients with AF has not been evaluated. Objective: We aim to examine whether higher serum Mg is associated with a lower risk of MACE, heart failure (HF), stroke, and all-cause mortality among patients with AF. Methods: We evaluated prospectively 413 participants of the Atherosclerosis Risk in Communities (ARIC) Study with a diagnosis of AF at the time of Mg measurement participating in visit 5 (2011-2013). Serum Mg was modeled in tertiles and as a continuous variable in standard deviation units. Endpoints (HF, MI, stroke, cardiovascular (CV) death, all-cause mortality, and MACE) were identified and modeled separately using Cox proportional hazard regression adjusting for potential confounders. Results: During a mean follow-up of 5.8 years, there were 79 HFs, 34 MIs, 24 strokes, 80 CV deaths, 110 MACEs, and 198 total deaths. After adjustment for demographic and clinical variables, participants in the second and third tertiles of serum Mg had lower rates of most endpoints, with the strongest inverse association for the incidence of MI (HR 0.20, 95% CI 0.07, 0.61) comparing top to bottom tertile. Serum Mg modeled linearly as a continuous variable did not show clear associations with endpoints except MI (HR 0.50, 95% CI 0.31, 0.80). Due to the limited number of events, the precision of most estimates of association was relatively low. Conclusions: Among patients with AF, higher serum Mg was associated with a lower risk of developing incident MI and, to a lesser extent, other CV endpoints. Further studies in larger patients with AF cohorts are needed to evaluate the role of serum Mg in preventing adverse CV outcomes in these patients.

Management for Electrolytes Disturbances during Continuous Renal Replacement Therapy

Despite the lack of proven superiority in mortality compared to intermittent hemodialysis, continuous renal replacement therapy (CRRT) is the preferred renal replacement therapy modality for critically ill patients with acute kidney injury (AKI) due to better hemodynamic stability and steady correction of electrolytes disturbances and volume overload. Multiple and complex electrolyte disorders in patients with AKI can be managed effectively with CRRT because controlled and predictable correction is feasible. Thus, CRRT has an advantage with safety over conventional hemodialysis, especially in patients with both renal dysfunction and electrolyte disorder that require a sophisticated treatment with avoidance of rapid correction. On the contrary, CRRT can potentially lead to paradoxical disturbance of electrolytes such as hypokalemia or hypophosphatemia, especially in patients under high dose or prolonged duration of CRRT treatment. These electrolytes related complications can be prevented with close monitoring followed by the appropriate use of CRRT fluids. Although there is a lack of solid evidence and standardized guideline for CRRT prescriptions, optimal management of various electrolyte disturbances can be achieved with individualized and tailored dialysate and replacement fluid prescriptions. Several commercially available CRRT solutions with varying compositions provide flexibility to manage electrolyte disorders and maintain the stability of electrolyte. In this review, we discuss various prescription methods to manage common electrolyte imbalances as well as preventative strategies to maintain electrolyte homeostasis during CRRT providing detailed protocols used in our center. This review may contribute to future research that can lead to the development of clinical practice guidelines.

Hypomagnesemia and Cardiovascular Risk in Type 2 Diabetes

Hypomagnesemia is tenfold more common in individuals with type 2 diabetes (T2D), compared to the healthy population. Factors that are involved in this high prevalence are low Mg2+ intake, gut microbiome composition, medication use and presumably genetics. Hypomagnesemia is associated with insulin resistance, which subsequently increases the risk to develop T2D or deteriorates glycaemic control in existing diabetes. Mg2+ supplementation decreases T2D associated features like dyslipidaemia and inflammation; which are important risk factors for cardiovascular disease (CVD). Epidemiological studies have shown an inverse association between serum Mg2+ and the risk to develop heart failure (HF), atrial fibrillation (AF) and microvascular disease in T2D. The potential protective effect of Mg2+ on HF and AF may be explained by reduced oxidative stress, fibrosis and electrical remodeling in the heart. In microvascular disease, Mg2+ reduces the detrimental effects of hyperglycemia and improves endothelial dysfunction. Though, clinical studies assessing the effect of long-term Mg2+ supplementation on CVD incidents are lacking and gaps remain on how Mg2+ may reduce CVD risk in T2D. Despite the high prevalence of hypomagnesemia in people with T2D, routine screening of Mg2+ deficiency to provide Mg2+ supplementation when needed is not implemented in clinical care as sufficient clinical evidence is lacking. In conclusion, hypomagnesemia is common in people with T2D and is both involved as cause, probably through molecular mechanisms leading to insulin resistance, and consequence and is prospectively associated with development of HF, AF and microvascular complications. Whether long-term supplementation of Mg2+ is beneficial, however, remains to be determined.

Strategy for sodium-salt substitution: On the relationship between hypertension and dietary intake of cations

Chronic diseases, especially cardiovascular diseases (CVD), have become one of the main causes affecting human health. Hypertension is a prominent representative of CVD. The formation and development of hypertension is closely related to people's daily diet. A large number of studies have shown that excessive intake of salt (NaCl) could increase the risk of hypertension. In recent years, more and more investigations have focused on other cations that may be contained in edible salt, exploring whether they have an effect on hypertension and the underlying mechanism. This article focuses on the relationship between four metal elements (potassium, calcium, magnesium, and zinc) and hypertension, by discussing the main metabolic pathway, the impact of diet intake on blood pressure, and especially the regulation mechanisms on blood pressure in detail. At the same time, some opinions and suggestions are put forward, combined with the current hot topics "salt reduction" and "salt substitution".

High magnesium mitigates the vasoconstriction mediated by different types of calcium influx from monocrotaline-induced pulmonary hypertensive rats

NEW FINDINGS

What is the central question of this study? The aim was to examine and explore the involvement of Mg²⁺ in mitigating the vasoconstriction in PAs and sPAs in the MCT-PAH rat model. What are the main finding and its importance? 1.Both SOCE- and ROCE-mediated vasoconstriction enhanced in the MCT-PAH model. 2.High magnesium inhibited vasoconstriction due to directly antagonizing Ca²⁺ and increasing NO release. 3.The inhibition effect of high magnesium was more notable in sPA.

ABSTRACT

Increased extracellular magnesium concentration ([Mg²⁺ ]_e ) has been evidenced to attenuate the endothelin-1 (ET-1)-induced contractile response via the release of nitric oxide (NO) from the endothelium in proximal pulmonary arteries (PAs) of chronic hypoxic (CH) mice. Here we further examined the involvement of Mg²⁺ in the inhibition of vasoconstriction in PAs and distal smaller pulmonary arteries (sPAs) in a monocrotaline-induced pulmonary arterial hypertension (MCT-PAH) rat model. The data showed that in control rats, vasoconstriction in sPAs is more intense than that in PAs. In MCT-PAH rats, the store-operated Ca²⁺ entry (SOCE)-, and receptor-operated Ca²⁺ entry (ROCE)-mediated contraction was significantly strengthened. However, there was no upregulation of the vasoconstriction mediated by voltage-dependent calcium entry (VDCE). Furthermore, high magnesium greatly inhibited the VDCE-mediated contraction in PAs instead of sPAs, which was opposite to the ROCE-mediated contraction. Moreover, MCT pretreatment partly eliminated the endothelium-dependent vasodilation in PAs, which in sPAs, however, was still promoted by magnesium due to the increased NO release in pulmonary microvascular endothelial cells (PMVECs). In conclusion, the findings suggest that both SOCE- and ROCE-mediated vasoconstriction in the MCT-PAH model are enhanced, especially in sPAs. The inhibition effect of high magnesium on vasoconstriction can be achieved partly by its direct role as a Ca²⁺ antagonist and partly by increasing the NO release in PMVECs. This article is protected by copyright. All rights reserved.

Serum Magnesium, Blood Pressure, and Risk of Hypertension and Chronic Kidney Disease Progression in the CRIC Study

[Figure: see text].

The Association Between Exposure to Low Magnesium Blood Levels After Renal Transplantation and Cardiovascular Morbidity and Mortality

Background: Serum magnesium levels are associated with cardiovascular disease and all-cause mortality in the general population and chronic kidney disease patients, but the association between serum magnesium levels and cardiovascular risk after kidney transplantation is not established. We sought to evaluate whether exposure to low serum magnesium levels after renal transplantation is related to cardiovascular morbidity and mortality.

Methods: We conducted a single center retrospective study that included all transplanted patients who had a functioning graft for at least 6 months after transplantation between January 2001 and December 2013. We calculated exposure to magnesium using time weighted average for serum magnesium levels, using all values available during the follow-up. Several statistical methods were used, including liner regression analysis, χ² test, and multivariate Cox proportional hazard model.

Results: Four hundred ninety-eight patients were included. Median follow-up was 5.26 years. High time weighted average of serum magnesium was associated with a hazard ratio of 1.94 for all-cause mortality and major cardiovascular outcome compared to low levels (95% CI 1.18–3.19, p = 0.009). The high quartile of time weighted average of serum magnesium was associated with death censored major cardiovascular outcome (hazard ratio 2.13, 95% CI 1.17–3.86, p = 0.013) in multivariate analysis.

Conclusions: Exposure to low serum magnesium levels in renal transplant recipients was associated with a lower risk for all-cause mortality and major cardiovascular outcome. These findings contrast the higher risk found in the general population.

Beneficial Effects of Intravenous Magnesium Administration During Robotic Radical Prostatectomy: A Randomized Controlled Trial

INTRODUCTION

Robotic radical prostatectomy requires prolonged pneumoperitoneum and a steep Trendelenburg position. Magnesium can attenuate the stress response and hemodynamic perturbations. This study aimed to evaluate the effects of intravenous magnesium administration on hemodynamics and the stress response in patients undergoing robotic radical prostatectomy.

METHODS

In this prospective, double-blind, randomized controlled study, 52 patients undergoing robotic radical prostatectomy were randomized into two groups: 26 in the magnesium group and 26 in the control group. The patients in the magnesium group received magnesium sulfate 50 mg/kg intravenously, followed by infusion at a rate of 10 mg/kg/h during surgery. The patients in the control group received an equal volume of 0.9% saline. The primary outcomes were the changes in heart rate and mean arterial pressure (MAP) during surgery. The serum stress hormones (adrenocorticotropic hormone, cortisol, epinephrine, and norepinephrine) were also measured.

RESULTS

MAP showed a significant intergroup difference over time (P_group*time = 0.017); it increased significantly at 5 min after Trendelenburg position in the control group and decreased significantly at 30 min after Trendelenburg position in the magnesium group. The intergroup difference in the change in cortisol concentrations was significant over time (P_group*time = 0.006). The cortisol concentration decreased significantly from baseline to 24 h after surgery in the magnesium group but did not change significantly in the control group. The requirement for intraoperative remifentanil was 35% lower in the magnesium group (P = 0.011), and the severity of postoperative pain at 30 min and 6 h after surgery was also lower in the magnesium group (P = 0.024 and P = 0.015).

CONCLUSION

There is a possibility that intravenous magnesium administration during robotic radical prostatectomy reduces the increases in arterial pressure, cortisol concentrations, opioid requirements, and postoperative pain.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02833038.

High-magnesium exposure to bullfrog heart causes ST segment elevation

Hypermagnesemia occurs in elderly people or patients with renal insufficiency after excessive ingestion of magnesium-containing laxatives. In addition to typical electrocardiogram (ECG) findings caused by conduction defects, changes in the ST segments and T waves are also observed in patients with severe hypermagnesemia. This suggested the involvement of similar pathophysiology to acute myocardial infarction, as we previously demonstrated using burn-induced subepicardial injury model in frog hearts. In the present study, by exposing the bullfrog heart to high-magnesium solution, we reproduced prominent ST segment changes in ECG as actually observed in patients with severe hypermagnesemia. In addition to the great increase in the T waves, the ECG showed a marked elevation of the ST segments and the cardiac action potential demonstrated a marked shift of the resting membrane potential to the depolarized side. High-magnesium exposure did not affect the abundance of Na⁺/K⁺-ATPase proteins. However, the pharmacological stimulation of Na⁺/K⁺-ATPase activity by insulin quickly retrieved the elevated ST segments in ECG. From these results, the functional blockade of Na⁺/K⁺-ATPase activity by magnesium ions was thought to be responsible for generating the potassium concentration gradient and the subsequent ST segment changes.

Influences of Hypomagnesemia on Optic Nerve and Retinal Vascular Structure Determined Using Optical Coherence Tomography (OCT) Angiography

Purpose: To evaluate the effects of low blood magnesium levels on the optic nerve, retina, and retinal vascular structure.Methods: This observational and cross-sectional study was conducted between June 2019 and May 2020 with participants aged 20-39 years, who had a visual acuity of ≥20/20, the axial length of 22-24.5 mm, refractive defect spherical equivalent of ≤±3D, and intraocular pressure of ≤21 mm Hg. All participants had a complaint of twitching in their eyes. The participants with normal serum magnesium levels constituted the control group, and patients with hypomagnesemia constituted the patient group. Updated AngioScan software (Navis ver. 1.8.0.) of Nidek's RS-3000 Advance system was used to analyze the spectral domain-optical coherence tomography (SD-OCT) and optical coherence tomography-angiography (OCT-A) images.Results: A total of 100 right eyes of 100 individuals was included in the study. The mean retinal nerve fiber layer (RNFL) thickness was 108.52 ± 12.46 μm in the control group, and 97.3 ± 9.7 μm in the hypomagnesemia group (P < .001). In the control group, the global superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel densities (VDs) were 41.92 ± 2.29, and 37.54 ± 3.83, respectively. In the patient group, the global SCP and DCP VDs were 37.66 ± 3.14, and 32.95 ± 5.57, respectively. The SCP and DCP VD percentages were significantly lower in the patient group. The mean foveal avascular zone (FAZ) area, perimeter and circularity index (CI) were 0.32 ± 0.13 mm², 2.89 ± 0.59 mm, and 0.52 ± 0.09, respectively, for the control group and 0.38 ± 0.11 mm², 2.99 ± 0.64 mm, and 0.38 ± 0.1, respectively, for the patient group. The FAZ area and perimeter were significantly higher (P = .013 and P = .001) and FAZ CI was significantly lower (P < .001) in the patients with hypomagnesemia.Conclusion: Our study revealed that OCT and OCT-A measurements may be used in the determination of the optic nerve and retinal vascular structure changes in hypomagnesemia.

Drinking Water Salinity, Urinary Macro-Mineral Excretions, and Blood Pressure in the Southwest Coastal Population of Bangladesh

Background

Sodium (Na⁺) in saline water may increase blood pressure (BP), but potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺) may lower BP. We assessed the association between drinking water salinity and population BP.

Methods and Results

We pooled 6487 BP measurements from 2 cohorts in coastal Bangladesh. We used multilevel linear models to estimate BP differences across water salinity categories: fresh water (electrical conductivity, <0.7 mS/cm), mild salinity (electrical conductivity ≥0.7 and <2 mS/cm), and moderate salinity (electrical conductivity ≥2 and <10 mS/cm). We assessed whether salinity categories were associated with hypertension using multilevel multinomial logistic models. Models included participant‐, household‐, and community‐level random intercepts. Models were adjusted for age, sex, body mass index (BMI), physical activity, smoking, household wealth, alcohol consumption, sleep hours, religion, and salt consumption. We evaluated the 24‐hour urinary minerals across salinity categories, and the associations between urinary minerals and BP using multilevel linear models. Compared with fresh water drinkers, mild‐salinity water drinkers had lower mean systolic BP (−1.55 [95% CI: −3.22–0.12] mm Hg) and lower mean diastolic BP (−1.26 [95% CI: −2.21–−0.32] mm Hg) adjusted models. The adjusted odds ratio among mild‐salinity water drinkers for stage 1 hypertension was 0.60 (95% CI: 0.43–0.84) and for stage 2 hypertension was 0.56 (95% CI: 0.46–0.89). Mild‐salinity water drinkers had high urinary Ca²⁺, and Mg²⁺, and both urinary Ca²⁺ and Mg²⁺ were associated with lower BP.

Conclusions

Drinking mild‐salinity water was associated with lower BP, which can be explained by higher intake of Ca²⁺ and Mg²⁺ through saline water.

See Editorial Bispham and Nowak

Posterior reversible encephalopathy syndrome in an oncological normotensive patient: evidence for a pathogenic role of concomitant low magnesium serum levels and chemotherapy treatment

Background:

Posterior reversible encephalopathy (PRES) is a rare syndrome characterized by headache, confusion, seizures, visual changes and white matter edema at radiological imaging. Its pathophysiology is not clarified and different causes, including uncontrolled hypertension, eclampsia, chemotherapy and hypomagnesemia have been suggested.

Case report:

A woman affected by stage IV breast cancer with lower extremity deep vein thrombosis treated with low-molecular-weight-heparin, currently in therapy with Palbociclib/Fulvestrant (antiCDK4 and 6/estrogen receptor antagonist) but previously treated with several other chemotherapy lines (including VEGF inhibitor bevacizumab), was admitted to our Internal Medicine department because of ascites and abdominal pain. She was treated with diuretics (and paracentesis). Recently (six-month earlier) a pan-encephalic radiotherapy was done because of brain and skull metastasis. Among blood tests, low serum levels of hypomagnesemia were observed. She developed PRES that rapidly progressed to lethargy, unresponsiveness till coma without changes in blood pressure. Magnetic Resonance Imaging study showed bilateral parieto-occipital edema and a thrombosis of left transverse and sigmoid sinuses. Anti-edema therapy, intravenous supplementation of magnesium and decoagulation were started, with complete and rapid recovery (within 18 hours) of clinical and radiologic changes.

Conclusions:

PRES diagnosis was based on the rapid clinical recovery after antiedema treatment and magnesium supplementation. Low magnesium level related to both diuretic and Fulvestrant/Palbociclib therapies and recent radiotherapy can represent potential mechanisms favouring PRES development. The previous bevacizumab treatment may also be involved as a PRES predisposing factor. The concomitant occurrence of cerebral thrombosis can have precipitated the clinical situation. (www.actabiomedica.it)

Association Between Nutrient Patterns and Hypertension Among Adults in the United States: A Population-Based Survey

INTRODUCTION

Hypertension (HTN) is a common medical condition associated with many adverse health outcomes. Diet plays a crucial role in the pathology, prevention, and management of HTN.

AIM

To identify nutrient patterns (NPs) and to investigate their association with the risk of HTN among adults in the United States (US).

METHODS

This cross-sectional study used data from the US community-based National Health and Nutrition Examination Survey (NHANES). Participants with data on dietary intake and blood pressure were analyzed. NPs were determined by principal components analysis (PCA). In all the analyses (analysis of covariance and multivariate logistic regression), we accounted for the survey design and sample weights.

RESULTS

Overall, 22,184 (4002 hypertensive and 18,182 normotensive) individuals were included. We identified three NPs which explained 50.8% of the variance of the dietary nutrient consumption. There was a graded decrease in the odds of association with HTN by quartiles of mono-unsaturated fatty acids (MUFA) dietary pattern where the 4th quartile was associated with a 28% (odds ratio [OR] 0.72, 95% confidence interval [CI] 0.63-0.82; p < 0.001) lower odds of HTN compared with the first quartile. The second NP "high in micronutrients and vitamins" presented a decreasing trend in the odds of association with HTN with the 4th quartile having a 20% [OR 0.80, 95% CI 0.63-0.97; p < 0.001] lower odds of HTN compared with the 1st quartile.

CONCLUSION

Our findings provide further evidence on the inverse association between a high intake of minerals, vitamins, and MUFA and the risk of HTN. Further observational studies and clinical trials are needed to better understand the influence of MUFA, vitamins, and mineral consumption on HTN.

Magnesium Regulates Endothelial Barrier Functions through TRPM7, MagT1, and S1P1

Mg2+-deficiency is linked to hypertension, Alzheimer's disease, stroke, migraine headaches, cardiovascular diseases, and diabetes, etc., but its exact role in these pathophysiological conditions remains elusive. Mg2+ can regulate vascular functions, yet the mechanistic insight remains ill-defined. Data show that extracellular Mg2+ enters endothelium mainly through the TRPM7 channel and MagT1 transporter. Mg2+ can act as an antagonist to reduce Ca2+ signaling in endothelium. Mg2+ also reduces the intracellular reactive oxygen species (ROS) level and inflammation. In addition, Mg2+-signaling increases endothelial survival and growth, adhesion, and migration. Endothelial barrier integrity is significantly enhanced with Mg2+-treatment through S1P1-Rac1 pathways and barrier-stabilizing mediators including cAMP, FGF1/2, and eNOS. Mg2+ also promotes cytoskeletal reorganization and junction proteins to tighten up the barrier. Moreover, Mg2+-deficiency enhances endothelial barrier permeability in mice, and Mg2+-treatment rescues histamine-induced transient vessel hyper-permeability in vivo. In summary, Mg2+-deficiency can cause deleterious effects in endothelium integrity, and Mg2+-treatment may be effective in the prevention or treatment of vascular dysfunction.

Association of hypomagnesemia with cardiovascular diseases and hypertension

OBJECTIVE

The objective of this study was to review the current evidence on the effects of Mg2+ deficiency on cardiovascular disease (CVD) and hypertension, since Mg2+ is a potent vasodilator and modulates vasomotor tone, blood pressure and peripheral blood flow. Several factors could contribute to its deficiency and when it occurs, is associated with an increased incidence of cardiovascular disease (CVD), hypertension, heart failure (HF), and cardiac arrhythmias.

METHODS

In order to get a better to get an updated perspective of the current status of Mg2+ deficiency and its implications in CVD, hypertension, and cardiac arrhythmias, a focused Medline search of the English language literature was conducted between 2014 and 2018 and 30 pertinent papers were retrieved.

RESULTS

The analysis of data showed that Mg2+ deficiency is difficult to occur, under normal circumstances, because it is plentiful in green leafy vegetables, cereals, nuts, and the drinking water. However, Mg2+ deficiency can occur under special circumstances such as hypertension and HF treated with large doses of diuretics, patients with chronic kidney disease (CKD) treated with hemodialysis, and patients with gastroesophageal reflux disease treated with proton pump inhibitors. When hypomagnesemia occurs, it is associated with serious cardiac arrhythmias and aggravation of hypertension.

CONCLUSION

The analysis of data suggests that Mg2+ deficiency does occur and it is associated with an increased incidence of CVD, HF, serious cardiac arrhythmias, and hypertension. Retaining normal Mg2+ levels will prevent the onset of these diseases.

Effects of diabetic ketoacidosis in the respiratory system

Diabetes affects approximately 30 million persons in the United States. Diabetes ketoacidosis is one of the most serious and acute complications of diabetes. At the time of presentation and during treatment of diabetic ketoacidosis (DKA), several metabolic and electrolyte derangements can ultimately result in respiratory compromise. Most commonly, hypokalemia, hypomagnesemia and hypophosphatemia can eventually lead to respiratory muscles failure. Furthermore, tachypnea, hyperpnea and more severely, Kussmaul breathing pattern can develop. Also, hydrostatic and non-hydrostatic pulmonary edema can occur secondary to volume shifts into the extracellular space and secondary to increased permeability of the pulmonary capillaries. The presence of respiratory failure in patients with DKA is associated with higher morbidity and mortality. Being familiar with the causes of respiratory compromise in DKA, and how to treat them, may represent better outcomes for patients with DKA.

Magnesium Urinary Excretion in Diabetic Adolescents

Objective: to define peculiarities of urinary magnesium (Mg) excretion in diabetic adolecents; to elucidate gender-related differences in Mg urinary excretion; to determine urinary Mg excretion differences between diabetic and age-matched healthy children. The diurnal, nocturnal and 24–h urinary Mg level in adolescent boys and girls (aged 13–17 years) with type I diabetes mellitus (DM) and in age-matched control groups of healthy boys and girls was examined. Additionally the adolescent girls were examined during different phases of their menstrual cycle. Results: Diurnal, overnight and 24–h Mg urinary excretion in diabetic adolescent boys and girls was significantly higher than in healthy ones. In diabetic boys 24 h Mg excretion was higher than in diabetic girls (4.59±1.4 vs. 3.34±1.5 mmol; p<0.05). The investigation showed gender-related differences in Mg urinary excretion in healthy adolescents: 24–h Mg urinary excretion was significantly higher in boys than in girls (2.66±0.9 vs. 2.1±0.9 mmol; p<0.05). The level of Mg in the nocturnal urine of boys and girls was significantly higher than in diurnal. Urine Mg was negatively related to height in adolescent girls. Conclusion: Diabetic adolescents excrete significantly more Mg with urine as compared to healthy ones.

The Role of Magnesium in Neurological Disorders

Magnesium is well known for its diverse actions within the human body. From a neurological standpoint, magnesium plays an essential role in nerve transmission and neuromuscular conduction. It also functions in a protective role against excessive excitation that can lead to neuronal cell death (excitotoxicity), and has been implicated in multiple neurological disorders. Due to these important functions within the nervous system, magnesium is a mineral of intense interest for the potential prevention and treatment of neurological disorders. Current literature is reviewed for migraine, chronic pain, epilepsy, Alzheimer’s, Parkinson’s, and stroke, as well as the commonly comorbid conditions of anxiety and depression. Previous reviews and meta-analyses are used to set the scene for magnesium research across neurological conditions, while current research is reviewed in greater detail to update the literature and demonstrate the progress (or lack thereof) in the field. There is strong data to suggest a role for magnesium in migraine and depression, and emerging data to suggest a protective effect of magnesium for chronic pain, anxiety, and stroke. More research is needed on magnesium as an adjunct treatment in epilepsy, and to further clarify its role in Alzheimer’s and Parkinson’s. Overall, the mechanistic attributes of magnesium in neurological diseases connote the macromineral as a potential target for neurological disease prevention and treatment.

Magnesium and Cardiovascular Disease

Magnesium is the most abundant intracellular divalent cation and essential for maintaining normal cellular physiology and metabolism, acting as a cofactor of numerous enzymes, regulating ion channels and energy generation. In the heart, magnesium plays a key role in modulating neuronal excitation, intracardiac conduction, and myocardial contraction by regulating a number of ion transporters, including potassium and calcium channels. Magnesium also has a role in regulating vascular tone, atherogenesis and thrombosis, vascular calcification, and proliferation and migration of endothelial and vascular smooth muscle cells. As such, magnesium potentially has a major influence on the pathogenesis of cardiovascular disease. As the kidney is a major regulator of magnesium homeostasis, kidney disorders can potentially lead to both magnesium depletion and overload, and as such increase the risk of cardiovascular disease. Observational data have shown an association between low serum magnesium concentrations or magnesium intake and increased atherosclerosis, coronary artery disease, arrhythmias, and heart failure. However, major trials of supplementation with magnesium have reported inconsistent benefits and also raised potential adverse effects of magnesium overload. As such, there is currently no firm recommendation for routine magnesium supplementation except when hypomagnesemia has been proven or suspected as a cause for cardiac arrhythmias.

Magnesium Sulfate Treatment Correlates With Improved Neurological Function in Posterior Reversible Encephalopathy Syndrome (PRES): Report of a Case

Posterior reversible encephalopathy syndrome (PRES) is a potentially reversible failure of cerebral autoregulation managed by correction of hypertension or underlying medical condition. Nonresponding cases progress to irreversible brain damage. There is some evidence of association of hypomagnesemia with PRES. We describe a case of nonresolving PRES where use of magnesium sulfate led to improvement in neurological function and eventual recovery. Our case highlights the need for a randomized controlled trial to test the efficacy of magnesium in PRES.

Magnesium attenuates endothelin-1-induced vasoreactivity and enhances vasodilatation in mouse pulmonary arteries: Modulation by chronic hypoxic pulmonary hypertension

NEW FINDINGS

What is the central question of this study? The central goal of this study was to elucidate the role of magnesium in the regulation of pulmonary vascular reactivity in relationship to hypoxic pulmonary hypertension. What is the main finding and its importance? We found that magnesium is essential for normal vasoreactivity of the pulmonary artery. Increasing the magnesium concentration attenuates vasoconstriction and improves vasodilatation via release of nitric oxide. Pulmonary hypertension is associated with endothelial dysfunction resulting in the suppression of magnesium modulation of vasodilatation. These results provide evidence that magnesium is important for the modulation of pulmonary vascular function.

ABSTRACT

Pulmonary hypertension (PH) is characterized by enhanced vasoreactivity and sustained pulmonary vasoconstriction, arising from aberrant Ca²⁺ homeostasis in pulmonary arterial (PA) smooth muscle cells. In addition to Ca²⁺ , magnesium, the most abundant intracellular divalent cation, also plays crucial roles in many cellular processes that regulate cardiovascular function. Recent findings suggest that magnesium regulates vascular functions by altering the vascular responses to vasodilator and vasoactive agonists and affects endothelial function by modulating endothelium-dependent vasodilatation in hypertension. Administration of magnesium also decreased pulmonary arterial pressure and improved cardiac output in animal models of PH. However, the role of magnesium in the regulation of pulmonary vascular function related to PH has not been studied. In this study, we examined the effects of magnesium on endothelin-1 (ET-1)-induced vasoconstriction, ACh-induced vasodilatation and the generation of NO in PAs of normoxic mice and chronic hypoxia (CH)-treated mice. Our data showed that removal of extracellular magnesium suppressed vasoreactivity of PAs to both ET-1 and ACh. A high concentration of magnesium (4.8 mm) inhibited ET-1-induced vasoconstriction in endothelium-intact or endothelium-disrupted PAs of normoxic and CH-treated mice, and enhanced the ACh-induced production of NO in PAs of normoxic mice. Moreover, magnesium enhanced ACh-induced vasodilatation in PAs of normoxic mice, and the enhancement was completely abolished after exposure to CH. Hence, in this study we demonstrated that increasing the magnesium concentration can attenuate the ET-1-induced contractile response and improve vasodilatation via release of NO from the endothelium. We also demonstrated that chronic exposure to hypoxia can cause endothelial dysfunction resulting in suppression of the magnesium-dependent modulation of vasodilatation.

A feasibility study of using biodegradable magnesium alloy in glaucoma drainage device

Technological advances in glaucoma have challenged the traditional treatment paradigm. Historically incisional surgery has been used in cases of advanced disease and/or uncontrolled intraocular pressures resistant to medical or laser interventions. More recently, perhaps due to advancements in imaging, surgery has been suggested to be beneficial earlier in the treatment paradigm. Despite these trends, surgical manipulation of the tissues and unpredictability of wound healing continue to result in surgical failure. Magnesium is an essential element for human body and plays a critically important role in maintaining the functional and structural integrity of several tissues, including the eye. Due to several of its advantageous properties such as non-toxicity, biodegradability, and high biological compatibility, magnesium alloy has attracted great attention as a novel biomaterial. Biodegradable cardiovascular stents made of magnesium alloy have already been introduced into clinical practice. The purpose of this review is to determine if bioabsorbable magnesium alloys can be utilized as a promising candidate for the development of a new generation of glaucoma surgical assistive devices.

Cardioprotective and Anti-arrhythmic Effects of Magnesium Pretreatment Against Ischaemia/Reperfusion Injury in Isoprenaline-Induced Hypertrophic Rat Heart

The effects of magnesium (Mg²⁺) on ischaemic complications of pathological cardiac hypertrophy are unclear. In this study, we investigated effects of Mg²⁺ pretreatment on ischaemia/reperfusion (I/R) injury in isoprenaline (ISO)-induced hypertrophic hearts. Wistar rats were treated for 7 days with different combinations of ISO (1.25 mg/kg) subcutaneously, MgSO₄ (270 mg/kg) intraperitoneally, or vehicle (saline). On the eighth day, hearts were either subjected to regional I/R during Langendorff perfusion or histologically stained with haematoxylin and eosin and Masson's trichrome. Haemodynamic and electrocardiographic parameters were recorded using the PowerLab data-acquisition system. Infarcts were identified by triphenyltetrazolium chloride staining. Plasma Mg²⁺ was measured using photometric assays. Mg²⁺ pretreatment significantly decreased I/R-induced infarct size (p = 0.001) and the overall arrhythmia score (p < 0.001) of I/R-induced ventricular ectopics, ventricular tachycardia, and ventricular fibrillation in hypertrophic hearts, but not non-hypertrophied hearts. Mg²⁺ also improved post-I/R left ventricular developed pressure in hypertrophic hearts. However, Mg²⁺ did not reverse the ISO-induced myocyte thickening and interstitial fibrosis or increases in heart weight. Plasma Mg²⁺ was not different among treatment groups. These results suggest that Mg²⁺ pretreatment may protect against I/R-induced injury and malignant arrhythmias in hypertrophic hearts, possibly via mechanisms unrelated to long-lasting changes in plasma Mg²⁺ or prevention of structural changes such as fibrosis.

Cardiac Dysrhythmias and Neurological Dysregulation: Manifestations of Profound Hypomagnesemia

Magnesium is the second most common intracellular cation and serves as an important metabolic cofactor to over 300 enzymatic reactions throughout the human body. Among its various roles, magnesium modulates calcium entry and release from sarcoplasmic reticulum and regulates ATP pumps in myocytes and neurons, thereby regulating cardiac and neuronal excitability. Therefore, deficiency of this essential mineral may result in serious cardiovascular and neurologic derangements. In this case, we present the clinical course of a 76-year-old woman who presented with marked cardiac and neurological signs and symptoms which developed as a result of severe hypomagnesemia. The patient promptly responded to magnesium replacement once the diagnosis was established. We herein discuss the clinical presentation, pathophysiology, diagnosis, and management of severe hypomagnesemia and emphasize the implications of magnesium deficiency in the cardiovascular and central nervous systems. Furthermore, this case highlights the importance of having high vigilance for hypomagnesemia in the appropriate clinical setting.

Metal Ion-Loaded Nanofibre Matrices for Calcification Inhibition in Polyurethane Implants

Pathologic calcification leads to structural deterioration of implant materials via stiffening, stress cracking, and other structural disintegration mechanisms, and the effect can be critical for implants intended for long-term or permanent implantation. This study demonstrates the potential of using specific metal ions (MI)s for inhibiting pathological calcification in polyurethane (PU) implants. The hypothesis of using MIs as anti-calcification agents was based on the natural calcium-antagonist role of Mg²⁺ ions in human body, and the anti-calcification effect of Fe³⁺ ions in bio-prosthetic heart valves has previously been confirmed. In vitro calcification results indicated that a protective covering mesh of MI-doped PU can prevent calcification by preventing hydroxyapatite crystal growth. However, microstructure and mechanical characterisation revealed oxidative degradation effects from Fe³⁺ ions on the mechanical properties of the PU matrix. Therefore, from both a mechanical and anti-calcification effects point of view, Mg²⁺ ions are more promising candidates than Fe³⁺ ions. The in vitro MI release experiments demonstrated that PU microphase separation and the structural design of PU-MI matrices were important determinants of release kinetics. Increased phase separation in doped PU assisted in consistent long-term release of dissolved MIs from both hard and soft segments of the PU. The use of a composite-sandwich mesh design prevented an initial burst release which improved the late (>20 days) release rate of MIs from the matrix.

Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: A pilot study

Background

Oral magnesium supplementation is commonly used to support a low magnesium diet. This investigation set out to determine whether magnesium in a cream could be absorbed transdermally in humans to improve magnesium status.

Methods and findings

In this single blind, parallel designed pilot study, n = 25 participants (aged 34.3+/-14.8y, height 171.5+/-11cm, weight 75.9 +/-14 Kg) were randomly assigned to either a 56mg/day magnesium cream or placebo cream group for two weeks. Magnesium serum and 24hour urinary excretion were measured at baseline and at 14 days intervention. Food diaries were recorded for 8 days during this period. Mg test and placebo groups’ serum and urinary Mg did not differ at baseline. After the Mg²⁺ cream intervention there was a clinically relevant increase in serum magnesium (0.82 to 0.89 mmol/l,p = 0.29) that was not seen in the placebo group (0.77 to 0.79 mmol/L), but was only statistically significant (p = 0.02)) in a subgroup of non-athletes. Magnesium urinary excretion increased from baseline slightly in the Mg²⁺ group but with no statistical significance (p = 0.48). The Mg²⁺ group showed an 8.54% increase in serum Mg²⁺ and a 9.1% increase in urinary Mg²⁺ while these figures for the placebo group were smaller, i.e. +2.6% for serum Mg²⁺ and -32% for urinary Mg^2+. In the placebo group, both serum and urine concentrations showed no statistically significant change after the application of the placebo cream.

Conclusion

No previous studies have looked at transdermal absorbency of Mg²⁺ in human subjects. In this pilot study, transdermal delivery of 56 mg Mg/day (a low dose compared with commercial transdermal Mg²⁺ products available) showed a larger percentage rise in both serum and urinary markers from pre to post intervention compared with subjects using the placebo cream, but statistical significance was achieved only for serum Mg²⁺ in a subgroup of non-athletes. Future studies should look at higher dosage of magnesium cream for longer durations.

Trial registration

ISRCTN registry ID No. ISRTN15136969

Food and plant bioactives for reducing cardiometabolic disease risk: an evidence based approach

Nutraceuticals active on the main cardiovascular disease risk factors.

Review of epidemiological studies on drinking water hardness and cardiovascular diseases

BACKGROUND

Major risk factors do not entirely explain the worldwide variability of morbidity and mortality due to cardiovascular disease. Environmental exposures, including drinking water minerals may affect cardiovascular disease risks.

METHOD

We conducted a qualitative review of the epidemiological studies of cardiovascular disease and drinking water hardness and calcium and magnesium levels.

RESULTS

Many but not all ecological studies found an inverse (i.e., protective) association between cardiovascular disease mortality and water hardness, calcium, or magnesium levels; but results are not consistent. Some case-control studies and one cohort study found either a reduced cardiovascular disease mortality risk with increased drinking water magnesium levels or an increased risk with low magnesium levels. However, the analytical studies provide little evidence that cardiovascular risks are associated with drinking water hardness or calcium levels.

CONCLUSION

Information from epidemiological and other studies supports the hypothesis that a low intake of magnesium may increase the risk of dying from, and possibly developing, cardiovascular disease or stroke. Thus, not removing magnesium from drinking water, or in certain situations increasing the magnesium intake from water, may be beneficial, especially for populations with an insufficient dietary intake of the mineral.

Effects of Magnesium Supplementation on Blood Pressure

The antihypertensive effect of magnesium (Mg) supplementation remains controversial. We aimed to quantify the effect of oral Mg supplementation on blood pressure (BP) by synthesizing available evidence from randomized, double-blind, placebo-controlled trials. We searched trials of Mg supplementation on normotensive and hypertensive adults published up to February 1, 2016 from MEDLINE and EMBASE databases; 34 trials involving 2028 participants were eligible for this meta-analysis. Weighted mean differences of changes in BP and serum Mg were calculated by random-effects meta-analysis. Mg supplementation at a median dose of 368 mg/d for a median duration of 3 months significantly reduced systolic BP by 2.00 mm Hg (95% confidence interval, 0.43–3.58) and diastolic BP by 1.78 mm Hg (95% confidence interval, 0.73–2.82); these reductions were accompanied by 0.05 mmol/L (95% confidence interval, 0.03, 0.07) elevation of serum Mg compared with placebo. Using a restricted cubic spline curve, we found that Mg supplementation with a dose of 300 mg/d or duration of 1 month is sufficient to elevate serum Mg and reduce BP; and serum Mg was negatively associated with diastolic BP but not systolic BP (all P <0.05). In the stratified analyses, a greater reduction in BP tended to be found in trials with high quality or low dropout rate (all P values for interaction <0.05). However, residual heterogeneity may still exist after considering these possible factors. Our findings indicate a causal effect of Mg supplementation on lowering BPs in adults. Further well-designed trials are warranted to validate the BP-lowering efficacy of optimal Mg treatment.

The relationship between elevated magnesium levels and coronary artery ectasia

Backround

Coronary artery ectasia (CAE) without specific symptoms is the localised or diffuse swelling of the epicardial coronary arteries. Magnessium (Mg) plays an important role in cardiac excitability, vascular tonus, contractibility, reactivity and vasodilatation. In our research, we aimed to study the vasodilatory effect of Mg in the aetiopathogenesis of ectasia.

Methods

Patients identified during routine coronary angiograms in our clinic between January 2010 and 2013 were included in the study. Sixty-two patients with isolated CAE, 57 with normal coronary angiograms (NCA), 73 with severe coronary artery disease (CAD), and 95 with stenosis of at least one coronary artery and CAE (CAD + CAE) were included in the study. Serum Mg levels were measured in mg/ dl after 12 hours of fasting.

Results

There were no statistically significant differences between the groups in terms of age, hypertension, smoking, hyperlipidaemia, diabetes mellitus, family history of coronary artery disease and medications used. Serum glucose, thyroid stimulating hormone (TSH), urea, total cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, sodium and potassium levels were similar in all groups. Serum Mg levels were 1.90 ± 0.19 mg/dl in patients with isolated CAE, 1.75 ± 0.19 mg/dl in those with CAD, 1.83 ± 0.20 mg/dl in those with CAD + CAE, and 1.80 ± 0.16 mg/dl in the NCA group. These results show that Mg levels were higher in ectasia patients with or without CAD.

Conclusions

The histopathological characteristics of patients with CAE were similar to those with CAD. The specific mechanism of abnormal luminal dilatation seen in CAE however remains to be elucidated. Mg is a divalent cation with powerful vasodilatory effects. In our study, serum Mg levels were found to be statistically higher in ectasia patients with or without CAD.

Nutraceuticals with a clinically detectable blood pressure-lowering effect: a review of available randomized clinical trials and their meta-analyses

AIMS

The aim of the present study was to review and comment on the available evidence on nutraceuticals with a clinically demonstrable blood pressure (BP)-lowering effect.

METHODS

We reviewed studies published in the English language from 1990 to 2015 on dietary supplements or nutraceuticals claiming to show an effect on human BP. An initial list of possibly effective agents and studies was obtained from the online reference, the Natural Medicine Comprehensive Database. Using PubMed, we searched agents identified from this list using the MeSH terms 'hypertension', 'blood pressure', 'dietary supplement' and 'nutraceuticals', alone and in combination. We then focused our attention on meta-analyses and randomized clinical trials.

RESULTS

Beyond the well-known effects on BP of the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean diet, a large number of studies have investigated the possible BP-lowering effect of different dietary supplements and nutraceuticals, most of which are antioxidant agents with a high tolerability and safety profile. In particular, a relatively large body of evidence supports the use of potassium, magnesium, L-arginine, vitamin C, cocoa flavonoids, beetroot juice, coenzyme Q10, controlled-release melatonin and aged garlic extract. The antihypertensive effect of all these nutraceuticals seems to be dose related and the overall tolerability is good.

CONCLUSION

Some nutraceuticals might have a positive impact on BP in humans. Further clinical research is needed, to identify from the available active nutraceuticals those with the best cost-effectiveness and risk-benefit ratio for widespread and long-term use in the general population with a low-added cardiovascular risk related to uncomplicated hypertension.

Severe hypomagnesaemia causing reversible cerebellopathy

Hypomagnesaemia is common among hospitalised patients and is often under-recognised. Chronic alcohol abuse and alcohol withdrawal are known causes for severe hypomagnesaemia. Hypomagnesaemia can present with cardiac arrhythmias, seizures and other neurological symptoms, among which ataxia. We present a 57-year-old man with a history of chronic alcohol abuse who developed a subacute cerebellar syndrome with hypertension after alcohol withdrawal. A severe hypomagnesaemia of 0.19 mmol/L (normal values 0.70-1.10) was found. MRI showed diffuse, T2 hyperintense lesions in and swelling of the cerebellum. Symptoms, hypertension and MRI abnormalities significantly improved rapidly after intravenous magnesium supplementation. Hypomagnesaemia can cause a subacute, cerebellar syndrome and hypertension. Symptoms, hypertension and MRI abnormalities can be reversed with rapid magnesium supplementation. MRI abnormalities are similar to those caused by vascular endothelial dysregulation seen in posterior reversible encephalopathy syndrome (PRES). A similar case was recently described. We confirm that magnesium is likely to be involved in the pathophysiology of PRES.

The effect of acute vs chronic magnesium supplementation on exercise and recovery on resistance exercise, blood pressure and total peripheral resistance on normotensive adults

Background

Magnesium supplementation has previously shown reductions in blood pressure of up to 12 mmHg. A positive relationship between magnesium supplementation and performance gains in resistance exercise has also been seen. However, no previous studies have investigated loading strategies to optimise response. The aim of this study was to assess the effect of oral magnesium supplementation on resistance exercise and vascular response after intense exercise for an acute and chronic loading strategy on a 2-day repeat protocol.

Methods

The study was a randomised, double-blind, cross-over design, placebo controlled 2 day repeat measure protocol (n = 13). Intense exercise (40 km time trial) was followed by bench press at 80% 1RM to exhaustion, with blood pressure and total peripheral resistance (TPR) recorded. 300 mg/d elemental magnesium was supplemented for either a 1 (A) or 4 (Chr) week loading strategy. Food diaries were recorded.

Results

Dietary magnesium intake was above the Reference Nutrient Intake (RNI) for all groups. Bench press showed a significant increase of 17.7% (p = 0.031) for A on day 1. On day 2 A showed no decrease in performance whilst Chr showed a 32.1% decrease. On day 2 post-exercise systolic blood pressure (SBP) was significantly lower in both A (p = 0.0.47) and Chr (p = 0.016) groups. Diastolic blood pressure (DBP) showed significant decreases on day 2 solely for A (p = 0.047) with no changes in the Chr. TPR reduced for A on days 1 and 2 (p = 0.031) with Chr showing an increase on day 1 (p = 0.008) and no change on day 2.

Conclusion

There was no cumulative effect of Chr supplementation compared to A. A group showed improvement for bench press concurring with previous research which was not seen in Chr. On day 2 A showed a small non-significant increase but not a decrement as expected with Chr showing a decrease. DBP showed reductions in both Chr and A loading, agreeing with previous literature. This is suggestive of a different mechanism for BP reduction than for muscular strength. TPR showed greater reductions with A than Chr, which would not be expected as both interventions had reductions in BP, which is associated with TPR.

Nutraceuticals and Blood Pressure Control: Results from Clinical Trials and Meta-Analyses

Beyond the well-known effects on blood pressure (BP) of the dietary approaches to stop hypertension (DASH) and the Mediterranean diets, a large number of studies has investigated the possible BP lowering effect of different dietary supplements and nutraceuticals, the most part of them being antioxidant agents with a high tolerability and safety profile. In particular relatively large body of evidence support the use of potassium, L-arginine, vitamin C, cocoa flavonoids, beetroot juice, coenzyme Q10, controlled-release melatonin, and aged garlic extract. However there is a need for data about the long-term safety of a large part of the above discussed products. Moreover further clinical research is advisable to identify between the available active nutraceuticals those with the best cost-effectiveness and risk-benefit ratio for a large use in general population with low-added cardiovascular risk related to uncomplicated hypertension.

Lower serum magnesium is associated with cardiovascular risk factors and mortality in haemodialysis patients

BACKGROUND

Hypomagnesaemia is a cardiovascular (CV) risk factor in the general population. The aim of this study was to evaluate the relationship between pre-dialysis magnesium (Mg) and CV risk markers, [including pulse pressure (PP), left ventricular mass index (LVMI) and vascular calcifications (VC)], and mortality in haemodialysis (HD) patients.

METHODS

We performed a 48-month prospective study in 206 patients under pre-dilution haemodiafiltration with a dialysate Mg concentration of 1 mmol/l.

RESULTS

Lower Mg concentrations were predictors of an increased PP (≥65 mm Hg) (p = 0.002) and LVMI (≥140 g/m(2)) (p = 0.03) and of a higher VC score (≥3) (p = 0.01). Patients with Mg <1.15 mmol/l had a lower survival at the end of the study (p = 0.01). Serum Mg <1.15 mmol/l was an independent predictor of all-cause (p = 0.01) and CV mortality (p = 0.02) when adjusted for multiple CV risk factors.

CONCLUSIONS

Lower Mg levels seem to be associated with increased CV risk markers, like PP, LVMI and VC, and with higher mortality in HD patients.

Nutraceuticals for blood pressure control

Significant effects on blood pressure (BP) have been reported from large nutritional interventions, particularly the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean diet. In more recent years, numerous studies have investigated the possible BP-lowering effect of different nutraceuticals; these range from specific foods to minerals, lipids, whole proteins, peptides, amino acids, probiotics, and vitamins. While a very large body of evidence supports the use of potassium, L-arginine, vitamins C and D, cocoa flavonoids, beetroot juice, some probiotics, coenzyme Q10, controlled-release melatonin, aged garlic extract, and coffee, the use of other nutraceuticals, such as green tea, flaxseed, and resveratrol, has not as yet been supported by adequate evidence. In some cases, e.g. proteins/peptides, the responsible component needs also to be fully uncovered. Finally, while for most of the products only short-term studies are available, with no specific end-points, an ongoing very large prospective study on chocolate flavanols will answer the question whether this may reduce cardiovascular risk. Thus, in addition to data on long-term safety, further clinical research is advisable in order to identify, among active nutraceuticals, those with the best cost-effectiveness and risk-benefit ratio for a wide use in the general population with a raised cardiovascular risk consequent to uncomplicated hypertension.

Role of magnesium in cardiovascular diseases

Magnesium, the fourth most abundant cation in the human body, is involved in several essential physiological, biochemical, and cellular processes regulating cardiovascular function. It plays a critical role in modulating vascular smooth muscle tone, endothelial cell function, and myocardial excitability and is thus central to the pathogenesis of several cardiovascular disorders such as hypertension, atherosclerosis, coronary artery disease, congestive heart failure, and cardiac arrhythmias. This review discusses the vasodilatory, anti-inflammatory, anti-ischemic, and antiarrhythmic properties of magnesium and its current role in the prevention and treatment of cardiovascular disorders.

Prevalence of Hypomagnesaemia among Obese Type 2 Diabetic Patients Attending the National Center for Diabetes, Endocrinology and Genetics (NCDEG)

BACKGROUND

Some observations suggested that magnesium supplementation could be helpful in the treatment of diabetic patients by improving glycemic control and preventing the development of diabetes-related complications.

OBJECTIVES

To estimate the prevalence of hypomagnesaemia among obese patients with type 2 diabetes attending the National Center for Diabetes, Endocrinology and Genetics (NCDEG) in Amman, Jordan.

PATIENTS AND METHODS

A cross-sectional study was carried out at the National Center for diabetes, Endocrinology and Genetics (NCDEG) in Amman-Jordan. A total of 1105 patients with type 2 diabetes (51.9% females and 48.1% males) who attended this center between first of October 2011and end of February 2012 were included in the study. The mean age and duration of diabetes were 57.1 years and 5.1 years, respectively and the mean value of HbA1c was 7.9%. Our study also performed a comparison of the prevalence of hypomagnesaemia between our studied sample and 3600 individuals enrolled in the National Vitamin D study completed in Jordan in 2009. The obtained data included patients' age, gender, smoking history, HbA1c level, comorbid history including hypertension, dyslipidemia, and presence of neuropathy and retinopathy.

RESULTS

Out of 1105 patients with type 2 diabetes, 210 patients (19%) (95% CI, 16.8%-21.4%) were hypomagnesaemic. Female gender, hypertension, statin therapy, HbA1c between 7-7.9% or ≥ 9% and patients with diabetes duration more than five years were independent risk factors for hypomagnesaemia. No association between hypomagnesaemia and age distribution, smoking history, neuropathy and retinopathy was found. In comparison with individuals enrolled in the National Vitamin D study, diabetic patients in this study had a much higher prevalence of hypomagnesaemia (19% vs. 0.7%) with odd's ratio of 32 (95% CI, 21-48.2).

CONCLUSIONS

As the prevalence of hypomagnesaemia among patients with type 2 diabetes treated at the NCDEG was found to be 19% (95% CI, 16.8%-21.4%), we recommend periodic determination of magnesium level and appropriate magnesium replacement therapy particularly among the above defined groups.

The role of nutrition and nutraceutical supplements in the treatment of hypertension

Vascular biology, endothelial and vascular smooth muscle and cardiac dysfunction play a primary role in the initiation and perpetuation of hypertension, cardiovascular disease and target organ damage. Nutrient-gene interactions and epigenetics are predominant factors in promoting beneficial or detrimental effects in cardiovascular health and hypertension. Macronutrients and micronutrients can prevent, control and treat hypertension through numerous mechanisms related to vascular biology. Oxidative stress, inflammation and autoimmune dysfunction initiate and propagate hypertension and cardiovascular disease. There is a role for the selected use of single and component nutraceutical supplements, vitamins, antioxidants and minerals in the treatment of hypertension based on scientifically controlled studies which complement optimal nutrition, coupled with other lifestyle modifications.

Hypomagnesemia and prehypertension in otherwise healthy individuals

BACKGROUND

Given the potential implications in the policies focused on the prevention of hypertension, we evaluate the relationship between low serum magnesium levels and prehypertension in otherwise healthy subjects.

METHODS

A cross-sectional study that enrolled 175 healthy men and non-pregnant women, 20 to 65 years of age was carried out. Type 2 diabetes, impaired fasting glucose, hypertension, chronic diarrhea, cancer, impaired renal function, as well as the intake of magnesium supplements in the previous six months, were the exclusion criteria. Hypomagnesemia was defined by serum magnesium concentration of <0.7 mmol/L and prehypertension by Systolic (S) and Diastolic (D) blood pressure (BP) of 120 to 139 and 80 to 89 mmHg. A multivariate logistic conditional forward analysis, adjusted by sex, age, alcohol consumption waist circumference, body mass index, fasting glucose and triglyceride levels was conducted to evaluate the association between hypomagnesemia and prehypertension.

RESULTS

Prehypertension was identified in 68 (13.2%) subjects who were compared with 107 (20.8%) control individuals without prehypertension. Individuals with prehypertension showed lower magnesium (0.73±0.20 vs. 0.77±0.21, p<0.001) and higher triglyceride levels (2.8±3.5 vs. 1.8±1.2, p=0.04) as compared with non-prehypertensive individuals. There were no other significant differences between the groups. The adjusted multivariate logistic conditional forward analysis showed a significant association between hypomagnesemia and prehypertension (OR 1.98; 95% CI 1.11-4.20, p=0.04).

CONCLUSIONS

Our finding suggests that low serum magnesium levels could play an important role in the pathophysiology of prehypertension in otherwise healthy subjects.

Evidence of clinically relevant efficacy for dietary supplements and nutraceuticals

Beyond the well-known effects on blood pressure (BP) of the DASH and the Mediterranean diets, a large number of studies have investigated the possible a BP-lowering effect from different dietary supplements and nutraceuticals, mostly antioxidant agents with a high tolerability and safety profile. In particular, a relatively large body of evidence support the use of potassium, L-arginine, vitamin C, cocoa flavonoids, coenzyme Q10, controlled-release melatonin, and aged garlic extract. However there is a need for data about the long-term safety of a large part of these products. Moreover, further clinical research is advisable to identify between the available active nutraceuticals and those with the best cost-effectiveness and risk-benefit ratio for widespread use in a general population with low added cardiovascular risk related to uncomplicated hypertension.

Pathogenetic role of magnesium deficiency in ophthalmic diseases

Magnesium is one of the most important regulatory cation involved in several biological processes. It is important for maintaining the structural and functional integrity of several vital ocular tissues such as cornea, lens and retina. The magnesium content of lens, especially in its peripheral part, is higher than that in aqueous and vitreous humor. Magnesium has also been shown to play critically important role in retinal functions. Magnesium plays significant role as a cofactor for more than 350 enzymes in the body and regulates neuroexcitability and several ion channels. Membrane associated ATPase functions that are crucial in regulating the intracellular ionic environment, are magnesium-dependent. Moreover, the enzymes involved in ATP production and hydrolysis are also magnesium-dependent. Magnesium deficiency by interfering with ATPase functions causes increased intracellular calcium and sodium and decreases intracellular potassium concentration. Such ionic imbalances in turn alter the other cellular enzymatic reactions and form the basis of the association of magnesium deficiency with ophthalmic diseases such as cataract. In presence of magnesium deficiency, an imbalance between mediators of vasoconstriction and vasorelaxation may underlie the vasospasm, which is one of the pathogenic factors in primary open angle glaucoma. Furthermore, magnesium deficiency is also a contributing factor in increased oxidative stress and inducible NOS stimulation that can further contribute in the initiation and progression of ocular pathologies such as cataract, glaucoma and diabetic retinopathy. In this paper we review the association of disturbances of magnesium homeostasis with several ophthalmic diseases.