Reduction of blood pressure with oral magnesium supplementation in women with mild to moderate hypertension

Discover QTLs for the level of blood components in Shaoxing duck using GWAS and haplotype sharing analysis

Blood composition is indicative of health-related traits such as immunity and metabolism. The use of molecular genetics to investigate alterations in these attributes in laying ducks is a novel approach. Our objective was to employ genome - wide association studies (GWAS) and haplotype - sharing analysis to identify genomic regions and potential genes associated with 11 blood components in Shaoxing ducks. Our findings revealed 35 SNPs and 1 SNP associated with low-density lipoprotein cholesterol (LDL) and globulin (GLB), respectively. We identified 36 putative candidate genes for the LDL trait in close proximity to major QTLs and key loci. Based on their biochemical and physiological properties, TRA2A, NPY, ARHGEF26, DHX36, and AADAC are the strongest putative candidate genes. Through linkage disequilibrium analysis and haplotype sharing analysis, we identified three haplotypes and one haplotype, respectively, that were significantly linked with LDL and GLB. These haplotypes could be selected as potential candidate haplotypes for molecular breeding of Shaoxing ducks. Additionally, we utilized a bootstrap test to verify the reliability of GWAS with small experimental samples. The test can be accessed at https://github.com/xuwenwu24/Bootstrap-test.

Association and dose-response relationship of plasma magnesium with metabolic syndrome in Chinese adults older than 45 years

Purpose

Magnesium (Mg) is an essential nutrient for the maintenance of vital physiological functions. Magnesium deficiency is associated with diseases such as obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome (MetS); however, conclusions have been inconsistent, and there is a particular lack of evidence regarding this association in Chinese population older than 45 years. This study aimed to assess the association between plasma magnesium and the risk of MetS and its components, the dose-response relationship, and the threshold effect relationship in a Chinese population involving older than 45 years.

Methods

A total of 2,101 individuals were randomly selected from the China Nutrition and Health Surveillance (CNHS) (2015-2017) by considering monitoring points. We used the joint statement of the International Diabetes Federation (IDF) in 2009 to define participants with MetS. The plasma magnesium was tested by inductively coupled plasma mass spectrometry (ICP-MS). The logistic regression and restricted cubic spline (RCS) models were used to analyze the association and dose-response relationship between plasma Mg and MetS and its components.

Results

Compared with the lowest quintile (Q1) for plasma Mg, the odds ratios (ORs) and 95% confidence intervals (95% CI) for MetS, impaired fasting glucose (IFG), hypertension, and triglyceride (TG) elevation at the highest quintile (Q5) were 0.419 (0.301, 0.583), 0.303 (0.221, 0.415), 0.446 (0.322, 0.618), and 0.526 (0.384, 0.720), respectively, with all p < 0.05. However, in the components of decreased high-density lipoprotein cholesterol (HDL-C) and central obesity, no trend toward lowering with higher plasma magnesium was observed (p = 0.717, p = 0.865). These associations were not altered by further adjustment for potential confounding variables, including age, gender, education, nationality, area, residence, body mass index (BMI), and heart rate. The RCS analysis showed that, when plasma magnesium was lower than 0.85 mmol/L, the curve was leveled off, and then, the curve showed a decreasing trend with the increase in plasma magnesium.

Conclusion

Therefore, plasma Mg was negatively associated with MetS and its components (including IFG, hypertension, and elevated TG) in people older than 45 years. In addition, plasma Mg greater than or equal to 0.85 mmol/L, which is higher than the commonly used threshold of 0.75 mmol/L, may be protective against MetS and its components (including elevated FPG, elevated blood pressure, and elevated TG). More prospective studies, such as randomized controlled trials, are necessary to confirm the effective impact of Mg on MetS and its components. Plasma Mg levels in the MetS population older than 45 years require attention.

Genome-wide association study of 17 serum biochemical indicators in a chicken F2 resource population

BACKGROUND

Serum biochemical indicators are often regarded as direct reflections of animal metabolism and health. The molecular mechanisms underlying serum biochemical indicators metabolism of chicken (Gallus Gallus) have not been elucidated. Herein, we performed a genome-wide association study (GWAS) to identify the variation associated with serum biochemical indicators. The aim of this research was to broaden the understanding of the serum biochemical indicators in chickens.

RESULTS

A GWAS of serum biochemical indicators was carried out on 734 samples from an F2 Gushi× Anka chicken population. All chickens were genotyped by sequencing, 734 chickens and 321,314 variants were obtained after quality control. Based on these variants, a total of 236 single-nucleotide polymorphisms (SNPs) on 9 chicken chromosomes (GGAs) were identified to be significantly (-log10(P) > 5.72) associated with eight of seventeen serum biochemical indicators. Ten novel quantitative trait locis (QTLs) were identified for the 8 serum biochemical indicator traits of the F2 population. Literature mining revealed that the ALPL, BCHE, GGT2/GGT5 genes at loci GGA24, GGA9 and GGA15 might affect the alkaline phosphatase (AKP), cholinesterase (CHE) and γ-glutamyl transpeptidase (GGT) traits, respectively.

CONCLUSION

The findings of the present study may contribute to a better understanding of the molecular mechanisms of chicken serum biochemical indicator regulation and provide a theoretical basis for chicken breeding programs.

Magnesium and Hypertension: Decoding Novel Anti-hypertensives

Hypertension (HTN) is a complex multifactorial disease that is one of the most prevalent disorders in our modern world. It can lead to fatal complications like coronary artery disease (CAD) and congestive heart failure (CHF) in high-risk individuals. The silent nature of HTN also contributes to its immense caseload and, today, with a number of combinations and various antihypertensive agents, patient compliance is becoming increasingly difficult. This article has reviewed the role and mechanisms of magnesium (Mg) in reducing HTN in the human body so as to provide more information that may help include it as a mainstream antihypertensive regimen. This review has also shed light on the cardioprotective nature of Mg against pathologies like CHF with special mention to patient groups who are at high risk for low Mg levels. Many studies included in this article solidify the former link, but some also provide contradicting data.

The effect of magnesium supplementation on anthropometric indices: a systematic review and dose-response meta-analysis of clinical trials

The aim of this study was to determine the effects of Mg supplementation on anthropometric indices consisting of body weight, waist circumference (WC), BMI and body fat percentage. In this systematic review and dose–response meta-analysis, we searched PubMed, Cochrane Library, Scopus, Web of Science and Google Scholar from databases inception up to February 2020 for relevant randomised controlled trials. Quality of evidence was evaluated using the Cochrane Collaboration Tool. All the outcomes of this meta-analysis were pooled using the random effect model. Analysis of dose–response for Mg dosage was carried out using a fractional polynomial model. The systematic review and meta-analysis include twenty-eight randomised clinical trials, comprising 2013 participants. There were no significant changes in anthropometric indices after Mg supplementation in the overall analysis. However, subgroup analysis revealed that Mg supplementation decreases WC in subjects with BMI > 30 kg/m2 (obese) (twelve trials, n 997 participants; weighted mean difference = –2·09 cm, 95 % CI –4·12, –0·07, P = 0·040; I2 = 0 %). Dose–response analysis revealed a non-significant non-linear effect of supplementation dosage on anthropometric indices. The results suggest that Mg supplementation is associated with lower WC only in obese subjects. However, more high-quality studies are needed to clarify the nature of this association.

Effectively Prescribing Oral Magnesium Therapy for Hypertension: A Categorized Systematic Review of 49 Clinical Trials

Trials and meta-analyses of oral magnesium for hypertension show promising but conflicting results. An inclusive collection of 49 oral magnesium for blood pressure (BP) trials were categorized into four groups: (1) Untreated Hypertensives; (2) Uncontrolled Hypertensives; (3) Controlled Hypertensives; (4) Normotensive subjects. Each group was tabulated by ascending magnesium dose. Studies reporting statistically significant (p < 0.05) decreases in both systolic BP (SBP) and diastolic BP (DBP) from both baseline and placebo (if reported) were labeled "Decrease"; all others were deemed "No Change." Results: Studies of Untreated Hypertensives (20 studies) showed BP "Decrease" only when Mg dose was >600 mg/day; <50% of the studies at 120-486 mg Mg/day showed SBP or DBP decreases but not both while others at this Mg dosage showed no change in either BP measure. In contrast, all magnesium doses (240-607 mg/day) showed "Decrease" in 10 studies on Uncontrolled Hypertensives. Controlled Hypertensives, Normotensives and "magnesium-replete" studies showed "No Change" even at high magnesium doses (>600 mg/day). Where magnesium did not lower BP, other cardiovascular risk factors showed improvement. Conclusion: Controlled Hypertensives and Normotensives do not show a BP-lowering effect with oral Mg therapy, but oral magnesium (≥240 mg/day) safely lowers BP in Uncontrolled Hypertensive patients taking antihypertensive medications, while >600 mg/day magnesium is required to safely lower BP in Untreated Hypertensives; <600 mg/day for non-medicated hypertensives may not lower both SBP and DBP but may safely achieve other risk factor improvements without antihypertensive medication side effects.

The effects of magnesium supplementation on obesity measures in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

Previous studies reported inconsistent findings regarding the effects of magnesium supplementation on obesity measures. This study was done to quantify the effect of magnesium supplementation on body weight, Body Mass Index (BMI), Waist Circumference (WC), Body Fat (BF) percentage and Waist to Hip Ratio (WHR). Four online databases (Scopus, PubMed, Google Scholar and Cochrane library) were searched until March 2020 using relevant keywords. Random-effects model was used to pool effect sizes; Cochran's Q-test and I2 index assessed heterogeneity. Sensitivity analysis and Egger test were used to check the robustness of findings and the possibility of publication bias, respectively. Thirty-two RCTs including different dosage of magnesium (48-450 mg/d), and duration (6-24 weeks) were entered to this study. Magnesium supplementation resulted in a great reduction in BMI [Weighted Mean Difference (WMD): -0.21 kg/m², 95% CI: -0.41, -0.001, P = 0.048, I² = 89.5%, n = 22], which was mainly driven by the effect among those with magnesium deficiency, insulin resistance related disorders, and obesity at baseline. No significant change was observed in bodyweight, WC, BF percentage and WHR as compared to controls. However, the change in body weight, and WC was significant in subgroups of participants with insulin resistance related disorders, hypertension, obesity, magnesium deficiency at baseline, and females. We found a significant reduction in BMI following magnesium supplementation. The change in body weight and WC were evident in certain subgroups.

Genome-wide association study of the level of blood components in Pekin ducks

Blood components are considered to reflect nutrient metabolism and immune activity in both humans and animals. In this study, we measured 12 blood components in Pekin ducks and performed genome-wide association analysis to identify the QTLs (quantitative trait locus) using a genotyping-by-sequencing strategy. A total of 54 QTLs were identified for blood components. One genome-wide significant QTL for alkaline phosphatase was identified within the intron-region of the OTOG gene (P = 1.31E-07). Moreover, 21 genome-wide significant SNPs for the level of serum cholinesterase were identified on six different scaffolds. In addition, for serum calcium, one genome-wide significant QTL was identified in the upstream region of gene RAB11B. These results provide new markers for functional studies in Pekin ducks, and several candidate genes were identified, which may provide additional insights into specific mechanisms for blood metabolism in ducks and their potential application for duck breeding programs.

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.

Effect of magnesium supplementation on lipid profile: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

We performed a meta-analysis of randomized controlled trials (RCTs) in order to evaluate the effect of oral magnesium supplementation on lipid profile of both diabetic and non-diabetic individuals.

METHODS

PubMed-Medline, SCOPUS, Web of Science, and Google Scholar databases were searched (from inception to February 23, 2016) to identify RCTs evaluating the effect of magnesium on lipid concentrations. A random-effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate the impact of potential confounders on lipid concentrations.

RESULTS

Magnesium treatment was not found to significantly affect plasma concentrations of any of the lipid indices including total cholesterol (WMD 0.03 mmol/L, 95% CI -0.11, 0.16, p = 0.671), LDL-C (WMD -0.01 mmol/L, 95% CI -0.13, 0.11, p = 0.903), HDL-C (WMD 0.03 mmol/L, 95% CI -0.003, 0.06, p = 0.076), and triglycerides concentrations (WMD -0.10 mmol/L, 95% CI -0.25, 0.04, p = 0.149). In a subgroup analysis comparing studies with and without diabetes, no difference was observed between subgroups in terms of changes in plasma total cholesterol (p = 0.924), LDL-C (p = 0.161), HDL-C (p = 0.822), and triglyceride (p = 0.162) concentrations.

CONCLUSIONS

Results of the present meta-analysis indicated that magnesium supplementation showed no significant effects on the lipid profile of either diabetic or non-diabetic individuals.

Perspective: The Case for an Evidence-Based Reference Interval for Serum Magnesium: The Time Has Come

The 2015 Dietary Guidelines Advisory Committee indicated that magnesium was a shortfall nutrient that was underconsumed relative to the Estimated Average Requirement (EAR) for many Americans. Approximately 50% of Americans consume less than the EAR for magnesium, and some age groups consume substantially less. A growing body of literature from animal, epidemiologic, and clinical studies has demonstrated a varied pathologic role for magnesium deficiency that includes electrolyte, neurologic, musculoskeletal, and inflammatory disorders; osteoporosis; hypertension; cardiovascular diseases; metabolic syndrome; and diabetes. Studies have also demonstrated that magnesium deficiency is associated with several chronic diseases and that a reduced risk of these diseases is observed with higher magnesium intake or supplementation. Subclinical magnesium deficiency can exist despite the presentation of a normal status as defined within the current serum magnesium reference interval of 0.75-0.95 mmol/L. This reference interval was derived from data from NHANES I (1974), which was based on the distribution of serum magnesium in a normal population rather than clinical outcomes. What is needed is an evidenced-based serum magnesium reference interval that reflects optimal health and the current food environment and population. We present herein data from an array of scientific studies to support the perspective that subclinical deficiencies in magnesium exist, that they contribute to several chronic diseases, and that adopting a revised serum magnesium reference interval would improve clinical care and public health.

Low Serum Magnesium Levels and Its Association with High Blood Pressure in Children

OBJECTIVE

To evaluate the association of hypomagnesemia with prehypertension (preHTN) and hypertension in children.

STUDY DESIGN

A total of 3954 apparently healthy Mexican children were enrolled in a cross-sectional study. Exclusion criteria were type 2 diabetes; hepatic, renal, or endocrine disease; impaired fasting glucose; chronic diarrhea; and intake of vitamins or magnesium supplements in the previous 6 months. preHTN was defined by systolic and/or diastolic blood pressure ≥90th to <95th percentile and hypertension by systolic and/or diastolic blood pressure ≥95th percentile, according to age, sex, and height percentile. Hypomagnesemia was defined by serum magnesium concentration <1.8 mg/dL (<0.74 mmol/L). To control for potential sources of bias related to age, participants were allocated into 2 groups, aged 6-10 years and 11-15 years.

RESULTS

The prevalence of preHTN and hypertension was 12.2% and 6.4%, respectively, in children aged 6-10 years and 13.9% and 10.6% in those aged 11-15 years. Hypomagnesemia was identified in 59 children with preHTN (27.3%) and 52 (45.6%) with hypertension in the 6-10 year age group, and in 115 children with preHTN (36.0%) and 109 (49.6%) with hypertension in the 11-15 year age group. Adjusted multiple logistic regression analysis showed that in children in both age groups, hypomagnesemia was associated with both preHTN (6-10 years: OR, 2.18, P < .0005; 11-15 years: OR, 1.38, P = .018) and hypertension (6-10 years: OR, 4.87, P < .0005; 11-15 years: OR, 1.83, P = .0002).

CONCLUSION

Our results indicate that serum magnesium level <1.8 mg/dL is significantly associated with preHTN and hypertension in apparently healthy children.

Intakes of magnesium, potassium, and calcium and the risk of stroke among men

BACKGROUND

Intakes of magnesium, potassium, and calcium have been inversely associated with the incidence of hypertension, a known risk factor for stroke. However, only a few studies have examined intakes of these cations in relation to risk of stroke.

AIM

The aim of this study was to investigate whether high intake of magnesium, potassium, and calcium is associated with reduced stroke risk among men.

METHODS

We prospectively examined the associations between intakes of magnesium, potassium, and calcium from diet and supplements, and the risk of incident stroke among 42 669 men in the Health Professionals Follow-up Study, aged 40 to 75 years and free of diagnosed cardiovascular disease and cancer at baseline in 1986. We calculated the hazard ratio of total, ischemic, and haemorrhagic strokes by quintiles of each cation intake, and of a combined dietary score of all three cations, using multivariate Cox proportional hazard models.

RESULTS

During 24 years of follow-up, 1547 total stroke events were documented. In multivariate analyses, the relative risks and 95% confidence intervals of total stroke for men in the highest vs. lowest quintile were 0·87 (95% confidence interval, 0·74-1·02; P, trend = 0·04) for dietary magnesium, 0·89 (95% confidence interval, 0·76-1·05; P, trend = 0·10) for dietary potassium, and 0·89 (95% confidence interval, 0·75-1·04; P, trend = 0·25) for dietary calcium intake. The relative risk of total stroke for men in the highest vs. lowest quintile was 0·74 (95% confidence interval, 0·59-0·93; P, trend = 0·003) for supplemental magnesium, 0·66 (95% confidence interval, 0·50-0·86; P, trend = 0·002) for supplemental potassium, and 1·01 (95% confidence interval, 0·84-1·20; P, trend = 0·83) for supplemental calcium intake. For total intake (dietary and supplemental), the relative risk of total stroke for men in the highest vs. lowest quintile was 0·83 (95% confidence interval, 0·70-0·99; P, trend = 0·04) for magnesium, 0·88 (95% confidence interval, 0·75-4; P, trend = 6) for potassium, and 3 (95% confidence interval, 79-09; P, trend = 84) for calcium. Men in the highest quintile for a combined dietary score of all three cations had a multivariate relative risk of 0·79 (95% confidence interval, 0·67-0·92; P, trend = 0·008) for total stroke, compared with those in the lowest.

CONCLUSIONS

A diet rich in magnesium, potassium, and calcium may contribute to reduced risk of stroke among men. Because of significant collinearity, the independent contribution of each cation is difficult to define.

The relationship between dietary magnesium intake, stroke and its major risk factors, blood pressure and cholesterol, in the EPIC-Norfolk cohort

BACKGROUND

Dietary magnesium could modify the major stroke risk factors, high blood pressure (BP) and cholesterol, but has been understudied in both sexes in a single population. This study aimed to investigate if dietary magnesium intake was associated with BP, total cholesterol (TC) and incident stroke risk in an adult population.

METHODS

We conducted cross-sectional analyses in a case-cohort study of 4443, men and women aged 40-75, representative of 25,639 participants years of the EPIC (European Prospective Investigation into Cancer)-Norfolk cohort. The cohort included 928 stroke cases (42,556.5 person years). Dietary data from 7 day food diaries were analysed using multivariate regression to assess associations between quintiles or data-derived categories of dietary magnesium intake and BP, TC and stroke risk, adjusted for relevant confounders.

RESULTS

We observed differences of -7 mmHg systolic BP (P trend ≤ 0.01) and -3.8 mmHg diastolic BP (P trend=0.01) between extreme intakes of magnesium in men, a significant inverse association with TC was observed (P trend=0.02 men and 0.04 women). Compared to the bottom 10%, the top 30% of magnesium intake was associated with a 41% relative reduction in stroke risk (HR 0.59; 95% CI 0.38-0.93) in men.

CONCLUSIONS

Lower dietary magnesium intake was associated with higher BP and stroke risk, which may have implications for primary prevention.

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.

Refeeding and metabolic syndromes: two sides of the same coin

Refeeding syndrome describes the metabolic and clinical changes attributed to aggressive rehabilitation of malnourished subjects. The metabolic changes of refeeding are related to hypophosphatemia, hypokalemia, hypomagnesemia, sodium retention and hyperglycemia, and these are believed to be mainly the result of increased insulin secretion following high carbohydrate intake. In the past few decades, increased consumption of processed food (refined cereals, oils, sugar and sweeteners, and so on) lowered the intake of several macrominerals (mainly phosphorus, potassium and magnesium). This seems to have compromised the postprandial status of these macrominerals, in a manner that mimics low grade refeeding syndrome status. At the pathophysiological level, this condition favored the development of the different components of the metabolic syndrome. Thus, it is reasonable to postulate that metabolic syndrome is the result of long term exposure to a mild refeeding syndrome.

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.

Serum magnesium in the metabolically-obese normal-weight and healthy-obese subjects

BACKGROUND

Given that hypomagnesemia is related with hyperglycemia, hypertension, hypertriglyceridemia, and insulin resistance, the objective of this study was to determine whether serum magnesium levels are associated with the metabolically obese normal weight (MONW) and the metabolically healthy obese (MHO) phenotypes.

METHODS

Population-based cross-sectional study that enrolled 427 subjects, men and non-pregnant women aged 20 to 65years, to participate in the study. Subjects were allocated into groups with and without obesity; among non-obese individuals, the subgroup of MONW subjects was compared with a control group of healthy normal-weight individuals. Among obese individuals, the subgroup of MHO subjects was compared with a control group of obese subjects who exhibited at least one metabolic abnormality. In the absence of obesity, the presence of fasting hyperglycemia, insulin resistance, hypertriglyceridemia, and/or hypertension defined the presence of MONW phenotype. In the absence of hypertension, insulin resistance and metabolic abnormalities of fasting glucose and triglycerides levels, the phenotypically obese subjects were defined as MHO individuals.

RESULTS

The sex-adjusted prevalence of MONW and MHO phenotypes was 40.8% and 27.9%. The multivariate logistic regression model adjusted by family history of diabetes, age, body mass index, and waist-circumference, showed a positive association between hypomagnesemia and the MONW phenotype (OR 6.4; 95%CI 2.3-20.4) and negative relationship between serum magnesium and the MHO phenotype (OR 0.32; 95%CI 0.17-0.61).

CONCLUSIONS

Our results show that hypomagnesemia is positively associated with the presence of MONW phenotype, and the normomagnesemia negatively with the MHO phenotype.

Nutrient intake and risk of open-angle glaucoma: the Rotterdam Study

Open-angle glaucoma (OAG) is the commonest cause of irreversible blindness worldwide. Apart from an increased intraocular pressure (IOP), oxidative stress and an impaired ocular blood flow are supposed to contribute to OAG. The aim of this study was to determine whether the dietary intake of nutrients that either have anti-oxidative properties (carotenoids, vitamins, and flavonoids) or influence the blood flow (omega fatty acids and magnesium) is associated with incident OAG. We investigated this in a prospective population-based cohort, the Rotterdam Study. A total of 3502 participants aged 55 years and older for whom dietary data at baseline and ophthalmic data at baseline and follow-up were available and who did not have OAG at baseline were included. The ophthalmic examinations comprised measurements of the IOP and perimetry; dietary intake of nutrients was assessed by validated questionnaires and adjusted for energy intake. Cox proportional hazard regression analysis was applied to calculate hazard ratios of associations between the baseline intake of nutrients and incident OAG, adjusted for age, gender, IOP, IOP-lowering treatment, and body mass index. During an average follow-up of 9.7 years, 91 participants (2.6%) developed OAG. The hazard ratio for retinol equivalents (highest versus lowest tertile) was 0.45 (95% confidence interval 0.23–0.90), for vitamin B1 0.50 (0.25–0.98), and for magnesium 2.25 (1.16–4.38). The effects were stronger after the exclusion of participants taking supplements. Hence, a low intake of retinol equivalents and vitamin B1 (in line with hypothesis) and a high intake of magnesium (less unambiguous to interpret) appear to be associated with an increased risk of OAG.

Effect of magnesium supplementation on blood pressure: a meta-analysis

To date, there has been inconclusive evidence regarding the effect of magnesium supplements on blood pressure (BP). This meta-analysis was conducted to assess the effect of magnesium supplementation on BP and to establish the characteristics of trials showing the largest effect size. Primary outcome measures were systolic blood pressure (SBP) and diastolic blood pressure (DBP) at the end of the follow-up period. One hundred and forty-one papers were identified, of which 22 trials with 23 sets of data (n=1173), with 3 to 24 weeks of follow-up met the inclusion criteria, with a supplemented elemental magnesium range of 120-973 mg (mean dose 410 mg). 95% confidence intervals (CI) were calculated using DerSimonian and Laird's random-effects model, with effect size calculated using Hedges G. Combining all data, an overall effect of 0.36 and 0.32 for DBP and SBP, respectively, was observed (95% CI 0.27-0.44 for DBP and 0.23-0.41 for SBP), with a greater effect being seen for the intervention in crossover trials (DBP 0.47, SBP 0.51). Effect size increased in line with increased dosage. Although not all individual trials showed significance in BP reduction, combining all trials did show a decrease in SBP of 3-4 mm Hg and DBP of 2-3 mm Hg, which further increased with crossover designed trials and intake >370 mg/day. To conclude, magnesium supplementation appears to achieve a small but clinically significant reduction in BP, an effect worthy of future prospective large randomised trials using solid methodology.

The role of magnesium in hypertension and cardiovascular disease

Magnesium intake of 500 mg/d to 1000 mg/d may reduce blood pressure (BP) as much as 5.6/2.8 mm Hg. However, clinical studies have a wide range of BP reduction, with some showing no change in BP. The combination of increased intake of magnesium and potassium coupled with reduced sodium intake is more effective in reducing BP than single mineral intake and is often as effective as one antihypertensive drug in treating hypertension. Reducing intracellular sodium and calcium while increasing intracellular magnesium and potassium improves BP response. Magnesium also increases the effectiveness of all antihypertensive drug classes. It remains to be conclusively proven that cardiovascular disease such as coronary heart disease, ischemic stroke, and cardiac arrhythmias can be prevented or treated with magnesium intake. Preliminary evidence suggests that insulin sensitivity, hyperglycemia, diabetes mellitus, left ventricular hypertrophy, and dyslipidemia may be improved with increased magnesium intake. Various genetic defects in magnesium transport are associated with hypertension and possibly with cardiovascular disease. Oral magnesium acts as a natural calcium channel blocker, increases nitric oxide, improves endothelial dysfunction, and induces direct and indirect vasodilation.

Feasibility and antihypertensive effect of replacing regular salt with mineral salt -rich in magnesium and potassium- in subjects with mildly elevated blood pressure

Background

High salt intake is linked to hypertension whereas a restriction of dietary salt lowers blood pressure (BP). Substituting potassium and/or magnesium salts for sodium chloride (NaCl) may enhance the feasibility of salt restriction and lower blood pressure beyond the sodium reduction alone. The aim of this study was to determine the feasibility and effect on blood pressure of replacing NaCl (Regular salt) with a novel mineral salt [50% sodium chloride and rich in potassium chloride (25%), magnesium ammonium potassium chloride, hydrate (25%)] (Smart Salt).

Methods

A randomized, double-blind, placebo-controlled study was conducted with an intervention period of 8-weeks in subjects (n = 45) with systolic (S)BP 130-159 mmHg and/or diastolic (D)BP 85-99 mmHg. During the intervention period, subjects consumed processed foods salted with either NaCl or Smart Salt. The primary endpoint was the change in SBP. Secondary endpoints were changes in DBP, daily urine excretion of sodium (24-h dU-Na), potassium (dU-K) and magnesium (dU-Mg).

Results

24-h dU-Na decreased significantly in the Smart Salt group (-29.8 mmol; p = 0.012) and remained unchanged in the control group: resulting in a 3.3 g difference in NaCl intake between the groups. Replacement of NaCl with Smart Salt resulted in a significant reduction in SBP over 8 weeks (-7.5 mmHg; p = 0.016). SBP increased (+3.8 mmHg, p = 0.072) slightly in the Regular salt group. The difference in the change of SBP between study groups was significant (p < 0.002).

Conclusions

The substitution of Smart Salt for Regular salt in subjects with high normal or mildly elevated BP resulted in a significant reduction in their daily sodium intake as well as a reduction in SBP.

Trial Registration

ISRCTN: ISRCTN01739816

Seaweed intake and blood pressure levels in healthy pre-school Japanese children

Background

Few studies have examined whether dietary factors might affect blood pressure in children. We purposed to investigate whether seaweed intake is associated with blood pressure level among Japanese preschool children.

Methods

The design of the study was cross-sectional and it was conducted in autumn 2006. Subjects were healthy preschoolers aged 3-6 years in Aichi, Japan. Blood pressure and pulse were measured once by an automated sphygmomanometer, which uses oscillometric methods. Dietary data, including seaweed intake, were assessed using 3-day dietary records covering 2 consecutive weekdays and 1 weekend day. Of a total of 533 children, 459 (86.1 percent) agreed to be enrolled in our study. Finally, blood pressure measurement, complete dietary records and parent-reported height and weight were obtained for 223 boys and 194 girls.

Results

When we examined Spearman's correlation coefficients, seaweed intake was significantly negatively related to systolic blood pressure in girls (P = 0.008). In the one-way analysis of covariance for blood pressure and pulse after adjustments for age and BMI, the boys with the lowest, middle and highest tertiles of seaweed intake had diastolic blood pressure readings of 62.8, 59.3 and 59.6 mmHg, respectively (P = 0.11, trend P = 0.038). Girls with higher seaweed intake had significantly lower systolic blood pressure readings (102.4, 99.2 and 96.9 mmHg for girls with the lowest, middle and highest tertiles of seaweed intake, respectively; P = 0.037, trend P = 0.030).

Conclusion

Our study showed that seaweed intake was negatively related to diastolic blood pressure in boys and to systolic blood pressure in girls. This suggests that seaweed might have beneficial effects on blood pressure among children.

Lack of association between serum magnesium and the risks of hypertension and cardiovascular disease

BACKGROUND

Experimental studies have linked hypomagnesemia with the development of vascular dysfunction, hypertension, and atherosclerosis. Prior clinical studies have yielded conflicting results but were limited by the use of self-reported magnesium intake or short follow-up periods.

METHODS

We examined the relationship between serum magnesium concentration and incident hypertension, cardiovascular disease (CVD), and mortality in 3,531 middle-aged adult participants in the Framingham Heart Study offspring cohort. Analyses were performed using Cox proportional hazards regressions, adjusted for traditional CVD risk factors.

RESULTS

Follow-up was 8 years for new-onset hypertension (551 events) and 20 years for CVD (554 events). There was no association between baseline serum magnesium and the development of hypertension (multivariable-adjusted hazards ratio per 0.15 mg/dL 1.03, 95% CI 0.92-1.15, P = .61), CVD (0.83, 95% CI 0.49-1.40, P = .49), or all-cause mortality (0.77, 95% CI 0.41-1.45, P = .42). Similar findings were observed in categorical analyses, in which serum magnesium was modeled in categories (<1.5, 1.5-2.2, >2.2 mg/dL) or in quartiles.

CONCLUSIONS

In conclusion, data from this large, community-based cohort do not support the hypothesis that low serum magnesium is a risk factor for developing hypertension or CVD.

Genome-wide association studies of serum magnesium, potassium, and sodium concentrations identify six Loci influencing serum magnesium levels

Magnesium, potassium, and sodium, cations commonly measured in serum, are involved in many physiological processes including energy metabolism, nerve and muscle function, signal transduction, and fluid and blood pressure regulation. To evaluate the contribution of common genetic variation to normal physiologic variation in serum concentrations of these cations, we conducted genome-wide association studies of serum magnesium, potassium, and sodium concentrations using ∼2.5 million genotyped and imputed common single nucleotide polymorphisms (SNPs) in 15,366 participants of European descent from the international CHARGE Consortium. Study-specific results were combined using fixed-effects inverse-variance weighted meta-analysis. SNPs demonstrating genome-wide significant (p<5×10⁻⁸) or suggestive associations (p<4×10⁻⁷) were evaluated for replication in an additional 8,463 subjects of European descent. The association of common variants at six genomic regions (in or near MUC1, ATP2B1, DCDC5, TRPM6, SHROOM3, and MDS1) with serum magnesium levels was genome-wide significant when meta-analyzed with the replication dataset. All initially significant SNPs from the CHARGE Consortium showed nominal association with clinically defined hypomagnesemia, two showed association with kidney function, two with bone mineral density, and one of these also associated with fasting glucose levels. Common variants in CNNM2, a magnesium transporter studied only in model systems to date, as well as in CNNM3 and CNNM4, were also associated with magnesium concentrations in this study. We observed no associations with serum sodium or potassium levels exceeding p<4×10⁻⁷. Follow-up studies of newly implicated genomic loci may provide additional insights into the regulation and homeostasis of human serum magnesium levels.

Magnesium, potassium, and sodium are involved in important physiological processes. To better understand how common genetic variation may contribute to inter-individual differences in serum concentrations of these electrolytes, we evaluated single nucleotide polymorphisms (SNPs) across the genome in association with serum magnesium, potassium, and sodium levels in 15,366 participants of European descent from the CHARGE Consortium. We then verified the associations in an additional 8,463 study participants. Six different genomic regions contain variants that are reproducibly associated with serum magnesium levels, and only one of the regions had been previously known to influence serum magnesium concentrations in humans. The identified SNPs also show association with clinically defined hypomagnesemia, and some of them with traits that have been linked to serum magnesium levels, including kidney function, fasting glucose, and bone mineral density. We further provide evidence for a physiological role of magnesium transporters in humans which have previously only been studied in model systems. None of the SNPs evaluated in our study are significantly associated with serum levels of sodium or potassium. Additional studies are needed to investigate the underlying molecular mechanisms in order to help us understand the contribution of these newly identified regions to magnesium homeostasis.

Oral magnesium supplementation reduces ambulatory blood pressure in patients with mild hypertension

BACKGROUND

Accumulating evidence implicates a role of Mg(2+) in the pathophysiology of essential hypertension. Previous studies evaluating the antihypertensive efficacy of Mg(2+) supplementation gave contradictory results. This study aimed to investigate the effect of oral Mg(2+) supplementation on 24-h blood pressure (BP) and intracellular ion status in patients with mild hypertension.

METHODS

A total of 48 patients with mild uncomplicated hypertension participated in the study. Among them, 24 subjects were assigned to 600 mg of pidolate Mg(2+) daily in addition to lifestyle recommendations for a 12-week period and another 24 age- and sex-matched controls were only given lifestyle recommendations. At baseline and study-end (12 weeks) ambulatory BP monitoring, determination of serum and intracellular ion levels, and 24-h urinary collections for determination of urinary Mg(2+) were performed in all study subjects.

RESULTS

In the Mg(2+) supplementation group, small but significant reductions in mean 24-h systolic and diastolic BP levels were observed, in contrast to control group (-5.6 +/- 2.7 vs. -1.3 +/- 2.4 mm Hg, P < 0.001 and -2.8 +/- 1.8 vs. -1 +/- 1.2 mm Hg, P = 0.002, respectively). These effects of Mg(2+) supplementation were consistent in both daytime and night-time periods. Serum Mg(2+) levels and urinary Mg(2+) excretion were significantly increased in the intervention group. Intracellular Mg(2+) and K(+) levels were also increased, while intracellular Ca(2+) and Na(+) levels were decreased in the intervention group. None of the intracellular ions were significantly changed in the control group.

CONCLUSION

This study suggests that oral Mg(2+) supplementation is associated with small but consistent ambulatory BP reduction in patients with mild hypertension.

Treatment of hypertension with nutraceuticals, vitamins, antioxidants and minerals

Hypertension is the most common reason for visits to physicians' offices and the primary reason for prescription drug use. The target organ damage associated with hypertension, such as stroke, myocardial infarction, congestive heart failure, renal disease and large artery disease, can be mitigated by aggressive nondrug and drug therapies. Hypertension is a syndrome of various metabolic, functional and structural abnormalities that must be viewed in a more global setting of cardiovascular risk. Aggressive detection, evaluation and treatment of the 'blood vessel health' is mandatory to modern hypertensive care. Lifestyle modifications in conjunction with vitamins, minerals, antioxidants, nutraceutical supplements, optimal nutrition and drug therapy will prevent and treat hypertension and its sequelae while addressing global cardiovascular risk, vascular biology, endothelial dysfunction and overall vascular health.

Diuretic, hypotensive, and hypocholesterolemic effects of Eclipta alba in mild hypertensive subjects: a pilot study

The combined effect of dried Eclipta alba leaf powder (3 g/day) in encapsulated form on blood pressure, diuresis, and lipid profile of 60 mildly hypertensive male subjects in the age group of 40-55 years was studied. The subjects were divided into two groups, i.e., a control (placebo) and the Eclipta group, and were given six capsules (500 mg each) per day in three equal doses for a period of 60 days. Clinical parameters, viz., blood pressure, urine volume, electrolytes (Na and K) in serum and urine, lipid profile, and plasma lipid peroxides, were analyzed before and after the feeding trials. The findings revealed that the Eclipta-supplemented group showed a marked reduction in mean arterial pressure by 15%, total cholesterol (17%), low-density lipoprotein fraction (24%), triglycerides (14%), very-low-density lipoprotein fraction (14%), and plasma lipid peroxides (18%). Results also revealed a remarkable increase in urine volume (34%), urine sodium (24%), serum vitamin C (17%), and serum tocopherols (23%) of the Eclipta group. In conclusion, it would appear that E. alba is diuretic, hypotensive, and hypocholesterolemic and helps in the alleviating oxidative stress-induced complications in hypertensives.

Dietary Supplements for The Prevention and Treatment of Coronary Artery Disease

PURPOSE

With the recent growth in the use of dietary supplements, it is increasingly important for clinicians to be familiar with the evidence for and against their efficacy. We set out to systematically review the dietary supplements available for the prevention and treatment of coronary artery disease.

METHODS

Between May 2004 and May 2006, we searched MEDLINE, the Cochrane Library, and Pro-Quest using the MeSH terms hypertension, hypercholesterolemia, myocardial infarction, dietary supplements, and herb-drug interactions. The MeSH terms of individual supplements identified were then added to the search. Reference lists of pertinent papers were also searched to find appropriate papers for inclusion. We included randomized controlled trials published in English of at least 1 week's duration that studied the efficacy of supplements in the treatment of hypercholesterolemia, or hypertension, or in the prevention of cardiac events. Qualifying papers were identified and assigned a Jadad quality score. In areas of uncertainty, a second investigator independently scored the trial.

RESULTS

Fifteen (15) supplements were identified. Of these, most had little data available and most of the data were of poor quality. The supplements with the most supporting data were policosanol and garlic, both for hyperlipidemia.

CONCLUSIONS

A growing body of literature exists for numerous supplements in the prevention of coronary artery disease, but much of these data are inconclusive. Clinicians should become familiar with the extent and limitations of this literature so that they may counsel their patients better.

Magnesium supplementation for the management of essential hypertension in adults

BACKGROUND

Epidemiological evidence on the effects of magnesium on blood pressure is inconsistent. Metabolic and experimental studies suggest that magnesium may have a role in the regulation of blood pressure.

OBJECTIVES

To evaluate the effects of magnesium supplementation as treatment for primary hypertension in adults.

SEARCH STRATEGY

We searched the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, ISI Proceedings, ClinicalTrials.gov, Current Controlled Trials, CAB abstracts, and reference lists of systematic reviews, meta-analyses and randomised controlled trials (RCTs) included in the review.

SELECTION CRITERIA

Inclusion criteria were: 1) RCTs of a parallel or crossover design comparing oral magnesium supplementation with placebo, no treatment, or usual care; 2) treatment and follow-up >/=8 weeks; 3) participants over 18 years old, with raised systolic blood pressure (SBP) >/=140 mmHg or diastolic blood pressure (DBP) >/=85 mmHg; 4) SBP and DBP reported at end of follow-up. We excluded trials where: participants were pregnant; received antihypertensive medication which changed during the study; or magnesium supplementation was combined with other interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Random effects meta-analyses and sensitivity analyses were conducted.

MAIN RESULTS

Twelve RCTs (n=545) with eight to 26 weeks follow-up met our inclusion criteria. The results of the individual trials were heterogeneous. Combining all trials, participants receiving magnesium supplements as compared to control did not significantly reduce SBP (mean difference: -1.3 mmHg, 95% CI: -4.0 to 1.5, I(2)=67%), but did statistically significantly reduce DBP (mean difference: -2.2 mmHg, 95% CI: -3.4 to -0.9, I(2)=47%). Sensitivity analyses excluding poor quality trials yielded similar results. Sub-group analyses and meta-regression indicated that heterogeneity between trials could not be explained by dose of magnesium, baseline blood pressure or the proportion of males among the participants.

AUTHORS' CONCLUSIONS

In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of a causal association between magnesium supplementation and blood pressure reduction is weak and is probably due to bias. This is because poor quality studies generally tend to over-estimate the effects of treatment. Larger, longer duration and better quality double-blind placebo controlled trials are needed to assess the effect of magnesium supplementation on blood pressure and cardiovascular outcomes.

Lifestyle interventions to reduce raised blood pressure: a systematic review of randomized controlled trials

PURPOSE

To quantify effectiveness of lifestyle interventions for hypertension.

DATA SOURCES

Electronic bibliographic databases from 1998 onwards, existing guidelines, systematic reviews.

STUDY SELECTION AND DATA ABSTRACTION

We included randomized, controlled trials with at least 8 weeks' follow-up, comparing lifestyle with control interventions, enrolling adults with blood pressure at least 140/85 mmHg. Primary outcome measures were systolic and diastolic blood pressure. Two independent reviewers selected trials and abstracted data; differences were resolved by discussion.

RESULTS

We categorized trials by type of intervention and used random effects meta-analysis to combine mean differences between endpoint blood pressure in treatment and control groups in 105 trials randomizing 6805 participants. Robust statistically significant effects were found for improved diet, aerobic exercise, alcohol and sodium restriction, and fish oil supplements: mean reductions in systolic blood pressure of 5.0 mmHg [95% confidence interval (CI): 3.1-7.0], 4.6 mmHg (95% CI: 2.0-7.1), 3.8 mmHg (95% CI: 1.4-6.1), 3.6 mmHg (95% CI: 2.5-4.6) and 2.3 mmHg (95% CI: 0.2-4.3), respectively, with corresponding reductions in diastolic blood pressure. Relaxation significantly reduced blood pressure only when compared with non-intervention controls. We found no robust evidence of any important effect on blood pressure of potassium, magnesium or calcium supplements.

CONCLUSIONS

Patients with elevated blood pressure should follow a weight-reducing diet, take regular exercise, and restrict alcohol and salt intake. Available evidence does not support relaxation therapies, calcium, magnesium or potassium supplements to reduce blood pressure.

Increased dietary potassium and magnesium attenuate experimental volume dependent hypertension possibly through endogenous sodium-potassium pump inhibitor

We and others have shown that inhibition of cardiovascular muscle (CVM) cell Na+,K-ATPase activity (NKPTA) due to increased level of endogenous sodium potassium pump inhibitor (SPI) is involved in the mechanism of volume expanded (VE) experimental and human essential hypertension (HT). Since diets fortified with very high potassium (K) or very high magnesium (Mg) decrease blood pressure (BP), we have examined the effect of a moderate increase in dietary K alone and a moderate increase in dietary K and Mg on plasma levels of SPI, CVM cell NKPTA, and BP in reduced renal mass (RRM)-salt HT rats, a classical model of VE HT. Seventy Percent-RRM rats were divided in four dietary groups, (1) Na free and normal K and Mg (0Na-K-Mg); (2) normal Na, K and Mg (Na-K-Mg); (3) normal Na and high K (2 x normal), and normal Mg (Na-2K-Mg); and (4) normal Na and high K (2 x normal), and high Mg (2 x normal) (Na-2K-2Mg). As expected, compared to control 0Na-K-Mg rats, Na-K-Mg rats developed HT. Blood pressure increased significantly less in Na-2K-Mg rats whereas, BP did not increase in Na-2K-2Mg rats. Hypertension in NA-K-Mg rats was associated with an increase in plasma SPI and digitalis like factor (DIF) and a decrease in renal and myocardial NKPTA. However, doubling the Mg along with K in the diet (Na-2K-2Mg) normalized SPI and DIF and increased myocardial and renal NKPTA, compared to control 0Na-K-Mg rats. Also, compared to 0Na-K-Mg rats, water consumption, urine excretion, urinary sodium excretion urinary potassium excretion (U(Na)V), and (U(K)V) increased in the other three groups, more so in Na-2K-2Mg rats. These data show that K and Mg have additive effects in preventing an increase in SPI, thus probably preventing the BP increase in RRM rats.

The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials

BACKGROUND

An increased intake of magnesium might lower blood pressure (BP), yet evidence from clinical trials is inconsistent, perhaps as a result of small sample size or heterogeneity in study design.

METHODS

We performed a meta-analysis of randomized trials that tested the effects of magnesium supplementation on BP. Twenty trials meeting the inclusion criteria were identified. Random effects models and meta-regression methods were used to pool study results and to determine the dose-response relationship of magnesium to BP.

RESULTS

The 20 studies included 14 of hypertensive and 6 of normotensive persons totaling 1220 participants. The doses of magnesium ranged from 10 to 40 mmol/day (median, 15.4 mmol/day). Magnesium supplementation resulted in only a small overall reduction in BP. The pooled net estimates of BP change (95% confidence interval [CI]) were -0.6 (-2.2 to 1.0) mm Hg for systolic BP and -0.8 (-1.9 to 0.4) mm Hg for diastolic BP. However, there was an apparent dose-dependent effect of magnesium, with reductions of 4.3 mm Hg systolic BP (95% CI 6.3 to 2.2; P < .001) and of 2.3 mm Hg diastolic BP (95% CI 4.9 to 0.0; P = .09) for each 10 mmol/day increase in magnesium dose.

CONCLUSIONS

Our meta-analysis detected dose-dependent BP reductions from magnesium supplementation. However, adequately powered trials with sufficiently high doses of magnesium supplements need to be performed to confirm this relationship.

Premenopausal black women are uniquely at risk for coronary heart disease compared to white women

Premenopausal black women have a two to threefold greater rate of coronary heart disease than premenopausal white women. This study was designed to provide greater insight into the reasons for this difference which is currently unclear. Coronary heart disease risk factors were compared in 100 black and 100 white, healthy premenopausal women, ages 18-45 years, and of relatively advantaged socioeconomic status. Compared to white women, black women had a higher body mass index (32.0±9.2 vs. 29.0±9.4 kg/m2, p=0.021), and higher systolic (124±17 vs. 115±14 mm Hg, p<0.0001) and diastolic (79±14 vs. 75±11 mm Hg, p=0.048) blood pressures. The mean plasma lipoprotein(a) concentration was markedly higher in the black women (40.2±31.3 mg/dL) than in the white women (19.2±23.7 mg/dL, p<0.0001). The plasma total homocysteine level was also higher in the black women (8.80±3.38 vs. 7.81±2.58 mmol/L, p=0.013). The black women, however, had lower plasma triglyceride levels (0.91±0.46 vs. 1.22±0.60 mmol/L, p<0.0001) and a trend toward higher high-density lipoprotein cholesterol levels (1.37±0.34 vs. 1.29±0.31 mmol/L, p=0.064) than the white women. Plasma total and low-density lipoprotein cholesterol levels were similar. Black women consumed more saturated fat and cholesterol. Rates of cigarette smoking and alcohol intake were low and similar between the races. In summary, compared to white women, black women had a higher mean body mass index, higher blood pressures, higher lipoprotein(a) and plasma total homocysteine levels, and greater consumption of saturated fat and cholesterol. The differences in coronary risk factors between these two premenopausal groups may explain the higher incidence of coronary heart disease in black women. (c) 2000 by CHF, Inc.

Magnesium abnormalities of skeletal muscle in dermatomyositis and juvenile dermatomyositis

OBJECTIVE

To characterize abnormalities in magnesium levels in the muscles of patients with dermatomyositis (DM) and juvenile dermatomyositis (JDM) and to evaluate the beneficial effects of prednisone and immunosuppressive therapy in elevating free magnesium (Mg(2+)) and ATP-bound magnesium (Mg-ATP).

METHODS

The study groups consisted of 12 adult patients with DM and 10 juvenile patients with JDM. The 2 control groups were 11 normal adults and 6 healthy children. Levels of total ATP in the quadriceps muscles of the subjects were determined during rest, exercise, and recovery, using noninvasive P-31 magnetic resonance spectroscopy (MRS). Concentrations of the biologically active free Mg(2+) and the enzymatically active Mg-ATP complex were determined from the spectroscopy data by calculation of the chemical shifts of the beta-phosphate peak of ATP.

RESULTS

Mg-ATP levels in DM and JDM myopathic muscles were at least 37% lower than those in normal muscles during rest, exercise, and recovery from exercise (P < 0.0005). Free Mg(2+) levels were normal in DM and JDM myopathic muscles at rest, but were significantly lower than control values during exercise and recovery (P < 0.029 and P < 0.005 for DM and JDM, respectively). Prednisone and immunosuppressive therapy partially reversed the magnesium abnormalities, as evidenced by elevation of the levels of Mg-ATP and free Mg(2+).

CONCLUSION

Low levels of Mg-ATP and free Mg(2+) are concordant with weakness and fatigue observed in DM and JDM patients. Immunosuppressive therapy alleviates, in part, the magnesium deficits in the diseased muscles. Therefore, Mg-ATP and free Mg(2+) may play a significant role in the pathophysiology of these diseases.

Promising hypotensive effect of hawthorn extract: a randomized double-blind pilot study of mild, essential hypertension

This pilot study was aimed at investigating the hypotensive potential of hawthorn extract and magnesium dietary supplements individually and in combination, compared with a placebo. Thirty-six mildly hypertensive subjects completed the study. At baseline, anthropometric and dietary assessment, as well as blood pressure measurements were taken at rest, after exercise and after a computer 'stress' test. Volunteers were then randomly assigned to a daily supplement for 10 weeks of either: (a) 600 mg Mg, (b) 500 mg hawthorn extract, (c) a combination of (a) and (b), (d) placebo. Measurements were repeated at 5 and 10 weeks of intervention. There was a decline in both systolic and diastolic blood pressure in all treatment groups, including placebo, but ANOVA provided no evidence of difference between treatments. However, factorial contrast analysis in ANOVA showed a promising reduction (p = 0.081) in the resting diastolic blood pressure at week 10 in the 19 subjects who were assigned to the hawthorn extract, compared with the other groups. Furthermore, a trend towards a reduction in anxiety (p = 0.094) was also observed in those taking hawthorn compared with the other groups. These findings warrant further study, particularly in view of the low dose of hawthorn extract used.

Identification of an antihypertensive peptide from peptic digest of wakame (Undaria pinnatifida)

A peptide fraction having activity against angiotensin I-converting enzyme (ACE) was separated from the peptic digest of protein prepared from wakame (Undaria pinnatifida) by ion-exchange chromatographies and gel-filtration. Fractions with high ACE inhibitory activity were combined and further chromatographed on a reverse-phase column to yield four tetrapeptides with ACE inhibitory properties. These tetrapeptides were identified by sequence analysis and fast atom bombardment mass spectrometry as Ala-Ile-Tyr-Lys (IC(50): 213 microM), Tyr-Lys-Tyr-Tyr (64.2 microM), Lys-Phe-Tyr-Gly (90.5 microM), and Tyr-Asn-Lys-Leu (21 microM). Each tetrapeptide was synthesized and its antihypertensive activity was determined after oral administration in spontaneously hypertensive rats. The blood pressure significantly decreased after tetrapeptide ingestion. The present study demonstrated that dietary wakame may have beneficial effects on hypertension.

Effect of chronic magnesium supplementation on magnesium distribution in healthy volunteers evaluated by 31P-NMRS and ion selective electrodes

AIMS

The role of magnesium (Mg) intake in the prevention and treatment of diseases is greatly debated. Mg biodistribution after chronic Mg supplementation was investigated, using state-of-the-art technology to detect changes in free ionized Mg, both at extra- and intracellular levels.

METHODS

Thirty young healthy male volunteers participated in a randomised, placebo (P)-controlled, double-blind trial. The treated group (MgS) took 12 mmol magnesium lactate daily for 1 month. Subjects underwent in vivo 31P-NMR spectroscopy and complete clinical and biological examinations, on the first and last day of the trial. Total Mg was measured in plasma, red blood cells and 24 h urine ([Mg]U ). Plasma ionized Mg was measured by ion-selective electrodes. Intracellular free Mg concentrations of skeletal muscle and brain tissues were determined noninvasively by in vivo 31P-NMR at 3T. NMR data were automatically processed with the dedicated software MAGAN.

RESULTS

Only [Mg]U changed significantly after treatment (in mmol/24 h, for P, from 4.2+/-1.4 before to 4.1+/-1.3 after and, for MgS, from 3.9+/-1.1 before to 5. 1+/-1.1 after, t=2.15, P=0.04). The two groups did not differ, either before or after the trial, in any other parameter, whether clinical, biological or in relation with the Mg status.

CONCLUSIONS

Chronic oral administration of Mg tablets to young healthy male volunteers at usual pharmaceutical doses does not alter Mg biodistribution. This study shows that an adequate and very complete noninvasive methodology is now available and compatible with the organization of clinical protocols which aim at a thorough evaluation of Mg biodistribution.

Dietary Approaches to Stop Hypertension: rationale, design, and methods. DASH Collaborative Research Group

Epidemiologic studies across societies have shown consistent differences in blood pressure that appear to be related to diet. Vegetarian diets are consistently associated with reduced blood pressure in observational and interventional studies, but clinical trials of individual nutrient supplements have had an inconsistent pattern of results. Dietary Approaches to Stop Hypertension (DASH) was a multicenter, randomized feeding study, designed to compare the impact on blood pressure of 3 dietary patterns. DASH was designed as a test of eating patterns rather than of individual nutrients in an effort to identify practical, palatable dietary approaches that might have a meaningful impact on reducing morbidity and mortality related to blood pressure in the general population. The objectives of this article are to present the scientific rationale for this trial, review the methods used, and discuss important design considerations and implications.