Relationship between dietary magnesium, manganese, and copper and metabolic syndrome risk in Korean adults: the Korea National Health and Nutrition Examination Survey (2007-2008)

Positive association between dietary manganese intake and new-onset hypertension: A nationwide cohort study in China

BACKGROUND AND AIM

To date, few studies have investigated the association between dietary manganese intake and the risk of hypertension, so the prospective relationship of dietary manganese intake and new-onset hypertension remains uncertain. We aimed to investigate the association between dietary manganese intake and the risk of new-onset hypertension in the general Chinese population.

METHODS AND RESULTS

This prospective cohort study included 12,177 participants who were free of hypertension at baseline from China Health and Nutrition Survey (CHNS). Dietary intake was measured by 3 consecutive 24-h dietary recalls combined with a household food inventory. The study outcome was new-onset hypertension, defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg or diagnosed by a physician or under antihypertensive treatment during the follow-up. During a median follow-up duration of 6.1 years, 4269 (44.9 per 1000 person-years) participants developed new-onset hypertension. Overall, there was a positive association between dietary manganese intake and new-onset hypertension. The adjusted HRs (95%CIs) of new-onset hypertension were 1.00 (reference), 0.97 (0.87, 1.08), 1.24 (1.10, 1.39) and 1.75 (1.52, 2.01) across the quartiles of dietary manganese intake, respectively. Accordingly, a significantly higher risk of new-onset hypertension (HR, 1.38; 95%CI: 1.27, 1.50) was found in participants in quartiles 3-4 of dietary manganese intake (≥6.0 mg/day), compared with those in quartiles 1-2 (<6.0 mg/day).

CONCLUSIONS

In the general Chinese population, dietary manganese intake was positively associated with the risk of new hypertension, independent of sodium intake and other important covariates.

Scientific opinion on the tolerable upper intake level for manganese

Following a request from the European Commission (EC), the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for manganese. Systematic reviews of the literature of human and animal data were conducted to assess evidence regarding excess manganese intake (including authorised manganese salts) and the priority adverse health effect, i.e. manganese-induced neurotoxicity. Available human and animal studies support neurotoxicity as a critical effect, however, data are not sufficient and suitable to characterise a dose-response relationship and identify a reference point for manganese-induced neurotoxicity. In the absence of adequate data to establish an UL, estimated background dietary intakes (i.e. manganese intakes from natural dietary sources only) observed among high consumers (95th percentile) were used to provide an indication of the highest level of intake where there is reasonable confidence on the absence of adverse effects. A safe level of intake of 8 mg/day was established for adults ≥ 18 years (including pregnant and lactating women) and ranged between 2 and 7 mg/day for other population groups. The application of the safe level of intake is more limited than an UL because the intake level at which the risk of adverse effects starts to increase is not defined.

The association between lipid profile, oxidized LDL and the components of metabolic syndrome with serum mineral status and kidney function in individuals with obesity

BACKGROUND

Metabolic syndrome (MetS) is presented with a cluster of cardio-metabolic risk factors with widespread prevalence. In the present case-control study, we aimed to examine the relationship between several minerals and renal function tests with the components of MetS in individuals with obesity.

METHODS

This study included 127 individuals with obesity of both gender with or without MetS as the case and control, respectively. MetS was characterized based on the Adult Treatment Panel III (ATP III) criteria. Anthropometric variables and blood pressure were recorded. Mineral status including serum magnesium, copper, calcium, phosphorous, and iron were measured using standard colorimetric methods. Also, the serum lipid levels, concentrations of oxidized low-density lipoprotein (Ox-LDL), and renal function tests, including total protein, albumin, urea, creatinine, and uric acid were evaluated using commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

According to our results, individuals with obesity and MetS had higher levels of waist circumference (WC) and diastolic blood pressure (P < 0.05) compared to individuals with obesity and without MetS. Moreover, individuals with obesity and MetS had higher levels of serum total cholesterol (TC), triglyceride (TG), insulin, and iron (P < 0.05). In individuals with obesity and MetS, iron and albumin showed a positive relationship with LDL cholesterol and TG concentrations, respectively (P < 0.05 for all of them). Also, there was a positive association between serum magnesium and Ox- LDL in individuals with obesity with MetS. While, in individuals with obesity and without MetS, only a positive association between urea and uric acid with WC was observed (P < 0.05).

CONCLUSION

Our results suggest that disturbed serum lipids in obesity-metabolic syndrome is associated with homeostatic changes in the level of minerals or proteins that are involved in their metabolism. Although, further studies are needed to better explain and clarify the underlying mechanism of observed relationships.

Magnesium intake and dietary sources among Koreans: findings from the Korea National Health and Nutrition Examination Survey 2016-2019

BACKGROUND/OBJECTIVES

Magnesium is an essential nutrient for human health. However, inadequate intake is commonly reported worldwide. Along with reduced consumption of vegetables and fruits and increased consumption of refined or processed foods, inadequate magnesium intake is increasingly reported as a serious problem. This study aimed to assess magnesium intake, its dietary sources, and the adequacy of magnesium intake in Korean populations.

SUBJECTS/METHODS

Data was obtained from the Korea National Health and Nutrition Examination Survey 2016-2019 and included individuals aged ≥1 yr who had participated in a nutrition survey (n=28,418). Dietary intake was assessed by 24-h recall, and dietary magnesium intake was estimated using a newly established magnesium database. Diet adequacy was evaluated by comparing dietary intake with the estimated average requirement (EAR) suggested in the Korean Dietary Reference Intakes 2020.

RESULTS

The mean dietary magnesium intake of Koreans aged ≥1 yr was 300.4 mg/d, which was equivalent to 119.8% of the EAR. The prevalence of individuals whose magnesium intake met the EAR was 56.8%. Inadequate intake was observed more in females, adolescents and young adults aged 12-29 yrs, elders aged ≥65 yrs, and individuals with low income. About four-fifths of the daily magnesium came from plant-based foods, and the major food groups contributing to magnesium intake were grains (28.3%), vegetables (17.6%), and meats (8.4%). The top 5 individual foods that contributed to magnesium intake were rice, Baechu (Korean cabbage) kimchi, tofu, pork, and milk. However, the contribution of plant foods and individual contributing food items differed slightly by sex and age groups.

CONCLUSIONS

This study found that the mean dietary magnesium intake among Koreans was above the recommended intake, whereas nearly one in 2 Koreans had inadequate magnesium intake. To better understand the status of magnesium intake, further research is required, which includes the intake of dietary supplements.

Evaluation among trace elements, clinical parameters and type 1 diabetes according to sex: A new sight of auxiliary prediction in negative insulin auto-antibodies population

BACKGROUND

Type 1 diabetes (T1D) exhibited sex-specific metabolic status including oxidative stress with dynamic change of trace elements, which emphasized the importance of the evaluation of trace elements according to sex. Besides, the most significant characteristic, insulin auto-antibodies, could not be found in all T1D patients, which needed the auxiliary prediction of clinical parameters. And it would benefit the early detection and treatment if some high-risk groups of T1D could predict and prevent the occurrence of disease through common clinical parameters. Hence, there was an urgent need to construct more effective and scientific statistical prediction models to serve clinic better. This study aimed to evaluate the sex-specific levels of trace elements and the relationship between trace elements and clinical parameters in T1D, and construct sex-specific auxiliary prediction model combined with trace elements and clinical parameters.

METHODS

A total of 105 T1D patients with negative insulin auto-antibodies and 105 age/sex-matched healthy individuals were enrolled in First Hospital of Jilin University. Inductively Coupled Plasma Mass Spectrometry was performed for the measurement of calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), iron (Fe), selenium (Se) in the serum, and the data of clinical parameters were received from medical record system. The lambda-mu-sigma method was used to evaluate the relationship between abnormal clinical parameters and trace elements. Training set and validation set were divided for the construction of predictable models in males and females: clinical parameters model, trace element model and the combined model (clinical parameters and trace elements). Goodness fit test, decision curve analysis and other related statistical methods were used to perform data analysis.

RESULTS

Lower levels of Mg, Ca, Fe in the serum were found in T1D population in females compared with healthy population, while levels of Fe, Zn and Cu of serum in T1D individuals were higher than those of healthy population in males. Levels of serum Mg, Fe and Cu in T1D group were found with significant sex difference for (P < 0.05), and the levels of Fe and Cu in serum of males were higher than those of females, level of serum Mg in males was lower than those of females. Levels of serum Mg and Zn showed fluctuation trend with increased numbers of abnormal clinical parameters (NACP) in males. Serum Zn in females showed consistent elevated trend with NACP; serum Se increased first and then decreased with NACP in males and females. The auxiliary prediction model (Triglyceride, Total protein, serum Mg) was found with the highest predicted efficiency in males (AUC=0.993), while the model in females (Apolipoprotein A, Creatinine, Fe, Se, Zn/Cu ratio) showed the best predicted efficiency (AUC=0.951). The models had passed the verification in validation set, and Chi-square goodness-of-fit test, DCA results both confirmed their satisfactory clinical applicability.

CONCLUSION

Sex-specific difference were found in serum Mg, Fe and Cu in T1D. The combination of triglyceride, total protein and serum Mg for males, and apolipoprotein A, creatinine, Fe, Se, Zn/Cu ratio for females could effectively predict T1D in patients with negative anti-bodies, which would provide alarm for the population with high-risk of T1D and serve the T1D prediction in patients with negative anti-bodies.

A Longitudinal Study of Exposure to Manganese and Incidence of Metabolic Syndrome

The association between manganese (Mn) and metabolic syndrome (MetS) is unclear, and no prior study has studied this association longitudinally. The aim of this study was to assess longitudinal associations of Mn exposure with MetS and metabolic outcomes. We used data from the San Luis Valley Diabetes Study (SLVDS), a prospective cohort from rural Colorado with data collected from 1984−1998 (n = 1478). Urinary Mn was measured at baseline (range = 0.20−42.5 µg/L). We assessed the shape of the cross-sectional association between Mn and MetS accounting for effect modification by other metals at baseline using Bayesian kernel machine regression. We assessed longitudinal associations between baseline quartiles of Mn and incident MetS using Fine and Gray competing risks regression models (competing risk = mortality) and between quartiles of Mn and metabolic outcomes using linear mixed effects models. We did not observe evidence that quartiles of Mn were associated with incident MetS (p-value for trend = 0.52). Quartiles of Mn were significantly associated with lower fasting glucose (p-value for trend < 0.01). Lead was found to be a possible effect modifier of the association between Mn and incident MetS. Mn was associated with lower fasting glucose in this rural population. Our results support a possible beneficial effect of Mn on diabetic markers.

The Levels of Bioelements in Postmenopausal Women with Metabolic Syndrome

(1) Metabolic syndrome is a set of factors that considerably increase the risk of developing atherosclerosis, type 2 diabetes, and their cardiovascular complications. Studies show that menopause and the levels of elements may be significantly associated with increased risk of MetS. The present study evaluated the relationship between element levels (Ca, P, Na, K, Fe, Mg, Cu, Zn, Sr) and the incidence of MetS and concomitant metabolic disorders in peri-menopausal women. (2) The study involved 170 perimenopausal women. The methods used were: survey, anthropometric measurement (WC, height, BMI, WHtR), blood pressure measurement, and biochemical analysis of venous blood (lipid profile, glucose, insulin, HbA1C). (3) The study demonstrated statistically significantly higher WC, WHtR, SBP, and DBP values in women with pre-Mets than in those with Mets and the control group. Significantly higher FPG, TG, LDL, HbA1C, insulin, TG/HDL ratio, and TC/HDL ratio were recorded in the MetS group compared to the rest of respondents. In addition, post hoc analysis revealed statistically significant differences in mean K concentrations between pre-MetS and MetS women. (4) Low blood K levels in perimenopausal women are associated with an increased risk of MetS. Significantly higher Cu levels were observed in overweight women. The concentration of Cu negatively correlates with the values of TC, LDL, and SBP.

Relationship between Dietary Magnesium Intake and Metabolic Syndrome

Metabolic syndrome (MetS) is increasingly prevalent, and the relationship between dietary magnesium and MetS remains controversial. Therefore, we aimed to explore the association and dose-response relationship between dietary magnesium intake and MetS and its single component. The sample was adults aged 18 years and above who participated in at least two follow-up surveys in 2009, 2015 and 2018. Food consumption data were collected from three consecutive 24-h dietary recalls. The multivariate Cox proportional risk regression model and restricted cubic spline (RCS) model were used to analyze the association and dose-response relationship between dietary magnesium intake and MetS and its components. In our study, 6104 subjects were included, with a total follow-up of 37,173.36 person-years, and the incidence was 33.16%. Cox regression analysis showed that the multivariable-adjusted Hazard Ratio (HR) for MetS comparing the highest to the lowest quintile of dietary magnesium intake was 0.84 (95% confidence intervals [CI] = 0.71-0.99). Central obesity, elevated TG, elevated blood pressure and elevated blood glucose were reduced by 18%, 41%, 20% and 42%, respectively. The risk of decreased HDL-C was reduced by 23% in the third quintile of dietary magnesium intake, with a slightly increased risk in the highest group. RCS analysis showed that the overall and non-linear associations between dietary magnesium and MetS and its components were statistically significant, the risk of them decreased significantly when magnesium intake was lower than 280 mg/day, and then the curve leveled off or slightly increased.

Non-linear associations between metabolic syndrome and four typical heavy metals: Data from NHANES 2011-2018

Previous studies have found that heavy metals are associated with metabolic syndrome (MetS), although findings are inconsistent. Further, investigations into potential associations that consider age- or gender-specific effects and dose-response associations for metal exposure and MetS are rare. In this study, we explore the associations between blood levels of typical heavy metals [lead (Pb), cadmium (Cd), mercury (Hg) and manganese (Mn)] and MetS among adults using logistic regression analysis and restricted cubic splines (RCS) logistic analysis using data from the US National Health and Nutrition Examination Survey 2011-2018. After adjusting for covariates, higher levels of blood Pb, Cd and Hg were associated with lower risks of MetS in participants overall, and in all subgroup analyses, by logistic regression analysis (all P-values <0.05); in contrast, higher levels of blood Mn had a higher risk of MetS only in the age group of 30-49 years (P-values <0.05). We also found non-linear associations of heavy metal levels in blood with risk of MetS in participants overall, in specific age groups and in both genders, using RCS logistic regressions (all P-values <0.05). In addition, the non-linear associations of Pb and Hg we observed in different subgroups differed. In conclusion, blood levels of four heavy metals were associated with the risk of MetS through a variety of non-linear patterns.

Manganese Exposure and Metabolic Syndrome: A Systematic Review and Meta-Analysis

Manganese (Mn) is an essential element acting as a co-factor of superoxide dismutase, and it is potentially beneficial for cardiometabolic health by reducing oxidative stress. Although some studies have examined the relationship between Mn and metabolic syndrome (MetS), no systematic review and meta-analysis has been presented to summarize the evidence. Therefore, the present review examined the association between dietary and environmental Mn exposure, and MetS risk. A total of nine cross-sectional studies and three case-control studies were included, which assessed Mn from diet, serum, urine, and whole blood. The association of the highest Mn level from diet (three studies, odds ratio (OR): 0.83, 95% confidence interval (C.I.) = 0.57, 1.21), serum (two studies, OR: 0.87, 95% C.I. = 0.66, 1.14), urine (two studies, OR: 0.84, 95% C.I. = 0.59, 1.19), and whole blood (two studies, OR: 0.92, 95% C.I. = 0.53, 1.60) were insignificant, but some included studies have suggested a non-linear relationship of urinary and blood Mn with MetS, and higher dietary Mn may associate with a lower MetS risk in some of the included studies. While more evidence from prospective cohorts is needed, future studies should use novel statistical approaches to evaluate relative contribution of Mn on MetS risk along with other inter-related exposures.

U-shaped association between dietary copper intake and new-onset hypertension

AIMS

To investigate the relationship of dietary copper intake with new-onset hypertension among Chinese adults.

METHODS

A total of 12,245 participants who were free of hypertension at baseline from the China Health and Nutrition Survey (CHNS) were included. Dietary intake was measured by 3 consecutive 24-h dietary recalls combined with a household food inventory. New-onset hypertension was defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg or diagnosed by a physician or under antihypertensive treatment during the follow-up.

RESULTS

During a median follow-up of 6.1 years, 4304 participants developed new-onset hypertension. Overall, the associations between dietary copper intake and new-onset hypertension followed a U-shape (P for nonlinearity <0.001). The risk of new-onset hypertension significantly decreased with the increment of dietary copper intake (per SD increment: HR, 0.71; 95% CI, 0.57-0.88) in participants with copper intake <1.57 mg/day, and increased with the increment of dietary copper intake (per SD increment: HR, 1.09; 95% CI: 1.07-1.12) in participants with copper intake ≥1.57 mg/day.

CONCLUSIONS

There was a U-shaped association between dietary copper intake and new-onset hypertension in general Chinese adults, with an inflection point at about 1.57 mg/day. Our results emphasized the importance of maintaining optimal copper intake levels for the primary prevention of hypertension.

Associations of the Dietary Iron, Copper, and Selenium Level With Metabolic Syndrome: A Meta-Analysis of Observational Studies

Background

Epidemiological studies have investigated the associations of dietary iron, copper, and selenium level with metabolic syndrome (MetS). However, their results are conflicting. This meta-analysis of observational study was, therefore, employed to investigate the associations above.

Methods

A comprehensive literature search was employed using PubMed, Web of Science, Embase, and Scopus database up to October 2021 (no restriction was set for the initiate time). The pooled relative risk (RR) of MetS for the highest vs. lowest dietary iron, copper, and selenium level was estimated, respectively.

Results

A total of 14 observational studies (55,131 participants) were identified as meeting the inclusion criteria. Specifically, 7 studies were related to the dietary iron level. The overall multivariable adjusted RR demonstrated that the dietary iron level was positively associated with MetS (RR = 1.27, 95% CI: 1.12–1.44; p &lt; 0.001). With regard to the dietary copper level, 7 studies were included for meta-analysis. The overall multivariable adjusted RR showed that the dietary copper level was inversely associated with MetS (RR = 0.85, 95% CI: 0.78–0.93; p &lt; 0.001). In addition, 4 studies were specified for the dietary selenium level. The overall multivariable adjusted RR indicated that the dietary selenium level was inversely associated with MetS (RR = 0.77, 95% CI: 0.63–0.95; p = 0.01) as well.

Conclusion

Our results suggest that the dietary iron level is positively associated with MetS, whereas a negative association between the dietary copper and selenium level and MetS is obtained. Further large well-designed prospective cohort studies are warranted to elaborate on the issues examined in this study.

Relationships Between Indicators of Metabolic Disorders and Selected Concentrations of Bioelements and Lead in Serum and Bone Tissue in Aging Men

BACKGROUND

The aim of this study was to investigate the relationships between serum and bone concentrations of selected bioelements, ie, zinc (Zn), copper (Cu), iron (Fe), chrome (Cr), magnesium (Mg), and selenium (Se), and a heavy metal, ie, lead (Pb), and the selected indicators of metabolic disorders - Visceral Adiposity Index (VAI), Lipid Accumulation Product (LAP) and Body Mass Index (BMI).

MATERIAL AND METHODS

The study comprised 151 men aged 60 to 75 years who were scheduled for hip replacement surgery due to osteoarthritis. The concentrations of elements in the serum and bone tissue were measured using inductively coupled plasma optical emission spectrometry (Mg, Zn, Cu, Cr, Fe, and Pb) and the spectrofluorometric method (Se). Fasting plasma glucose (FPG), high-density cholesterol (HDL-Ch), and triacylglycerols (TAG) were determined. Lipid accumulation product (LAP) and visceral adiposity index (VAI) were calculated.

RESULTS

There was no relationship between serum and bone concentrations of bioelements and lead and the BMI index. Bone Mg was significantly higher in men with higher VAI, but no such relation was observed in the serum. Similarly, bone Mg and Zn were higher in patients with higher LAP, which was not observed in the serum. Multivariate logistic regression analysis with adjustment for age was performed. There was a correlation between serum Zn concentration and the cut-off point for VAI. The cut-off point for LAP was related to the bone tissue concentrations of Mg, Zn, and Cu.

CONCLUSION

We found some relationships between the concentrations of selected bioelements and Pb and VAI, LAP, and BMI in bone but not in the serum. VAI positively correlated with bone Mg, while LAP positively correlated with bone Cu, Zn, and Mg.

Low hepatic manganese concentrations in patients with hepatic steatosis - A cohort study of copper, iron and manganese in liver biopsies

BACKGROUND AND AIMS

Hepatic steatosis is the most common histopathological finding on liver biopsy, with the most prevalent etiology being NAFLD. The pathogenesis of hepatic steatosis and NAFLD is multifactorial, however, studies on the importance of manganese in NAFLD are limited. We aimed to study hepatic manganese content, and other trace elements, in relation to hepatic steatosis in patients with chronic liver diseases of different etiology, mainly NAFLD.

METHODS

Patients with chronically elevated liver function tests underwent a diagnostic work-up, including routine blood tests and two liver biopsies. One of the biopsies was sent for histopathological evaluation, and the other for ultra-trace elemental determinations. Steatosis was graded using conventional histopathological methodology, and fat content was also quantitated in biopsy samples by measuring the steatotic area of the section using stereological point counting (SPC). Ultra-trace elemental analysis was utilized for determining manganese, iron, and copper using inductively coupled plasma sector field mass spectrometry (ICP-SFMS).

RESULTS

76 patients were included in the study. Hepatic manganese concentrations in patients with steatosis were lower than in patients without hepatic steatosis (3.8 ± 1.1 vs. 6.4 ± 1.8, P < 0.001). Similar results were seen for blood manganese levels and hepatic steatosis. We found a strong inverse correlation between steatosis grade and hepatic manganese content (ρ=-0.743, P < 0.001). Also, low levels of manganese independently predicted the presence of steatosis (aOR 0.07 [95%CI: 0.01-0.63]).

CONCLUSION

Patients with NAFLD, or other CLD and concomitant hepatic steatosis, showed lower levels of hepatic manganese content with increasing grade of steatosis.

Associations between blood and urinary manganese with metabolic syndrome and its components: Cross-sectional analysis of National Health and Nutrition Examination Survey 2011-2016

Manganese (Mn) may improve cardiometabolic health with its anti-oxidative ability. However, epidemiological evidence on the overall and sex-specific relationship between Mn exposure and metabolic syndrome (MetS) has been inconclusive. We evaluated the associations of urinary (n = 1713) and blood (n = 3335) Mn levels with the prevalence of MetS, its components (elevated waist circumference, impaired glucose metabolism, elevated blood pressure and dyslipidemia) and sex-dependent heterogeneities among participants in the United States National Health and Nutrition Examination Survey 2011-2016. After adjusting for multiple covariates and the levels of other metals (Arsenic, Barium, Cadmium, Mercury, Molybdenum, Tin and Uranium), urinary Mn at the third quartile associated with a lower odd of MetS (odds ratio [OR] = 0.55, 95% confidence interval [C.I.] = 0.32-0.97), elevated waist circumference (OR = 0.56, 95% C.I. = 0.36-0.86) and elevated fasting plasma glucose (OR = 0.46, 95% C.I. = 0.27-0.76) among overall participants, and lower odds of MetS (OR = 0.40, 95% C.I. = 0.16-0.99), elevated waist circumference (OR = 0.39, 95% C.I. = 0.19-0.81) and elevated fasting plasma glucose (OR = 0.44, 95% C.I. = 0.22-0.90) among men. The U-shaped dose-response relationship between urinary Mn and MetS (P non-linear = 0.008) was observed among all participants. We did not observe the significant associations of blood Mn with the prevalence of MetS. Compared with other metals, urinary Mn played a less important role in development of MetS (posterior inclusion probabilities [PIP] = 0.49 for Mn versus 0.54 to 0.91 for other metals), but the contribution of blood Mn (PIP = 0.59 versus 0.60 to 0.61) was similar to other blood metals (Cadmium, Lead, Mercury and Selenium). These findings have provided new evidence of the potential roles of Mn in cardiometabolic health, and the needs to explore how Mn interacts with multiple metals in sex-specific manner.

Crosstalk of Magnesium and Serum Lipids in Dyslipidemia and Associated Disorders: A Systematic Review

Dyslipidemia is a significant threat to public health worldwide and the identification of its pathogenic mechanisms, as well as novel lipid-lowering agents, are warranted. Magnesium (Mg) is a key element to human health and its deficiency has been linked to the development of lipid abnormalities and related disorders, such as the metabolic syndrome, type 2 diabetes mellitus, or cardiovascular disease. In this review, we explored the associations of Mg (dietary intake, Mg concentrations in the body) and the lipid profile, as well as the impact of Mg supplementation on serum lipids. A systematic search was computed in PubMed/MEDLINE and the Cochrane Library and 3649 potentially relevant papers were detected and screened (n = 3364 following the removal of duplicates). After the removal of irrelevant manuscripts based on the screening of their titles and abstracts (n = 3037), we examined the full-texts of 327 original papers. Finally, after we applied the exclusion and inclusion criteria, a number of 124 original articles were included in this review. Overall, the data analyzed in this review point out an association of Mg concentrations in the body with serum lipids in dyslipidemia and related disorders. However, further research is warranted to clarify whether a higher intake of Mg from the diet or via supplements can influence the lipid profile and exert lipid-lowering actions.

A Nonlinear Relation Between Maternal Red Blood Cell Manganese Concentrations and Child Blood Pressure at Age 6-12 y: A Prospective Birth Cohort Study

BACKGROUND

Although manganese (Mn) is an essential trace element and a common component of most multivitamins on the market, an adverse effect on blood pressure (BP) has been reported in adults. In addition, the longitudinal relation between prenatal Mn status and childhood BP is still unknown.

OBJECTIVE

This study investigated the association between prenatal Mn concentrations and risk of elevated BP at ages 3-12 y.

METHOD

The analyses included 1268 mother-child dyads who were enrolled at birth and followed prospectively at the Boston Medical Center. Maternal RBC Mn concentrations were measured by inductively coupled plasma mass spectrometry, using RBCs collected within 1-3 d after delivery (reflecting late-pregnancy Mn exposure). Child elevated BP was defined as systolic or diastolic BP ≥90th percentile for a given age, sex and height. Multivariate logistic regression models were conducted. Path analysis was applied to mediation estimation.

RESULTS

The median (IQR) maternal RBC Mn concentration was 37.5 (29.2-48.5) μg/L. The rate of child elevated BP at ages 3-12 y was 25%. Both the lowest and highest quartiles of maternal RBC Mn concentrations were associated with higher risk of elevated BP among children aged 6-12 y (OR: 1.52; 95% CI: 1.04, 2.21 and OR: 1.65; 95% CI: 1.13, 2.40, respectively) compared with those in the second and third quartiles. Gestational age and fetal growth mediated the association between low maternal RBC Mn (first quartile) and child elevated BP, explaining 25% of the association, but not for high (fourth quartile) maternal RBC Mn concentrations. No association was found between maternal RBC Mn concentrations and BP among children aged 3-5 y.

CONCLUSION

We found a nonlinear association between maternal RBC Mn concentrations and elevated BP among children aged 6-12 y from a high-risk, predominantly minority population. Our findings warrant further investigation.

Association of Serum Levels of Zinc, Copper, and Iron with Risk of Metabolic Syndrome

The association between serum concentrations of zinc, copper, or iron and the risk of metabolic syndrome are inconclusive. Therefore, we conduct a case-control study to explore the relationship between serum levels of zinc, copper, or iron and metabolic syndrome as well as each metabolic factor and insulin resistance. We enrolled 1165 adults, aged ≥ 40 (65.8 ± 10) years in a hospital-based population to compare the serum levels of zinc, copper, and iron between subjects with and without metabolic syndrome by using multivariate logistic regression analyses. The least square means were computed by general linear models to compare serum concentrations of zinc, copper, and iron in relation to the number of metabolic factors. The mean serum concentrations of zinc, copper, and iron were 941.91 ± 333.63 μg/L, 1043.45 ± 306.36 μg/L, and 1246.83 ± 538.13 μg/L, respectively. The odds ratios (ORs) of metabolic syndrome for the highest versus the lowest quartile were 5.83 (95% CI: 3.35-10.12; p for trend < 0.001) for zinc, 2.02 (95% CI: 1.25-3.25; p for trend: 0.013) for copper, and 2.11 (95% CI: 1.24-3.62; p for trend: 0.021) for iron after adjusting for age, sex, personal habits, body mass index, and homeostatic model assessment insulin resistance. Additionally, the serum zinc, copper, and iron concentrations increased as the number of metabolic factors rose (p for trend < 0.001). This was the first study to clearly demonstrate that higher serum levels of zinc, copper, and iron were associated with the risk of metabolic syndrome and the number of metabolic factors independent of BMI and insulin resistance.

Magnesium in Obesity, Metabolic Syndrome, and Type 2 Diabetes

Magnesium (Mg²⁺) deficiency is probably the most underestimated electrolyte imbalance in Western countries. It is frequent in obese patients, subjects with type-2 diabetes and metabolic syndrome, both in adulthood and in childhood. This narrative review aims to offer insights into the pathophysiological mechanisms linking Mg²⁺ deficiency with obesity and the risk of developing metabolic syndrome and type 2 diabetes. Literature highlights critical issues about the treatment of Mg²⁺ deficiency, such as the lack of a clear definition of Mg²⁺ nutritional status, the use of different Mg²⁺ salts and dosage and the different duration of the Mg²⁺ supplementation. Despite the lack of agreement, an appropriate dietary pattern, including the right intake of Mg²⁺, improves metabolic syndrome by reducing blood pressure, hyperglycemia, and hypertriglyceridemia. This occurs through the modulation of gene expression and proteomic profile as well as through a positive influence on the composition of the intestinal microbiota and the metabolism of vitamins B1 and D.

Associations of Heavy Metals with Metabolic Syndrome and Anthropometric Indices

Previous studies have revealed associations between heavy metals and extensive health problems. However, the association between heavy metals and metabolic problems remains poorly defined. This study aims to investigate relationships between heavy metals and metabolic syndrome (MetS), lipid accumulation product (LAP), visceral adiposity index (VAI), and anthropometric indices, including body roundness index (BRI), conicity index (CI), body adiposity index (BAI), and abdominal volume index (AVI). We conducted a health survey of people living in southern Taiwan. Six heavy metals were measured: lead (Pb) in blood and nickel (Ni), chromium (Cr), manganese (Mn), arsenic (As), and copper (Cu) in urine. A total of 2444 participants (976 men and 1468 women) were enrolled. MetS was defined according to the Adult Treatment Panel III for Asians. Multivariable analysis showed that participants with high urine Ni (log per 1 μg/L; odds ratio (OR): 1.193; 95% confidence interval (CI): 1.019 to 1.397; p = 0.028) and high urine Cu (log per 1 μg/dL; OR: 3.317; 95% CI: 2.254 to 4.883; p < 0.001) concentrations were significantly associated with MetS. There was a significant trend of a stepwise increase in blood Pb and urine Ni, As, and Cu according to the number of MetS components (from 0 to 5, a linear p ≤ 0.002 for trend). For the determinants of indices, urine Cu was positively correlated with LAP, BRI, CI, and VAI; blood Pb was positively correlated with BRI, BAI, and AVI; urine Ni was positively correlated with LAP. High urine Cu and urine Ni levels were significantly associated with MetS, and there was a significant trend for stepwise increases in blood Pb and urine Ni, As, and Cu, accompanied by an increasing number of MetS components. Furthermore, several indices were positively correlated with urine Cu, urine Ni, and blood Pb.

Dietary Intake and Urinary Excretion of Manganese in Korean Healthy Adults

Manganese (Mn) is an essential element for the body's composition and is required for various functions, including nutrient metabolism, immune system function, and antioxidant ability. However, there are insufficient data on the nutritional status of Mn. In this study, we aimed to analyze the relationship between Mn intake and urinary excretion in Korean adults. A twice dietary intake survey using a 24-h recall method was conducted on 640 adults (320 men and 320 women), aged 20 to 69 years. Eighty 24-h urine samples were also twice collected and urinary Mn excretions were analyzed. Results indicated that total Mn intake per day was 4.1 mg for men and 3.9 mg for women (p < 0.05). Mn intake per 1000 kcal of energy consumption was significantly higher in women than in men (2.0 mg/1,000 kcal vs. 2.2 mg/1000 kcal, p < 0.01). Additionally, Mn intake as a percentage of Adequate Intake was 103.0% for men and 110.3% for women (p < 0.05). Mn was mostly consumed from cereals (1.78 mg/day for men and 1.53 mg/day for women), followed by vegetables, seasonings, fruits, and pulses. The main food sources of Mn were rice (27.8% for men, 22.0% for women), kimchi (3.5% for men, 1.4% for women), and tofu (2.8% for men, 2.3% for women); the percentage of Mn consumed from 20 types of foods was 55.6% (women) to 60.4% (men). Urinary Mn excretion was negatively correlated with Mn intake from cereals and positively with mushrooms only for women after adjusting for confounding factors (p < 0.05). In conclusion, dietary Mn intake by Korean adults was adequate to meet the Dietary Reference Intake, but the relationship between Mn intake and urinary excretion was not clear.

Association between dietary mineral nutrient intake, body mass index, and waist circumference in U.S. adults using quantile regression analysis NHANES 2007-2014

OBJECTIVE

Mineral nutrients play an important role in maintaining material and energy metabolism. Reports on mineral nutrient intakes and body mass index (BMI) and waist circumference (WC) are rare in the United States. This study examined the relationship between BMI, WC and dietary mineral intakes.

METHOD

We used the data from National Health and Nutrition Examination Survey 2007-2014. Nutrient intakes were adjusted for energy according to the residual adjustment method. We used the quantile regression model to analyze the relationship between BMI, WC under different distributions and the average daily mineral intakes.

RESULT

A total of 19,952 people were included in the study, including 9,879 men and 10,073 women (≥20 years old). The median BMI was 27.935 kg/m2 and the median WC was 97.700 cm. The results of quantile regression showed that calcium, magnesium, potassium, copper, zinc and iron intakes were negatively correlated with BMI and WC, after adjusting for age and gender. Sodium and phosphorus intakes were positively correlated with BMI, sodium intakes were positively correlated with WC. This correlation was enhanced with increasing quantiles of risk levels. In high BMI or high WC populations, mineral intakes had a greater impact on BMI and WC. The quantile regression coefficients of selenium intakes were not statistically significant at each quantile.

CONCLUSION

Our results suggested that the mineral nutrient intakes were associated with BMI and WC in American adults. However, we also need to further study the longitudinal effects of mineral intakes and obesity.

Is There a Link between Zinc Intake and Status with Plasma Fatty Acid Profile and Desaturase Activities in Dyslipidemic Subjects?

The prevalence of obesity and dyslipidemia has increased worldwide. The role of trace elements in the pathogenesis of these conditions is not well understood. This study examines the relationship between dietary zinc (Zn) intake and plasma concentrations of Zn, copper (Cu) and iron (Fe) with lipid profile indicators, fatty acid composition in plasma phospholipids and desaturase enzyme activities in a dyslipidemic population. The role of the newly proposed biomarker of Zn status, the linoleic:dihomo-gama-linolenic acid (LA:DGLA) ratio, in predicting Zn status of dyslipidemic subjects has been explored. The study included 27 dyslipidemic adults, 39-72 years old. Trace elements were determined using atomic absorption spectrometry and fatty acid composition by a liquid gas chromatography. Desaturase activities were calculated from product-precursor fatty acid ratios. Dietary data were obtained using 24 h recall questionnaires. Insufficient dietary intake of Zn, low plasma Zn concentrations and an altered Cu:Zn ratio is related to modified fatty acid profile in subjects with dyslipidemia. Plasma Zn status was associated with obesity. There was no correlation between dietary Zn intake and plasma Zn status. The LA:DGLA ratio was inversely linked to dietary Zn intake. Cu, in addition to Zn, may directly or indirectly, affect the activity of desaturase enzymes.

Changes in blood pressure associated with lead, manganese, and selenium in a Bangladeshi cohort

BACKGROUND

Heavy metal contamination is widespread in Bangladesh. Previous studies have observed lead increases blood pressure over time. However, the role of other metal contaminants and essential micronutrients, which could also adversely affect blood pressure or act as protective factors, is understudied.

OBJECTIVES

We therefore evaluated the associations of lead, manganese, and selenium with blood and pulse pressure trajectories.

METHODS

We prospectively followed placebo-assigned participants nested within a randomized trial for the prevention of arsenic-related skin cancer (n = 255). Blood lead, manganese, and selenium were measured at baseline; blood pressure was measured at baseline and at 3 biennial follow-up examinations. Mixed-effect linear regression models were used to estimate associations with average annual changes in systolic, diastolic, and pulse pressure.

RESULTS

In models simultaneously adjusted for baseline blood lead, manganese, and selenium concentrations in addition to other potential confounders, lead was linearly associated with increases in systolic blood pressure, but not with diastolic blood pressure or pulse pressure. A non-linear association was observed for manganese, such that mid-range concentrations were associated with decreases in systolic, diastolic, and pulse pressure. Baseline selenium concentrations in the highest quartile were also associated with longitudinal decreases in both systolic and diastolic blood pressure, while null associations were observed with pulse pressure. In exploratory analyses, the combination of mid-range manganese and high selenium concentrations completely offset lead-associated increases in blood and pulse pressure.

CONCLUSIONS

The results indicate a direct, linear association of lead exposure with systolic blood pressure, and manganese and selenium exposures within certain ranges may have a blood pressure-lowering effect in this population.

Dietary manganese and type 2 diabetes mellitus: two prospective cohort studies in China

AIMS/HYPOTHESIS

The association between dietary Mn and type 2 diabetes is unclear. We aimed to elucidate whether dietary Mn is associated with type 2 diabetes, to investigate whether this association is independent of dietary total antioxidant capacity (TAC) and to explore the underlying mechanisms in their association.

METHODS

Two prospective cohorts of 3350 and 7133 Chinese adults (20-74 years old) were enrolled including, respectively, 244 and 578 individuals newly diagnosed with type 2 diabetes, with mean values of 4.2 and 5.3 years of follow-up. Cox's proportional-hazards regression and linear regression were performed to investigate the association between dietary Mn and type 2 diabetes (diagnosed by OGTT) or HbA_lc and to analyse the joint association between dietary Mn and TAC. Restricted cubic spline (RCS) regression was applied to the non-linear association between dietary Mn and incidence of type 2 diabetes. Mediation analysis was applied to explore potential mediators in their association in a subgroup of 500 participants.

RESULTS

Dietary Mn intakes were 4.58 ± 1.04 and 4.61 ± 1.08 (mean ± SD) mg/day in the two cohorts. Dietary Mn was inversely associated with type 2 diabetes incidence and HbA_lc concentration in both cohorts (p_trend < 0.01 and <0.01 for type 2 diabetes, and p_trend < 0.01 and =0.02 for HbA_lc, respectively, in each cohort) independent of TAC, adjusted for age, sex, BMI, tobacco use, alcohol consumption, physical activity, diabetes inheritance, total energy, carbohydrate, total fatty acids, fibre, calcium, Mg, hypertension, hyperlipidaemia, and impaired glucose tolerance or FBG (all at baseline). Their inverse association was stronger in the presence of diets with high, compared with low, TAC. In RCS, intakes of >6.01 and 6.10-6.97 mg/day were associated with a significantly lower type 2 diabetes incidence in the two respective cohorts. Mediation analysis showed that high plasma Mn and low oxidative stress (increased Mn superoxide dismutase and decreased 8-hydroxydeoxyguanosine) contributed to the association between dietary Mn and both type 2 diabetes and HbA_lc.

CONCLUSIONS/INTERPRETATION

Dietary Mn was inversely associated with type 2 diabetes independently of TAC. In addition, this association was stronger in a high- rather than low-TAC diet. Plasma Mn and oxidative stress were mediators in the association between dietary Mn and type 2 diabetes. Future studies on absolute Mn intake should be conducted to study the potential non-linearity and optimal levels of dietary Mn and type 2 diabetes.

Dietary Flavonoids, Copper Intake, and Risk of Metabolic Syndrome in Chinese Adults

The effects of flavonoids and copper (Cu) on metabolic syndrome (MetS) have been investigated separately, but no information exists about the joint associations between flavonoids and Cu on the risk of MetS in population studies. In this cross-sectional study, a total of 9108 people aged 20⁻75 years from the Harbin Cohort Study on Diet, Nutrition, and Chronic Non-Communicable Diseases (HDNNCDS) were included. Flavonoid intakes were calculated based on the flavonoid database created in our laboratory. Cu and other nutrient intakes were estimated using the Chinese Food Composition Table. Among all study subjects, a total of 2635 subjects (28.9%) met the diagnostic criteria for inclusion in the MetS group. Total flavonoids (fourth vs. first quartile, odds ratio (OR): 0.77, 95% confidence interval (CI) 0.66⁻0.90, P_trend = 0.002) and Cu (OR 0.81, 90% CI: 0.70⁻0.94, P_trend = 0.020) were inversely associated with the risk of MetS after adjusting for potential confounders. Higher flavonoid intake was more strongly associated with a lower risk of MetS with high levels of Cu intake (P_interaction = 0.008). Dose⁻response effects showed an L-shaped curve between the total intake of five flavonoids and the risk of MetS. These results suggest that higher flavonoid intake is associated with a lower risk of MetS, especially under high levels of Cu intake.

Relationship Between Serum Zinc Level and Metabolic Syndrome: A Meta-Analysis of Observational Studies

Objective: This research sought to summarize the evidence regarding the relationship between serum zinc level and metabolic syndrome (MetS).Methods: The electronic databases of PubMed, Web of Science, and Embase were searched up to October 2017 for observational studies on the association between serum zinc level and MetS. The standard mean difference (SMD) and its corresponding 95% confidence interval (CI) of the serum zinc level for MetS versus control participants were calculated. In addition, the pooled odds ratio (OR) and relative risk (RR) of MetS for the highest versus lowest category of serum zinc level, as well as their corresponding 95% CI, were also calculated.Results: A total of 11 observational studies (8 cross-sectional, 1 case-control, and 2 cohort studies) were included in this meta-analysis. The combined SMD demonstrated that the serum zinc level in MetS was higher than that in control participants (SMD = 0.11; 95% CI, 0.03-0.19; p = 0.009). Moreover, the overall multivariable-adjusted RR showed that the increased serum zinc level was associated with a higher risk of MetS (RR = 1.82; 95% CI, 1.33-2.50; p < 0.001). On the contrary, the overall multivariable-adjusted OR showed that there was no significant relationship between serum zinc level and MetS (OR = 1.00; 95% CI, 0.99-1.01; p = 0.841).Conclusions: Although the serum zinc level in participants with MetS was significantly higher than that in control ones, the existing evidence was still insufficient to conclude a definite relationship between serum zinc level and MetS. More well-designed prospective cohort studies are needed to elaborate the concerned issues further.

The Essential Element Manganese, Oxidative Stress, and Metabolic Diseases: Links and Interactions

Manganese (Mn) is an essential element that is involved in the synthesis and activation of many enzymes and in the regulation of the metabolism of glucose and lipids in humans. In addition, Mn is one of the required components for Mn superoxide dismutase (MnSOD) that is mainly responsible for scavenging reactive oxygen species (ROS) in mitochondrial oxidative stress. Both Mn deficiency and intoxication are associated with adverse metabolic and neuropsychiatric effects. Over the past few decades, the prevalence of metabolic diseases, including type 2 diabetes mellitus (T2MD), obesity, insulin resistance, atherosclerosis, hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and hepatic steatosis, has increased dramatically. Previous studies have found that ROS generation, oxidative stress, and inflammation are critical for the pathogenesis of metabolic diseases. In addition, deficiency in dietary Mn as well as excessive Mn exposure could increase ROS generation and result in further oxidative stress. However, the relationship between Mn and metabolic diseases is not clear. In this review, we provide insights into the role Mn plays in the prevention and development of metabolic diseases.

Biomarkers of the metabolic syndrome: Influence of minerals, oligo- and trace elements

Influences of minerals, oligo- and trace elements on the concentration of biomarkers of the metabolic syndrome (MetS) are reviewed. Since food is a complex mixture of caloric compounds and essential non-caloric food components with multiple interactions and varying bioavailability, it is hard to separate or identify the effect of one single component in a total meal or diet. Moreover the diet contains various non-nutritive biologically active components, which may add some beneficial characteristics. Therefore, conclusions on the effect of components on various biomarkers of MetS are sometimes quite contradictory. Reasons therefore are mentioned. Literature data should be studied in detail to conclude whether a component is related to a reduction of MetS-related symptoms or whether its influence is merely affecting a biomarker.

Link of dietary patterns with metabolic syndrome: analysis of the National Health and Nutrition Examination Survey

BACKGROUND

Population-based interventions aimed at halting the increasing prevalence of metabolic syndrome (MetS) require thorough understanding of dietary interplays. Objective is to identify the independent dietary nutrients associated with MetS and its components using dietary pattern identification and the single-nutrient approaches in The United States.

METHODS

This is a cross-sectional observation. Participants are selected from the National Health and Nutrition Examination Survey (NHANES) with available dietary intake, biochemical and anthropometrical data from 2001 to 2012. Exposure is diet obtained from 24-h dietary recall. Main outcome measure is MetS and its components.

RESULTS

Overall, 23 157 eligible individuals including 6561 with MetS were included in the final analysis. Using principle component analysis, we identified three food patterns that explained 50.8% of the variance of the dietary nutrient consumption. The highest quartile of the factor score representative of saturated/monounsaturated fatty acids or the first dietary pattern was associated with 1.27-fold (95% confidence interval (CI): 1.10-1.46, P=0.001) higher odds of association with MetS when compared with the first quartile. The second pattern representative of vitamins and trace elements had an odds ratio of 0.79 (95% CI: 0.70-0.89, P<0.001) for association with MetS, and the third pattern representative of polyunsaturated fatty acids did not have any association with MetS. The nutrient-by-nutrient approach showed that mild alcohol intake and lower consumption of total saturated fatty acids and sodium were associated with lower risk of MetS.

CONCLUSIONS

Application of multiple complementary analytic approaches reveals more comprehensive dietary determinants of MetS and its components as potential intervening targets.

Daily Intake of Magnesium and its Relation to Urinary Excretion in Korean Healthy Adults Consuming Self-Selected Diets

Magnesium (Mg) is an essential nutrient as a structural constituent of bone and regulator of >300 enzymes. However, studies on intake and urinary excretion of Mg are limited. The purpose of this study was to evaluate Mg intake and its relation to 24-h urinary excretion in healthy adults. Anthropometric measurements and dietary intake by the 24-h recall method were conducted in 80 adults aged 21-69 (average 44.3) years. Urine was collected for 24 h on the day following the dietary survey. Dietary assessment and 24-h urine collection were repeated 3 days later. Daily intake and urinary excretion of Mg were analyzed using Can-Pro and ICP-OES, respectively. The statistical analysis was conducted using SAS program. Mg intake of the subjects was 319 ± 129 mg/day for men and 277 ± 94 mg/day for women and the proportion of subjects who did not meet the estimated average requirement was 50 and 67.5 % for men and women, respectively. Urinary Mg excretion was 30.3 % of the daily Mg intake. Urinary Mg excretion was not significantly correlated with the daily Mg intake. Korean adults are not meeting the recommended intake of Mg, but its urinary excretion suggests homeostasis is not compromised.

Relationship between Selected Serum Metallic Elements and Obesity in Children and Adolescent in the U.S

The prevalence of obesity has increased at an alarming rate worldwide. Metallic elements are involved in the pathogenesis of obesity and related diseases. To date, whether environmental exposure to metallic elements has effects on obesity in children and adolescents is still unclear. The aim of the current study was to investigate the association of blood metallic elements with obesity in U.S. children and adolescents. This cross-sectional study was performed with 5404 children and adolescents (6-19 years, 2745 males and 2659 females) who participated in the US National Health and Nutrition Examination Survey 2011-2014. Blood lead, mercury, selenium, manganese, copper, and zinc, as well as biochemical parameters including triglyceride (TG), cholesterol, low-density lipoprotein (LDL), and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed for all subjects. Multivariate logistic regression and linear regression were applied to assess associations of metallic elements and overweight, obesity status, and serum metabolites as distinct outcomes adjusted for age, gender, ethnicity, and the poverty income ratio. When stratified by age and sex, significant associations were found between the highest quartile of copper concentrations in blood with obesity status (OR = 9.27, 95% CI: 5.43, 15.82, p_{for trend} < 0.001) and cholesterol (OR = 3.08, 95% CI: 1.43, 6.63, p_{for trend} < 0.001). The highest concentrations of manganese in the blood was associated with obesity in those aged 6-19 years (OR = 2.29, 95% CI: 1.74, 3.02, p_{for trend} < 0.001). Moreover, blood mercury and selenium showed positive relationships with cholesterol. Further, a negative association existed between blood zinc and obesity. The National Health and Nutrition Examination Survey data provide epidemiological evidence that blood metallic elements are positively associated with obesity in children and adolescents. However, the underlying mechanisms still need further exploration.

Low magnesium diet alters distribution of macroelements and trace elements in tissues and organs of female rats

The aim of the present study was to assess whether dietary magnesium deficiency can alter distribution of macroelements and trace elements in different organs and tissues. Experiments were carried out on 12 adult female Wistar rats, which were fed either a diet with low Mg content (≤20mgkg^-1 of diet) (LMgD) or a diet with daily recommended Mg content (≈500mgkg^-1) as control group (CG) for 70 days. On the 70th day of the experiment heart, aorta, femoral skeletal muscle, forebrain, cerebellum, pituitary gland, thyroid gland, ovaries, uterus, liver, kidneys, and spleen were taken for analysis of mineral content. Concentrations of Fe and Ca were measured by inductively coupled plasma-atomic emission spectrometry, and levels of Na, K, Mg, Co, Cu, Zn, Ni, Se, I were determined by inductively coupled plasma mass spectrometry. On the 70th day, LMgD led to significant reduction of Mg level in red blood cells, plasma, aorta, uterus and thyroid gland compared to CG as well as resulted in significant decrease of Mg/Ca ratio in kidneys, spleen and ovaries. Contrary to this, an increase of Mg/Ca ratio was found in cerebellum of LMgD group. Significant decrease of K concentration was shown in aorta of LMgD animals compared to CG whereas myocardial K concentration was increased in LMgD group. Na level was two-fold higher in skeletal muscles of rats that received LMgD in comparison to CG (p=0.006). Increased concentrations of Fe in ovaries and uterus were found in LMgD. Mg restriction did not affect Zn concentration in any of tasted tissues. Se level was higher in spleen and lower in uterus of LMgD animals compared to CG. MgD was accompanied by increased level of Co in skeletal muscles and decreased its level in kidneys and uterus. LMgD feeding was associated with decreased concentrations of Ni in heart, thyroid gland, spleen, uterus and Co in heart, aorta, liver, kidneys, spleen and ovaries. The changes of Mg, K, Co content were accompanied by dramatic (10-fold) decrease of I concentration in aorta of LMgD animals. LMgD causes decrease of I content in ovaries and increase of I level in uterus vs CG. Thus, distribution of macroelements (Ca, Na, K) was weakly affected by Mg restriction that led to the most evident alterations of Co and Ni tissue levels. Moreover, mineral balance of uterus seems to be the most susceptible to low Mg intake. Hypomagnesaemia resulted in significant changes of 5 studied trace elements (Fe, Se, Cu, Ni and Co).

International variability in diet and requirements of manganese: Causes and consequences

Manganese (Mn) is an essential trace element that is critical for human health and development. At the turn of the century when diets were based on whole grains, cereals and other traditional foods, Mn intakes (8-9mg/d) were much greater than that prevalent today (2mg/d). As societies have developed, diets have shifted as part of a nutrition transition, to those that are high in processed foods, fat, and sugar. These foods are virtually devoid of Mn. Thus, dietary Mn has declined substantially throughout the world, as confirmed by several wide-scale, total diet studies. International variability in dietary Mn is considerable, due to tremendous diversity in food and culture. In countries where fruit and vegetable intake may be limited, i.e. the United Kingdom, populations may ingest much lower levels of Mn (1.4mg/d) as compared to Asian cultures (4mg/d) which have an abundance of plant foods in their food supply and cuisine. The bioavailability of Mn must be considered, including chemical form, oxidation state, mineral-mineral interactions, presence of dietary components and traditional food processing techniques (milling, germination, malting, fermentation). Manganese toxicity is a public health problem that results from exposure to a naturally high water source or contaminated environment of the soil and/or drinking water. In contrast, inadequate intake is associated with adverse health effects such as diabetes, metabolic syndrome, poor birth outcomes and possibly, cancer. Future studies are recommended to set dietary standards for this mineral in countries that lack recommendations to help achieve optimal health.

Dietary intake of manganese and the risk of the metabolic syndrome in a Chinese population

Animal studies have suggested that Mn might be associated with some components of the metabolic syndrome (MetS). A few epidemiological studies have assessed dietary Mn intake and its association with the risk of the MetS and its components among Chinese adults. In this study, we assessed daily dietary Mn intake and its relationship with MetS risk among Chinese adults in Zhejiang Province using data from the 5th Chinese National Nutrition and Health Survey (2010–2012). A total of 2111 adults were included. Dietary Mn intake was assessed using 3-d 24-h dietary recalls; health-related data were obtained by questionnaire surveys, physical examinations and laboratory assessments. The mean intake of Mn was 6·07 (sd 2·94) mg/d for men (n 998) and 5·13 (sd 2·65) mg/d for women (n 1113). Rice (>42 %) was the main food source of Mn. The prevalence of the MetS was 28·0 % (590/2111). Higher Mn intake was associated with a decreased risk of the MetS in men (Q4 v. Q1 OR 0·62; 95 % CI 0·42, 0·92; P_trend=0·043) but an increased risk in women (Q4 v. Q1 OR 1·56; 95 % CI 1·02, 2·45; P_trend=0·078). In addition, Mn intake was inversely associated with abdominal obesity (P_trend=0·016) and hypertriacylglycerolaemia (P_trend=0·029) in men, but positively associated with low HDL-cholesterol in both men (P_trend=0·003) and women (P_trend<0·001). Our results suggest that higher Mn intakes may be protective against the MetS in men. The inverse association between Mn intake and the MetS in women might be due to the increased risk for low HDL-cholesterol.

Association of Magnesium Intake with High Blood Pressure in Korean Adults: Korea National Health and Nutrition Examination Survey 2007-2009

Background

Magnesium is known to lower the risk of cardiovascular disease. However, studies on its relationship with hypertension, a single and common cause of various chronic diseases, are limited and their findings are not consistent. The purpose of the present study is to identify the relationship between magnesium intake and high blood pressure (HBP) risk in Koreans.

Methods

This research is a cross-sectional study based on the 2007~2009 Korean National Health and Nutritional Examination Survey data. This study investigated 11,685 adults aged over 20 to examine their general characteristics, anthropometry and blood pressure. Daily magnesium intake was analyzed using the 24-hour dietary recall method. To calculate the odds ratio (OR) of HBP risk (130/85 mmHg or over) according to the quartile of magnesium intake (mg/1000kcal) together with its 95% confidence interval (CI), multivariable logistic regression analysis was performed.

Results

No significant association between dietary magnesium intake and the risk of HBP was found. In obese women, particularly, after adjusting relevant factors, the adjusted odds ratio of HBP prevalence in the highest magnesium intake quartile was 0.40 compared with the lowest magnesium intake quartile (95% CI = 0.25~0.63, P for trend = 0.0014). Women, especially obese women, were found to have a negative relationship of magnesium intake with HBP.

Conclusions

The present results indicate that sufficient magnesium intake could be useful in decreasing the high blood pressure risk of obese women.

Relationship between the concentrations of heavy metals and bioelements in aging men with metabolic syndrome

Heavy metals may exacerbate metabolic syndrome (MS) but abnormal serum concentrations of bioelements may also co-exist with MS. The primary aim of the study was to assess the relationship of blood heavy metal and bioelement concentrations and MS, in men aged 50-75 years. Heavy metals-lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), tungsten (W), Macroelements-magnesium (Mg) and calcium (Ca), and microelements-iron (Fe), zinc (Zn) copper (Cu), chromium (Cr), molybdenum (Mo), selenium (Se) and manganese (Mn), body mass index (BMI), waist to hip ratio (WHR), abdominal circumference (AC) and blood pressure (BP), total cholesterol (TCh), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG), fasting plasma glucose (FPG), insulin, and Homeostasis Model Assessment-Insulin resistance (HOMA-IR). The men with MS showed statistically significant higher Zn and lower Mg concentrations. Those with diabetes had higher Ca concentration and lower Mg concentration. Cr and Mn concentrations were significantly higher in obese men. The participants with hypertension had lower Mg concentration. We found statistically significant positive correlations (W-TCh, W-LDL, Mg-TCh, Mg-LDL, Ca-TCh, Ca-LDL, Ca-insulin, Ca-HOMAR-IR, Zn-TG, Zn-insulin, Zn-HOMA-IR, Cu-BP systolic, Mn-BMI, Mn-AC, Mn-WHR, Mn-insulin, Mn-HOMA-IR, Se-TCh, Se-LDL, Se-TG, Se-insulin, Se-HOMA-IR, Cr-TCh, Cr-HDL, Cr-LDL, Cr-TG) and negative correlations (Cd-insulin, Hg-WHR, W-insulin, W-HOMA-IR, Mg-BMI, Mg-AC, Mg-WHR, Mg-BP systolic, Mo-insulin, Mn-HDL). Tungsten may contribute to lipid disorders. Magnesium appears to play the protective role in the occurrence of metabolic disorders. Microelements Mn, Cr and Se may intensify MS.

Dietary magnesium intake and metabolic syndrome in the adult population: dose-response meta-analysis and meta-regression

ncreasing evidence has suggested an association between dietary magnesium intake and metabolic syndrome. However, previous research examining dietary magnesium intake and metabolic syndrome has produced mixed results. Our objective was to determine the relationship between dietary magnesium intake and metabolic syndrome in the adult population using a dose-response meta-analysis. We searched the PubMed, Embase and the Cochrane Library databases from August, 1965, to May, 2014. Observational studies reporting risk ratios with 95% confidence intervals (CIs) for metabolic syndrome in ≥ 3 categories of dietary magnesium intake levels were selected. The data extraction was performed independently by two authors, and the quality of the studies was evaluated using the Risk of Bias Assessment Tool for Nonrandomized Studies (RoBANS). Based on eight cross-sectional studies and two prospective cohort studies, the pooled relative risks of metabolic syndrome per 150 mg/day increment in magnesium intake was 0.88 (95% CI, 0.84-0.93; I(2) = 36.3%). The meta-regression model showed a generally linear, inverse relationship between magnesium intake (mg/day) and metabolic syndrome. This dose-response meta-analysis indicates that dietary magnesium intake is significantly and inversely associated with the risk of metabolic syndrome. However, randomized clinical trials will be necessary to address the issue of causality and to determine whether magnesium supplementation is effective for the prevention of metabolic syndrome.