Update on the assessment of magnesium status

Method validation of an inductively coupled plasma mass spectrometry (ICP-MS) assay for the analysis of magnesium, copper and zinc in red blood cells

Background

Laboratory measurements of trace elements such as magnesium (Mg), copper (Cu), and zinc (Zn) in red blood cells (RBCs) are essential for assessing nutritional status and diagnosing metal toxicity. The purpose of this study was to develop and validate an ICP-MS method for quantifying these elements in RBCs.

Methods

Packed RBCs were aliquoted and diluted in an alkaline diluent solution containing internal standards, 0.1 % Triton X-100, 0.1 % EDTA, and 1 % ammonium hydroxide. The resulting diluted specimen was analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to quantitatively determine the levels of Mg, Cu, and Zn. The method underwent validation for accuracy, precision, method comparison, linearity, analytical sensitivity, and carryover. Additionally, retrospective data were analyzed, and non-parametric reference intervals were calculated.

Results

Accuracy and linearity fell within the expected range of ≤±15 % for all analytes. Within-run, between-run, and total imprecision were ≤15 % coefficient of variation. All other validation experiments met the established acceptance criteria. Retrospective data analysis was conducted on patient samples using the method. The application of Tukey's HSD test for multiple comparisons revealed statistically significant mean differences (p < 0.05) in Mg, Cu, and Zn concentrations between all pairwise groups of age and sex, except for the mean Cu concentration in adult males versus females and the mean Mg concentrations in adult versus minor males.

Conclusions

The presented method was successfully validated and met the criteria for clinical use. Retrospective data analysis of patient results demonstrated the method's suitability for assessing nutritional deficiency and toxicity.

Effect of Magnesium on Ventricular Extrasystoles in Children

Magnesium (Mg) is a crucial element for cardiovascular system and its deficiency results in a variety of cardiac arrhythmias. The aim of this study is to determine the effect of oral Mg supplementation on the frequency of ventricular extrasystoles (VES) in children. Magnesium supplementation was given to 42 children who had VES without structural heart disease. Clinical, electrocardiographic, and Holter monitoring studies were reviewed. The mean baseline 24 h VES burden on Holter monitoring was 10.26% ± 4.13% and it was decreased to 6.62% ± 3.88% after. There was no significant difference between the pre-treatment serum Mg levels and the decrease in the frequency of VES. In conclusion, oral Mg therapy was found to be effective at suppressing VES in children regardless of serum Mg levels. Large and randomized studies are needed to demonstrate the effect of magnesium on VES suppression.

High serum magnesium level is associated with increased mortality in patients with sepsis: an international, multicenter retrospective study

Magnesium imbalances commonly exist in septic patients. However, the association of serum magnesium levels with mortality in septic patients remains uncertain. Herein, we elucidated the association between serum magnesium and all-cause mortality in septic patients from American and Chinese cohorts by analyzing data from 9099 patients in the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database and 1727 patients from a university-affiliated hospital' intensive care unit in China. Patients in both cohorts were categorized into five groups based on serum magnesium quintiles from the MIMIC-IV dataset. Patients with higher serum magnesium levels exhibited an increased risk of 28-day mortality in both cohorts. The restricted cubic spline (RCS) curves revealed a progressively elevated risk of 28-day mortality with increasing serum magnesium in MIMIC-IV cohort, while a J-shaped correlation was observed in institutional cohort. Our findings have validated the association between high serum magnesium and high mortality in sepsis across different races and medical conditions. Serum magnesium levels might be useful in identifying septic patients at higher mortality risk.

The Association between Magnesium Depletion Score and Hypertension in US Adults: Evidence from the National Health and Nutrition Examination Survey (2007-2018)

The magnesium depletion score (MDS) emerges as a new valuable predictor of the body's magnesium status index. This study aims to explore the link between MDS and hypertension (HTN) using the National Health and Nutrition Examination Survey (NHANES) data. A total of 9708 participants from NHANES (2007-2018) were enrolled to investigate MDS's connection with HTN. HTN was defined based on clinical guidelines. MDS classification (low, 0-1; middle, 2; high, 3-5) relied on alcohol consumption, diuretic use, proton-pump inhibitor (PPI) usage, and kidney disease. Multivariable logistic regression assessed MDS-HTN association. Subsequent analyses included interaction tests, subgroups, and sensitivity analysis. Each unit increase in MDS correlated with an 87% higher HTN risk (OR, 1.87; 95% CI, 1.64-2.13) after adjusting for confounders. High MDS participants exhibited significantly elevated HTN risk compared to low MDS counterparts (OR, 8.31; 95% CI, 4.81-14.36), with a significant trend across MDS groups (p < 0.001). Subgroup analyses supported a consistent positive correlation. Sensitivity analysis confirmed a robust association. The results indicated a positive correlation between MDS and the risk of developing HTN in US adults.

Association between magnesium deficiency score and sleep quality in adults: A population-based cross-sectional study

BACKGROUND

The association between magnesium status and sleep quality is unclear. The aim of this study was to determine the relationship between renal reabsorption-related magnesium depletion score (MDS) and sleep quality.

METHODS

This study was conducted through a cross-sectional survey of adults aged ≥20 years who participated in NHANES 2005-2014. We used weighted logistic regression to examine the association between MDS and sleep quality and performed trend tests to analyze for the presence of a dose-response relationship. Subgroup analyses were performed based on various sleep outcomes and covariates.

RESULTS

A total of 20,585 participants were included in the study, with a mean age of 48.8 years and 50.7 % female. After adjusting for all covariates, we found a graded dose-response relationship between MDS and sleep trouble as well as sleep disorder. Further analyses revealed a significant positive association between MDS and sleep apnea (OR = 3.01; 95 % CI 1.37-6.62), but no association with restless legs, insomnia or insufficient sleep. In addition, subgroup analyses revealed that middle-aged, male, obese, low magnesium intake, and depressed patients were more prone to sleep trouble and sleep disorder; interestingly, MDS was positively associated with excessive sleep in subjects ≥60 years and without depression.

CONCLUSIONS

Our study found a significant association between MDS and sleep quality, particularly sleep apnea, but adequate magnesium intake may be beneficial in mitigating this association. MDS may be associated with excessive sleep in older adults, but not with insufficient sleep or insomnia.

Application and Perspectives: Magnesium Materials in Bone Regeneration

The field of bone regeneration has always been a hot and difficult research area, and there is no perfect strategy at present. As a new type of biodegradable material, magnesium alloys have excellent mechanical properties and bone promoting ability. Compared with other inert metals, magnesium alloys have significant advantages and broad application prospects in the field of bone regeneration. By searching the official Web sites and databases of various funds, this paper summarizes the research status of magnesium composites in the field of bone regeneration and introduces the latest scientific research achievements and clinical transformations of scholars in various countries and regions, such as improving the corrosion resistance of magnesium alloys by adding coatings. Finally, this paper points out the current problems and challenges, aiming to provide ideas and help for the development of new strategies for the treatment of bone defects and fractures.

Higher Magnesium Depletion Score Increases the Risk of All-cause and Cardiovascular Mortality in Hypertension Participants

The magnesium depletion score (MDS) is a novel index utilized for evaluating body magnesium status. The present study intended to explore the association of MDS with mortality among hypertension (HTN) participants. In this cohort study, we utilized data from the National Health and Nutrition Examination Survey (NHANES) covering the years 2003 to 2018. MDS levels were categorized into three groups (lower: MDS = 0-1; middle: MDS = 2; higher: MDS = 3-5). Kaplan-Meier curves were employed to illustrate survival differences between groups with varying MDS levels. The relationship between MDS and mortality was assessed through weighted multivariate Cox regression models. Subgroup analyses, along with sensitivity analyses, were also conducted to further explore and validate the findings. This study encompassed 12,485 participants, recording 2537 all-cause deaths and 707 cardiovascular deaths. The Kaplan-Meier curves revealed that the higher MDS group had the highest rates of all-cause and cardiovascular death. (P < 0.001). Controlling for all confounding variables, participants belonging to the higher MDS group demonstrated a substantially elevated risk of mortality in comparison to the lower MDS group (all-cause mortality: hazard ratio (HR) = 1.31, 95% confidence interval (CI) 1.10-1.54; cardiovascular mortality: HR = 1.63, 95% CI 1.19-2.22). There were no interaction factors found in subgroup analyses that affected the relationship between MDS and mortality, except for cardiovascular disease. The findings were confirmed to be robust through further sensitivity analyses. Higher MDS levels independently predict an elevated risk of mortality among US adults with HTN. Therefore, MDS may serve as a cost-effective and widely available prognostic marker for HTN.

Buprenorphine induced opioid withdrawal syndrome relieved by adjunctive Magnesium: A clinical trial

INTRODUCTION

Precipitated opioid withdrawal syndrome (OWS) is a severe and intolerable situation that may occur by a pharmaceutical agent. Reactivation of inhibited N-methyl-d-aspartate (NMDA) receptor in person with prolonged opioid use can led to severe OWS. We conducted a double-blind, randomized clinical trial to assess the effect of magnesium sulfate (MGSO4) as an NMDA receptor antagonist on OWS.

MATERIALS AND METHODS

The study randomly divided forty patients with precipitated OWS due to partial agonist (buprenorphine) use referred to the emergency unit of Toxicology Department of Mashhad University of Medical Sciences, Iran; into two groups. The control group received conventional therapies, including clonidine 0.1 mg tablet each hour, intravenous infusion of 10 mg diazepam every 30 min, and IV paracetamol (Acetaminophen) 1 g, while the intervention group received 3 g of MGSO4 in 20 min and then 10 mg/kg/h up to 2 h, in addition to the conventional treatment. The clinical opiate withdrawal scale (COWS) evaluated OWS at the start of the treatment, 30 min, and 2 h later.

RESULTS

Both groups had similar demographic, opiate types, and COWS severity at the start of the intervention. COWS was lower in the intervention than the control group at 30 min (11.20 ± 2.86 and 14.65 ± 2.36, respectively, P = 0.002) and at 2 h (3.2 ± 1.61 and 11.25 ± 3.27, respectively, P < 0.001) after treatment. The intervention group received lesser doses of clonidine (0.12 ± 0.51 and 0.17 ± 0.45 mg, P = 0.003) and Diazepam (13.50 ± 5.87, 24.0 ± 6.80 mg, P = 0.001) than the control group. Serum magnesium levels raised from 1.71 ± 0.13 mmol/L to 2.73 ± 0.13 mmol/L in the intervention group.

CONCLUSION

Magnesium can significantly reduce the severity of OWS. Additional studies are required to confirm these results.

Dose response of running on blood biomarkers of wellness in generally healthy individuals

Exercise is effective toward delaying or preventing chronic disease, with a large body of evidence supporting its effectiveness. However, less is known about the specific healthspan-promoting effects of exercise on blood biomarkers in the disease-free population. In this work, we examine 23,237 generally healthy individuals who self-report varying weekly running volumes and compare them to 4,428 generally healthy sedentary individuals, as well as 82 professional endurance runners. We estimate the significance of differences among blood biomarkers for groups of increasing running levels using analysis of variance (ANOVA), adjusting for age, gender, and BMI. We attempt and add insight to our observational dataset analysis via two-sample Mendelian randomization (2S-MR) using large independent datasets. We find that self-reported running volume associates with biomarker signatures of improved wellness, with some serum markers apparently being principally modified by BMI, whereas others show a dose-effect with respect to running volume. We further detect hints of sexually dimorphic serum responses in oxygen transport and hormonal traits, and we also observe a tendency toward pronounced modifications in magnesium status in professional endurance athletes. Thus, our results further characterize blood biomarkers of exercise and metabolic health, particularly regarding dose-effect relationships, and better inform personalized advice for training and performance.

Influence of Isoflavones and Probiotics on Magnesium Status in Healthy Female Rats

Isoflavones and probiotics are promising nutrients for bone health, and magnesium (Mg) is essential for bone metabolism. This study aimed to determine the effects of daidzein, genistein and Lactobacillus acidophilus on the Mg status of healthy female rats. Forty-eight rats were randomly assigned to six groups, with the control group receiving a standard diet (AIN 93M). The remaining groups were fed the same diet with added ingredients such as tempeh flour; soy flour; pure daidzein and genistein; L. acidophilus or a combination of daidzein, genistein, and L. acidophilus. Tissue samples were collected after the eight-week intervention, and Mg concentrations were analysed using flame atomic absorption spectrometry. Myeloid and erythroid cells were determined using the haematoxylin and eosin bone staining method. Statistical analyses were conducted using one-way ANOVA with Tukey's post hoc test and Pearson's correlation coefficient. The threshold for significance was p < 0.05. Compared with the control group, adding tempeh to the diet of rats resulted in significant changes in Mg concentrations in various tissues, with a decrease in the kidneys and an increase in the fur. Although not statistically significant compared to the control group, the tempeh group showed increased Mg concentrations in the femur and spleen. The myeloid-to-erythroid cell ratio did not differ significantly among groups, but all intervention groups showed higher ratios than the control group. A strong negative correlation was observed between Mg concentrations in the kidneys and fur. Conversely, a positive correlation was identified between Mg concentrations in the pancreas and fur. Daily consumption of tempeh may improve Mg status in the organism. Intake of pure daidzein, genistein, or probiotic seems to have no effect on Mg concentrations in healthy rats.

Association of Magnesium Depletion Score With Cardiovascular Disease and Its Association With Longitudinal Mortality in Patients With Cardiovascular Disease

Background Dietary magnesium and serum magnesium play an important part in cardiovascular disease (CVD). However, the association between magnesium depletion score (MDS) and CVD development and prognosis remains unclear. This analysis examines the cross-sectional relationship between MDS and CVD, and the longitudinal association between MDS and all-cause and CVD mortality in individuals with CVD. Methods and Results In all, 42 711 individuals were selected from the National Health and Nutrition Examination Survey, including 5015 subjects with CVD. The association between MDS and total and individual CVDs was examined using the survey-weighted multiple logistic regression analysis. Among 5011 patients with CVD, 2285 and 927 participants were recorded with all-cause and CVD deaths, respectively. We applied survey-weighted Cox proportional hazards regression analyses to investigate the impact of MDS on the mortality of individuals with CVD. The CVD group had higher MDS levels than the non-CVD groups. After controlling all confounding factors, individuals with MDS of 2 and ≥3 had higher odds of total CVD and specific CVD than those with MDS of 0. Besides, each 1-unit increase in MDS was strongly related to the risk of total CVD and specific CVD. The relationship between MDS and total CVD was stable and significant in all subgroups. The fully adjusted Cox regression model indicated that high MDS, irrespective of MDS as a categorical or continuous variable, was significantly associated with an elevated risk of all-cause and CVD deaths. Conclusions MDS is a vital risk factor for the prevalence and mortality of individuals with CVD.

Longitudinal plasma magnesium status during pregnancy and the risk of gestational diabetes mellitus: a prospective cohort study

Emerging evidence has shown that magnesium (Mg) was associated with type 2 diabetes while few focused on abnormal glucose metabolism during pregnancy. The study is aimed at investigating the association between longitudinal changes in plasma Mg during pregnancy and subsequent risk of gestational diabetes (GDM) and exploring the possible influence of iron supplementation on the changes of plasma Mg levels. One thousand seven hundred fifty-six pregnant women from Tongji Maternal and Child Health Cohort (TMCHC) were involved. Blood samples were collected at gestational weeks 17.0 ± 0.9 and later 26.2 ± 1.4. Plasma Mg was measured by inductively coupled plasma mass spectrometry (ICP-MS) with decline rates calculated. Information on general characteristics and iron supplementation was collected by questionnaires. Oral glucose tolerance test (OGTT) was conducted at 24-28 gestational weeks to diagnose GDM. Poisson regression with robust error variance was used to estimate relative risks (RR) of GDM. Median concentrations of plasma Mg were 0.69 mmol/L and 0.63 mmol/L respectively at two collections. The prevalence of hypomagnesemia at the first collection was 73% and associated with a 1.59 (95%CI: 1.07, 2.37) fold risk of GDM. Adjusted RRs were 1.74 (95%CI: 1.06, 2.83) and 2.44 (95%CI: 1.54, 3.85) for women with hypomagnesemia and followed more tertile (T2 and T3 vs. T1) of Mg decrement. Iron supplementation above 30 mg/day was found associated with more Mg decrement (25.5% and 27.5% in T2 and T3 vs. 19.5% in T1). In conclusion, hypomagnesemia during pregnancy is prevalent and associated with increased GDM risk, especially in women followed by more plasma Mg decrement during pregnancy. High-dose iron supplementation may involve more plasma Mg decrement.

Physiology of a Forgotten Electrolyte-Magnesium Disorders

Magnesium (Mg²⁺) is the second most common intracellular cation and the fourth most abundant element on earth. However, Mg²⁺ is a frequently overlooked electrolyte and often not measured in patients. While hypomagnesemia is common in 15% of the general population, hypermagnesemia is typically only found in preeclamptic women after Mg²⁺ therapy and in patients with ESRD. Mild to moderate hypomagnesemia has been associated with hypertension, metabolic syndrome, type 2 diabetes mellitus, CKD, and cancer. Nutritional Mg²⁺ intake and enteral Mg²⁺ absorption are important for Mg²⁺ homeostasis, but the kidneys are the key regulators of Mg²⁺ homeostasis by limiting urinary excretion to less than 4% while the gastrointestinal tract loses over 50% of the Mg²⁺ intake in the feces. Here, we review the physiological relevance of Mg²⁺, the current knowledge of Mg²⁺ absorption in the kidneys and the gut, the different causes of hypomagnesemia, and a diagnostic approach on how to assess Mg²⁺ status. We highlight the latest discoveries of monogenetic conditions causing hypomagnesemia, which have enhanced our understanding of tubular Mg²⁺ absorption. We will also discuss external and iatrogenic causes of hypomagnesemia and advances in the treatment of hypomagnesemia.

Magnesium Depletion Score is Associated with Long-Term Mortality in Chronic Kidney Diseases: A Prospective Population-Based Cohort Study

BACKGROUND

Magnesium deficiency is common in patients with chronic kidney diseases (CKD) due to restricted magnesium intake and impaired magnesium reabsorption. Based on pathophysiological risk factors influencing kidney magnesium reabsorption, a magnesium depletion score (MDS) was developed. Using MDS as a novel indicator for assessing body magnesium status, we hypothesized that it was associated with clinical prognosis.

METHODS

We conducted a prospective population-based cohort study using data from the National Health and Nutrition Examination Survey 1999-2014 to explore the impact of MDS on the clinical outcomes of CKD patients. Propensity score-matched analyses were conducted to increase comparability. The primary outcome was all-cause mortality, and the secondary outcomes were cardiovascular-cause and cancer-cause mortality.

RESULTS

After propensity score matching, 3294 CKD patients were divided into 2 groups: MDS ≤ 2 (N = 1647), and MDS > 2 (N = 1647). During a median follow-up of 75 months, Kaplan-Meier analyses showed that MDS > 2 was associated with worse 5- and 10-year overall survival (78.5% vs 73.4%; 53.1% vs 43.1%, P < 0.001). After adjusting for confounding variables, MDS was found to be an independent risk factor for all-cause mortality (HR:1.34, 95% CI 1.20-1.50, P < 0.001). MDS > 2 was also associated with higher cardiovascular-cause mortality (16.2% VS 11.6%, P = 0.005). Multivariate competing risk analysis revealed that MDS > 2 was an independent risk factor (HR: 1.33, 95% CI 1.06-1.66, P = 0.012). Subgroup analyses reported that MDS > 2 increased all-cause mortality and cardiovascular-cause mortality only in patients with inadequate magnesium intake (P < 0.001, P < 0.001) but not in those with adequate intake (P = 0.068, P = 0.920).

CONCLUSIONS

A magnesium depletion score > 2 was independently associated with higher long-term cardiovascular-cause and all-cause mortality in CKD patients.

The Role of Hypomagnesemia in Cardiac Arrhythmias: A Clinical Perspective

The importance of magnesium (Mg2+), a micronutrient implicated in maintaining and establishing a normal heart rhythm, is still controversial. It is known that magnesium is the cofactor of 600 and the activator of another 200 enzymatic reactions in the human organism. Hypomagnesemia can be linked to many factors, causing disturbances in energy metabolism, ion channel exchanges, action potential alteration and myocardial cell instability, all mostly leading to ventricular arrhythmia. This review article focuses on identifying evidence-based implications of Mg2+ in cardiac arrhythmias. The main identified benefits of magnesemia correction are linked to controlling ventricular response in atrial fibrillation, decreasing the recurrence of ventricular ectopies and stopping episodes of the particular form of ventricular arrhythmia called torsade de pointes. Magnesium has also been described to have beneficial effects on the incidence of polymorphic ventricular tachycardia and supraventricular tachycardia. The implication of hypomagnesemia in the genesis of atrial fibrillation is well established; however, even if magnesium supplementation for rhythm control, cardioversion facility or cardioversion success/recurrence of AF after cardiac surgery and rate control during AF showed some benefit, it remains controversial. Although small randomised clinical trials showed a reduction in mortality when magnesium was administered to patients with acute myocardial infarction, the large randomised clinical trials failed to show any benefit of the administration of intravenous magnesium over placebo.

The kidney reabsorption-related Magnesium Depletion Score is associated with increased likelihood of abdominal aortic calcification among US adults

BACKGROUND

Kidney reabsorption has a vital role in magnesium homeostasis. This study aimed to determine the relationship between the kidney reabsorption-related magnesium depletion score (MDS) and abdominal aortic calcification (AAC).

METHODS

We obtained the data of 2640 individuals from the National Health and Nutrition Examination Survey (NHANES) database and analyzed the relationship between MDS and AAC scores. MDS is a scoring system developed to predict status of magnesium deficiency that fully considered the pathophysiological factors influencing the kidneys' reabsorption capability. AAC was quantified by the Kauppila score system based on dual-energy X-ray absorptiometry. We performed stratified analysis and multiple equation regression analysis. R and EmpowerStats were used for data analysis.

RESULTS

A total of 2640 participants were included with the mean AAC score of 1.47 ± 0.07. Participants in higher MDS tended to have higher AAC scores (MDS scored 0: 0.75 (0.56, 0.93), MDS scored 1: 1.02 (0.84, 1.21), MDS scored 2: 2.34 (1.80, 2.87), MDS scored 3: 3.19 (2.46, 3.92), MDS ≥ 4: 4.99 (3.49, 6.49)). Compared with those in the lowest MDS scored 0, the highest subgroup (MDS ≥ 4) was associated with a higher AAC score (β = 4.24, 95% CI: 2.78-5.70, p < 0.001), and the association was not altered (β = 1.81, 95% CI: 0.54-3.09, p = 0.002) after adjusting for numerous covariates. Subgroup analyses showed that stronger associations between MDS and AAC score were detected in adults with lower levels of magnesium intake and older (all p for interaction < 0.05).

CONCLUSIONS

The MDS is a promising tool for identifying individuals with magnesium deficiency status who may benefit from dietary magnesium supplementation to reduce the risks of AAC.

Magnesium Status and Ca/Mg Ratios in a Series of Children and Adolescents with Chronic Diseases

Magnesium (Mg) is an essential divalent cation involved in various enzymatic reactions that regulate vital biological functions. The main goal was to evaluate Mg status and its association with nutritional indicators in 78 children and adolescents with chronic diseases. We assessed anthropometric, biochemical, diet, body composition, and bone densitometry valuations. Serum Mg and Ca levels were determined using the standardized method and diet calcium (Ca) and Mg consumption by a prospective 72 h diet survey. Mean serum Ca (9.9 mg/dL), Mg (2.08 mg/dL) dietary Ca (102% DRI: Dietary Reference Intake), and Mg intake (105% DRI) were normal. A total of 45% had hypomagnesemia, 12% had hypermagnesemia, and 26% and 24% had inadequate and high Mg intake, respectively. Only 6% of patients had poor Mg intake and hypomagnesemia, and 54% and 90% of our series had an elevated serum Ca/Mg ratio > 4.70 (mean 4.79) and a low Ca/Mg intake ratio < 1.70 (mean 1.06), respectively. Both Ca/Mg ratios were linked with the risk of developing other chronic conditions such as cardiovascular disease, type 2 diabetes, syndrome metabolic, and even several cancers. Therefore, 79% of children and adolescents with chronic diseases were at elevated risk of having abnormal Mg status and developing other chronic illnesses.

Associations of the Dietary Magnesium Intake and Magnesium Depletion Score With Osteoporosis Among American Adults: Data From the National Health and Nutrition Examination Survey

Objectives

The study aimed to explore the associations between dietary magnesium (Mg) intake and magnesium depletion score (MDS) among American adults with osteoporosis.

Methods

The continuous data from the National Health and Nutrition Examination Survey 2005–2006, 2007–2008, 2009–2010, 2013–2014, and 2017–2018 were merged to ensure a large and representative sample and a total of 14,566 participants were enrolled for the analysis. The weighted multivariate linear regression model was performed to assess the linear relationship between dietary Mg intake and osteoporosis. Further, the non-linear relationship was also characterized by smooth curve fitting (SCF) and weighted generalized additive model (GAM). In addition, the odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations between the MDS and osteoporosis were assessed by weighted logistic regression models.

Results

After adjusting all covariates, the weighted multivariable linear regression models demonstrated that the dietary Mg intake negatively correlated with osteoporosis, especially in participants aged 55 years or older. In addition, the non-linear relationship characterized by SCF and weighted GAM showed that the dietary Mg intake presented an L-shaped association with osteoporosis among females aged 55 years or older. Moreover, the weighted logistic regression model demonstrated that compared with MDS 0, the OR between MDS ≥3 and osteoporosis was 2.987 (95% CI 1.904, 4.686) in the male-middle intake group. Moreover, compared with MDS 0, the ORs between MDS ≥3 and osteoporosis was 5.666 (95% CI 3.188, 10.069) in the female-low intake group and 1.691 (95% CI 1.394, 2.051) in the female-middle intake group.

Conclusion

The present study indicated that in people with a daily intake of Mg level below the recommended daily intake (RDI), the dietary Mg intake and Mg bioavailability represented by MDS have a negative correlation with osteoporosis. According to the results, the combination of MDS and dietary Mg intake may be more comprehensive and rigorous in screening the population with osteoporosis. Therefore, early monitoring and interventions for osteoporosis may be necessary for those with insufficient dietary Mg intake or high MDS scores.

Magnesium Status and Calcium/Magnesium Ratios in a Series of Cystic Fibrosis Patients

Magnesium (Mg) is an essential micronutrient that participates in various enzymatic reactions that regulate vital biological functions. The main aim was to assess the Mg status and its association with nutritional indicators in seventeen cystic fibrosis (CF) patients. The serum Mg and calcium (Ca) levels were determined using standardized methods and the dietary Mg intake by prospective 72 h dietary surveys. The mean serum Ca (2.45 mmol/L) and Mg (0.82 mmol/L) had normal levels, and the mean dietary intake of the Ca (127% DRI: Dietary Reference Intake) and Mg (125% DRI) were high. No patients had an abnormal serum Ca. A total of 47% of the subjects had hypomagnesemia and 12% insufficient Mg consumption. One patient had a serum Mg deficiency and inadequate Mg intake. A total of 47 and 82% of our series had a high serum Ca/Mg ratio of >4.70 (mean 4.89) and a low Ca/Mg intake ratio of <1.70 (mean 1.10), respectively. The likelihood of a high Ca/Mg ratio was 49 times higher in patients with a serum Mg deficiency than in normal serum Mg patients. Both Ca/Mg ratios were associated with the risk of developing cardiovascular disease (CVD), type 2 diabetes (T2D), metabolic syndrome (MetS), and even several cancers. Therefore, 53% of the CF patients were at high risk of a Mg deficiency and developing other chronic diseases.

The Role of Magnesium in the Pathogenesis of Metabolic Disorders

Magnesium (Mg) is an essential nutrient for maintaining vital physiological functions. It is involved in many fundamental processes, and Mg deficiency is often correlated with negative health outcomes. On the one hand, most western civilizations consume less than the recommended daily allowance of Mg. On the other hand, a growing body of evidence has indicated that chronic hypomagnesemia may be implicated in the pathogenesis of various metabolic disorders such as overweight and obesity, insulin resistance (IR) and type 2 diabetes mellitus (T2DM), hypertension (HTN), changes in lipid metabolism, and low-grade inflammation. High Mg intake with diet and/or supplementation seems to prevent chronic metabolic complications. The protective action of Mg may include limiting the adipose tissue accumulation, improving glucose and insulin metabolism, enhancing endothelium-dependent vasodilation, normalizing lipid profile, and attenuating inflammatory processes. Thus, it currently seems that Mg plays an important role in developing metabolic disorders associated with obesity, although more randomized controlled trials (RCTs) evaluating Mg supplementation strategies are needed. This work represents a review and synthesis of recent data on the role of Mg in the pathogenesis of metabolic disorders.

Associations between gene expression of magnesium transporters and glucose metabolism in pregnancy

BACKGROUND/PURPOSE

To assess the relationship between gene expressions of the magnesium transporters and glucose parameters in pregnant women.

METHODS

A cohort of women without ongoing or prior medical illnesses was recruited at the start of an early singleton pregnancy. Expression levels of the magnesium transporters-SLC41A1, CNNM2, MAGT1, TRPM6, and TRPM7-were assessed in the peripheral leukocytes, while total calcium and magnesium were assessed in the serum between 10 and 13 weeks gestation. Glucose parameters were assessed between 24 and 28 weeks gestation using the 75 g oral glucose tolerance test.

RESULTS

A total of 208 patients were included in the study. The expressions of the magnesium transports were generally unrelated to age, body mass index (BMI), or serum levels of calcium and magnesium. The magnesium transporters were correlated with each other at baseline (correlation coefficients: 0.31 to 0.51). BMI was a strong predictor of fasting glucose levels, while both BMI and age were strong predictors of post-load glucose levels. The expression of TRPM7 was found to be predictive of 1-h post-load blood glucose after accounting for the effects of age and BMI (β = -0.196, p = 0.020).

CONCLUSION

The increased maternal expression of the magnesium transporter TRPM7 may be associated with decreased glucose tolerance in pregnant women. In particular, the association between TRPM7 and 1-h post-load glucose levels was found to be independent of the effects of age and BMI. Future studies are needed to determine whether a mechanistic relationship can be demonstrated between TRPM7 and glucose metabolism.

The relevance of magnesium homeostasis in COVID-19

Purpose

In less than one and a half year, the COVID-19 pandemic has nearly brought to a collapse our health care and economic systems. The scientific research community has concentrated all possible efforts to understand the pathogenesis of this complex disease, and several groups have recently emphasized recommendations for nutritional support in COVID-19 patients. In this scoping review, we aim at encouraging a deeper appreciation of magnesium in clinical nutrition, in view of the vital role of magnesium and the numerous links between the pathophysiology of SARS-CoV-2 infection and magnesium-dependent functions.

Methods

By searching PubMed and Google Scholar from 1990 to date, we review existing evidence from experimental and clinical studies on the role of magnesium in chronic non-communicable diseases and infectious diseases, and we focus on recent reports of alterations of magnesium homeostasis in COVID-19 patients and their association with disease outcomes. Importantly, we conduct a census on ongoing clinical trials specifically dedicated to disclosing the role of magnesium in COVID-19.

Results

Despite many methodological limitations, existing data seem to corroborate an association between deranged magnesium homeostasis and COVID-19, and call for further and better studies to explore the prophylactic or therapeutic potential of magnesium supplementation.

Conclusion

We propose to reconsider the relevance of magnesium, frequently overlooked in clinical practice. Therefore, magnesemia should be monitored and, in case of imbalanced magnesium homeostasis, an appropriate nutritional regimen or supplementation might contribute to protect against SARS-CoV-2 infection, reduce severity of COVID-19 symptoms and facilitate the recovery after the acute phase.

Increased Mortality Associated with Hypermagnesemia in Severe COVID-19 Illness

Background

Although electrolyte abnormalities are common among patients with COVID-19, very little has been reported on magnesium homeostasis in these patients. Here we report the incidence of hypermagnesemia, and its association with outcomes among patients admitted with COVID-19.

Methods

We retrospectively identified all patients with a positive test result for SARS-CoV-2 who were admitted to a large quaternary care center in New York City in spring 2020. Details of the patients' demographics and hospital course were obtained retrospectively from medical records. Patients were defined as having hypermagnesemia if their median magnesium over the course of their hospitalization was >2.4 mg/dl.

Results

A total of 1685 patients hospitalized with COVID-19 had their magnesium levels checked during their hospitalization, and were included in the final study cohort, among whom 355 (21%) had hypermagnesemia. Patients who were hypermagnesemic had a higher incidence of shock requiring pressors (35% vs 27%, P<0.01), respiratory failure requiring mechanical ventilation (28% vs 21%, P=0.01), AKI (65% vs 50%, P<0.001), and AKI severe enough to require renal replacement therapy (18% vs 5%, P<0.001). In an adjusted multivariable model, hypermagnesemia was observed more commonly with increasing age, male sex, AKI requiring RRT, hyperkalemia, and higher CPK. Survival probability at 30 days was 34% for the patients with hypermagnesemia, compared with 65% for patients without hypermagnesemia. An adjusted multivariable time to event analysis identified an increased risk of mortality with older age, need for vasopressors, higher C-reactive protein levels, and hypermagnesemia (HR, 2.03; 95% CI, 1.63 to 2.54, P<0.001).

Conclusions

In conclusion, we identified an association between hypermagnesemia among patients hospitalized with COVID-19 and increased mortality. Although the exact mechanism of this relationship remains unclear, hypermagnesemia potentially represents increased cell turnover and higher severity of illness, which is frequently associated with more severe forms of AKI.

Magnesium Deficiency Alters Expression of Genes Critical for Muscle Magnesium Homeostasis and Physiology in Mice

Chronic Mg²⁺ deficiency is the underlying cause of a broad range of health dysfunctions. As 25% of body Mg²⁺ is located in the skeletal muscle, Mg²⁺ transport and homeostasis systems (MgTHs) in the muscle are critical for whole-body Mg²⁺ homeostasis. In the present study, we assessed whether Mg²⁺ deficiency alters muscle fiber characteristics and major pathways regulating muscle physiology. C57BL/6J mice received either a control, mildly, or severely Mg²⁺-deficient diet (0.1%; 0.01%; and 0.003% Mg²⁺ wt/wt, respectively) for 14 days. Mg²⁺ deficiency slightly decreased body weight gain and muscle Mg²⁺ concentrations but was not associated with detectable variations in gastrocnemius muscle weight, fiber morphometry, and capillarization. Nonetheless, muscles exhibited decreased expression of several MgTHs (MagT1, CNNM2, CNNM4, and TRPM6). Moreover, TaqMan low-density array (TLDA) analyses further revealed that, before the emergence of major muscle dysfunctions, even a mild Mg²⁺ deficiency was sufficient to alter the expression of genes critical for muscle physiology, including energy metabolism, muscle regeneration, proteostasis, mitochondrial dynamics, and excitation–contraction coupling.

Magnesium Depletion Score (MDS) Predicts Risk of Systemic Inflammation and Cardiovascular Mortality among US Adults

BACKGROUND

Kidney reabsorption of magnesium (Mg) is essential for homeostasis.

OBJECTIVES

We developed and validated models with the kidney reabsorption-related magnesium depletion score (MDS) to predict states of magnesium deficiency and disease outcomes.

METHODS

MDS was validated in predicting body magnesium status among 77 adults (aged 62 ± 8 y, 51% men) at high risk of magnesium deficiency in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (registered at clinicaltrials.gov as NCT01105169) using the magnesium tolerance test (MTT). We then validated MDS for risk stratification and for associations with inflammation and mortality among >10,000 US adults (weighted: aged 48 ± 0.3 y, 47% men) in the NHANES, a nationally representative study. A proportional hazards regression model was used for associations between magnesium intake and the MDS with risks of total and cardiovascular disease (CVD) mortality.

RESULTS

In the PPCCT, the area under the receiver operating characteristic (ROC) curve (AUC) for magnesium deficiency was 0.63 (95% CI: 0.50, 0.76) for the model incorporating the MDS with sex and age compared with 0.53 (95% CI: 0.40, 0.67) for the model with serum magnesium alone. In the NHANES, mean serum C-reactive protein significantly increased with increasing MDS (P-trend < 0.01) after adjusting for age and sex and other covariates, primarily among individuals with magnesium intake less than the Estimated Average Requirement (EAR; P-trend < 0.05). Further, we found that low magnesium intake was longitudinally associated with increased risks of total and CVD mortality only among those with magnesium deficiency predicted by MDS. MDS was associated with increased risks of total and CVD mortality in a dose-response manner only among those with magnesium intake less than the EAR.

CONCLUSIONS

The MDS serves as a promising measure in identifying individuals with magnesium deficiency who may benefit from increased intake of magnesium to reduce risks of systemic inflammation and CVD mortality. This lays a foundation for precision-based nutritional interventions.

Functional Frailty, Dietary Intake, and Risk of Malnutrition. Are Nutrients Involved in Muscle Synthesis the Key for Frailty Prevention?

Frailty is a reversible condition, which is strongly related to physical function and nutritional status. Different scales are used to screened older adults and their risk of being frail, however, Short Physical Performance Battery (SPPB) may be more adequate than others to measure physical function in exercise interventions and has been less studied. Thus, the main aims of our study were: (1) to describe differences in nutritional intakes by SPPB groups (robust, pre-frail and frail); (2) to study the relationship between being at risk of malnourishment and frailty; and (3) to describe differences in nutrient intake between those at risk of malnourishment and those without risk in the no-frail individuals. One hundred one participants (80.4 ± 6.0 year old) were included in this cross-sectional study. A validated semi-quantitative food frequency questionnaire was used to determine food intake and Mini Nutritional Assessment to determine malnutrition. Results revealed differences for the intake of carbohydrates, n-3 fatty acids (n3), and saturated fatty acids for frail, pre-frail, and robust individuals and differences in vitamin D intake between frail and robust (all p < 0.05). Those at risk of malnutrition were approximately 8 times more likely to be frail than those with no risk. Significant differences in nutrient intake were found between those at risk of malnourishment and those without risk, specifically in: protein, PUFA n-3, retinol, ascorbic acid, niacin equivalents, folic acid, magnesium, and potassium, respectively. Moreover, differences in alcohol were also observed showing higher intake for those at risk of malnourishment (all p < 0.05). In conclusion, nutrients related to muscle metabolism showed to have different intakes across SPPB physical function groups. The intake of these specific nutrients related with risk of malnourishment need to be promoted in order to prevent frailty.

A mini-review on ion fluxes that regulate NLRP3 inflammasome activation

The activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome can be induced by a wide spectrum of activators. This is unlikely achieved by the binding of different activators directly to the NLRP3 protein itself, as the activators found so far show different forms of chemical structures. Previous studies have shown that these activators can induce potassium ion (K+) and chloride ion (Cl-) efflux, calcium (Ca2+) and other ion mobilization, mitochondrial dysfunction, and lysosomal disruption, all of which are believed to cause NLRP3 inflammasome activation; how these events are induced by the activators and how they coordinate with each other in inducing the NLRP3 inflammasome activation are not fully understood. Increasing evidence suggests that the coordinated change of intracellular ion concentrations may be a common mechanism for the NLRP3 activation by different activators. In this mini-review, we present a brief summary of the current knowledge about how different ionic flows (including K+, sodium ion, Ca2+, magnesium ion, manganese ion, zinc ion, iron ion, and Cl-) are involved in regulating the NLRP3 inflammasome activation in macrophages.

EDTA as a chelating agent in quantitative 1H-NMR of biologically important ions

Biologically important ions such as Ca, K, Mg, Fe, and Zn play major roles in numerous biological processes, and their homeostatic balance is necessary for the maintenance of cellular activities. Sudden and severe loss in homeostasis of just one biologically important ion can cause a cascade of negative effects. The ability to quickly, accurately, and reliably quantify biologically important ions in samples of human bio-fluids is something that has been sorely lacking within the field of metabolomics. ¹H-NMR spectra. The foundation of our investigation was the a-priori knowledge that free ethylenediaminetetraacetic acid (EDTA) produces two clear single peaks on ¹H-NMR spectra, and that EDTA chelated to different ions produces unique ¹H-NMR spectral patterns due to 3D conformational changes in the chemical structure of chelated-EDTA and varying degrees of electronegativity. The aim of this study was to develop and test a ¹H-NMR-based method, with application specifically to the field of metabolomics, to quantify biologically important ions within the physiological pH range of 6.50-7.50 using EDTA as a chelating agent. Our method produced linear, accurate, precise, and repeatable results for Ca, Mg, and Zn; however, K and Fe did not chelate with EDTA.

Perspective: US Adult Magnesium Requirements Need Updating: Impacts of Rising Body Weights and Data-Derived Variance

Adequate magnesium intakes are associated with lower diabetes, hypertension, and cardiovascular disease (CVD) risk but are low in modern diets. Magnesium DRIs, estimated using standard reference body weights (SRBWs) lower than current mean US adult body weights (BWs), need revision. Magnesium DRIs assume variance at 10% CV, whereas balance study data suggests 20-30% CV. Here, estimated average requirements (EARs), the DRI measure estimating average magnesium requirements for healthy adults, were corrected using 2011-2014 mean US adult BWs. Magnesium EARs (in mg magnesium/d) increased 17% for men (330-350 to 386-409) and 25% for women (255-265 to 319-332). RDAs, the DRI measure meant to cover the magnesium needs of 98% of healthy adults, were calculated using BW-corrected EARs given 3 CV levels: 1) 10% (assumed in 1997 DRIs), 2) 20% (model-derived variance from USDA magnesium studies), and 3) 30% (using USDA plus older human magnesium balance data). BW-corrected magnesium RDAs (in mg magnesium/d) rose from 400-420 and 310-320 for men and women, respectively, to 1) 463-491 and 383-398 (16.5% and 23.5% increases), 2) 540-573 and 447-465 (35.5% and 44.5% increases), and 3) 617-654 and 511-531 (55% and 65.5% increases). These recalculations move magnesium intakes estimated to prevent disease into ranges found in traditional diets and to intake levels shown to lower hypertension, diabetes, and CVD risk. In conclusion, mean BW rises over the last ≥20 y and data-driven estimates of CV indicate that reliable US adult magnesium RDAs are ≥60-235 and 70-210 mg magnesium/d higher for men and women, respectively, than the current 1997 RDAs. US adult BMIs are <25 kg/m2 when calculated with SRBWs but >25 with actual mean BWs. Adjustments for rising BW are necessary for magnesium DRIs to remain useful tools for defining magnesium intake adequacy/deficiency.

Possibility of magnesium supplementation for supportive treatment in patients with COVID-19

Magnesium as an enzymatic activator is essential for various physiological functions such as cell cycle, metabolic regulation, muscle contraction, and vasomotor tone. A growing body of evidence supports that magnesium supplementation (mainly magnesium sulfate and magnesium oxide) prevents or treats various types of disorders or diseases related to respiratory system, reproductive system, nervous system, digestive system, and cardiovascular system as well as kidney injury, diabetes and cancer. The ongoing pandemic coronavirus disease 19 (COVID-19) characterized by respiratory tract symptoms with different degrees of important organ and tissue damages has attracted global attention. Particularly, effective drugs are still lacking in the COVID-19 therapy. In this review, we find and summarize the effectiveness of magnesium supplementation on the disorders or diseases, and provide a reference to the possibility of magnesium supplementation for supportive treatment in patients with COVID-19.

Urinary magnesium predicts risk of cardiovascular disease in Chronic Kidney Disease stage 1-4 patients

Observational studies on dietary or circulating magnesium and risk of cardiovascular disease (CVD) in Chronic Kidney Disease (CKD) stage 1-4 have reported no-to-modest inverse associations. 24 h Urinary magnesium concentration (24 h UMg), an indicator of intestinal magnesium absorption, may provide better insight into the connection of CKD progression. We examined 3179 participants aged 18-74 years with CKD stage 1-4 in the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE) study, a prospective population-based cohort study. Data were analysed using Spearman rank-order correlation coefficients for all comparisons. We also performed a time-to-event analysis of the data using the Kaplan-Meier survival model, Cox proportional hazard model and competing risk Fine and Gray subdistribution hazard model. During a median follow-up of 4.19 years (interquartile range, 3.43-5.09 years), when modelling end-stage renal disease (ESRD), CVD and death, 24 h UMg was associated with risk of CVD (HR, 1.612 (95% CI, 1.056-2.460)), while no significant association with ESRD and death endpoints could be detected. 24 h UMg risk variants display a modest association with CVD in CKD stage 1-4 patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03041987. Registered January 1, 2012. (retrospectively registered) (https://www.clinicaltrials.gov/ct2/show/NCT03041987?term=Chinese+Cohort+Study+of+Chronic+Kidney+Disease+%28C-STRIDE%29&rank=1).

Comparison of two methods for the assessment of intra-erythrocyte magnesium and its determinants: Results from the LifeLines cohort study

BACKGROUND

Direct methods for the assessment of intra-erythrocyte magnesium (dIEM) require extensive sample preparation, making them labor intensive. An alternative, less labor intensive method is indirect calculation of intra-erythrocyte magnesium (iIEM). We compared dIEM and iIEM and studied determinants of dIEM and iIEM, plasma magnesium and 24-h urinary magnesium excretion in a large population-based cohort study.

METHODS

dIEM and iIEM were measured using a validated inductively coupled plasma mass spectrometry (ICP-MS) method in 1669 individuals from the second screening from the LifeLines Cohort Study. We used linear regression analyses to study the determinants of IEM, plasma magnesium and 24-h urinary magnesium excretion.

RESULTS

Mean dIEM and iIEM were 0.20 ± 0.04 mmol/10¹² cells and 0.25 ± 0.04 mmol/10¹² cells, respectively. We found a strong correlation between dIEM and iIEM (r = 0.75). Passing-Bablok regression analyses showed an intercept of 0.015 (95% CI: 0.005; 0.023) and a slope of 1.157 (95% CI: 1.109; 1.210). In linear regression analyses, plasma levels of total- and LDL -cholesterol, and triglycerides were positively associated dIEM, iIEM, and plasma magnesium, while glucose and HbA1c were inversely associated with plasma magnesium.

CONCLUSIONS

We observed a strong correlation between dIEM and iIEM, suggesting that iIEM is a reliable alternative for the labor intensive dIEM method.

Higher Fibroblast Growth Factor 23 Levels Are Causally Associated With Lower Bone Mineral Density of Heel and Femoral Neck: Evidence From Two-Sample Mendelian Randomization Analysis

Background: Previous observational studies have indicated that high levels of fibroblast growth factor 23 (FGF23), a phosphoric hormone that inhibits calcitriol synthesis, in the blood is associated with the reduced bone mineral density (BMD); however, whether this association is causal remains unclear. In this study, we conducted a Mendelian Random (MR) study to investigate whether the genetic predisposition of higher FGF23 levels was causally associated with lower BMD in adults.

Methods: A two-sample MR was performed with five single nucleotide polymorphisms significantly associated with FGF23, selected as instrumental variables. Two-sample MR estimates were derived from summary-level data of large-sample genome-wide association studies for BMD and the levels of bone metabolism characteristics.

Results: The two-sample MR analysis showed that for every 1-unit increase in the log-transformed blood FGF23 level (pg/mL), the decreased levels of adult heel BMD (β = −0.201, se = 0.084, P = 0.016) and femoral neck BMD (β = −0.286, se = 0.126, P = 0.022) were noted, indicative of a causal relationship based on the inverse variance weighting method. However, FGF23 levels were not correlated with adult lumbar spine BMD (β = −0.166, se = 0.193, P = 0.389), and forearm BMD (β = −0.186, se = 0.366, P = 0.610). Moreover, the two-sample MR analysis suggested that there was no evidence for associations between FGF23 and adult calcium, phosphorus, 25(OH)D, creatinine, and magnesium levels.

Conclusions: This study suggests that there may be a causal relationship between blood FGF23 levels and BMD of the heel and femoral neck in adults; however, more investigations are necessary to determine whether FGF23 may be a potential biomarker and/or therapeutic target for diseases that affect bone mineralization.

Prediction of preterm labor by the level of serum magnesium using an optimized linear classifier

Background: This study investigates the possibility of predicting preterm labor by utilizing serum Magnesium level, BMI, and muscular cramp.

Methods: In this case-control study, 75 preterm and 75 term labor women are included. Different factors such as serum magnesium level, mother’s age, infant’s sex, mother’s Body Mass Index (BMI), infant’s weight, gravid, and muscular cramp experience are measured. Preterm labor is predicted by developing a linear discriminant model using Matlab, and the prediction accuracy is also computed.

Results: The results show that each of the studied variables has a significant correlation with preterm labor. The p-value between BMI and preterm labor is 0.005, and by including the muscular cramp, it becomes less than 0.001. The correlation between serum magnesium level and the preterm labor is less than 0.0001. Using these three significant variables, a linear discriminant function is developed, which improves the accuracy of predicting preterm labor.

Conclusion: The prediction error of preterm labor decreases from 31% (using only serum magnesium level) to 24% using the new proposed discriminant function. Based on this, it is suggested to use the optimized linear discriminant function to enhance the prediction of preterm labor, since the serum magnesium level cannot predict the preterm labor accurately.

Microstructure, mechanical properties, and degradation of Mg-Ag alloy after equal-channel angular pressing

Enhancing the strength of Mg-based biodegradable alloys without decreasing their corrosion resistance is a major engineering challenge. In addition, the growing demand for effective reduction of infections and inflammation after implant placement motivates the design of alloys with appropriate compositions or coatings. One promising alloying element is silver, whose antibacterial effect has long been known. Therefore, a Mg-4% Ag alloy was selected for this study. The alloy was investigated under three conditions: as-cast, after T4 treatment, and after T4 treatment with subsequent equal-channel angular pressing (ECAP) using a newly developed double-ECAP die, which offers an equivalent strain per pass of 1.6. The first pass through the double-ECAP die was conducted at 370 °C and the second at 330 °C using route B_C. The microstructure of the as-cast Mg-4% Ag consisted of large grains (several hundred microns) and a dendritic structure with micron-sized Mg₅₄Ag₁₇ precipitates. T4 heat treatment caused dissolution of the dendrites and formation of a solid solution without changing the grain size. Consequently, the ultimate compressive strength (UCS) was increased by approximately 30%, and the compressive strain at fracture reached approximately 23%. The compressive yield strength (CYS) remained nearly constant at approximately 30 MPa. Subsequent ECAP led to strong grain refinement (from 350 μm to 38 μm after one pass and 15 μm after two passes) and further increases in the CYS and UCS, to 45 and 300 MPa after the first pass and 62 and 325 MPa after the second pass, respectively. The as-cast alloy exhibited a very high degradation rate in a simulated body fluid at approximately 36 °C. The degradation rate of the alloy after T4 treatment was much lower. Subsequent ECAP had no significant effect on the degradation properties. Thus, it can be concluded that grain refinement has little effect on the degradation rate.

Blood Biomarker Profiling and Monitoring for High-Performance Physiology and Nutrition: Current Perspectives, Limitations and Recommendations

Blood test data were traditionally confined to the clinic for diagnostic purposes, but are now becoming more routinely used in many professional and elite high-performance settings as a physiological profiling and monitoring tool. A wealth of information based on robust research evidence can be gleaned from blood tests, including: the identification of iron, vitamin or energy deficiency; the identification of oxidative stress and inflammation; and the status of red blood cell populations. Serial blood test data can be used to monitor athletes and make inferences about the efficacy of training interventions, nutritional strategies or indeed the capacity to tolerate training load. Via a profiling and monitoring approach, blood biomarker measurement combined with contextual data has the potential to help athletes avoid injury and illness via adjustments to diet, training load and recovery strategies. Since wide inter-individual variability exists in many biomarkers, clinical population-based reference data can be of limited value in athletes, and statistical methods for longitudinal data are required to identify meaningful changes within an athlete. Data quality is often compromised by poor pre-analytic controls in sport settings. The biotechnology industry is rapidly evolving, providing new technologies and methods, some of which may be well suited to athlete applications in the future. This review provides current perspectives, limitations and recommendations for sports science and sports medicine practitioners using blood profiling and monitoring for nutrition and performance purposes.

A Direct Quantitative Analysis of Erythrocyte Intracellular Ionized Magnesium in Physiological and Pathological Conditions

Magnesium (Mg²⁺) is an endogenous cation that is involved in many essential biological reactions. Abnormal Mg²⁺ metabolisms in the body affect important physiological and pathological processes. However, most endogenous Mg²⁺ markers fail to represent body Mg²⁺ status; they are disadvantageous in terms of representational capacity, applied range, operational convenience, etc. In this article, we evaluated some of the most popular Mg²⁺ marker candidates. A logical model of the blood Mg²⁺ compartments was established, which consisted of unstable Mg²⁺ pools, representative Mg²⁺ pools, and conserved Mg²⁺ pools. These pools were based on the metabolic efficiency of Mg²⁺ in an acute Mg²⁺ intake test. The results of this study showed that only the erythrocyte intracellular ionized Mg²⁺ (RBC [Mg²⁺]_i), a representative Mg²⁺ pool, could effectively represent abnormal body Mg²⁺ metabolisms in various conditions, including dietary Mg²⁺ adjustments, aging and metabolic syndrome. These results suggest that RBC [Mg²⁺]_i might be a widely applicable marker of body Mg²⁺ levels. On unified technology platform and evaluation system, this research compared the representative capacities of RBC [Mg²⁺]_i, plasma Mg²⁺ concentration (plasma [Mg²⁺]), erythrocyte intracellular total Mg (RBC [Mg]_total) and Mg retention in rats and mice under various Mg²⁺-metabolism-related physiological and pathological conditions. Our technique for the direct quantitative analysis of RBC [Mg²⁺]_i may prove valuable for basic physiological research, dietary Mg²⁺ regulation, as well as clinical monitoring/intervention of Mg²⁺-metabolism-related pathology.

Magnesium status and attention deficit hyperactivity disorder (ADHD): A meta-analysis

Current research suggests conflicting evidence surrounding the association between serum magnesium levels and the diagnosis of attention deficit hyperactivity disorder (ADHD). This systematic review and meta-analysis aims to explore, summarize and quantify the published literature addressing this topic. We conducted an exhaustive literature search on Scopus and PubMed for all the relevant observational studies published up to August 2018. A meta-analysis using a random-effects model was used to summarize the overall association between serum magnesium level and ADHD from the available data. We identified seven studies which reported the mean and standard deviation (SD) of magnesium concentration in both ADHD and control groups. The random-effects meta-analysis showed that subjects with ADHD had 0.105 mmol/l (95% CI: -0.188, -0.022; P < 0.013) lower serum magnesium levels compared with to their healthy controls. Moreover, we observed striking and statistically significant heterogeneity among the included studies (I² = 96.2%, P = 0.0103). The evidence from this meta-analysis supports the theory that an inverse relationship between serum magnesium deficiency and ADHD exists. High heterogeneity amongst the included studies suggests that there is a residual need for observational and community-based studies to further investigate this issue.

Improved Magnesium Levels in Morbidly Obese Diabetic and Non-diabetic Patients After Modest Weight Loss

Serum magnesium (Mg) is reported to be reduced in individuals with obesity, hypertension, and diabetes mellitus and has been suggested as a marker for metabolic syndrome. We have studied changes in serum Mg concentrations in a group of obese patients (n = 92) with and without diabetes mellitus after weight loss induced by dieting and bariatric surgery. At inclusion, 11% (10/92) of the population had severe Mg deficiency (< 0.75 mmol/L) and median serum Mg was lower in diabetic (n = 20) compared to non-diabetic (n = 72) patients (p = 0.002). A weight loss of 10 kg after 8 weeks of lifestyle interventions was accompanied by increased serum Mg of about 5% in both diabetic and non-diabetic patients. Serum Mg remained stable thereafter in the non-diabetic patients, while it continued to increase in the diabetic patients after bariatric surgery. Six months after bariatric surgery, there was no significant difference in serum Mg concentration between the groups (p = 0.08). The optimal range of circulating Mg concentration is not known, but as even small increments in serum Mg are reported to lower the risk of cardiovascular and ischemic heart disease, our results are interesting in a public health perspective.

Magnesium and health outcomes: an umbrella review of systematic reviews and meta-analyses of observational and intervention studies

PURPOSE

To map and grade all health outcomes associated with magnesium (Mg) intake and supplementation using an umbrella review.

METHODS

Umbrella review of systematic reviews with meta-analyses of observational studies and randomized controlled trials (RCTs) using placebo/no intervention as control group. We assessed meta-analyses of observational studies based on random-effect summary effect sizes and their p values, 95% prediction intervals, heterogeneity, small-study effects and excess significance. For meta-analyses of RCTs, outcomes with a random-effect p value < 0.005 and a high-GRADE assessment were classified as strong evidence.

RESULTS

From 2048 abstracts, 16 meta-analyses and 55 independent outcomes were included (36 in RCTs and 19 in observational studies). In RCTs of Mg versus placebo/no active treatment, 12 over 36 outcomes reported significant results (p < 0.05). A strong evidence for decreased need for hospitalization in pregnancy and for decreased risk of frequency and intensity of migraine relapses in people with migraine was observed using the GRADE assessment. In observational studies, 9/19 outcomes were significant (p < 0.05). However, only one outcome presented highly suggestive evidence (lower incidence of type 2 diabetes in people with higher Mg intake at baseline) and one suggestive (lower incidence of stroke associated with higher Mg intake at baseline).

CONCLUSION

Strong evidence according to the GRADE suggests that Mg supplementation can decrease the risk of hospitalization in pregnant women and reduce the intensity/frequency of migraine. Higher Mg intake is associated with a decreased risk of type 2 diabetes and stroke with highly suggestive and suggestive evidence, respectively, in observational studies.

Elemental Metabolomics and Pregnancy Outcomes

Trace elements are important for human health and development. The body requires specific micronutrients to function, with aberrant changes associated with a variety of negative health outcomes. Despite this evidence, the status and function of micronutrients during pregnancy are relatively unknown and more information is required to ensure that women receive optimal intakes for foetal development. Changes in trace element status have been associated with pregnancy complications such as gestational diabetes mellitus (GDM), pre-eclampsia (PE), intrauterine growth restriction (IUGR), and preterm birth. Measuring micronutrients with methodologies such as elemental metabolomics, which involves the simultaneous quantification and characterisation of multiple elements, could provide insight into gestational disorders. Identifying unique and subtle micronutrient changes may highlight associated proteins that are affected underpinning the pathophysiology of these complications, leading to new means of disease diagnosis. This review will provide a comprehensive summary of micronutrient status during pregnancy, and their associations with gestational disorders. Furthermore, it will also comment on the potential use of elemental metabolomics as a technique for disease characterisation and prediction.

Ethnic Differences in Magnesium Intake in U.S. Older Adults: Findings from NHANES 2005⁻2016

Magnesium plays a crucial role in hundreds of bodily processes relevant to aging, but consumption of dietary magnesium intake has been shown to be inadequate in a large proportion of older adults. Identifying groups at risk of low magnesium intake is important for informing targeted advice. Using data from the National Health and Nutrition Examination Survey (NHANES) 2005–2016, we examined the association between ethnicity (Caucasian/African American/Hispanic/other) and magnesium intake in a large representative sample of U.S. older adults (≥65 y, n = 5682, mean (SD) 72.9 (0.10) y). Analyses adjusted for total energy intake and a range of relevant covariates. Overall, 83.3% of participants were not meeting the recommended level of dietary magnesium intake, ranging from 78.1% of other ethnic groups to 90.6% of African Americans. In the fully adjusted model, magnesium intake was lower among African American older adults (−13.0 mg/d, 95% CI: −18.8 to −7.2), and higher among Hispanics (14.0 mg/d, 95% CI: 7.5 to 20.5) and those from other ethnic groups (17.2, 95% CI: 3.8 to 30.5) compared with Caucasian older adults. These results highlight the need for targeted interventions to increase magnesium intake in U.S. older adults, with a focus on African Americans, in order to reduce the burden of morbidity and ethnic inequalities in health in later life.

[In vivo study of a novel micro-arc oxidation coated magnesium-zinc-calcium alloy scaffold/autologous bone particles repairing critical size bone defect in rabbit]

Objective

To evaluate the effect of a novel micro-arc oxidation (MAO) coated magnesium-zinc-calcium (Mg-Zn-Ca) alloy scaffold/autologous bone particles to repair critical size bone defect (CSD) in rabbit and explore the novel scaffold in vivo corrosion resistance and biocompatibility.

Methods

Seventy-two New Zealand white rabbits were randomly divided into 3 groups ( n=24), group A was uncoated Mg-Zn-Ca alloy scaffold group, group B was 10 μm MAO coated Mg-Zn-Ca alloy scaffold group, and group C was control group with only autologous bone graft. The animals were operated to obtain bilateral ulnar CSD (15 mm in length) models. The bone fragment was removed and minced into small particles and were filled into the scaffolds of groups A and B. Then, the scaffolds or autologous bone particles were replanted into the defects. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery (6 rabbits each group). The local subcutaneous pneumatosis was observed and recorded. The ulna defect healing was evaluated by X-ray image and Van Gieson staining. The X-ray images were assessed and scored by Lane-Sandhu criteria. The percentage of the lost volume of the scaffold (ΔV) and corrosion rate (CR) were calculated by the Micro-CT. The Mg ²⁺ and Ca ²⁺ concentrations were monitored during experiment and the rabbit liver, brain, kidney, and spleen were obtained to process HE staining at 12 weeks after surgery.

Results

The local subcutaneous pneumatosis in group B was less than that in group A at 2, 4, and 8 weeks after surgery, showing significant differences between 2 groups at 2 and 4 weeks after surgery ( P<0.05); and the local subcutaneous pneumatosis was significantly higher in group B than that in group A at 12 weeks after surgery ( P<0.05). The X-ray result showed that the score of group C was significantly higher than those of groups A and B at 4 and 8 weeks after surgery ( P<0.05), and the score of group B was significantly higher than that of group A at 8 weeks ( P<0.05). At 12 weeks after surgery, the scores of groups B and C were significantly higher than that of group A ( P<0.05). Meanwhile, the renew bone moulding of group B was better than that in group A at 12 weeks after surgery. Micro-CT showed that ΔV and CR in group B were significantly lower than those in group A ( P<0.05). Van Gieson staining showed that group B had better biocompatibility and osteanagenesis than group A. The Mg ²⁺ and Ca ²⁺ concentrations in serum showed no significant difference between groups during experiments ( P>0.05). And there was no obvious pathological changes in the liver, brain, kidney, and spleen of the 3 groups with HE staining at 12 weeks.

Conclusion

The MAO coated Mg-Zn-Ca alloy scaffold/autologous bone particles could be used to repair CSD effectively. At the same time, 10 μm MAO coating can effectively improve the osteanagenesis, corrosion resistance, and biocompatibility of Mg-Zn-Ca alloy scaffold.

Challenges in the Diagnosis of Magnesium Status

Magnesium is a critical mineral in the human body and is involved in ~80% of known metabolic functions. It is currently estimated that 60% of adults do not achieve the average dietary intake (ADI) and 45% of Americans are magnesium deficient, a condition associated with disease states like hypertension, diabetes, and neurological disorders, to name a few. Magnesium deficiency can be attributed to common dietary practices, medications, and farming techniques, along with estimates that the mineral content of vegetables has declined by as much as 80⁻90% in the last 100 years. However, despite this mineral's importance, it is poorly understood from several standpoints, not the least of which is its unique mechanism of absorption and sensitive compartmental handling in the body, making the determination of magnesium status difficult. The reliance on several popular sample assays has contributed to a great deal of confusion in the literature. This review will discuss causes of magnesium deficiency, absorption, handling, and compartmentalization in the body, highlighting the challenges this creates in determining magnesium status in both clinical and research settings.

Uromodulin regulates renal magnesium homeostasis through the ion channel transient receptor potential melastatin 6 (TRPM6)

Up to 15% of the population have mild to moderate chronic hypomagnesemia, which is associated with type 2 diabetes mellitus, hypertension, metabolic syndrome, and chronic kidney disease. The kidney is the key organ for magnesium homeostasis, but our understanding of renal magnesium regulation is very limited. Uromodulin (UMOD) is the most abundant urinary protein in humans, and here we report that UMOD has a role in renal magnesium homeostasis. Umod-knockout (Umod ^-/-) mice excreted more urinary magnesium than WT mice and displayed up-regulation of genes promoting magnesium absorption. The majority of magnesium is absorbed in the thick ascending limb. However, both mouse strains responded similarly to the diuretic agent furosemide, indicating appropriate function of the thick ascending limb in the Umod ^-/- mice. Magnesium absorption is fine-tuned in the distal convoluted tubule (DCT) via the apical magnesium channel transient receptor potential melastatin 6 (TRPM6). We observed decreased apical Trpm6 staining in the DCT of Umod ^-/- mice. Applying biotinylation assays and whole-cell patch-clamp recordings, we found that UMOD enhances TRPM6 cell-surface abundance and current density from the extracellular space. UMOD physically interacted with TRPM6 and thereby impaired dynamin-dependent TRPM6 endocytosis. WT mice fed a low-magnesium diet had an increased urinary UMOD secretion compared with the same mice on a regular diet. Our results suggest that increased urinary UMOD secretion in low-magnesium states reduces TRPM6 endocytosis and thereby up-regulates TRPM6 cell-surface abundance to defend against further urinary magnesium losses.

Role of Magnesium Deficiency in Promoting Atherosclerosis, Endothelial Dysfunction, and Arterial Stiffening as Risk Factors for Hypertension

Arterial hypertension is a disease with a complex pathogenesis. Despite considerable knowledge about this socially significant disease, the role of magnesium deficiency (MgD) as a risk factor is not fully understood. Magnesium is a natural calcium antagonist. It potentiates the production of local vasodilator mediators (prostacyclin and nitric oxide) and alters vascular responses to a variety of vasoactive substances (endothelin-1, angiotensin II, and catecholamines). MgD stimulates the production of aldosterone and potentiates vascular inflammatory response, while expression/activity of various antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase) and the levels of important antioxidants (vitamin C, vitamin E, and selenium) are decreased. Magnesium balances the effects of catecholamines in acute and chronic stress. MgD may be associated with the development of insulin resistance, hyperglycemia, and changes in lipid metabolism, which enhance atherosclerotic changes and arterial stiffness. Magnesium regulates collagen and elastin turnover in the vascular wall and matrix metalloproteinase activity. Magnesium helps to protect the elastic fibers from calcium deposition and maintains the elasticity of the vessels. Considering the numerous positive effects on a number of mechanisms related to arterial hypertension, consuming a healthy diet that provides the recommended amount of magnesium can be an appropriate strategy for helping control blood pressure.

Serum magnesium, phosphorus, and calcium levels and subclinical calcific aortic valve disease: A population-based study

BACKGROUND AND AIMS

Calcific aortic valve disease (CAVD) is the most common valve disease. Although micronutrients are known to contribute to cardiovascular disease, the relationship with CAVD remains poorly evaluated. We examined the association of serum levels of magnesium, phosphorus, and calcium with prevalence, incidence, and progression of aortic valve calcification (AVC).

METHODS

We conducted a prospective study in a population-based sample of Japanese men aged 40-79 years without known cardiovascular disease and chronic kidney disease at baseline, and quantified AVC from serial computed tomographic images with the Agatston method.

RESULTS

Of 938 participants at baseline (mean age, 63.7 ± 9.9 years), AVC prevalence was observed in 173 (18.4%). Of 596 participants without baseline AVC at follow-up (median duration, 5.1 years), AVC incidence was observed in 138 (23.2%). After adjustment for demographics, behaviors and cardiovascular risk factors, relative risks (95% confidence intervals) in the highest versus lowest categories of serum magnesium, phosphorus, and calcium were 0.62 (0.44-0.86), 1.45 (1.02-2.04), and 1.43 (0.95-2.15), respectively, for AVC prevalence and 0.62 (0.42-0.92), 1.93 (1.28-2.91), and 1.09 (0.77-1.55), respectively, for AVC incidence. Their linear trends of serum magnesium and phosphorus were also all statistically significant. Of 131 participants with baseline AVC, there was no association of any serum micronutrients with AVC progression.

CONCLUSIONS

Serum magnesium was inversely associated, while serum phosphorus was positively associated with AVC prevalence and incidence, suggesting that these serum micronutrients may be potential candidates for risk prediction or prevention of CAVD, and warranting further studies.

Survey of content of cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, mercury, sodium and zinc in chamomile and green tea leaves by electrothermal or flame atomizer atomic absorption spectrometry

Due to the simplicity of tea preparation (pouring hot water onto different dried herbs) and its high popularity as a beverage, monitoring and developing a screening methodology for detecting the metal content is very important. The concentrations of Cd, Ca, Cr, Cu, Fe, Pb, Mg, Mn, Hg, Na and Zn in 8 samples of green tea (Camellia sinesis) and in 11 samples chamomile (Matricaria chamomilla L.) purchased both at local herbal pharmacies and supermarkets were determined using electrothermal atomizer atomic absorption spectrometry (ETAAS) and flame atomizer atomic absorption spectrometry (FAAS). The found concentrations in chamomile were: Cd (0.008 – 284 mg kg−1), Ca (2.42 – 6.29%), Cr (0.91 – 6.92 mg kg−1), Cu (6.27 – 11.39 mg kg−1), Fe (133.5 – 534 mg kg−1), Pb (0.561 – 1.277 mg kg−1), Mg (2.27 – 3.73%), Mn (62.2 – 165.6 mg kg−1), Hg (0.660 – 1.346 μg kg−1), Na (0.91 – 1.28%) and Zn (63.37 – 108.5 mg kg−1), in green tea Cd (36.29 – 202.1 mg kg−1), Ca (2.77 – 6.40%), Cr (1.520 – 5.278 mg kg−1), Cu (9.354 – 22.56 mg kg−1), Fe (162.6 – 513.3 mg kg−1), Pb (1.808 – 4.770 mg kg−1), Mg (1.41 – 2.62 %), Mn (1.147 – 1.729 g kg−1), Hg (1.045 – 2.802 μg kg−1), Na (0.44 – 0.98%) and Zn (30.65 – 115.6 mg kg−1), respectively. Principal Component Analysis (PCA) was applied to identify factors (soil, climate and country of origin) influencing the content of the measured elements in herbal samples. The proposed methodology developed in this work was successfully applied to the detection of metals in herbal samples. The analysis showed that the content of toxic metals in green tea samples was significantly higher and very close to the maximum dose recommended by the World Health Organization (WHO).

Applications of Metals for Bone Regeneration

The regeneration of bone tissue is the main purpose of most therapies in dental medicine. For bone regeneration, calcium phosphate (CaP)-based substitute materials based on natural (allo- and xenografts) and synthetic origins (alloplastic materials) are applied for guiding the regeneration processes. The optimal bone substitute has to act as a substrate for bone ingrowth into a defect, as well as resorb in the time frame needed for complete regeneration up to the condition of restitution ad integrum. In this context, the modes of action of CaP-based substitute materials have been frequently investigated, where it has been shown that such materials strongly influence regenerative processes such as osteoblast growth or differentiation and also osteoclastic resorption due to different physicochemical properties of the materials. However, the material characteristics needed for the required ratio between new bone tissue formation and material degradation has not been found, until now. The addition of different substances such as collagen or growth factors and also of different cell types has already been tested but did not allow for sufficient or prompt application. Moreover, metals or metal ions are used differently as a basis or as supplement for different materials in the field of bone regeneration. Moreover, it has already been shown that different metal ions are integral components of bone tissue, playing functional roles in the physiological cellular environment as well as in the course of bone healing. The present review focuses on frequently used metals as integral parts of materials designed for bone regeneration, with the aim to provide an overview of currently existing knowledge about the effects of metals in the field of bone regeneration.