Magnesium Intake Is Related to Improved Insulin Homeostasis in the Framingham Offspring Cohort

Nutrition in Gynecological Diseases: Current Perspectives

Diet and nutrition are fundamental in maintaining the general health of populations, including women's health. Health status can be affected by nutrient deficiency and vice versa. Gene-nutrient interactions are important contributors to health management and disease prevention. Nutrition can alter gene expression, as well as the susceptibility to diseases, including cancer, through several mechanisms. Gynecological diseases in general are diseases involving the female reproductive system and include benign and malignant tumors, infections, and endocrine diseases. Benign diseases such as uterine fibroids and endometriosis are common, with a negative impact on women's quality of life, while malignant tumors are among the most common cause of death in the recent years. In this comprehensive review article, a bibliographic search was performed for retrieving information about nutrients and how their deficiencies can be associated with gynecological diseases, namely polycystic ovary syndrome, infertility, uterine fibroids, endometriosis, dysmenorrhea, and infections, as well as cervical, endometrial, and ovarian cancers. Moreover, we discussed the potential beneficial impact of promising natural compounds and dietary supplements on alleviating these significant diseases.

Magnesium intake, insulin resistance and markers of endothelial function among women

OBJECTIVE

We investigated the association of dietary Mg intake with insulin resistance and markers of endothelial function among Iranian women.

DESIGN

A cross-sectional study.

SETTING

Usual dietary intakes were assessed using a validated FFQ. Dietary Mg intake was calculated by summing up the amount of Mg in all foods. A fasting blood sample was taken to measure serum concentrations of glycemic indices (fasting plasma glucose and insulin) and endothelial function markers (E-selectin, soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1). Insulin resistance and sensitivity were estimated using the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR), Homeostasis Model Assessment β-cell function (HOMA-β) and quantitative insulin sensitivity check index (QUICKI).

PARTICIPANTS

Iranian female nurses (n 345) selected by a multistage cluster random sampling method.

RESULTS

The Mg intake across energy-adjusted quartiles was 205 (se 7), 221·4 (se 8), 254·3 (se 7) and 355·2 (se 9) mg/d, respectively. After adjustments for potential confounders, QUICKI level was significantly different across quartiles of Mg intake (Q1: 0·34 (se 0·02), Q2: 0·36 (se 0·01), Q3: 0·40 (se 0·01), and Q4: 0·39 (se 0·02), P = 0·02); however, this association disappeared after considering markers of endothelial function, indicating that this relation might be mediated through endothelial dysfunction. After controlling for all potential confounders, Mg intake was inversely, but not significantly, associated with serum concentrations of sICAM (Q1: 239 (se 17), Q2: 214 (se 12), Q3: 196 (se 12), and Q4: 195 (se 17), P = 0·29). There was no other significant association between dietary Mg intake and other indicators of glucose homoeostasis or endothelial markers.

CONCLUSIONS

Higher dietary Mg intake was associated with better insulin sensitivity in Iranian females. This linkage was mediated through reduced endothelial dysfunction.

Magnesium: The recent research and developments

Magnesium is the fourth most abundant mineral in the human body, which facilitates more than 300 enzymatic reactions. Magnesium is essential for nucleic material and protein synthesis, neuromuscular conduction, cardiac contractility, energy metabolism, and immune system function. Gastrointestinal system and kidneys closely regulate magnesium absorption and elimination to maintain adequate storage of magnesium. Magnesium deficiency has been linked to many diseases and poor health outcomes. Magnesium has also been proven to be an effective therapeutic agent in many diseases, such as bronchial asthma, cardiac arrhythmia, and pre-eclampsia.

Effects of magnesium supplementation on carotid intima-media thickness and metabolic profiles in diabetic haemodialysis patients: a randomised, double-blind, placebo-controlled trial

This study evaluated the effects of Mg administration on carotid intima-media thickness (CIMT), glycaemic control and markers of cardio-metabolic risk in diabetic haemodialysis (HD) patients. This randomised, double-blind, placebo-controlled clinical trial was conducted in fifty-four diabetic HD patients. Participants were randomly divided into two groups to take either 250 mg/d Mg as magnesium oxide (n 27) or placebo (n 27) for 24 weeks. Mg supplementation resulted in a significant reduction in mean (P<0·001) and maximum levels of left CIMT (P=0·02) and mean levels of right CIMT (P=0·004) compared with the placebo. In addition, taking Mg supplements significantly reduced serum insulin levels (β=-9·42 pmol/l; 95% CI -14·94, -3·90; P=0·001), homoeostasis model of assessment-insulin resistance (β=-0·56; 95 % CI -0·89, -0·24; P=0·001) and HbA1c (β=-0·74 %; 95 % CI -1·10, -0·39; P<0·001) and significantly increased the quantitative insulin sensitivity check index (β=0·008; 95 % CI 0·002, 0·01; P=0·002) compared with the placebo. In addition, Mg administration led to a significant reduction in serum total cholesterol (β=-0·30 mmol/l; 95% CI -0·56, -0·04; P=0·02), LDL-cholesterol (β=-0·29 mmol/l; 95% CI -0·52, -0·05; P=0·01), high-sensitivity C-reactive protein (hs-CRP) (P<0·001) and plasma malondialdehyde (MDA) (P=0·04) and a significant rise in plasma total antioxidant capacity (TAC) levels (P<0·001) compared with the placebo. Overall, we found that taking Mg for 24 weeks by diabetic HD patients significantly improved mean and maximum levels of left and mean levels of right CIMT, insulin metabolism, HbA1c, total cholesterol and LDL-cholesterol, hs-CRP, TAC and MDA levels.

Association of dietary and serum magnesium with glucose metabolism markers: The Furukawa Nutrition and Health Study

BACKGROUND & AIMS

Magnesium may play an important role in cardio-metabolic abnormalities, including type 2 diabetes, but epidemiological evidence linking magnesium status to glucose metabolism is limited among Asians. We cross-sectionally examined the association of dietary and serum magnesium with markers of glucose metabolism among Japanese subjects.

METHODS

Subjects were 1796 workers, aged 18-78 years, who participated in a health survey. Dietary magnesium intake was assessed with a validated brief diet history questionnaire. Serum magnesium concentrations were measured using an enzymatic method. Multivariable linear regression models were used to estimate means of fasting insulin, fasting plasma glucose, homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β), and glycated hemoglobin (HbA1c), with adjustments made for potential confounding variables.

RESULTS

Dietary magnesium was inversely associated with HOMA-IR (P_trend = 0.01). Multivariable-adjusted means (95% confidence intervals) of HOMA-IR for the lowest to highest quartiles of dietary magnesium were 0.94 (0.89-0.99), 0.92 (0.88-0.97), 0.88 (0.83-0.92), and 0.86 (0.81-0.90). Serum magnesium concentrations were also inversely associated with HOMA-IR (P_trend = 0.04) and HbA1c (P_trend <0.01). Multivariable-adjusted means (95% confidence intervals) for the lowest to highest quartiles of serum magnesium were 0.94 (0.90-0.98), 0.87 (0.83-0.91), 0.90 (0.85-0.95), and 0.86 (0.81-0.92) for HOMA-IR and 5.41 (5.36-5.45), 5.33 (5.28-5.37), 5.30 (5.25-5.36), and 5.28 (5.22-5.35) for HbA1c. Excluding subjects with diabetes did not materially change the association between dietary magnesium and HOMA-IR (P_trend <0.01), while it attenuated the association of serum magnesium with HOMA-IR (P_trend = 0.27) and HbA1c (P_trend = 0.15).

CONCLUSIONS

The present findings suggest that lower dietary magnesium, but not serum magnesium, is associated with IR in apparently healthy adults.

Rising trend of diabetes mellitus amongst the undernourished: State -of- the -art review

Diabetes mellitus is prevailing in the malnourished populations congruently in well-nourished ones with an escalating trend in the former group regardless of the absence of obesity as an etiologic determining factor as per the studies in underprivileged sectors of the population. Chronic undernutrition across a lifetime may be an imperative stimulator of diabetes in an individual either by progressively reducing beta cell function alongside islet cell volume and increasing the individual predisposition to other genetic or environmental diabetogenic influences with modifying influence on the course of clinical syndrome. Ketosis resistant insulinopenia is irreversible to the sustained vigorous nutritional convalescence in a substantial fraction of malnourished subjects. It also debunks a latent diabetic stage with insulin resistance reflected by greater insulin requirement in comparison to the patients with type I diabetes with the same beta cell failure fraction and obese type II diabetic patients with equivalent glycemic control gauged by HbA1c levels. Current tendency warrants the replacement of conventional therapy by community oriented theranostic approaches and health programs to curb the epidemic.

Nutritional management in women with polycystic ovary syndrome: A review study

Polycystic ovary syndrome (PCOS) is endocrine disorder in women of reproductive age, which leads to reproductive, hormonal and metabolic abnormalities. Due to the presence of insulin resistance, PCOS increases the risk of chronic diseases like type 2 diabetes, hypertension, lipid disorders, cardiovascular diseases and malignancies such as breast and endometrial cancer. The actual cause of this syndrome is unknown but environmental factors such as dietary habits play an important role in prevention and treatment and lifestyle modifications are the most important therapeutic strategies in these patients. The approach of the diet therapy in these patients must be to reach specific goals such as improving insulin resistance, metabolic and reproductive functions that will be possible through the design of low-calorie diet to achieve weight loss or maintaining a healthy weight, limit the intake of simple sugars and refined carbohydrates and intake foods with a low glycemic index, reduction of saturated and trans fatty acids and attention to possible deficiencies such as vitamin D, chromium and omega-3. Given the prevalence of overweight and obesity and insulin resistance, a relatively low reduction in weight, about 5%, can improve problems such as insulin resistance, high levels of androgens, reproductive system dysfunctions and fertility in these women.

Systems biology of personalized nutrition

Personalized nutrition is fast becoming a reality due to a number of technological, scientific, and societal developments that complement and extend current public health nutrition recommendations. Personalized nutrition tailors dietary recommendations to specific biological requirements on the basis of a person's health status and goals. The biology underpinning these recommendations is complex, and thus any recommendations must account for multiple biological processes and subprocesses occurring in various tissues and must be formed with an appreciation for how these processes interact with dietary nutrients and environmental factors. Therefore, a systems biology-based approach that considers the most relevant interacting biological mechanisms is necessary to formulate the best recommendations to help people meet their wellness goals. Here, the concept of "systems flexibility" is introduced to personalized nutrition biology. Systems flexibility allows the real-time evaluation of metabolism and other processes that maintain homeostasis following an environmental challenge, thereby enabling the formulation of personalized recommendations. Examples in the area of macro- and micronutrients are reviewed. Genetic variations and performance goals are integrated into this systems approach to provide a strategy for a balanced evaluation and an introduction to personalized nutrition. Finally, modeling approaches that combine personalized diagnosis and nutritional intervention into practice are reviewed.

A systematic review and meta-analysis of randomized controlled trials on the effects of magnesium supplementation on insulin sensitivity and glucose control

A systematic review and meta-analysis was conducted to evaluate the effect of oral magnesium supplementation on insulin sensitivity and glucose control in both diabetic and non-diabetic individuals. PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched (from inception to November 25, 2015) to identify RCTs evaluating the effect of magnesium on insulin sensitivity and glucose control. A random-effects model and generic inverse variance method were used to compensate for the heterogeneity of studies. Publication bias, sensitivity analysis, and meta-regression assessments were conducted using standard methods. The impact of magnesium supplementation on plasma concentrations of glucose, glycated hemoglobin (HbA1c), insulin, and HOMA-IR index was assessed in 22, 14, 12 and 10 treatment arms, respectively. A significant effect of magnesium supplementation was observed on HOMA-IR index (WMD: -0.67, 95% CI: -1.20, -0.14, p=0.013) but not on plasma glucose (WMD: -0.20mmol/L, 95% CI: -0.45, 0.05, p=0.119), HbA1c (WMD: 0.018mmol/L, 95% CI: -0.10, 0.13, p=0.756), and insulin (WMD: -2.22mmol/L, 95% CI: -9.62, 5.17, p=0.556). A subgroup analysis comparing magnesium supplementation durations of <4 months versus ≥4 months, exhibited a significant difference for fasting glucose concentrations (p<0.001) and HOMA-IR (p=0.001) in favor of the latter subgroup. Magnesium supplementation for ≥4 months significantly improves the HOMA-IR index and fasting glucose, in both diabetic and non-diabetic subjects. The present findings suggest that magnesium may be a beneficial supplement in glucose metabolic disorders.

Impact of Nutrition on Cerebral Circulation and Cognition in the Metabolic Syndrome

The increasing prevalence of Metabolic Syndrome (MetS), defined as the clustering of abdominal obesity, dyslipidemia, hypertension, and hyperglycemia, appears to be driving the global epidemics cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Nutrition has a major impact on MetS and plays an important role in the prevention, development, and treatment of its features. Structural and functional alterations in the vasculature, associated with MetS, might form the link between MetS and the increased risk of developing CVD and T2DM. Not only does the peripheral vasculature seem to be affected, but the syndrome has a profound impact on the cerebral circulation and thence brain structure as well. Furthermore, strong associations are shown with stroke, cognitive impairment, and dementia. In this review the impact of nutrition on the individual components of MetS, the effects of MetS on peripheral and cerebral vasculature, and its consequences for brain structure and function will be discussed.

Magnesium supplementation affects metabolic status and pregnancy outcomes in gestational diabetes: a randomized, double-blind, placebo-controlled trial

BACKGROUND

To our knowledge, prior research has not examined the effects of magnesium supplementation on metabolic status and pregnancy outcomes in maternal-child dyads affected by gestational diabetes (GDM).

OBJECTIVE

This study was designed to assess the effects of magnesium supplementation on metabolic status and pregnancy outcomes in magnesium-deficient pregnant women with GDM.

DESIGN

A randomized, double-blind, placebo-controlled clinical trial was performed in 70 women with GDM. Patients were randomly assigned to receive either 250 mg magnesium oxide (n = 35) or a placebo (n = 35) for 6 wk. Fasting blood samples were taken at baseline and after a 6-wk intervention.

RESULTS

The change in serum magnesium concentration was greater in women consuming magnesium than in the placebo group (+0.06 ± 0.3 vs. -0.1 ± 0.3 mg/dL, P = 0.02). However, after controlling for baseline magnesium concentrations, the changes in serum magnesium concentrations were not significantly different between the groups. Changes in fasting plasma glucose (-9.7 ± 10.1 vs. +1.8 ± 8.1 mg/dL, P < 0.001), serum insulin concentration (-2.1 ± 6.5 vs. +5.7 ± 10.7 μIU/mL, P = 0.001), homeostasis model of assessment-estimated insulin resistance (-0.5 ± 1.3 vs. +1.4 ± 2.3, P < 0.001), homeostasis model of assessment-estimated β-cell function (-4.0 ± 28.7 vs. +22.0 ± 43.8, P = 0.006), and the quantitative insulin sensitivity check index (+0.004 ± 0.021 vs. -0.012 ± 0.015, P = 0.005) in supplemented women were significantly different from those in women in the placebo group. Changes in serum triglycerides (+2.1 ± 63.0 vs. +38.9 ± 37.5 mg/dL, P = 0.005), high sensitivity C-reactive protein (-432.8 ± 2521.0 vs. +783.2 ± 2470.1 ng/mL, P = 0.03), and plasma malondialdehyde concentrations (-0.5 ± 1.6 vs. +0.3 ± 1.2 μmol/L, P = 0.01) were significantly different between the supplemented women and placebo group. Magnesium supplementation resulted in a lower incidence of newborn hyperbilirubinemia (8.8% vs. 29.4%, P = 0.03) and newborn hospitalization (5.9% vs. 26.5%, P = 0.02).

CONCLUSION

Magnesium supplementation among women with GDM had beneficial effects on metabolic status and pregnancy outcomes. This trial was registered at www.irct.ir as IRCT201503055623N39.

Lower serum magnesium concentration is associated with diabetes, insulin resistance, and obesity in South Asian and white Canadian women but not men

Background

A large proportion of adults in North America are not meeting recommended intakes for magnesium (Mg). Women and people of South Asian race may be at higher risk for Mg deficiency because of lower Mg intakes relative to requirements and increased susceptibility to diabetes, respectively.

Objective

This study compared serum Mg concentrations in South Asian (n=276) and white (n=315) Canadian women and men aged 20–79 years living in Canada's Capital Region and examined the relationship with diabetes, glucose control, insulin resistance, and body mass index.

Results

Serum Mg concentration was lower in women of both races and South Asians of both genders. Racial differences in serum Mg were not significant after controlling for use of diabetes medication. A substantial proportion of South Asian (18%) and white (9%) women had serum Mg <0.75 mmol/L indicating hypomagnesemia. Use of diabetes medication and indicators of poorer glucose control, insulin resistance, and obesity were associated with lower serum Mg in women, but not in men.

Conclusions

These results suggest that the higher incidence of diabetes in South Asians increases their risk for Mg deficiency and that health conditions that increase Mg requirements have a greater effect on Mg status in women than men.

Sire breed effect on beef longissimus mineral concentrations and their relationships with carcass and palatability traits

The objective of this study was to evaluate sire breed effect on mineral concentration in beef longissimus thoracis (LT) and investigate the correlations between beef mineral concentrations and carcass and palatability traits. Steer progeny (N=246) from the Germplasm Evaluation project-Cycle VIII were used in this study. In addition to carcass traits, LT was evaluated for mineral concentrations, Warner-Bratzler shear force, and palatability traits. A mixed linear model estimated breed effects on mineral concentrations. No significant sire breed (P≥0.43) or dam breed (P≥0.20) effects were identified for mineral concentrations. Pearson correlation coefficients were calculated among mineral concentrations, carcass, and sensory traits. Zinc concentration was positively correlated (P≤0.05) with total iron (r=0.14), heme iron (r=0.13), and magnesium (r=0.19). Significant (P<0.05) correlations were identified between non-heme or heme iron and most traits in this study. Magnesium concentration was correlated with all carcass and palatability traits.

Dietary magnesium intake and risk of cancer: a meta-analysis of epidemiologic studies

The aim of this study was to investigate the association between dietary magnesium and the risk of overall cancer using a meta-analysis. We searched PubMed, SCOPUS, and the Cochrane Review through November 2012. All the articles searched were independently reviewed by 3 authors based on predetermined selection criterion. A total of 13 epidemiologic studies, 6 case-control studies, and 7 prospective cohort studies involving 1,236,004 participants were included in the final analysis. When all studies were pooled, the relative risk (RR) of overall cancer for the highest level of dietary magnesium intake was 0.801 [95% confidence interval (CI): 0.664-0.966) compared with the lowest level of dietary magnesium intake. In subgroup meta-analyses by study design, there was a significant inverse association between dietary magnesium and the risk of cancer in case-control studies (RR = 0.663, 95% CI: 0.475-0.925), whereas there was no significant association in prospective cohort studies (RR = 0.888, 95% CI: 0.745-1.060). Furthermore, there was a significant preventive effect of dietary magnesium for colorectal cancer (RR = 0.775, 95% CI: 0.655-0.919), but not for other cancer. Our meta-analysis showed that higher dietary magnesium intake seems to have a protective effect for cancer, especially colorectal cancer and in females.

Higher magnesium intake reduces risk of impaired glucose and insulin metabolism and progression from prediabetes to diabetes in middle-aged americans

OBJECTIVE

To assess 7-year associations between magnesium intake and incident prediabetes and/or insulin resistance (IR), and progression from these states to type 2 diabetes.

RESEARCH DESIGN AND METHODS

In 2,582 community-dwelling participants 26-81 years old at baseline, magnesium intake and risk of incident "metabolic impairment," defined as impaired fasting glucose (FG) (≥5.6 to <7.0 mmol/L), impaired glucose tolerance (2-h postload glucose ≥7.8 to <11.1 mmol/L), IR, or hyperinsulinemia (≥90th percentile of homeostasis model assessment of IR or fasting insulin, respectively), was estimated among those with normal baseline status, and risk of incident diabetes was estimated among those with baseline metabolic impairment. In participants without incident diabetes, we examined magnesium intake in relation to 7-year changes in fasting and postload glucose and insulin, IR, and insulin sensitivity.

RESULTS

After adjusting for age, sex, and energy intake, compared with those with the lowest magnesium intake, those with the highest intake had 37% lower risk of incident metabolic impairment (P trend = 0.02), and in those with baseline metabolic impairment, higher intake was associated with 32% lower risk of incident diabetes (P trend = 0.05). In the combined population, the risk in those with the highest intake was 53% (P trend = 0.0004) of those with the lowest intake. Adjusting for risk factors and dietary fiber attenuated associations in the baseline normal population but did not substantially affect associations in the metabolically impaired. Higher magnesium intake tended to associate with lower follow-up FG and IR, but not fasting insulin, postload values, or insulin sensitivity.

CONCLUSIONS

Magnesium intake may be particularly beneficial in offsetting risk of developing diabetes among those at high risk. Magnesium's long-term associations with non-steady-state (dynamic) measures deserve further research.

Dietary magnesium and genetic interactions in diabetes and related risk factors: a brief overview of current knowledge

Nutritional genomics has exploded in the last decade, yielding insights—both nutrigenomic and nutrigenetic—into the physiology of dietary interactions and our genes. Among these are insights into the regulation of magnesium transport and homeostasis and mechanisms underlying magnesium’s role in insulin and glucose handling. Recent observational evidence has attempted to examine some promising research avenues on interaction between genetics and dietary magnesium in relation to diabetes and diabetes risk factors. This brief review summarizes the recent evidence on dietary magnesium’s role in diabetes and related traits in the presence of underlying genetic risk, and discusses future potential research directions.

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.

Dietary magnesium intake improves insulin resistance among non-diabetic individuals with metabolic syndrome participating in a dietary trial

Many cross-sectional studies show an inverse association between dietary magnesium and insulin resistance, but few longitudinal studies examine the ability to meet the Recommended Dietary Allowance (RDA) for magnesium intake through food and its effect on insulin resistance among participants with metabolic syndrome (MetS). The dietary intervention study examined this question in 234 individuals with MetS. Magnesium intake was assessed using 24-h dietary recalls at baseline, 6, and 12 months. Fasting glucose and insulin levels were collected at each time point; and insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). The relation between magnesium intake and HOMA-IR was assessed using linear mixed models adjusted for covariates. Baseline magnesium intake was 287 ± 93 mg/day (mean ± standard deviation), and HOMA-IR, fasting glucose and fasting insulin were 3.7 ± 3.5, 99 ± 13 mg/dL, and 15 ± 13 μU/mL, respectively. At baseline, 6-, and 12-months, 23.5%, 30.4%, and 27.7% met the RDA for magnesium. After multivariate adjustment, magnesium intake was inversely associated with metabolic biomarkers of insulin resistance (P < 0.01). Further, the likelihood of elevated HOMA-IR (>3.6) over time was 71% lower [odds ratio (OR): 0.29; 95% confidence interval (CI): 0.12, 0.72] in participants in the highest quartile of magnesium intake than those in the lowest quartile. For individuals meeting the RDA for magnesium, the multivariate-adjusted OR for high HOMA-IR over time was 0.37 (95% CI: 0.18, 0.77). These findings indicate that dietary magnesium intake is inadequate among non-diabetic individuals with MetS and suggest that increasing dietary magnesium to meet the RDA has a protective effect on insulin resistance.

Whole grains, type 2 diabetes, coronary heart disease, and hypertension: links to the aleurone preferred over indigestible fiber

Higher whole grain cereal intakes are associated with substantially lower risks of type 2 diabetes, coronary heart disease, and hypertension. These reduced risks have been established in large prospective studies that now include millions of person-years of follow-up. We analyze the results of 11 major prospective studies to provide recommendations about whole grain consumption. The following review establishes the amount of whole grains that should ideally be consumed based on prospective evidence; defines the nature of whole grains; identifies that the whole grain evidence is robust and not due to confounding; and provides a detailed assessment of several potential mechanisms for the effect of whole grains on health. We draw the following conclusions. Firstly, to maintain health, 40 grams or more of whole grains should be consumed daily. This is about a bowl of whole grain breakfast cereal daily, but 80% of the population does not achieve this. Secondly, aleurone in bran is a critical grain component generally overlooked in favor of indigestible fiber. Live aleurone cells constitute 50% of millers' bran. They store minerals, protein, and the antioxidant ferulic acid, and are clearly more than just indigestible fiber. Finally, we suggest potential roles for magnesium, zinc, and ferulic acid in the development of chronic disease. If the results of prospective studies were applied to the life-style practices of modern societies there exists the potential for enormous personal health and public financial benefits.

Altered trace mineral milieu might play an aetiological role in the pathogenesis of polycystic ovary syndrome

Insulin resistance is a very common associate of polycystic ovary syndrome (PCOS). Pathophysiology in relation with the essential elements including copper, magnesium, zinc, manganese, chromium, and calcium has been reported in women with insulin resistance. This prospective study was designed to explore whether the women with PCOS do exhibit altered serum element levels in association with/without insulin resistance. One hundred and thirty-two women with PCOS and forty-six control women were studied. Women with PCOS were further divided based on the presence of insulin resistance (insulin resistant: n = 50; non-insulin resistant: n = 82). In all women, basal levels of gonadotropins, prolactin, testosterone, insulin, glucose, and the six different elements were measured. Serum levels of testosterone (p < 0.001), luteinizing hormone (p < 0.05), and fasting insulin (p < 0.004) were significantly higher in the PCOS population compared to controls as well as PCOS women without insulin resistance. Women with PCOS exhibited a significantly high calcium (p < 0.04) and lower manganese levels (p < 0.002) when compared to controls. However, the PCOS women with insulin resistance exhibited significantly lower serum levels of magnesium and chromium (p < 0.04), in addition to higher levels of zinc and copper (p < 0.04). The differences in calcium (p < 0.03) and manganese levels (p < 0.0001) became aggravated with the presence of insulin resistance when compared to control as well as PCOS women without insulin resistance. In PCOS-associated insulin resistance, circulating serum magnesium (r = -0.31; p < 0.03) and chromium (r = -0.38; p < 0.006) status significantly correlated with fasting insulin levels. We conclude that imbalanced element status may be a key foundation for insulin resistance in PCOS. The findings in this study should be investigated with further trials in order to obtain new insights into PCOS.

High dietary magnesium intake is associated with low insulin resistance in the Newfoundland population

Background

Magnesium plays a role in glucose and insulin homeostasis and evidence suggests that magnesium intake is associated with insulin resistance (IR). However, data is inconsistent and most studies have not adequately controlled for critical confounding factors.

Objective

The study investigated the association between magnesium intake and IR in normal-weight (NW), overweight (OW) and obese (OB) along with pre- and post- menopausal women.

Design

A total of 2295 subjects (590 men and 1705 women) were recruited from the CODING study. Dietary magnesium intake was computed from the Willett Food Frequency Questionnaire (FFQ). Adiposity (NW, OW and OB) was classified by body fat percentage (%BF) measured by Dual-energy X-ray absorptiometry according to the Bray criteria. Multiple regression analyses were used to test adiposity-specific associations of dietary magnesium intake on insulin resistance adjusting for caloric intake, physical activity, medication use and menopausal status.

Results

Subjects with the highest intakes of dietary magnesium had the lowest levels of circulating insulin, HOMA-IR, and HOMA-ß and subjects with the lowest intake of dietary magnesium had the highest levels of these measures, suggesting a dose effect. Multiple regression analysis revealed a strong inverse association between dietary magnesium with IR. In addition, adiposity and menopausal status were found to be critical factors revealing that the association between dietary magnesium and IR was stronger in OW and OB along with Pre-menopausal women.

Conclusion

The results of this study indicate that higher dietary magnesium intake is strongly associated with the attenuation of insulin resistance and is more beneficial for overweight and obese individuals in the general population and pre-menopausal women. Moreover, the inverse correlation between insulin resistance and dietary magnesium intake is stronger when adjusting for %BF than BMI.

Higher magnesium intake is associated with lower fasting glucose and insulin, with no evidence of interaction with select genetic loci, in a meta-analysis of 15 CHARGE Consortium Studies

Favorable associations between magnesium intake and glycemic traits, such as fasting glucose and insulin, are observed in observational and clinical studies, but whether genetic variation affects these associations is largely unknown. We hypothesized that single nucleotide polymorphisms (SNPs) associated with either glycemic traits or magnesium metabolism affect the association between magnesium intake and fasting glucose and insulin. Fifteen studies from the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium provided data from up to 52,684 participants of European descent without known diabetes. In fixed-effects meta-analyses, we quantified 1) cross-sectional associations of dietary magnesium intake with fasting glucose (mmol/L) and insulin (ln-pmol/L) and 2) interactions between magnesium intake and SNPs related to fasting glucose (16 SNPs), insulin (2 SNPs), or magnesium (8 SNPs) on fasting glucose and insulin. After adjustment for age, sex, energy intake, BMI, and behavioral risk factors, magnesium (per 50-mg/d increment) was inversely associated with fasting glucose [β = -0.009 mmol/L (95% CI: -0.013, -0.005), P < 0.0001] and insulin [-0.020 ln-pmol/L (95% CI: -0.024, -0.017), P < 0.0001]. No magnesium-related SNP or interaction between any SNP and magnesium reached significance after correction for multiple testing. However, rs2274924 in magnesium transporter-encoding TRPM6 showed a nominal association (uncorrected P = 0.03) with glucose, and rs11558471 in SLC30A8 and rs3740393 near CNNM2 showed a nominal interaction (uncorrected, both P = 0.02) with magnesium on glucose. Consistent with other studies, a higher magnesium intake was associated with lower fasting glucose and insulin. Nominal evidence of TRPM6 influence and magnesium interaction with select loci suggests that further investigation is warranted.

Serum magnesium concentrations in polycystic ovary syndrome and its association with insulin resistance

OBJECTIVE

It has been revealed that low serum magnesium (Mg) is often associated with insulin resistance (IR), cardiovascular problems, diabetes mellitus, and hypertension. Patients with polycystic ovary syndrome (PCOS) are known to have a high incidence of insulin resistance. This study was designed to determine whether women with PCOS exhibit serum magnesium deficiency and its potential association with IR.

SUBJECTS AND METHODS

In this cross-sectional study, 103 cases with PCOS and 103 normal women who were matched for their age and body mass index (BMI) were included. Blood samples were collected after an overnight fast and concentrations of calcium, magnesium, testosterone, dehydroepianderosterone sulfate, insulin, fasting plasma glucose (FPG), triglyceride, total cholesterol, and HDL-cholesterol were measured.

RESULTS

The risk of PCOS for subjects with Mg deficiency was 19 times greater than those who had normal serum Mg concentrations (p ≤ 0.0001). No correlation was found between Mg and insulin sensitivity or secretion, FPG, dyslipidemias, and also androgen concentrations. After adjustment for calcium concentration the role of magnesium to predict PCOS attenuated and became non-significant (β:-1.9, p: 0.7).

CONCLUSION

The present study provides the first evidence showing that magnesium deficiency is not associated with IR in PCOS. According the evidences of this study, serum calcium concentration is more potent predictor of PCOS than serum Mg and only calcium, not Mg, is related to insulin resistance in PCOS.

Insulin secretion is decreased in non-diabetic individuals with hypomagnesaemia

BACKGROUND

Magnesium modulates insulin-mediated glucose uptake but data regarding its role in insulin secretion are scarce; therefore, in this study we determined whether decreased serum magnesium levels are associated with the impairment of insulin secretion in non-diabetic individuals.

METHODS

A total of 182 apparently healthy subjects, men and non-pregnant women, 18-65 years of age, were enrolled in a population-based cross-sectional study and allocated to groups with hypomagnesaemia and normomagnesaemia. The groups in the study were subsequently stratified according to glucose status: normal glucose tolerance, impaired fasting glucose, and impaired glucose tolerance. Insulin secretion was evaluated by the first and second phases of insulin secretion.

RESULTS

The Spearman coefficient between serum magnesium and the first and second phases of insulin secretion showed a significant positive correlation in the overall (r = 0.265, p < 0.0005; r = 0.541, p < 0.0005), normal glucose tolerance (r = 0.369, p = 0.001; r = 0.618, p < 0.0005), impaired fasting glucose (r = 0.320, p = 0.02; r = 0.449, p = 0.001), and impaired glucose tolerance (r = 0.129, p = 0.37; r = 0.522, p < 0.0005) groups. The multivariate linear regression analysis showed a significant association between serum magnesium levels and the first and second phases of insulin secretion: for the entire groups [B = 75.2; 95% confidence interval (CI) 27.6-122.7; B = 25.4; 95% CI 16.4-34.3], normal glucose tolerance (B = 129.6, 95% CI 38.1-221.1; B = 40.3, 95% CI 23.7-56.8), impaired fasting glucose (B = 75.2, 95% CI 27.6-122.7; B = 15.1, 95% CI 4.2-30.2), and impaired glucose tolerance (B = 57.4, 95% CI 23.5-138.3; B = 25.4, 95% CI 16.4-34.3) groups.

CONCLUSIONS

Our results show that hypomagnesaemia is associated with the decrease of the first and second phases of insulin secretion in non-diabetic subjects with hypomagnesaemia.

Magnesium improves the beta-cell function to compensate variation of insulin sensitivity: double-blind, randomized clinical trial

BACKGROUND

Given that role of magnesium in insulin secretion is uncertain, our objective was to determine whether oral supplementation with magnesium chloride (MgCl(2)) improves the ability of beta-cells to compensate for variations in insulin sensitivity in non-diabetic individuals with significant hypomagnesaemia.

MATERIALS AND METHODS

Eligible individuals were non-diabetic, normo-tensive men and non-diabetic, normo-tensive, non-pregnant women with serum magnesium levels ≤0·70 mM/L; they were enrolled in a randomized double-blind clinical trial to receive either 50 mL of 5% MgCl(2) solution or 50 mL of inactive solution daily for 3 months. The primary trial end point was a change in the AUC of the hyperbolic model of beta-cell function (HMbCF) derived from the fasting state. Individuals, caregivers and personnel who assessed the outcomes were all blinded to the group assignments.

RESULTS

A total of 54 and 52 individuals were assigned to the MgCl(2) and placebo groups, respectively; five individuals in the MgCl(2) group and four in the placebo group dropped out. There were no serious adverse events or side effects because of MgCl(2) or placebo. At the beginning of the study, the AUC of the HMbCF was similar in both groups (AUC = 7·591 and 7·895 cm(2)); at the end of follow-up, the curve of the MgCl(2) group showed a hyperbolic distribution (AUC = 18·855 cm(2)), whereas in the placebo group, there were no changes (AUC = 7·631 cm(2)).

CONCLUSIONS

MgCl(2) 2·5 g daily improves the ability of beta-cells to compensate for variations in insulin sensitivity in non-diabetic individuals with significant hypomagnesaemia.

The underestimated problem of using serum magnesium measurements to exclude magnesium deficiency in adults; a health warning is needed for "normal" results

BACKGROUND

A major use of serum magnesium measurements in clinical practice is to identify patients with deficiency. However, numerous studies have shown that magnesium deficiency is common and may be present in over 10% of hospitalized patients, as well as in the general population. An important cause for under diagnosis of deficiency is that serum magnesium, the most commonly used test, can be normal despite negative body stores. This article focuses on the limitations of "normal" magnesium results and highlights the importance of lifestyle or "modus vivendi" as a pragmatic means of identifying those individuals potentially at risk for negative body magnesium stores.

METHODS

Researched peer reviewed articles on magnesium published between 1990 and 2008 in MEDLINE and EMBASE, using database keywords "magnesium, deficiency, diagnosis, treatment and hypomagnesaemia". Bibliographies of retrieved articles have been searched and followed. We have also performed a manual search of each individual issue in which most of these reports have appeared.

RESULTS

In 183 peer reviewed studies published from 1990 to 2008, magnesium deficiency was associated with increased prevalence and risk in 11 major conditions. Similarly, in 68 studies performed over the same period, magnesium deficiency was found to predict adverse events and a decreased risk of pathology was noted when supplementation or treatment was instituted.

CONCLUSIONS

The perception that "normal" serum magnesium excludes deficiency is common among clinicians. This perception is probably enforced by the common laboratory practice of highlighting only abnormal results. A health warning is therefore warranted regarding potential misuse of "normal" serum magnesium because restoration of magnesium stores in deficient patients is simple, tolerable, inexpensive and can be clinically beneficial.

Cross-sectional association of dietary patterns with insulin-resistant phenotypes among adults without diabetes in the Framingham Offspring Study

Cluster analysis is a valuable tool for exploring the health consequences of consuming different dietary patterns. We used this approach to examine the cross-sectional relationship between dietary patterns and insulin-resistant phenotypes, including waist circumference, BMI, fasting insulin, 2 h post-challenge insulin, insulin sensitivity index (ISI0,120), HDL-cholesterol, TAG and blood pressure, using data from the fifth examination cycle of the Framingham Offspring Study. Among 2875 participants without diabetes, we identified four dietary patterns based on the predominant sources of energy: 'Fruits, Reduced Fat Dairy and Whole Grains', 'Refined Grains and Sweets', 'Beer' and 'Soda'. After adjusting for multiple comparisons and potential confounders, compared with the 'Fruits, Reduced Fat Dairy and Whole Grains' pattern, the 'Refined Grains and Sweets' pattern had significantly higher mean waist circumference (92.4 v. 90.5 cm; P = 0.008) and BMI (27.3 v. 26.6 kg/m2; P = 0.02); the 'Soda' pattern had significantly higher mean fasting insulin concentration (31.3 v. 28.0 microU/ml; P < or = 0.001); the 'Beer' pattern had significantly higher mean HDL-cholesterol concentration (1.46 v. 1.31 mmol/l; P < 0.001). No associations were observed between dietary patterns and ISI0,120, TAG, and systolic or diastolic blood pressure. Our findings suggest that consumption of a diet rich in fruits, vegetables, whole grains and reduced-fat dairy protects against insulin-resistant phenotypes and displacing these healthy choices with refined grains, high-fat dairy, sweet baked foods, candy and sugar-sweetened soda may promote insulin-resistant phenotypes.

Association between magnesium : iron intake ratio and diabetes in Chinese adults in Jiangsu Province

BACKGROUND

The intake of iron is positively related to the risk of diabetes, whilst magnesium intake is inversely related. However, it is unknown whether there is an interaction between dietary magnesium and iron expressed as a ratio and diabetes.

METHODS

This is a cross-sectional household survey carried out in 2002 in Jiangsu Province, China. A total of 2849 men and women aged >or = 20 years participated (participation rate 89.0%). Iron and magnesium intake was assessed by 3-day weighed food records. Fasting plasma glucose, serum ferritin and haemoglobin were measured.

RESULTS

The mean intake of iron and magnesium was 25 mg/day and 332 mg/day, respectively. The prevalence of diabetes was 3.0% in men and 2.6% in women. Magnesium intake was negatively associated with diabetes when adjusted for age and sex, but not in a fully adjusted model. A strong inverse association between magnesium : iron intake ratio and diabetes was observed. In the fully adjusted model, the odds ratios of diabetes across quartiles of magnesium : iron intake ratio were: 1.0, 0.63 [95% confidence interval 0.32-1.25], 0.36 (0.16-0.81) and 0.48 (0.20-1.14) (P for trend 0.038). There was an interaction between central obesity and magnesium : iron ratio.

CONCLUSION

Magnesium : iron intake ratio is an independent risk marker for diabetes in Chinese adults. As this is a cross-sectional study, we cannot establish any causal relationship.

Hypomagnesaemia and risk for metabolic glucose disorders: a 10-year follow-up study

BACKGROUND

Although several lines of evidence suggest that hypomagnesaemia is a risk factor for developing type 2 diabetes, there are no studies regarding the association between hypomagnesaemia and the risk for developing impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). Our objective was to examine the association between serum magnesium levels and the risk for developing IFG, IGT and type 2 diabetes.

MATERIALS AND METHODS

A total of 1122 individuals (20-65 years of age) were enrolled between 1996 and 1997, and 817 individuals re-examined about 10 years later. New-onset IFG (5.6-7.0 mmol L(-1) fasting glucose), IGT (7.8-11.1 mmol L(-1) glucose 2-h postload), and type 2 diabetes were determined from the number of subjects who had these conditions at the second examination without evidence that they were present at the first one. The relative risk of new-onset metabolic glucose disorders and diabetes (dependent variables) was computed using Poisson regression model adjusted for age, sex, family history of diabetes, waist circumference and homeostasis model assessment for insulin resistance index. Serum magnesium levels of < 0.74 mmol L(-1) (independent variable) defined the exposed group.

RESULTS

At baseline, 420 (51.4%) individuals had hypomagnesaemia. New-onset IFG and IGT was identified in 276 (33.8%) individuals. The relative risk for IFG, IGT and IFG + IGT was 1.11 (95% confidence interval, 0.5-5.1), 1.38 (95% confidence interval, 1.1-6.3) and 1.49 (95% confidence interval, 1.1-4.9), respectively. New-onset diabetes was identified in 78 (9.5%) individuals (relative risk 2.54; 95% confidence interval, 1.1-4.1).

CONCLUSIONS

Hypomagnesaemia is independently associated with the development of IGT, IFG + IGT and type 2 diabetes, but not with the development of IFG.