Increased adiposity by feeding growing rats a high-fat diet results in iron decompartmentalisation.

The present study reports the effects of a high-fat (HF) diet of over 8 weeks on the Fe status of growing rats. Tissue Fe levels were analysed by atomic absorption spectrophotometry, and whole-body adiposity was measured by dual-energy X-ray absorptiometry. Histopathology and morphometry of adipose tissue were performed. Liver homogenates were used for measuring ferroportin-1 protein levels by immunoblotting, and transcript levels were used for Fe genes measured by real-time PCR. Tissue Fe pools were fit to a compartmental biokinetic model in which Fe was assessed using fourteen compartments and twenty-seven transfer constants (kj,i from tissue 'i' to tissue 'j') adapted from the International Commission on Radiological Protection (ICRP) 69. Ten kj,i were calculated from the experimental data using non-linear regression, and seventeen were estimated by allometry according to the formula ${k_{i,j}} = a \times {M^b}$. Validation of the model was carried out by comparing predicted and analysed Fe pool sizes in erythrocytes, the liver and the spleen. Body adiposity was negatively associated with serum Fe levels and positively associated with liver Fe stores. An inferred increase in Fe transfer from bone marrow to the liver paralleled higher hepatic Fe concentrations and ferritin heavy-chain mRNA levels in the HF diet-fed animals, suggesting that liver Fe accumulation occurred at least in part due to a favoured liver erythrocyte uptake. If this feeding condition was to be prolonged, impaired Fe decompartmentalisation may occur, ultimately resulting in dysmetabolic Fe overload.

No Difference in Magnesium Intake between Obese Women and Healthy Controls.

Magnesium is a predominantly intracellular ion and plays an important role in energy metabolism and in the maintenance of energy homeostasis. This study aimed to estimate the dietary intake of magnesium and its association with adiposity parameters in obese women. This cross-sectional study included 125 women, aged between 20 and 50 years, who were divided into two groups: obese group (n = 62) and control group (n = 63). The control group was age-matched. Adiposity parameters determined were weight, body mass index and waist circumference as well as the intake of calories, macronutrients, and magnesium were calculated. The cut-off for obesity was body mass index between 30.0 and 39.9 kg/m2 and for control group was between 18.5 and 24.9 kg/m2 Food intake was calculated using 3-day food records, and energy consumption as well as the intake of macronutrients and magnesium was calculated using the NutWin software version 1.5. The reference values used were the Acceptable Macronutrient Distribution Range for macronutrients and the Estimated Average Requirement (EAR) for magnesium. The average levels of magnesium found in the diet were lower than those recommended (169.1 ± 64.5 mg Mg/day and 158.5 ± 42.9 mg Mg/day, for obese women and control group, respectively) and the differences between the groups were not statistically different (p > 0.05). The correlation analysis indicated that the association between the dietary intake of magnesium and adiposity was not significant. The results of this study indicate that dietary magnesium does not influence the adiposity parameters in obese women.

Association between Serum Unmetabolized Folic Acid Concentrations and Folic Acid from Fortified Foods.

OBJECTIVE: To investigate the association between serum unmetabolized folic acid (UMFA) concentrations and folic acid from fortified foods and nutrients known as dietary methyl-group donors (folate, methionine, choline, betaine and vitamins B2, B6 and B12) in participants exposed to mandatory fortification of wheat and maize flours with folic acid. METHODS: Cross-sectional study carried out with 144 healthy Brazilian participants, both sexes, supplement nonusers. Serum folate, UMFA, vitamin B12 and total plasma homocysteine (tHcy) were biochemically measured. Dietary intake was assessed by 2 non-consecutive 24-hour dietary recalls (24-HRs) and deattenuated energy-adjusted nutrient data were used for statistical analysis. RESULTS: Ninety eight (68.1%) participants were women. Median (interquartile range) age was 35.5 (28.0-52.0) years. Elevated serum folate concentrations (>45 nmol/L) were found in 17 (11.8%), while folate deficiency (<7 nmol/L) in 10 (6.9%) participants. No one had vitamin B12 deficiency (<148 pmol/L). An elevated serum UMFA concentration was defined as > 1 nmol/L (90th percentile). UMFA concentrations were positively correlated with folic acid intake and negatively correlated to choline, methionine and vitamin B6 intakes. Participants in the lowest quartile of UMFA concentrations had lower dietary intake of total folate (DFEs) and folic acid, and higher dietary intake of methionine, choline and vitamin B6 than participants in the highest quartile of UMFA. Folic acid intake (OR [95% CI] = 1.02 [1.01-1.04)] and being a male (OR [95% CI] = 0.40 [0.19-0.87) were associated with increased and reduced odds for UMFA concentrations > 0.55 nmol/L (median values), respectively. CONCLUSION: UMFA concentrations were directly influenced by folic acid intake from fortified foods in a healthy convenience sample of adult Brazilians exposed to mandatory flour fortification with folic acid.

Fructo-oligosaccharides and iron bioavailability in anaemic rats: the effects on iron species distribution, ferroportin-1 expression, crypt bifurcation and crypt cell proliferation in the caecum.

The present study investigated the effects of fructo-oligosaccharides (FOS) on the bioavailability of Fe from ferric pyrophosphate (FP), a water-insoluble compound, in Fe-deficient anaemic rats that were subjected to a Hb repletion assay. Male Wistar rats (n 64) were fed adequate or low (8 mg/kg) Fe diets for 15 d followed by 1 or 2 weeks of Fe repletion with diets providing 35 mg Fe/kg as ferrous sulphate (FS), FP or FP that was mixed with 7·5% FOS in the form of yacon flour or Raftilose P95 (RAF), a purified source of FOS. The effects of FOS were observed within the 1st week of the repletion period. Fe bioavailability was improved by FOS supplementation, as measured by Hb regeneration efficiency and hepatic Fe stores, which were more pronounced in the RAF group. Moreover, RAF supplementation resulted in a higher biological value relative to that of the FP group. FOS supplementation resulted in caecal enlargement, in addition to acidification and Fe species redistribution in the caecal contents relative to the control rats. These effects occurred concomitantly with decreased ferroportin (FPN)-1 expression in the caecal mucosa, which was similar in magnitude to that observed in the FS group. Caecum mucosal morphometry was influenced by FOS supplementation, whereas crypt fission and cell proliferation were highest in the caecum of the RAF group. These results reinforce the effects of FOS as Fe bioavailability enhancers in anaemic rats that are sustained by early changes in their caecal environment (decreased mucosal FPN-1 expression and increased Fe absorbability, crypt fission and cellularity).

Magnesium status and the physical performance of volleyball players: effects of magnesium supplementation.

The aim of this study was to test the hypothesis that magnesium supplementation influences the physical performance of volleyball players, as the efficacy of this approach remains questionable. Twenty-five professional male volleyball players were assigned randomly to experimental (350 mg Mg · d(-1), 4 weeks) and control groups (500 mg maltodextrin · d(-1), 4 weeks) maintaining inter-group homogeneity of urinary magnesium. Erythrocyte, plasma and urinary magnesium levels, plasma creatine kinase activity, lactate production, maximal oxygen uptake (VO2 max) and plyometric (squat jump, countermovement jump, countermovement jump with arm swing) and isokinetic (peak torque, potency and total work) performances were evaluated before (T0) and after (T1) supplementation. Levels of erythrocyte and urinary magnesium and creatine kinase activity and VO2 max remained within normal ranges in both groups. Plasma magnesium decreased significantly only within the experimental group. Significant decreases in lactate production and significant increases (of up to 3 cm) in countermovement jump and countermovement jump with arm swing values were detected in the experimental group following magnesium supplementation, but not in the control group at T1. It is concluded that magnesium supplementation improved alactic anaerobic metabolism, even though the players were not magnesium-deficient.

Effects of dietary lipid composition and inulin-type fructans on mineral bioavailability in growing rats.

OBJECTIVE: This study reports the effects of feeding with a combination of inulin-type fructans (ITF) and fish oil (FO) on mineral absorption and bioavailability as part of a semipurified diet offered to rats. METHODS: Male Wistar rats (n = 24) were fed a 15% lipid diet (soybean oil [SO] or a 1:0.3 fish:soybean oil mixture [FSO]) and diets containing the same sources of lipids supplemented with 10% ITF (Raftilose Synergy 1) ad libitum for 15 d. Feces and urine were collected for mineral analyses during the last 5 d of the test period. Fatty acid composition was determined in liver and cecal mucosa homogenates. Liver and bone mineral analyses were performed by atomic absorption spectrophotometry. Bone biomechanical analyses were evaluated by a 3-point bending test. RESULTS: Compared with the controls, ITF-fed rats had enlarged ceca and a significant decrease in cecal content pH (P < 0.001). The apparent mineral absorption was improved in these rats, and this effect was enhanced by dietary combination with FO for all minerals except for magnesium. Addition of ITF to the diet resulted in higher bone mineral content (calcium and zinc) and bone strength, but increased bone mineral content was only statistically significant in FO-fed animals. A decrease in liver iron stores (P = 0.015) was observed in rats fed FO, considering that ITF consumption returned to levels comparable to the SO control group. CONCLUSION: These findings confirm the positive influence of ITF on mineral bioavailability, which was potentiated by addition of FO to the diet.

Effects of a moderate iron overload and its interaction with yacon flour, and/or phytate, in the diet on liver antioxidant enzymes and hepatocyte apoptosis in rats.

The effect of moderate Fe overload in the diet and its interaction with phytate, and/or yacon flour (YF), recognized as an inhibitor, and facilitator, of Fe absorption, respectively, was evaluated in healthy rats. For this purpose the following parameters were analyzed: (1) apparent iron (Fe), copper (Cu) and zinc (Zn) absorption; (2) blood Fe; (3) blood lipids (cholesterol, tryacylglicerol); (4) blood AST and ALT; (5) liver histology (histopathology, hemosiderin depots, apoptosis index; (6) liver fatty acid incorporation; (7) liver antioxidant enzyme activity. Moderate Fe overload may cause change in some liver markers (hemosiderin depots, apoptosis index and GPx) and blood lipids (total cholesterol and VLDL) and the interaction with yacon flour, and phytate, in the Fe overloaded diets may exert a protective effect on these alterations.

Dietary Iron Bioavailability: Agreement between Estimation Methods and Association with Serum Ferritin Concentrations in Women of Childbearing Age.

Predictive iron bioavailability (FeBio) methods aimed at evaluating the association between diet and body iron have been proposed, but few studies explored their validity and practical usefulness in epidemiological studies. In this cross-sectional study involving 127 women (18⁻42 years) with presumably steady-state body iron balance, correlations were checked among various FeBio estimates (probabilistic approach and meal-based and diet-based algorithms) and serum ferritin (SF) concentrations. Iron deficiency was defined as SF < 15 µg/L. Pearson correlation, Friedman test, and linear regression were employed. Iron intake and prevalence of iron deficiency were 10.9 mg/day and 12.6%. Algorithm estimates were strongly correlated (0.69≤ r ≥0.85; p < 0.001), although diet-based models (8.5⁻8.9%) diverged from meal-based models (11.6⁻12.8%; p < 0.001). Still, all algorithms underestimated the probabilistic approach (17.2%). No significant association was found between SF and FeBio from Monsen (1978), Reddy (2000), and Armah (2013) algorithms. Nevertheless, there was a 30⁻37% difference in SF concentrations between women stratified at extreme tertiles of FeBio from Hallberg and Hulthén (2000) and Collings’ (2013) models. The results demonstrate discordance of FeBio from probabilistic approach and algorithm methods while suggesting two models with best performances to rank individuals according to their bioavailable iron intakes.

Increased serum iron in preeclamptic women is likely due to low hepcidin levels.

The role of hepcidin in iron homeostasis in preeclamptic pregnant women is unclear. To test the hypothesis that increased serum iron in women diagnosed with preeclampsia results from decreased production of hepcidin, we performed an observational case-control study in which serum hepcidin concentration, dietary iron intake, hematological indices, iron status, liver function, and inflammatory markers in 18 preeclamptic women and 18 healthy normotensive pregnant women of similar age range were evaluated. Iron intake was established via a food frequency questionnaire, whereas hematological indices, iron status, liver function, and inflammatory markers were assessed using standard protocols. Hematocrit was significantly higher (P = .031) in the preeclamptic group compared with the control, whereas erythropoietin level was significantly lower (P = .003). The pronounced inflammatory status of preeclamptic women was confirmed by significantly higher concentrations of interleukin-6 (P = .001), tumor necrosis factor-α (P < .001), and ferritin (P < .001). Nonetheless, the preeclamptic group exhibited significantly higher serum iron (P = .012) and transferrin saturation (P = .006), and these alterations were accompanied by lower hepcidin levels (P = .047). No significant correlations between hepcidin concentration and iron status parameters were observed in either group. However, a positive and significant correlation between hepcidin concentration and C-reactive protein was observed in the preeclamptic group (r = 0.474; P = .047). We conclude that high serum iron in preeclamptic women is likely caused by low production of hepcidin, thus supporting the hypothesis originally stated.

An insight into the role of magnesium in the immunomodulatory properties of mesenchymal stem cells.

Magnesium (Mg2+) is a mineral with the ability to influence cell proliferation and to modulate inflammatory/immune responses, due to its anti-inflammatory properties. In addition, mesenchymal stem cells (MSCs) modulate the function of all major immune cell populations. Knowing that, the current work aimed to investigate the effects of Mg2+ enrichment, and its influence on the immunomodulatory capacity of MSCs. Murine C3H/10T1/2 MSCs were cultivated in media with different concentrations of Mg2+ (0, 1, 3 and 5 mM), in order to evaluate the effects of Mg2+ on MSC immunomodulatory properties, cell proliferation rates, expression of NFκB and STAT-3, production of IL-1ß, IL-6, TGF-ß, IL-10, PGE2 and NO, and TRPM7 expression. The results showed that TRPM7 is expressed in MSCs, but Mg2+, in the way that cells were cultivated, did not affect TRPM7 expression. Additionally, there was no difference in the intracellular concentration of Mg2+. Mg2+, especially at 5 mM, raised proliferation rates of MSCs, and modulated immune responses by decreasing levels of IL-1ß and IL-6, and by increasing levels of IL-10 and PGE2 in cells stimulated with LPS or TNF-α. In addition, MSCs cultured in 5 mM Mg2+ expressed lower levels of pNFκB/NFκB and higher levels of pSTAT-3/STAT-3. Furthermore, conditioned media from MSCs reduced lymphocyte and macrophage proliferation, but Mg2+ did not affect this parameter. In addition, conditioned media from MSCs cultured at 5 mM of Mg2+ modulated the production profile of cytokines, especially of IL-1ß and IL-6 in macrophages. In conclusion, Mg2+ is able to modulate some immunoregulatory properties of MSCs.

Magnesium Status and Its Association with Oxidative Stress in Obese Women.

The aim of this study was to assess the relationship between magnesium status and oxidative stress in obese and nonobese women. This cross-sectional study included 83 women, aged between 20 and 50 years, who were divided into two groups: the obese group (n = 31) and the control group (n = 52). The control group was age-matched with the obese group. Magnesium intake was monitored using 3-day food records and NutWin software version 1.5. The plasma and erythrocyte magnesium concentrations were determined by flame atomic absorption spectrophotometry. Plasma levels of thiobarbituric acid reactive substances (TBARS) were determined as biomarkers for lipid peroxidation and therefore of oxidative stress. The mean values of the magnesium content in the diet were found to be lower than those recommended, though there was no significant difference between groups (p > 0.05). The mean concentrations of plasma and erythrocyte magnesium were within the normal range, with no significant difference between groups (p > 0.05). The mean concentration of plasma TBARS was higher in obese woman, and the difference between the groups was statistically different (p < 0.05). There was a positive correlation between erythrocyte magnesium and plasma TBARS in the obese group (p = 0.021). Obese patients ingest low dietary magnesium content, which does not seem to affect the plasma and erythrocyte concentrations of the mineral. The study showed a negative correlation between erythrocyte magnesium concentrations and plasma TBARS, suggesting the influence of magnesium status on the parameters of oxidative stress in obese women.

Association between magnesium status, oxidative stress and inflammation in preeclampsia: A case-control study.

BACKGROUND & AIMS: Preeclampsia is responsible for more than one-third of all maternal deaths in Brazil. The objectives of the present study were to evaluate magnesium status and its association with oxidative stress and inflammation in preeclamptic women, and to identify the predictor variables of the disorder. METHODS: The study population consisted of 36 women divided into preeclamptic (n = 18) and control groups (n = 18). The preeclamptic group included women (≥20 weeks of pregnancy) with arterial pressure ≥ 140/90 mmHg and proteinuria >0.3 g/24 h, while the control group comprised pregnant women with no clinical/obstetric complications. Magnesium intake was assessed via a food frequency questionnaire validated for pregnant women in Brazil. Plasma, erythrocyte and urinary magnesium levels were determined by flame atomic absorption spectroscopy, while oxidative stress and inflammatory markers were assessed using standard protocols. Logistic regression analysis was used to identify the predictors of preeclampsia. RESULTS: Preeclamptic and control groups were similar with respect to magnesium intake and urinary excretion, while plasma and erythrocyte magnesium concentrations were higher in the former group. Plasma magnesium was positively correlated with catalase and glutathione peroxidase activities and with concentrations of interleukin-6 and tumor necrosis factor alpha. Regression analysis showed that plasma magnesium and urinary 8-isoprostane were associated with preeclampsia. CONCLUSION: Magnesium status appears to result from homeostatic imbalance and physiological alterations typical of preeclampsia. Increased plasma magnesium and decreased urinary 8-isoprostane were considered predictors of preeclampsia.

Magnesium Status and Its Relationship with C-Reactive Protein in Obese Women.

This study assessed the relationship between magnesium status and C-reactive protein concentration in obese and nonobese women. This cross-sectional study included 131 women, aged between 20 and 50 years, who were divided into two groups: obese (n=65) and control (n=66) groups. Magnesium intake was monitored using 3-day food records and NutWin software version 1.5. The plasma, erythrocyte, and urinary magnesium concentrations were determined by flame atomic absorption spectrophotometry. C-reactive protein concentration in serum was measured by immunoturbidimetric assay. The mean values of the magnesium content in the diet were lower than those recommended, though there was no significant difference between groups (p>0.05). The mean concentrations of plasma and erythrocyte magnesium were within the normal range, with no significant difference between groups (p>0.05). Urinary excretion of this mineral was less than the reference values in both groups, with no significant difference (p>0.05). The mean concentration of serum C-reactive protein was within the normal range in both groups, with no significant difference (p>0.05). There was a positive correlation between urinary magnesium and serum C-reactive protein (p=0.015). Obese patients ingest low dietary magnesium content, which seems to induce hypomagnesuria as a compensatory mechanism to keep plasma concentrations of the mineral at adequate levels. The study shows a positive correlation between urinary magnesium concentrations and serum C-reactive protein, suggesting the influence of hypomagnesuria on this inflammatory protein in obese women.

Chemical composition and glycemic index of Brazilian pine (Araucaria angustifolia) seeds.

The seeds of Parana pine (Araucaria brasiliensis syn. Araucaria angustifolia), named pinhão, are consumed after cooking and posterior dehulling, or they are used to prepare a flour employed in regional dishes. Native people that live in the South of Brazil usually consume baked pinhão. As a result of cooking, the white seeds become brown on the surface due to the migration of some tinted compounds present in the seed coat. In this work, the proximate composition, minerals, flavonoids, and glycemic index (GI) of cooked and raw pinhão seeds were compared. No differences in moisture, lipids, soluble fiber, and total starch after boiling were found. However, the soluble sugars and P, Cu, and Mg contents decreased, probably as a consequence of leaching in the cooking water. Also, the boiling process modified the profile of the phenolic compounds in the seeds. No flavonols were detected in raw pinhão seeds. The internal seed coat had a quercetin content five times higher than that of the external seed coat; also, quercetin migrated into the seed during cooking. The internal seed coat had a high content of total phenolics, and seeds cooked in normal conditions (with the seed coat) showed a total phenolics content five times higher than that of seeds cooked without the seed coat. Cooking was then extremely favorable to pinhão seeds bioactive compounds content. The carbohydrate availability was evaluated in a short-term assay in humans by the GI. The GI of pinhão seeds cooked with the coat (67%) was similar to that of the seeds cooked without a coat (62%) and lower than bread, showing that cooking does not interfere with starch availability. The low glycemic response can be partly due to its high content of resistant starch (9% of the total starch).

Magnesium-deficient high-fat diet: effects on adiposity, lipid profile and insulin sensitivity in growing rats.

BACKGROUND & AIMS: To determine if magnesium deficiency aggravates the effects of a high-fat diet in growing rats in terms of obesity, lipid profile and insulin resistance. METHODS: The study population comprised 48 newly weaned male Wistar Hannover rats distributed into four groups according to diet, namely, control group (CT; n = 8), control diet provided ad libitum; pair-feeding control group (PF; n = 16), control diet but in the same controlled amount as animals that received high-fat diets; high-fat diet group (HF; n = 12), and magnesium-deficient high-fat diet group (HFMg(-); n = 12). The parameters investigated were adiposity index, lipid profile, magnesium status, insulin sensitivity and the phosphorylation of proteins involved in the insulin-signaling pathway, i.e. insulin receptor ß-subunit, insulin receptor substrate 1 and protein kinase B. RESULTS: The HF and HFMg(-) groups were similar regarding gain in body mass, adiposity index and lipid profile, but were significantly different from the PF group. The HFMg(-) group exhibited alterations in magnesium homeostasis as revealed by the reduction in urinary and bone concentrations of the mineral. No inter-group differences were observed regarding glucose homeostasis. Protein phosphorylation in the insulin-signaling pathway was significantly reduced in the high-fat groups compared with the control groups, demonstrating that the intake of fat-rich diets increased insulin resistance, a syndrome that was aggravated by magnesium deficiency. CONCLUSIONS: Under the experimental conditions tested, the intake of a magnesium-deficient high-fat diet led to alterations in the insulin-signaling pathway and, consequently, increased insulin resistance.

Dietary iron overload: short- and long-term effects on cecal morphometry in growing rats.

In animal models, Fe overload is associated with organ oxidative stress and tissue injury. In this context, luminal Fe may affect the mucosal barrier and function or generate a pathological milieu in the intestine that triggers epithelial cell stress. Here, we hypothesized that increased liver Fe levels resulting from dietary Fe overload may be associated with architectural changes in the cecal mucosa. Weanling male Wistar rats (n=7-10/group) were fed diets (modified from AIN-93G) containing adequate or supplemental Fe (approximately 10 times the recommended levels) for 4 and 12 wk. At euthanasia, the blood Hb was determined, and Fe analyses were performed in stool and liver samples using atomic absorption spectrophotometry. Cecal tissue was collected for histological and morphometric analysis. No significant differences were observed in the blood Hb or Hb Fe pool between groups in either period. Iron overload led to a higher fecal Fe excretion, whereas the liver Fe was increased only after 12 wk when compared with controls. After 4 wk, the consumption of Fe-overloaded diets resulted in changes in the mucosal architecture of the cecum, which were intensified after 12 wk. At this time, these changes were significantly correlated with the hepatic Fe content. These findings suggest that changes in the cecal mucosa may have occurred as a result of oxidative stress caused by excessive amounts of Fe in the intestinal lumen. The consequences of these effects on the intestinal absorption and its implications for liver Fe homeostasis should be considered in future studies.

There is chronic latent magnesium deficiency in apparently healthy university students.

INTRODUCTION: Magnesium is an essential micronutrient for human body, and its deficiency has been associated with risk of non-communicable diseases. OBJECTIVE: Assessment of magnesium status, and evaluation of the frequency of magnesium deficiency in a group of healthy adults. METHODS: Plasma and erythrocyte magnesium levels, and magnesium intake were determined in 115 students (55 women and 60 men), from a public university in Brazil. RESULTS: The medians of magnesium concentration in plasma (0.76 mmol/L), erythrocyte (1.97 mmol/L), and of dietary daily intake (8.84 mmol/d) were low. Forty two percent of participants had plasma or erythrocyte magnesium below the limit of 0.75 and 1.65 mmol/L, respectively. A high percentage showed high probability of inadequate magnesium intake. CONCLUSIONS: There was a high frequency of subclinical magnesium deficiency in the adults assessed, that could be related to low dietary magnesium intake.

INTRODUCCIÓN: El magnesio es esencial, y su deficiencia ha sido asociada a mayor riesgo de enfermedades crónicas. OBJETIVOS: Evaluar el estado de nutrición de magnesio y su ingesta en adultos sanos, y determinar la frecuencia de su deficiencia en esta población. MÉTODOS: Fueron evaluados 115 adultos estudiantes de una universidad pública en Brasil, y se determinó la ingesta dietética y los niveles de magnesio en plasma y eritrocitos. RESULTADOS: Las medianas de distribución de magnesio en plasma (0,76 mmol/L), en eritrocitos (1,97 mmol/L), y la ingesta de magnesio (8,84 mmol/d) fueron bajas. Un 42% de la muestra tuvieron concentración de magnesio en plasma o eritrocitos por debajo de los respectivos 0,75 mmol/L y 1,65 mmol/L. Un alto porcentaje de ellos exhibió probabilidad de ingesta de magnesio inadecuada. CONCLUSIONES: Se observó una alta frecuencia de deficiencia de magnesio subclínica en los adultos evaluados.

Influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes.

INTRODUCTION: Studies have shown that oxidative stress, found in patients with type 2 diabetes, may be due to changes in the metabolism of minerals, such as magnesium and iron. Data related to compartmentalization of these minerals in diabetes are scarce and controversial. OBJECTIVE: This study assessed the influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes. METHODS: A case-control study in male and female subjects aged 27-59 years, divided into two groups: type 2 diabetes (n=40) and control (n=48). Intake of magnesium and iron was assessed by three-day food record. Plasma, erythrocyte and urinary levels of magnesium, serum iron, ferritin, total iron binding capacity, fasting glucose, glycated hemoglobin, insulin, creatinine clearance and plasma thiobarbituric acid reactive substances (TBARS) were analyzed. RESULTS AND DISCUSSION: Magnesium intake and plasma magnesium were lower in diabetic subjects. There was low urinary magnesium excretion, with no difference between groups. Although normal, the diabetic group had lower serum iron and ferritin concentrations compared to control subjects. Plasma TBARS in diabetic patients was higher than control while creatinine clearance was lower. An inverse correlation between erythrocyte magnesium and serum iron and ferritin was observed in the diabetes group. CONCLUSIONS: Diabetes induced hypomagnesemia and this, associated with chronic hyperglycemia, may have enhanced oxidative stress. Erythrocyte magnesium may have contributed to prevent iron overload and worsening of oxidative stress and hyperglycemic status.

Introducción: Los estudios han demostrado que el estrés oxidativo, que se encuentra en pacientes con diabetes tipo 2, puede ser debido a cambios en el metabolismo de los minerales, como el magnesio y el hierro. Los datos relacionados con la compartimentación de estos minerales en la diabetes son pocos y cuestionables. Objetivos: Evaluar la influencia del magnesio sobre parámetros bioquímicos de hierro y el estrés oxidativo en pacientes con diabetes tipo 2. Métodos: Estudio caso-control en los sujetos masculinos y femeninos de edad 27 a 59 años, divididos en dos grupos: la diabetes tipo 2 (n = 40) y control (n = 48). La ingesta de magnesio y hierro se evaluó por tres días registro de alimentos. Plasma, eritrocitos y los niveles urinarios de magnesio, hierro sérico, ferritina, capacidad total de fijación del hierro, glucosa en ayunas, hemoglobina glucosilada, la insulina, el aclaramiento de creatinina y el plasma se analizaron tiobarbitúrico sustancias reactivas al ácido (TBARS). Resultados y Discusión: La ingesta de magnesio y el magnesio en plasma fueron más bajos en los pacientes diabéticos. Hubo baja excreción urinaria de magnesio, sin diferencias entre los grupos. Aunque lo normal, el grupo de diabéticos tenían concentraciones de hierro y ferritina sérica inferiores en comparación con los sujetos control. TBARS plasmáticos en los pacientes diabéticos fue mayor que en el control, mientras que la depuración de creatinina fue menor. Se observó una correlación inversa entre el magnesio y el hierro en suero de los eritrocitos y la ferritina en el grupo de diabetes. Conclusiones: Diabetes hipomagnesemia inducida y esto, asociado a la hiperglucemia crónica, pueden haber mejorado el estrés oxidativo. Magnesio eritrocitaria puede haber contribuido a evitar la sobrecarga de hierro y el empeoramiento de estrés oxidativo y el estado de hiperglucemia.

Influence of magnesium on insulin resistance in obese women.

The present study evaluated the influence of magnesium on insulin resistance in obese women. A case-control study involving 114 women on the age between 20 and 50 years old, divided into two groups: control (eutrophic women, n = 59) and case (obese women, n = 55). The analysis of magnesium intake was carried out through the 3-day food record and also NutWin software version 1.5. The plasma, erythrocyte, and urinary magnesium concentrations were determined by flame atomic absorption spectrophotometry. The determinations of serum glucose and serum insulin were performed by enzymatic colorimetric method and chemiluminescence, respectively. The insulin resistance was assessed by homeostasis model assessment insulin resistance (HOMA-IR). The mean values of magnesium intake were lower than those recommended, without difference between groups (p > 0.05). All the patients who were evaluated showed adequate mean concentrations of magnesium in the plasma and erythrocyte. The urinary excretion of this mineral was lower than the reference values in both groups and did not show significant difference (p > 0.05). The values of serum glucose, serum insulin, and HOMA-IR were higher in obese women compared to the control group. A negative correlation was observed between erythrocyte magnesium and glycemic parameters (p < 0.05). Obese patients take in foods with low dietary magnesium content, and they show hypomagnesuria as a compensatory mechanism to keep the plasma concentration of this mineral in adequate levels. The correlation between the erythrocyte magnesium concentration and the parameters of glycemic control suggests the influence of this mineral on the index of insulin resistance in obese women.

Calcium and magnesium status is not impaired in pregnant women.

Deficiencies in calcium (Ca) and magnesium (Mg) are associated with various complications during pregnancy. To test the hypothesis that the status of these minerals is inadequate in pregnancy, a cross-sectional study was conducted of the dietary intake and status of Ca and Mg in pregnant women (n = 50) attending a general public university hospital in Brazil. Dietary intake was assessed from 4-day food records; levels of plasma Mg, erythrocyte Mg, and urinary Ca and Mg excretion were determined by flame atomic absorption spectroscopy; and type I collagen C-telopeptides were evaluated by enzyme-linked immunosorbent assay. Probabilities of inadequate Ca and Mg intake were exhibited by 58 and 98% of the study population, respectively. The mean levels of urinary Ca and Mg excretion were 8.55 and 3.77 mmol/L, respectively. Plasma C-telopeptides, plasma Mg, and erythrocyte Mg were within normal levels. Multiple linear regression analysis revealed positive relationships among urinary Ca excretion, Ca intake (P = .002) and urinary Mg excretion (P < .001) and between erythrocyte Mg and Mg intake (P = .023). It is concluded that the Ca and Mg status of participants was adequate even though the intake of Ca and Mg was lower than the recommended level.