Magnesium Supplementation and Blood Pressure in Pregnancy: A Double-Blind Randomized Multicenter Study

Association of maternal serum magnesium with pre-eclampsia in African pregnant women: a systematic review and meta-analysis

Pre-eclampsia (PE) is a pregnancy-related disorder characterized by hypertension and proteinuria occurring after 20 weeks of gestation. Several studies have been performed to determine the serum magnesium (Mg) level in PE, but most report inconclusive results. Consequently, this study was designed to resolve this controversy among African women. PubMed, Hinari, Google Scholar and African Journals Online electronic databases were searched for studies published in English. The qualities of included articles were appraised using the Newcastle-Ottawa quality assessment tool. Stata 14 software was utilized for analysis and serum Mg levels in cases and normotensive controls were compared through mean and standardized mean difference (SMD) at the 95% confidence interval (CI). In this review, we found that the mean serum Mg level was significantly reduced in cases (0.910±0.762 mmol/L) vs controls (1.167±1.060 mmol/L). The pooled SMD of serum Mg was significantly lower in cases (-1.20 [95% CI -1.64 to -0.75]). Therefore, since serum Mg is reduced in cases vs controls, we propose that Mg is involved in the pathophysiology of PE. Nevertheless, to know the exact mechanisms of Mg in PE development will require large-scale prospective studies.

The association between dietary mineral intake and the risk of preeclampsia in Chinese pregnant women: a matched case-control study

Previous studies on the relationship between dietary minerals and preeclampsia (PE) have given inconsistent results. The aim of this study was to further clarify the relationship between dietary minerals intake and PE in Chinese pregnant women. In this study, 440 pairs of hospital-based preeclamptic and healthy women were matched 1:1. Dietary intake was obtained through a 78-item semi-quantitative food frequency questionnaire. Multivariate conditional logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs). Restricted cubic splines were plotted to evaluate the dose-response relationship between dietary minerals intake and PE. This study found significant inverse associations for dietary intake of calcium, magnesium, phosphorus, iron, copper, manganese and zinc and the risk of PE in both univariate and multivariate models (all P- trend < 0.05). After adjusting for possible confounders, compared with the lowest quartile, the odds ratio of the highest quartile was 0.74 (95% CI 0.56-0.98) for calcium, 0.63 (95% CI 0.42-0.93) for magnesium, 0.45 (95% CI 0.31-0.65) for phosphorus, 0.44 (95% CI 0.30-0.65) for iron, 0.72 (95% CI 0.53-0.97) for copper, 0.66 (95% CI 0.48-0.91) for manganese and 0.38 (95% CI 0.25-0.57) for zinc. In addition, a reverse J-shaped relationship between dietary minerals intake and PE risk was observed (P-overall association < 0.05). In Chinese pregnant women, a higher intake of dietary minerals, including calcium, magnesium, phosphorus, copper, iron, manganese, and zinc was associated with a lower odds of PE.

Assessment of the Roles of Magnesium and Zinc in Clinical Disorders

The ability and facility of magnesium (Mg2+) and zinc (Zn2+) to interact with phosphate ions confer them the characteristics of essential trace elements. Trace elements are extremely necessary for the basic nucleic acid chemistry of cells of all known living organisms. More than 300 enzymes require zinc and magnesium ions for their catalytic actions, including all the enzymes involved in the synthesis of ATP. In addition, enzymes such as isomerases, oxidoreductases, lyases, transferases, ligases and hydrolases that use other nucleotides to synthesize DNA and RNA require magnesium and zinc. These nucleotides may trigger oxidative damage or important changes against free radicals. In the same way, nucleotides may play an important role in the pathophysiology of degenerative diseases, including in some clinical disorders, where vascular risk factors, oxidative stress and inflammation work to destabilize the patients` homeostatic equilibrium. Indeed, reduced levels of zinc and magnesium may lead to inadequate amount of antioxidant enzymes, and thus, acts as an important contributing factor for the induction of oxidative stress leading to cellular or tissue dysfunction. Hence, the development of zinc or magnesium enzyme inhibitors could be a novel opportunity for the treatment of some human disorders. Therefore, the objective of the present work was to assess the clinical benefits of zinc and magnesium in human health and their effects in some clinical disorders.

Oral Magnesium Supplementation for the Prevention of Preeclampsia: a Meta-analysis or Randomized Controlled Trials

Previous studies evaluating the role of magnesium supplementation as a preventative strategy for preeclampsia showed inconsistent results. We performed a meta-analysis or randomized controlled trials (RCTs) to evaluate the influence of oral magnesium supplementation on the incidence of preeclampsia in pregnant women. Relevant studies were obtained by search of Medline, Embase, and Cochrane's Library databases. A random effects model was used to pool the results. Influences of study characteristics of the outcome were evaluated by predefined subgroup analyses. Seven RCTs with 2653 pregnant women were included. Pooled results showed that oral magnesium supplementation during pregnancy significantly reduced the risk of preeclampsia (risk ratio [RR]: 0.76, 95% confidence interval [CI]: 0.59 to 0.98, P = 0.04) with no significant heterogeneity (P for Cochrane's Q test = 0.42, I² = 1%). The result was not significant for the outcome of severe preeclampsia (RR: 0.54, 95% CI: 0.18 to 1.69, P = 0.29; I² = 0%), although only two studies were available. Subgroup analysis showed that oral magnesium supplementation did not significantly reduce the risk of preeclampsia in normal pregnant women (RR: 0.91, 95% CI: 0.67 to 1.25, P = 0.57), but the preventative effect was significant in studies with normal and high-risk pregnant women (RR: 0.54, 95% CI: 0.35 to 0.83, P = 0.005; P for subgroup difference = 0.04). In conclusion, oral supplementation of magnesium may reduce the risk of preeclampsia, which may be more remarkable in high-risk pregnant women.

Dietary Magnesium Intake Modifies the Association Between Vitamin D and Systolic Blood Pressure: Results From NHANES 2007–2014

Introduction

Although the association between blood pressure and vitamin D has been well studied, the effects of dietary magnesium intake on this relationship are still unclear. Thus, this study aimed to determine the effects of dietary magnesium intake on the association between vitamin D and blood pressure.

Methods

The present study analyzed data from the continuous the National Health and Nutrition Examination Survey (NHANES) 2007–2014. We included 8,799 participants aged 20 years or older. Multivariable linear regression was performed to assess the association between vitamin D and systolic blood pressure (SBP) and diastolic blood pressure (DBP). Dietary magnesium intake was stratified by low magnesium intake (<299 mg/d) and high magnesium intake (≥299 mg/d). Effect modification by dietary magnesium intake was assessed through interaction tests between vitamin D and SBP in the multivariable linear regression.

Results

In this cross-sectional study, we found that vitamin D was negatively related to SBP, but not to DBP. The relationship between vitamin D and SBP was different in the low and high magnesium intake group (β: −0.25 95%Cl: −0.4~0.07 vs β: −0.32 95%Cl: −0.52~-0.12). Furthermore, magnesium intake significantly modified the negative relationship between vitamin D and SBP in most of the models.

Conclusion

Our research showed that magnesium and vitamin D have an interactive effect in reducing SBP, which may have great importance for clinical medication.

Disparities in Risks of Inadequate and Excessive Intake of Micronutrients during Pregnancy

BACKGROUND

Inadequate or excessive intake of micronutrients in pregnancy has potential to negatively impact maternal/offspring health outcomes.

OBJECTIVE

The aim was to compare risks of inadequate or excessive micronutrient intake in diverse females with singleton pregnancies by strata of maternal age, race/ethnicity, education, and prepregnancy BMI.

METHODS

Fifteen observational cohorts in the US Environmental influences on Child Health Outcomes (ECHO) Consortium assessed participant dietary intake with 24-h dietary recalls (n = 1910) or food-frequency questionnaires (n = 7891) from 1999-2019. We compared the distributions of usual intake of 19 micronutrients from food alone (15 cohorts; n = 9801) and food plus dietary supplements (10 cohorts with supplement data; n = 7082) to estimate the proportion with usual daily intakes below their age-specific daily Estimated Average Requirement (EAR), above their Adequate Intake (AI), and above their Tolerable Upper Intake Level (UL), overall and within sociodemographic and anthropometric subgroups.

RESULTS

Risk of inadequate intake from food alone ranged from 0% to 87%, depending on the micronutrient and assessment methodology. When dietary supplements were included, some women were below the EAR for vitamin D (20-38%), vitamin E (17-22%), and magnesium (39-41%); some women were above the AI for vitamin K (63-75%), choline (7%), and potassium (37-53%); and some were above the UL for folic acid (32-51%), iron (39-40%), and zinc (19-20%). Highest risks for inadequate intakes were observed among participants with age 14-18 y (6 nutrients), non-White race or Hispanic ethnicity (10 nutrients), less than a high school education (9 nutrients), or obesity (9 nutrients).

CONCLUSIONS

Improved diet quality is needed for most pregnant females. Even with dietary supplement use, >20% of participants were at risk of inadequate intake of ≥1 micronutrients, especially in some population subgroups. Pregnancy may be a window of opportunity to address disparities in micronutrient intake that could contribute to intergenerational health inequalities.

Is Supplementation with Micronutrients Still Necessary during Pregnancy? A Review

INTRODUCTION

Proper nutrition during pregnancy is important to prevent nutritional imbalances that interfere with pregnancy. Micronutrients play critical roles in embryogenesis, fetal growth, and maternal health, as energy, protein, vitamin, and mineral needs can increase during pregnancy. Increased needs can be met by increasing the intake of dietary micronutrients. Severe micronutrient deficiency or excess during pregnancy can have negative effects on fetal growth (intrauterine growth retardation, low birth weight, or congenital malformations) and pregnancy development (pre-eclampsia or gestational diabetes). We investigate whether it is necessary to continue micronutrient supplementation during pregnancy to improve women's health in this stage and whether this supplementation could prevent and control pathologies associated with pregnancy.

AIM

The present review aims to summarize evidence on the effects of nutritional deficiencies on maternal and newborn morbidity.

METHODS

This aim is addressed by critically reviewing results from published studies on supplementation with different nutrients during pregnancy. For this, major scientific databases, scientific texts, and official webpages have been consulted. PubMed searches using the terms "pregnancy" OR "maternal-fetal health" AND "vitamins" OR "minerals" OR "supplementation" AND "requirement" OR "deficiency nutrients" were performed.

RESULTS

There are accepted interventions during pregnancy, such as folic acid supplementation to prevent congenital neural tube defects, potassium iodide supplementation to correct neurodevelopment, and oral iron supplementation during the second half of pregnancy to reduce the risk of maternal anemia and iron deficiency. A number of micronutrients have also been associated with pre-eclampsia, gestational diabetes mellitus, and nausea and vomiting in pregnancy. In general, experimental studies are necessary to demonstrate the benefits of supplementation with different micronutrients and to adjust the recommended daily doses and the recommended periconceptional nutrition for mothers.

CONCLUSIONS

Presently, there is evidence of the benefits of micronutrient supplementation in perinatal results, but indiscriminate use is discouraged due to the fact that the side effects of excessive doses are not known. Evidence supports the idea that micronutrient deficiencies negatively affect maternal health and the outcome of pregnancy. No single micronutrient is responsible for the adverse effects; thus, supplementing or correcting one deficiency will not be very effective while other deficiencies exist.

The impact of micronutrient deficiency on pregnancy complications and development origin of health and disease

Due to the spread of the western style diet, which is characterized by high intake of processed food, micronutrients (vitamins and minerals) deficiency is increasing in the Japanese population of all ages and genders. During pregnancy, the elevated demand for micronutrients put pregnant women at even higher risk of micronutrients deficiency. Some micronutrients are relatively famous such that women with reproductive age are recommended to take folic acid supplementation for the prevention of neural tube defect. However, it is not generally known that folate is also important for fetal growth throughout the pregnancy course and for prevention of pregnancy complications, and that pregnant women should continue to take supplementation during pregnancy and lactation. The types of micronutrients and the duration of supplementation are both important factors to maintain normal pregnancies. This review focused on four micronutrients that are commonly deficient in Japanese pregnant women, folate, vitamin B12, vitamin D, calcium, and magnesium. The detrimental effects of homocysteine accumulation associated with the above micronutrient defects and its link to catechol-o-methyltransferase insufficiency are described. We also discussed possible molecular mechanisms of pregnancy complications and the development origin of health and disease (DOHaD) regarding micronutrient deficiencies from the point of view of one carbon metabolism.

Magnesium supplementation and preeclampsia in low-income pregnant women - a randomized double-blind clinical trial

BACKGROUND

Preeclampsia is the major cause of maternal morbidity and mortality in developing countries. Magnesium sulfate is considered first-line therapy against eclampsia and magnesium deficiency in pregnancy has been associated with unfavourable perinatal outcomes. However there are doubts if magnesium supplementation during pregnancy can previne preeclampsia especially in population with high nutritional risk. This trial aims to verify the effect of oral magnesium supplmentation on preeclampsia incidence in low income pregnant women.

METHODS

This randomized, double-blind, placebo-controlled trial investigated the effect of oral magnesium citrate supplementation for preeclampsia in low-income Brazilian pregnant women, i.e. annual per capita income of US$ 1025 or less. Participants were admitted to the study with gestational age between 12 and 20 weeks. Magnesium serum level was measured pre-randomization and participants with hypermagnesemia were excluded. After randomizationg participants received magnesium citrate capsule (300 mg magnesium citrate) or a daily placebo capsule, until delivery. Intent-to-treat analysis was performed.

RESULTS

A total of 416 pregnant women were screened and 318 enrolled according to the inclusion criteria; 159 for each arm. Twenty-eight pregnant women were lost to follow-up. 55/290 (18.9%) of pregnant women developed preeclampsia; 26/143 (18.1%) in magnesium group and 29/147 (19.7%) in the control group; OR 0.90 (CI 95% 0.48-1.69), p = 0.747. No cases of eclampsia were registered.

CONCLUSION

Oral magnesium supplementation did not reduce preeclampsia incidence in low-income and low-risk pregnant women.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov (Identifier NCT02032186), December 19, 2013.

Influence of Demographic and Lifestyle Variables on Plasma Magnesium Concentrations and Their Associations with Cardiovascular Risk Factors in a Mediterranean Population

Several studies have shown that a low magnesium (Mg) intake in the diet is associated with greater cardiovascular risk and greater risk of diabetes. However, the results are not consistent in all populations. To minimize the biases derived from diet measurement, more objective biomarkers of magnesium status have been proposed. Although there is still no ideal biomarker for Mg, several studies have shown that plasma Mg concentrations could be a relatively acceptable biomarker for cardiovascular risk assessment. However, further studies are required to better characterize this marker in different populations. Our aim was to analyze the association between plasma Mg concentrations (measured through inductively coupled plasma mass spectrometry (ICP-MS)) methods, and cardiovascular risk factors in individuals from a general Mediterranean population (aged 18–80 years). The influence of demographic and lifestyle variables, including adherence to the Mediterranean diet, on plasma Mg concentrations was analyzed. The mean Mg level of the population studied was 0.77 ± 0.08 mmol/L, the prevalence of hypomagnesemia (<0.70 mmol/L) being 18.6%. We did not find any statistically significant differences between plasma Mg concentrations and sex, age, tobacco smoking and total adherence to the Mediterranean diet (p > 0.05). We found a statistically significant association between plasma Mg concentrations and the prevalence of type-2 diabetes (0.77 ± 0.08 mmol/L in non-diabetics versus 0.73 ± 0.13 mmol/L in diabetics; p = 0.009). Despite the low prevalence of type-2 diabetes in this population (11.24% in subjects with hypomagnesemia versus 3.91%, in normomagnesemia; p = 0.005), hypomagnesemia was associated with greater odds of being diabetic in comparison with normomagnesemia (OR = 3.36; p = 0.016, even after adjustment for sex, age, obesity, and medications). On the other hand, no statistically significant association of plasma Mg concentrations with obesity, hypertension, fasting triglycerides, HDL-cholesterol or uric acid was found. However, in contrast to what was initially expected, a statistically significant association was found between plasma Mg concentrations (basically in the highest quartile) and greater total cholesterol (p < 0.05) and LDL-cholesterol concentrations (p < 0.05). In conclusion, our results contribute to increasing the evidence gathered by numerous studies on the inverse association between hypomagnesemia and type-2 diabetes, as well as to the observation, previously reported in some studies, of a direct association with hypercholesterolemia. This paradoxical link should be deeply investigated in further studies.