Iron in obesity. An ancient micronutrient for a modern disease

Both low and high body iron stores relate to metabolic syndrome in postmenopausal women: Findings from the VIKING Health Study-Shetland (VIKING I)

BACKGROUND

There are conflicting results among studies on the association between serum ferritin (SF) and metabolic syndrome (MetS), and by groups of sex/menopausal status. To date, there are no studies on British populations. The SF-MetS association might be U/J-shaped. We evaluated whether SF was independently associated with MetS (harmonized definition) in people from Shetland, Scotland.

METHODS

We analysed cross-sectional data from the Viking Health Study-Shetland (589 premenopausal women [PreMW], 625 postmenopausal women [PostW] and 832 men). Logistic regressions using two approaches, one with the lowest sex and menopausal status-specific ferritin quartile (Q) as the reference and other using the middle two quartiles combined (2-3) as the reference, were conducted to estimate the SF-MetS association. The shape of the association was verified via cubic spline analyses. The associations were adjusted for age, inflammatory and hepatic injury markers, alcohol intake, smoking and BMI.

RESULTS

Prevalence of MetS was 18.3%. Among PostMW both low and high SF were associated with MetS (fully adjusted odds ratios [95% confidence interval] compared to the middle two quartiles combined were: 1.99 [1.17-3.38] p =.011 for Q1 and 2.10 [1.27-3.49] p =.004 for Q4) This U-shaped pattern was confirmed in the cubic spline analysis in PostMW with a ferritin range of 15-200 ug/L. In men, a positive association between ferritin quartiles with Q1 as the reference, did not remain significant after adjustment for BMI.

CONCLUSION

Extreme quartiles of iron status were positively associated with MetS in PostMW, while no SF-MetS associations were found in men or PreMW. The ferritin-MetS association pattern differs between populations and U/J-shaped associations may exist.

Dose-response relationship of serum ferritin and dietary iron intake with metabolic syndrome and non-alcoholic fatty liver disease incidence: a systematic review and meta-analysis

Aim

This study aims to assess the dose-response impact of iron load on systemic and hepatic metabolic disorders including metabolic syndrome (MetS) and non-alcoholic fatty liver disease (NAFLD).

Methods

Serum ferritin (SF) and dietary iron intake were selected to represent the indicators of iron load in the general population. PubMed, EMBASE and Web of Science databases were searched for epidemiological studies assessing the impact of SF/dietary iron intake on MetS/NAFLD occurrence. All literature was published before September 1st, 2023 with no language restrictions.

Results

Fifteen and 11 papers were collected with a focus on connections between SF and MetS/NAFLD, respectively. Eight papers focusing on dietary iron and MetS were included in the following meta-analysis. For the impact of SF on MetS, the pooled odds ratio (OR) of MetS was 1.88 (95% CI: 1.58-2.24) for the highest versus lowest SF categories. In males, the OR was 1.15 (95% CI: 1.10-1.21) per incremental increase in SF of 50 μg/L, while for females, each 50 μg/L increase in SF was associated with a 1.50-fold higher risk of MetS (95% CI: 1.15-1.94). For connections between SF and NAFLD, we found higher SF levels were observed in NAFLD patients compared to the control group [standardized mean difference (SMD) 0.71; 95% CI: 0.27-1.15], NASH patients against control group (SMD1.05; 95% CI:0.44-1.66), NASH patients against the NAFLD group (SMD 0.6; 95% CI: 0.31-1.00), each 50 μg/L increase in SF was associated with a 1.08-fold higher risk of NAFLD (95% CI: 1.07-1.10). For the impact of dietary iron on MetS, Pooled OR of MetS was 1.34 (95% CI: 1.10-1.63) for the highest versus lowest dietary iron categories.

Conclusion

Elevated SF levels is a linear relation between the incidence of MetS/NAFLD. In addition, there is a positive association between dietary iron intake and metabolic syndrome. The association between serum ferritin and metabolic syndrome may be confounded by body mass index and C-reactive protein levels.

Plasma Ferritin Concentrations in the General Population: A Cross-Sectional Analysis of Anthropometric, Metabolic, and Dietary Correlates

BACKGROUND

Elevated concentrations of ferritin seem to be detrimental to human health while being quite common in the elderly. Data on dietary, anthropometric, and metabolic correlates of circulating ferritin levels in the elderly are scant.

OBJECTIVES

We aimed to identify a dietary pattern, anthropometric, and metabolic traits associated with plasma ferritin status in an elderly cohort (n = 460, 57% male, age: 66 ± 12 y) from Northern Germany.

METHODS

Plasma ferritin levels were measured by immunoturbidimetry. Reduced rank regression (RRR) yielded a dietary pattern explaining 13% of the variation in circulating ferritin concentrations. Cross-sectional associations of anthropometric and metabolic traits with plasma ferritin concentrations were assessed using multivariable-adjusted linear regression analysis. Restricted cubic spline regression was used to identify nonlinear associations.

RESULTS

The RRR pattern was characterized by a high intake of potatoes, certain vegetables, beef, pork, processed meat, fats (frying and animal fat), and beer and a low intake of snacks, representing elements of the traditional German diet. BMI, waist circumference, and CRP were directly, HDL cholesterol inversely, and age nonlinearly associated with plasma ferritin concentrations (all P < 0.05). After additional adjustment for CRP, only the association of ferritin with age remained statistically significant.

CONCLUSION

Higher plasma ferritin concentrations were associated with a traditional German dietary pattern. The associations of ferritin with unfavorable anthropometric traits and low HDL cholesterol were rendered statistically nonsignificant upon additional adjustment for chronic systemic inflammation (CRP), suggesting that these associations were largely driven by the proinflammatory role of ferritin (an acute-phase reactant). J Nutr 20xx;x:xx.

Recent advances in the application of ionomics in metabolic diseases

Trace elements and minerals play a significant role in human health and diseases. In recent years, ionomics has been rapidly and widely applied to explore the distribution, regulation, and crosstalk of different elements in various physiological and pathological processes. On the basis of multi-elemental analytical techniques and bioinformatics methods, it is possible to elucidate the relationship between the metabolism and homeostasis of diverse elements and common diseases. The current review aims to provide an overview of recent advances in the application of ionomics in metabolic disease research. We mainly focuses on the studies about ionomic or multi-elemental profiling of different biological samples for several major types of metabolic diseases, such as diabetes mellitus, obesity, and metabolic syndrome, which reveal distinct and dynamic patterns of ion contents and their potential benefits in the detection and prognosis of these illnesses. Accumulation of copper, selenium, and environmental toxic metals as well as deficiency of zinc and magnesium appear to be the most significant risk factors for the majority of metabolic diseases, suggesting that imbalance of these elements may be involved in the pathogenesis of these diseases. Moreover, each type of metabolic diseases has shown a relatively unique distribution of ions in biofluids and hair/nails from patients, which might serve as potential indicators for the respective disease. Overall, ionomics not only improves our understanding of the association between elemental dyshomeostasis and the development of metabolic disease but also assists in the identification of new potential diagnostic and prognostic markers in translational medicine.

Changes in obesity and iron deficiency between 4 and 9 years of age. Longitudinal study of childhood obesity (ELOIN)

BACKGROUND

Recent studies revealed that children who are overweight have a higher risk of iron deficiency, although the etiology of this relationship remains unclear. The aim of the study was to evaluate the association between changes in obesity status between 4 and 9 years of age and iron deficiency.

SUBJECTS

This population-based cohort study included 1347 children from the ELOIN study, conducted in Madrid, Spain. Follow-up with physical examinations and a computer-assisted telephone interview were carried out at 4, 6 and 9 years of age, and a blood test was performed at 9 years.

METHODS

Changes in obesity were estimated based on body mass index and waist circumference, according to the persistence or variation in obesity rates at 4, 6 and 9 years and were classified as follows: (1) Stable without obesity; (2) Remitting obesity at 9 years; (3) Incident obesity or relapse at 9 years; and (4) Stable with obesity. Iron deficiency was defined as transferrin saturation value below 16%. Odds ratios (ORs) for iron deficiency were estimated according to obesity status using logistic regression and adjusted for confounding variables, including C-reactive protein (CRP).

RESULTS

The prevalence of iron deficiency in the stable general obesity (GO) and abdominal obesity (AO) groups was 38.2% and 41.2%, versus 23.6% and 23.4% in the stable without obesity groups, respectively. The ORs for iron deficiency were 1.85 (95% CI: 1.03-3.32) in the stable GO group and 2.34 (95% CI: 1.29-4.24) in the stable AO group. This association disappeared when CRP was included in the analysis.

CONCLUSIONS

An extended state of obesity during the first stages of life is associated with iron deficiency, and this association may be mediated by CRP. Prevention and early detection of obesity in children should be a priority to avoid a double burden of malnutrition.

The impact of ferritin on the disassociation of HbA1c and mean plasma glucose

OBJECTIVE

To explore the impact of ferritin level on the disassociation of glycated hemoglobin A1c (HbA1c) and mean plasma glucose (MPG).

RESEACH DESIGN AND METHODS

We used a 2012-2013 cross-sectional survey conducted in Pinggu district, Beijing including 3095 Chinese participants aged 25-75 years. We categorized their glycemic status by interviewing for diagnosed diabetes and by measuring HbA1c, fasting plasma glucose (FPG), and 2-hours post-load plasma glucose (2-hours PPG). We fitted a multivariable regression model to explore the impact of ferritin on the association of HbA1c or glycated albumin (GA) and mean plasma glucose.

RESULTS

A total of 5.65% of participants were diagnosed as diabetes using HbA1c criteria, and 9.79% using oral glucose tolerance test criteria. Compared with males, females had significantly lower hemoglobin levels (159.82 ± 11.56 vs 135.93 ± 12.62) and lower ferritin levels (113.00 [68.55, 185.50] vs 33.40 [12.40, 70.13]). Linear regression analysis performed in different groups classified by different diagnose criterion indicated that the correlation between MPG and HbA1c differs in different tertiles of ferritin (lowest vs middle vs highest: R² = 0.507 vs 0.645 vs 0.687 in female; R² = 0.415 vs 0.715 vs 0.615 in male), and the association between MPG and HbA1c diminished in the lowest tertile of ferritin.

CONCLUSIONS

Ferritin level might affect the association between glucose and HbA1c, which should be taken into account when using HbA1c as a diagnosis criterion for diabetes and prediabetes.

Index of Nutritional Quality (INQ) and the Risk of Obesity in Male Adolescents: a Case-Control Study

Dietary factors may play a key role in the etiology of obesity. The Index of Nutritional Quality (INQ) provides a comprehensive overview of the nutrients content of the diet. This study aimed to investigate the association between INQ and obesity in male adolescents. We hypothesize that receiving a high-quality diet reduces the risk of overweight or obese. This study was carried out on 214 obese/overweight as the case group and 321 normal-weight male adolescents as the control group. Dietary intakes of the participants were collected using a food frequency questionnaire (FFQ). The FFQ-derived dietary data were used to calculate the INQ scores. After adjustments for age and height, an inverse association was found between obesity and INQ of iron, vitamin B6, and magnesium, and a positive association was found between obesity and INQ of zinc (all P < 0.05). After further adjustments for nutritional knowledge and calorie intake, an inverse association was observed between obesity and INQ of vitamin C, iron, vitamin B6, pantothenic acid, selenium, and magnesium (all P < 0.05). The positive association of obesity and INQ of zinc remained significant after adjustments. A higher intake of vitamin C, iron, vitamin B6, pantothenic acid, selenium, and magnesium and a lower intake of zinc may be protective against adolescent obesity. More longitudinal studies are required to investigate the relationship between these nutrients and obesity.

H. Shehada A, Abdelnasser AbouHassanein E, Moawad J, Bawadi H, Shi Z. Association between central obesity indices and iron status indicators among Qatari adults

Co-existence of iron deficiency and obesity in adults has been reported in many countries. However, little is known on the association between obesity and iron deficiency in Qatar. This study aimed to investigate the link between abdominal obesity indices and iron status among adults in Qatar. A random sample of 1000 healthy Qatari adults, aged 20-50 years, was obtained from Qatar Biobank study. Body weight, waist circumference, dual x-ray absorptiometry (DXA) parameters and iron status indicators were measured using standard techniques. Multiple regression analysis was used to examine the associations. The prevalence of iron deficiency and anaemia were 35.4 and 25%, respectively. Of the participants with a large waist circumference, 31.7% had anaemia. Ferritin significantly increased with the increase in the android fat to gynoid fat ratio and visceral fat in both genders. Serum iron and transferring saturation decreased significantly with the increase in waist circumference in women. In both genders, C-reactive protein increased with the increase in all obesity indices. Standardized values of waist circumference, android fat, gynoid fat ratio and visceral fat were significantly associated with log transformed ferritin in men and women. Waist circumference was inversely related to serum iron (β:-0.95, 95% CI:-1.50,-0.39) and transferrin saturation (β:-1.45, 95%CI:-2.46, -0.43) in women. In men, waist circumference was positively associated with haemoglobin level (β: 0.16, 95% CI:0.04, 0.29). Central obesity coexists with anaemia among the study population. Elevated central obesity indices were associated with an increase in ferritin concentration. The increased ferritin concentration may be attributed to the increase in inflammatory status as a result of an increase in c-reactive protein concentration associated with central obesity.

Iron Fortification and Supplementation: Fighting Anemia of Chronic Diseases or Fueling Obesity?

The significant worldwide increase in obesity has become a major health problem. Excess adiposity has been extensively linked to inflammation. Recently, studies have shown that dietary intake and microbiota dysbiosis can affect the health of the gut and lead to low-grade systemic inflammation, worsening the state of obesity and further exacerbating inflammation. The latter is shown to decrease iron status and potentially increase the risk of anemia by inhibiting iron absorption. Hence, anemia of obesity is independent of iron intake and does not properly respond to increased iron ingestion. Therefore, countries with a high rate of obesity should assess the health impact of fortification and supplementation with iron due to their potential drawbacks. This review tries to elucidate the relation between inflammation and iron status to better understand the etiology of anemia of obesity and chronic diseases and wisely design any dietary or medical interventions for the management of anemia and/or obesity.

Association of serum ferritin level and depression with respect to the body mass index in Korean male adults

BACKGROUND/OBJECTIVES

Obesity is globally a major public health issue. Evidence suggests that elevated ferritin levels are associated with obesity, dyslipidemia, insulin resistance, and metabolic syndrome. This study was undertaken to examine the relationship between the serum ferritin level and depression in Korean male adults with respect to classification of the prevailing obesity.

SUBJECTS/METHODS

This was a case-control study; subjects were classified into obese group (≥ 25.0 kg/m², 28 subjects) and normal group (18.5–22.9 kg/m², 27 subjects). A survey was conducted to assess the depression levels as per the guidelines suggested by the Center program for Epidemiological Studies-Depression (CES-D). Blood was collected from each group for assessing biomarkers, and isolated plasma was evaluated for fasting glucose, insulin, quantitative insulin sensitivity check index, and ferritin levels. Data were analyzed, and groups were compared with respect to Body Mass Index (BMI), depression scale and biomarkers.

RESULTS

The average depression score of the obesity group was 16.86, which was higher than the normal group (12.56). Subjects scoring more than 16 points comprised 53.6% of the population in the obese group, which was more than double that in the normal group, as assessed by the CES-D program. Furthermore, the serum ferritin level of the obesity group was 207.12 ng/mL, which was higher than that of the normal group (132.66 ng/mL). Lastly, the BMI appeared to be significantly correlated with both depression (r = 0.320, P = 0.017) and elevated ferritin levels (r = 0.352, P = 0.008).

CONCLUSION

This study provides evidence of existing correlation between ferritin and depression with obesity.

Serum ferritin, an early marker of cardiovascular risk: a study in Chinese men of first-degree relatives with family history of type 2 diabetes

BACKGROUND

Ferritin is one of the key proteins that regulate iron homeostasis and is widely available clinical biomarker of iron status. This study aimed to discuss the influence of serum ferritin (SF) on cardiovascular risk factors in the first-degree relatives with family history of type 2 diabetes (FHD).

METHODS

This cross-sectional study included 232 men. Anthropometric measurements and blood samples were analyzed. The people were divided into four groups according to median SF (102.8 ng/ml) and people with or without FHD. Group A (FHD-and low SF), group B (FHD-and high SF), group C (FHD+ and low SF), and group D (FHD+ and high SF).

RESULTS

The subjects in different categories of SF concentrations showed significant differences in BMI (SF main effect: P = 0.010), WC (P = 0.030), SBP (P < 0.001), FPG (P < 0.001), PPG-2 h (P < 0.001), FINS (P < 0.001), and HOMA-IR (P = 0.015; all: 2-way ANOVA). There was a significant difference in SBP (FHD main effect: P = 0.003), DBP (P = 0.006), and FINS (P = 0.013, all: 2-way ANOVA) between the groups with or without FHD. The interaction term between SF and FHD was significant for SBP (P = 0.011), DBP (P = 0.012), and PPG-2 h (P = 0.022). Logistic analysis showed that accumulation of CVD risk factors, which were ≥ 2 items and ≥ 3 items in group D were 7.546 and 3.343 times higher compared with group A (P < 0.05).

CONCLUSIONS

The increased SF levels increased the risk of cardiovascular risk factors and the occurrence of insulin resistance in first-degree relatives with FHD.

Iron Deficiency and Neuroendocrine Regulators of Basal Metabolism, Body Composition and Energy Expenditure in Rats

Although dietary iron is a determinant of iron status in animals, body fat mass has been reported to have an inverse association with iron status in human studies. The goal of this study was to determine the relationship between Fe homeostasis, body composition, energy expenditure and neuroendocrine regulators for severe Fe-deficiency anaemia. Forty male Wistar albino rats recently weaned were divided at random into two groups: the control group was fed the basal diet, AIN-93G diet (normal-Fe) and the anaemic group received a low-Fe diet for 40 days. Neuroendocrine parameters that regulate basal metabolism and appetite (thyroid hormones, ghrelin, glucose-dependent insulinotropic polypeptide (GIP), glucagon, insulin, adrenocorticotropic hormone and corticosterone), body composition, respiratory volumes, energy expenditure, haematological and biochemical were assessed. Total body fat was lower, whereas lean mass, free and total water were higher in the anemic group. O₂ consumption, CO₂ production, energy expenditure (EE) and respiratory quotient (RQ) were lower in the Fe-deficient animals. Triiodothyronine and thyroxine hormones decreased, while thyroid-stimulating hormone increased in the anemic group. Circulating levels of ghrelin were lower in the anemic group, while GIP, glucagon, insulin, corticosterone and adrenocorticotropic hormone levels were higher. Fe-deficiency impairs weight gain in the rats, with marked reductions in lean mass and body fat, indicating lower energy stores.

Ferritin, metabolic syndrome and its components: A systematic review and meta-analysis

BACKGROUND AND AIMS

Mechanisms for the association between iron stores and risk factors for diabetes and cardiovascular disease, such as metabolic syndrome (MetS) and its components, are still not clear. We evaluated the associations between ferritin levels, MetS and its individual components, and potential role of confounding, in a meta-analysis.

METHODS

We searched articles in MEDLINE and EMBASE until February 14th, 2018. There were two approaches: meta-analysis of 1) cross-sectional and longitudinal studies and 2) only cross-sectional studies. Meta-regressions were conducted to identify sources of heterogeneity in the associations of ferritin with MetS and its individual components.

RESULTS

Information from 26 studies (5 prospective) was systematically reviewed and 21 studies were meta-analysed. The pooled OR for MetS by increased ferritin was 1.78 (95%CI: 1.60-1.97) in the meta-analysis 1, and 1.70 (95%CI: 1.49-1.95) in the meta-analysis 2. The pooled association was weaker in studies adjusted for hepatic injury markers (meta-regression coefficient (95% CI): -0.34 (-0.60,-0.09) p = 0.008) and body mass index (BMI) (meta-regression coefficient (95% CI): -0.27 (-0.53,-0.01) p = 0.039). Among MetS components, the pooled association with increased ferritin was strongest with high triglycerides [OR (95%CI): 1.96 (1.65-2.32)] and high glucose levels [OR 95%CI: 1.60 (1.40-1.82)]. Higher cut-off points used to define high ferritin concentrations were more strongly associated with high triglycerides [meta-regression coefficient (95% CI): 0.22 (0.03, 0.041), p = 0.023].

CONCLUSIONS

High triglycerides and glucose are the components more strongly associated with ferritin. Hepatic injury and BMI appear to influence the ferritin-MetS association, and a threshold effect of high ferritin concentration on the ferritin-high triglycerides association was observed.

Early High-Fat Feeding Induces Alteration of Trace Element Content in Tissues of Juvenile Male Wistar Rats

The primary objective of the current study was to assess the influence of early high-fat feeding on tissue trace element content in young male Wistar rats. Twenty weanling male Wistar rats were divided into two groups fed standard (STD) or high-fat diet (HFD) containing 10 and 31.6 % of total calories from fat, respectively, for 1 month. Serum lipid spectrum, apolipoproteins, glucose, insulin, adiponectin, and leptin levels were assessed. The level of trace elements was estimated using inductively coupled plasma mass spectrometry. High-fat feeding significantly increased epidydimal (EDAT) and retroperitoneal adipose tissue (RPAT), as well as total adipose tissue mass by 34, 103, and 59 %, respectively. Serum leptin levels in HFD animals were twofold higher than those in the control rats. No significant difference in serum lipid spectrum, apolipoproteins, glucose, adiponectin, and insulin was detected between the groups. HFD significantly altered tissue trace element content. In particular, HFD-fed animals were characterized by significantly lower levels of Cu, I, Mn, Se, and Zn in the liver; Cr, V, Co, Cu, Fe, and I content of EDAT; Co, Cu, I, Cr, V, Fe, and Zn concentration in RPAT samples. At the same time, only serum Cu was significantly depressed in HFD-fed animals as compared to the control ones. Hair Co, Mn, Si, and V levels were significantly increased in comparison to the control values, whereas Se and I content was decreased. HFD feeding induced excessive adiposity and altered tissue trace element content in rats without insulin resistance, adiponectin deficiency, and proatherogenic state. Hypothetically, trace element disbalance may precede obesity-associated metabolic disturbances.

Association of serum ferritin with insulin resistance, abdominal obesity, and metabolic syndrome in Korean adolescent and adults: The Korean National Health and Nutrition Examination Survey, 2008 to 2011

This study aimed to evaluate the associations of serum ferritin with insulin resistance indices, body fat mass/percentage, and all the components of metabolic syndrome (MetS), as well as the risk for MetS according to serum ferritin levels in Korean adolescents and adults.A total of 15,963 Korean males and females aged 16 to 80 years were analyzed using data from the Korean National Health and Nutrition Examination Survey, 2005 to 2011.The median serum ferritin concentration was 98.82 ng/mL for males and 38.60 ng/mL for females (P < 0.001). Increased risks of greater waist circumference and elevated glucose levels, elevated triglyceride levels, and reduced high-density lipoprotein cholesterol levels were noted across the serum ferritin quartiles after adjustment for confounders in both genders (P ≤ 0.012 for trend). Insulin resistance indices and abdominal obesity (trunk fat mass/percent) increased across the ferritin concentration quartiles after adjustment for confounders in males and females (P ≤ 0.011 for trend), and the risk of MetS increased across the ferritin quartiles in males (P < 0.001 for trend) and females (P = 0.001 for trend). The highest serum ferritin quartile exhibited a 1.62-fold increased risk of MetS (95% CI, 1.28-2.12) in males and a 1.36-fold increased risk of MetS (95% CI, 1.09-1.69) in females compared with the lowest quartile after adjustment for confounders.Our results suggest that ferritin is associated with insulin resistance and abdominal obesity.

Effects of iron supplementation in mice with hypoferremia induced by obesity

Iron is an important micronutrient, but it can also act as a dangerous element by interfering with glucose homeostasis and inflammation, two features that are already disturbed in obese subjects. In this work, we study the effects of systemic iron supplementation on metabolic and inflammatory responses in mice with hypoferremia induced by obesity to better characterize whether iron worsens the parameters that are already altered after 24 weeks of a high-fat diet (HFD). Mice were maintained on a control diet or a HFD for 24 weeks and received iron-III polymaltose (50 mg/kg/every 2 days) during the last two weeks. Glucose homeostasis (basal glucose and insulin test tolerance) and systemic and visceral adipose tissue (VAT) inflammation were assessed. Iron levels were measured in serum. The Prussian blue reaction was used in isolated macrophages to detect iron deposition. Iron supplementation resulted in an increased number of VAT macrophages that were positive for Prussian blue staining as well as increased serum iron levels. Systemic hepcidin, leptin, resistin, and monocyte chemoattractant protein-1 (MCP-1) levels were not altered by iron supplementation. Local adipose tissue inflammation was also not made worse by iron supplementation because the levels of hepcidin, MCP-1, leptin, and interleukin (IL)-6 were not altered. In contrast, iron supplementation resulted in an increased production of IL-10 by adipose tissue and VAT macrophages. Leukocytosis and VAT plasminogen activator inhibitor-1 (PAI-1) level were reduced, but insulin resistance was not altered after iron supplementation. In conclusion, systemic iron supplementation in mice with hypoferremia induced by obesity did not worsen inflammatory marker or adipose tissue inflammation or the metabolic status established by obesity. Iron deposition was observed in adipose tissue, mainly in macrophages, suggesting that these cells have mechanisms that promote iron incorporation without increasing the production of inflammatory mediators.

Lower hepatic iron storage associated with obesity in mice can be restored by decreasing body fat mass through feeding a low-fat diet

High-fat diet (HFD)-induced obesity has been reported to result in low hepatic iron storage. In the current study, we tested the hypothesis that these obesity-related changes in hepatic iron status could be reversed by decreasing adiposity by feeding a low-fat diet. Five-week-old C57BL/6 mice were assigned to 3 groups: the LL group was fed a control diet for 31 weeks, the HH group was fed a HFD for 31 weeks, and the HL group was fed the HFD for 15 weeks and then switched to the control diet for 16 weeks. The fat mass of the HL group decreased by 3.2 g from the 14th to the 30th weeks. Fat mass was significantly different among the groups (11.4, 15.8, and 37.5 g in the LL, HH, and HL groups, respectively; P< .001). The liver iron concentration of the HL group was similar to that of the LL group, which was about 30% higher than that of the HH group (74.2, 72.7, and 55.7 μg/g in the LL, HL, and HH groups, respectively; P< .05). Duodenal cytochrome b messenger RNA (mRNA) levels were higher in the HL group than in the HH group. Although bone morphogenetic protein 6 (Bmp6) mRNA levels showed no significant differences in the liver, duodenal Bmp6 mRNA levels were significantly lower in the HH group compared with the LL and HL groups. Liver Smad1/5 proteins were differentially activated: the HH group had significantly less phosphorylated Smads than did the LL and HL groups. Our data demonstrate that hepatic iron storage levels are closely related to body adiposity, and reducing body fat mass through feeding a lower-fat diet to HFD-induced obese mice restores liver iron storage.

Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress

Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders.

The role of nerve inflammation and exogenous iron load in experimental peripheral diabetic neuropathy (PDN)

BACKGROUND

Iron is an essential but potentially toxic metal in mammals. Here we investigated a pathogenic role of exogenous iron in peripheral diabetic neuropathy (PDN) in an animal model for type 1 diabetes.

METHODS

Diabetes was induced by a single injection of streptozotocin (STZ) in 4-month-old Sprague-Dawley rats. STZ-diabetic rats and non-diabetic rats were fed with high, standard, or low iron diet. After three months of feeding, animals were tested.

RESULTS

STZ-rats on standard iron diet showed overt diabetes, slowed motor nerve conduction, marked degeneration of distal intraepidermal nerve fibers, mild intraneural infiltration with macrophages and T-cells in the sciatic nerve, and increased iron levels in serum and dorsal root ganglion (DRG) neurons. While motor fibers were afflicted in all STZ-groups, only a low iron-diet led also to reduced sensory conduction velocities in the sciatic nerve. In addition, only STZ-rats on a low iron diet showed damaged mitochondria in numerous DRG neurons, a more profound intraepidermal nerve fiber degeneration indicating small fiber neuropathy, and even more inflammatory cells in sciatic nerves than seen in any other experimental group.

CONCLUSIONS

These results indicate that dietary iron-deficiency rather than iron overload, and mild inflammation may both promote neuropathy in STZ-induced experimental PDN.

Iron Overload Coordinately Promotes Ferritin Expression and Fat Accumulation in Caenorhabditis elegans

The trace element iron is crucial for living organisms, since it plays essential roles in numerous cellular functions. Systemic iron overload and the elevated level of ferritin, a ubiquitous intracellular protein that stores and releases iron to maintain the iron homeostasis in cells, has long been epidemiologically associated with obesity and obesity-related diseases. However, the underlying mechanisms of this association remain unclear. Here, using Caenorhabditis elegans, we show that iron overload induces the expression of sgk-1, encoding the serum and glucocorticoid-inducible kinase, to promote the level of ferritin and fat accumulation. Mutation of cyp-23A1, encoding a homolog of human cytochrome P450 CYP7B1 that is related to neonatal hemochromatosis, further enhances the elevated expression of ftn-1, sgk-1, and fat accumulation. sgk-1 positively regulates the expression of acs-20 and vit-2, genes encoding homologs of the mammalian FATP1/4 fatty acid transport proteins and yolk lipoproteins, respectively, to facilitate lipid uptake and translocation for storage under iron overload. This study reveals a completely novel pathway in which sgk-1 plays a central role to synergistically regulate iron and lipid homeostasis, offering not only experimental evidence supporting a previously unverified link between iron and obesity, but also novel insights into the pathogenesis of iron and obesity-related human metabolic diseases.

A review of iron studies in overweight and obese children and adolescents: a double burden in the young?

INTRODUCTION

The connection between iron and excessive adiposity has received much research interest. Although children and adolescents have unique developmental phases and nutritional demands, to date, reviews of iron in the overweight (OW) and obese (OB) have combined studies of children and adults or have focussed on adults.

PURPOSE

The aim of this review was to critically evaluate studies of the relationship between iron and OW and obesity in children and adolescents, with emphasis on iron status, oral iron response, dietary intake and systemic inflammatory markers.

METHODS

A PubMed search was conducted to identify relevant articles published up to December 2015. Combinations of the following keywords were used: iron, OW, OB, children, adolescents, diet, hepcidin, inflammation, fortification, supplementation, weight loss, trace elements, obesity, iron deficiency (ID), minerals.

RESULTS AND CONCLUSION

A higher prevalence of ID, or risk of ID, among OW and OB children and adolescents has been consistently observed. Chronic inflammation caused by excessive adiposity offers a plausible explanation for this finding, rather than dietary factors. However, future studies must employ screening for the presence of both acute and chronic infections and inflammatory conditions and report other factors such as pubertal status. Intervention studies, although few, indicate that OW and OB children and adolescents have reduced response to oral iron. Further trials are needed to explore the connection between body fat mass, inflammatory proteins and iron absorption, together with the effect of weight loss on iron status in iron-deficient OW and OB children and adolescents.

Increased Body Mass Index may lead to Hyperferritinemia Irrespective of Body Iron Stores

Objective:

Obesity causes subclinical inflammation which results in the secretion of various bioactive peptides that are key players in metabolic regulation of iron homeostasis. We sought to establish correlation of one such peptide (ferritin) with marker of subclinical inflammation (CRP) in various BMI.

Methods:

Total 150 subjects between the ages of 20-60 years were included in the cross-sectional study conducted at Basic Medical Sciences Institute, Jinnah Post Graduate Medical Centre, Karachi, Pakistan. Body Mass Index (BMI) was calculated by weight (kg) /height (m²). The given values were used as reference for Group A: normal weight (18.0-22.9 kg/m2), Group B: overweight (23.0-24.9 kg/m2), Group C: obese (>25.0 kg/m2) according to South Asian criteria. Serum Iron, Total Iron Binding Capacity, serum Transferrin Saturation, serum Ferritin and C-reactive protein were measured by commercially available kits. ANNOVA with Tukey’s minimum significant difference and Spearman Rho correlation were used considering p<0.05 significant.

Results:

The results identified an increased serum Ferritin and CRP in obese versus lean subjects (p < 0.001). BMI showed significantly positive correlation with serum CRP (r = 0.815; p-value < 0.01) and Ferritin (r = 0.584; p-value < 0.01). However, serum Iron levels and Transferrin saturation decreased in obese versus normal weight individuals (p < 0.001).

Conclusion:

This integrated new data reveals that individuals with high BMI had high levels of Serum Ferritin despite low levels of iron with high levels of C- reactive protein. This might be caused due to inflammatory conditions prevailing in the presence of increased adipose tissue.

Non-transferrin-bound iron is associated with biomarkers of oxidative stress, inflammation and endothelial dysfunction in type 2 diabetes

AIMS

To investigate the association between circulating non-transferrin-bound iron [NTBI], and markers of oxidative stress, endothelial function and inflammation in subjects with type 2 diabetes and non-diabetic subjects with varying degrees of obesity.

METHODS

Plasma NTBI was measured by HPLC, together with total iron, iron-binding capacity, transferrin saturation and soluble transferrin receptor, together with total and reduced ascorbate, malondialdehyde [MDA], E-selectin and high-sensitivity c-reactive protein [hs-CRP] in groups of 28 subjects with type 2 diabetes, 28 non-obese controls and 17 obese non-diabetic subjects.

RESULTS

Levels of NTBI were higher than controls in the diabetes group, but the total serum iron levels were lower. MDA levels were higher than controls in both the diabetes and obese groups, and this was associated with higher levels of oxidised ascorbate. hs-CRP levels were higher in both the diabetes and obese groups, and E-selectin was significantly higher in the diabetes group. There were strong positive correlations between HbA1c levels and NTBI [P<0.01], HbA1c and E-selectin [P<0.001] and NTBI and E-selectin [P<0.02] in the diabetes group.

CONCLUSION

These results support the hypothesis that iron-mediated oxidative stress may be a mechanism linking poor glycaemic control with vascular dysfunction in type 2 diabetes.

Low-grade inflammation, diet composition and health: current research evidence and its translation

The importance of chronic low-grade inflammation in the pathology of numerous age-related chronic conditions is now clear. An unresolved inflammatory response is likely to be involved from the early stages of disease development. The present position paper is the most recent in a series produced by the International Life Sciences Institute's European Branch (ILSI Europe). It is co-authored by the speakers from a 2013 workshop led by the Obesity and Diabetes Task Force entitled ‘Low-grade inflammation, a high-grade challenge: biomarkers and modulation by dietary strategies’. The latest research in the areas of acute and chronic inflammation and cardiometabolic, gut and cognitive health is presented along with the cellular and molecular mechanisms underlying inflammation–health/disease associations. The evidence relating diet composition and early-life nutrition to inflammatory status is reviewed. Human epidemiological and intervention data are thus far heavily reliant on the measurement of inflammatory markers in the circulation, and in particular cytokines in the fasting state, which are recognised as an insensitive and highly variable index of tissue inflammation. Potential novel kinetic and integrated approaches to capture inflammatory status in humans are discussed. Such approaches are likely to provide a more discriminating means of quantifying inflammation–health/disease associations, and the ability of diet to positively modulate inflammation and provide the much needed evidence to develop research portfolios that will inform new product development and associated health claims.

Iron primes 3T3-L1 adipocytes to a TLR4-mediated inflammatory response

OBJECTIVE

Iron participates in several mechanisms involving inflammation and innate immunity, yet the dysregulation of its homeostasis is a major cause of metabolic syndrome. Adipocytes should play a major role in iron metabolism, as an impairment in iron turnover is closely related to insulin resistance, obesity, and type 2 diabetes. The aim of this study was to investigate the role of iron in an in vitro-inflamed adipocyte model.

METHODS

Gene expression of tumor necrosis factor-α, interleukin-6, inflammatory chemokines (CCL3, CCL4, and CXCL12), and molecules involved in iron metabolism were evaluated in an in vitro mouse 3T3-L1 cell model. Cells underwent treatment with FeSO4 heptahydrate and lipopolysaccharide (LPS) stimulation. Toll-like receptor 4 (TLR4) membrane expression, lipid droplet immunohystochemistry, and lipolysis were also evaluated.

RESULTS

Iron sulphate heptahydrate elicited gene expression of hepcidin, hemojuvelin, and ferroportin at different time courses. Additionally, it activated lipolysis but did not trigger any adipokine gene expression. When cells treated with physiological doses of iron were also stimulated with LPS, an enhancement in the LPS-induced gene expression of cytokines and chemokines was observed. The enhancement occurred with different patterns depending on different time courses and investigated genes, showing its maximal effect for IL-6 gene expression.

CONCLUSIONS

FeSO4 heptahydrate at a relatively physiological dose, induced gene expression of iron modulatory proteins and also enhanced RNA transcripts of several inflammatory cytokines and chemokines through a priming/synergistic mechanism involving membrane TLR4.

Pleiotropic actions of iron balance in diabetes mellitus

As an essential element, iron plays a central role in many physiological processes, including redox balance, inflammation, energy metabolism, and environment sensing. Perturbations in iron homeostasis are associated with several conditions, including hyperglycemia and diabetes, both of which have been studied in patients and animal models. To clarify the pleiotropic role of iron homeostasis in diabetes development, the early studies on diseases with iron-overload, studies on clinical iron depletion therapies, associations between iron-related genetic polymorphisms and diabetes, and etiological mechanisms underlying iron perturbations-impaired insulin secretion and insulin sensitivity were carefully reviewed and discussed. Hereditary hemochromatosis, transfusion-dependent thalassemia, and excess heme iron intake can increase the risk of developing diabetes. Genetically modified mice and mice fed a high-iron diet present with discrepant phenotypes due to differences in tissue iron distribution. Moreover, several genetic polymorphisms related to iron homeostasis have been associated with the risk of developing diabetes. Tightly controlled iron metabolism is essential for insulin secretion and insulin sensitivity, and iron overload in pancreatic islets alters reactive oxygen species (ROS) generation, as well as hypoxia-inducible factor-1α (HIF-1α) stability and adenosine triphosphate (ATP) synthesis, thereby impairing the function and viability of β-cells. Decreased levels of adiponectin, macrophage-mediated inflammation, and ROS-mediated liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK) activation can contribute to iron overload-induced insulin resistance, whereas iron deficiency could also participate in obesity-related inflammation, hypoxia, and insulin resistance. Because iron homeostasis is closely correlated with many metabolic processes, future studies are needed in order to elucidate the finely tuned network among iron homeostasis, carbohydrate and lipid metabolism, inflammation, and hypoxia.

The Relationship between Serum Ferritin and Insulin Resistance in Different Glucose Metabolism in Nonobese Han Adults

The exact mechanism through which elevated serum ferritin promotes the development of type 2 diabetes is unknown. This study showed that ferritin concentration in impaired glucose regulation and newly diagnosed diabetes mellitus subjects of nonobesity already significantly increased when compared with normal glucose tolerant subjects of nonobesity. Elevated serum ferritin levels are associated with insulin resistance and may be not associated with the decline of insulin beta cells in different status of glucose tolerance in nonobese Han adults.

Genetic variant coding for iron regulatory protein HFE contributes to hypertension, the TAMRISK study

Iron is essential for body homeostasis, but iron overload may lead to metabolic abnormalities and thus increase the risk for atherosclerosis and many other diseases. Major histocompatibility complex class I-like transmembrane protein (HFE) is involved in body iron metabolism. The gene coding for HFE has 3 well-known polymorphic sites of which H63D (rs1799945, C > G) has recently been associated with hypertension in a genome-wide association study (GWAS) study. In the present study, we wanted to clarify whether the genetic variant associates with hypertension in a Finnish cohort consisting of 50-year-old men and women. The study included 399 hypertensive cases and 751 controls from the Tampere adult population cardiovascular risk study (TAMRISK) cohort. Genotyping of polymorphisms was done by polymerase chain reaction using DNAs extracted from buccal swabs. We found that individuals with the mutated form of the H63D polymorphic site (G-allele) had a 1.4-fold risk (P = 0.037, 95% confidence interval [CI] 1.02-1.89) for hypertension at the age of 50 years compared with the CC genotype carriers. When obese subjects (body mass index > 30 kg/m²) were analyzed in their own group, the risk for hypertension was even stronger (odds ratio 4.15, P < 0.001, 95% CI 1.98-8.68). We also noticed that the blood pressure (BP) readings were higher in those with the minor G-allele when compared to ones having a normal genotype already at the age of 35 years. Means of systolic/diastolic BPs were 127/81 mm Hg for CC and 131/83 mm Hg for CG + GG groups (P < 0.001 for systolic and P = 0.005 for diastolic pressure). In conclusion, HFE genetic variant H63D was associated with essential hypertension in Finnish subjects from the TAMRISK cohort confirming a previous GWAS study. The effect of this SNP on BP was also confirmed from a longitudinal study.

Dietary patterns and physical inactivity, two contributing factors to the double burden of malnutrition among adults in Burkina Faso, West Africa

A population-based cross-sectional study was carried out in the northern neighbourhoods of Ouagadougou (Burkina Faso), to examine the relationship of nutritional deficiencies and cardiometabolic risk factors (CMRF) with lifestyle in adults. We randomly selected 330 households stratified by income tertile. In each income stratum, 110 individuals aged 25-60 years and having lived in Ouagadougou for at least 6 months were randomly selected. We performed anthropometric, dietary intake and physical activity measurements, and blood sample collection. Cluster analysis of dietary intake identified two dietary patterns: 'urban' (29 % of subjects) and 'traditional' (71 %). The 'urban' cluster exhibited a higher intake of fat and sugar, whereas a higher intake of plant protein, complex carbohydrate and fibre was observed in the 'traditional' pattern. Female sex, low income and lack of education were associated with the 'traditional' cluster, as well as Fe and vitamin A deficiency. CMRF prevalence (abdominal obesity, hypertension, hyperglycaemia, dyslipidaemia) was similar in both clusters. Subjects in the 'traditional' cluster spent more time in physical activity and had less sedentary time than those in the 'urban' cluster. 'Traditional' dietary pattern, low income, female sex and sedentary time were significant contributing factors to the double burden of malnutrition. The rapid nutrition transition is reflected in this co-occurrence of CMRF and nutritional deficiencies. This stresses the need for prevention strategies addressing both ends of the nutrition spectrum.

STEAP4 and insulin resistance

Obesity is a multifactorial disease that caused by the interactions between genetic susceptibility genes and environmental cues. Obesity is considered as a major risk factor of insulin resistance. STEAP4 is a novel anti-obesity gene that is significantly down-regulated in adipose tissue of obese patients. Over-expression of STEAP4 can improve glucose uptake and mitochondrial function, and increase insulin sensitivity. STEAP4 expression is regulated by a variety of inflammatory cytokines, hormones, or adipokines. In this review, we discuss function of STEAP4 in regulating insulin resistance in adipose tissue in vivo, as well as in adipocytes in vitro.

Estimation of dietary iron bioavailability from food iron intake and iron status

Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability) at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS). Data were analyzed in 873 subjects from the 2000-2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF) concentrations) were available. There were 495 men aged 19-64 y (mean age 42.7±12.1 y) and 378 pre-menopausal women (mean age 35.7±8.2 y). Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1-40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores) was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50th percentile for SF 85 µg/L) and 17% in women (50th percentile for SF 38 µg/L). At a ferritin level of 45 µg/L estimated absorption was similar in men (14%) and women (13%). This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration.

Attention-deficit/hyperactivity disorder, iron deficiency, and obesity: is there a link?

The exact etiopathophysiology of attention-deficit/hyperactivity disorder (ADHD) remains elusive, likely because of its phenotypic heterogeneity. Given the involvement of iron in neurocognitive and behavioral functions, iron deficiency (ID) has been suggested as a possible etiopathophysiological factor in a subsample of individuals with ADHD. Most studies assessing ID in ADHD have focused on serum ferritin, a marker of peripheral iron status. Results from these studies are mixed, and the largest studies failed to find a significant association between ADHD and low serum ferritin levels. However, serum ferritin may be influenced by several conditions, including inflammatory status. Increasing evidence, especially from epidemiological studies, points to a significant association between ADHD and obesity. Interestingly, obesity is associated with a chronic inflammatory status, characterized by ID with normal-to-high serum ferritin levels. This article reviews the literature on iron status in ADHD and on the relationship between ADHD and obesity; discusses a possible link among ADHD, ID, and obesity; and proposes that comorbid obesity contributes to ID, via chronic inflammation, in a subsample of individuals with ADHD. Thus, the comorbidity between ADHD and obesity suggests moving beyond serum ferritin levels and assessing the molecular pathways of chronic inflammation that lead to ID in individuals with ADHD and obesity. In turns, this may pave the way for novel treatment strategies for cognitive and behavioral dysfunctions related to ID in ADHD.

Is obesity associated with iron status in the elderly? A case study from Sharpeville, South Africa

Objective

To investigate the relationship between poor Fe status and overweight or obesity in elderly respondents in South Africa.

Design

Cross-sectional, observational baseline survey.

Setting

Sharpeville, South Africa.

Subjects

A sample size calculation determined a representative sample of 104 randomly selected elderly (≥60 years) respondents. Measurements included weight, height, biochemical and haematological parameters. Measured BMI was used to categorise the respondents into normal weight, overweight and obese groups.

Results

The majority of the women were overweight (28·4 %) or obese (54·6 %); 58 % of the respondents had normal Fe status, 15 % were classified as Fe depleted, 9 % as Fe deficient and 13 % as Fe-deficient anaemic. Ten per cent of the respondents had low Hb levels with no other low Fe status parameters, and were thus anaemic due to other causes. A significant correlation (r = 0·318, P < 0·001) existed between BMI and high-sensitivity C-reactive protein (hs-CRP). hs-CRP was negatively correlated to serum Fe levels (r = −0·319, P < 0·001). No significant relationships existed between BMI and Fe status parameters.

Conclusions

A coexistence of obesity and poor Fe status were observed in these elderly respondents. The positive relationship between hs-CRP and BMI indicated chronic inflammation in the higher BMI groups. The negative relationship between hs-CRP and serum Fe indicated that lower serum Fe levels were related to the inflammation linked with higher BMI. A relationship between obesity-related chronic, low-grade inflammation and poor Fe status has been found in adults, but the significance of the current study is that this relationship was also confirmed for elderly persons.

The impact of obesity and insulin resistance on iron and red blood cell parameters: a single center, cross-sectional study

Objective: Obesity and iron deficiency (ID) are the 2 most common nutritional disorders worldwide causing significant public health implications. Obesity is characterized by the presence of low-grade inflammation, which may lead to a number of diseases including insulin resistance (IR) and type 2 diabetes. Increased levels of acute-phase proteins such as C-reactive protein (CRP) have been reported in obesity-related inflammation. The aim of this study was to investigate the impact of obesity/IR on iron and red blood cell related parameters.

Materials and Methods: A total of 206 patients and 45 control subjects of normal weight were included in this cross-sectional study. Venous blood samples were taken from each patient to measure hemoglobin (Hb), serum iron (Fe), iron-binding capacity (IBC), ferritin, CRP, fasting blood glucose, and fasting insulin. Body mass index (BMI) and waist-to-hip ratio (WHR) were calculated for each patient. IR was determined using the HOMA-IR formula.

Results: Subjects were divided into 3 groups according to BMI. There were 152 severely obese (BMI: 42.6±10.1), 54 mildly obese (BMI: 32.4±2.1), and 45 normal-weight (BMI: 24.3±1.3) patients. Hb levels in severely obese patients and normal controls were 12.8±1.3 g/dL and 13.6±1.8 g/dL, respectively. We found decreasing Fe levels with increasing weight (14.9±6.9 µmol/L, 13.6±6.3 µmol/L, and 10.9±4.6 µmol/L for normal controls and mildly and severely obese patients, respectively). Hb levels were slightly lower in patients with higher HOMA-IR values (13.1±1.5 g/dL vs. 13.2±1.2 g/dL; p=0.36). Serum iron levels were significantly higher in the group with low HOMA-IR values (13.6±5.9 µmol/L vs. 11.6±4.9 µmol/L; p=0.008). IBC was found to be similar in both groups (60.2±11.4 µmol/L vs. 61.9±10.7 µmol/L; p=0.23). Ferritin was slightly higher in patients with higher HOMA-IR values (156.1±209.5 pmol/L vs. 145.3±131.5 pmol/L; p=0.62).

Conclusion: Elevated BMI and IR are associated with lower Fe and hemoglobin levels. These findings may be explained by the chronic inflammation of obesity and may contribute to obesity-related co-morbidities. People with IR may present with ID without anemia.

Obesity alters adipose tissue macrophage iron content and tissue iron distribution

Adipose tissue (AT) expansion is accompanied by the infiltration and accumulation of AT macrophages (ATMs), as well as a shift in ATM polarization. Several studies have implicated recruited M1 ATMs in the metabolic consequences of obesity; however, little is known regarding the role of alternatively activated resident M2 ATMs in AT homeostasis or how their function is altered in obesity. Herein, we report the discovery of a population of alternatively activated ATMs with elevated cellular iron content and an iron-recycling gene expression profile. These iron-rich ATMs are referred to as MFe(hi), and the remaining ATMs are referred to as MFe(lo). In lean mice, ~25% of the ATMs are MFe(hi); this percentage decreases in obesity owing to the recruitment of MFe(lo) macrophages. Similar to MFe(lo) cells, MFe(hi) ATMs undergo an inflammatory shift in obesity. In vivo, obesity reduces the iron content of MFe(hi) ATMs and the gene expression of iron importers as well as the iron exporter, ferroportin, suggesting an impaired ability to handle iron. In vitro, exposure of primary peritoneal macrophages to saturated fatty acids also alters iron metabolism gene expression. Finally, the impaired MFe(hi) iron handling coincides with adipocyte iron overload in obese mice. In conclusion, in obesity, iron distribution is altered both at the cellular and tissue levels, with AT playing a predominant role in this change. An increased availability of fatty acids during obesity may contribute to the observed changes in MFe(hi) ATM phenotype and their reduced capacity to handle iron.

Association between serum ferritin levels and the incidence of obesity in Korean men: a prospective cohort study

Elevated serum ferritin levels are associated with insulin resistance, type 2 diabetes, cardiovascular disease, and metabolic syndrome. To date, however, no cohort studies have examined whether serum ferritin levels are an independent risk factor for the obesity. Therefore, we conducted a prospective cohort study to evaluate the temporal relationship between serum ferritin levels and obesity development in Korean men. Total 17,812 healthy Korean men who participated in a medical health check-up program in 2005 were followed-up until 2010. Obesity was defined as a body mass index ≥25 kg/m(2). Cox proportional hazards model was used to measure the hazard ratio of the quartile groups of serum ferritin levels. During 64,446.5 person-years of follow-up carried out, 2,627 patients became obese. After adjusting for multiple covariates, we found that the hazard ratios (95% confidence interval) for incident obesity when we compared the second, third and fourth quartiles of serum ferritin levels with the first quartile were 1.08 (0.95-1.23), 1.14 (1.00-1.30), and 1.24 (1.09-1.41), respectively (p for trend = 0.003). Both severe obesity (body mass index ≥ 30 kg/m(2)) and abdominal obesity based on waist circumference (>90 cm) showed consistent longitudinal associations (p for trend <0.001). Elevated serum ferritin levels may have been a predictive factor for obesity during the 5-year follow-up in 17,812 Korean men.

Resveratrol and desferoxamine protect human OxLDL-treated granulosa cell subtypes from degeneration

CONTEXT

Obese women suffer from anovulation and infertility, which are driven by oxidative stress caused by increased levels of lipid peroxides and circulating oxidized low-density lipoprotein (oxLDL). OxLDL binds to lectin-like oxLDL receptor 1 (LOX-1), cluster of differentiation 36 (CD36), and toll-like receptor 4 (TLR4) and causes cell death in human granulosa cells (GCs).

OBJECTIVE

Our objective was to reveal whether treatment with antioxidants resveratrol (RES) and/or desferoxamine (DFO) protect GCs from oxLDL-induced damage.

DESIGN AND SETTING

This basic research study was performed at the Institute of Anatomy and the Clinic of Reproductive Medicine.

PATIENTS

Patients were women undergoing in vitro fertilization therapy.

MAIN OUTCOME MEASURES

GC cultures were treated with oxLDL alone or with RES or DFO under serum-free conditions for up to 36 hours. Dead cells were determined by propidium iodide uptake, cleaved caspase-3 expression, and electron microscopy. Mitosis was detected by Ki-67 immunostaining. LOX-1, TLR4, CD36, and heat-shock protein 60 were examined by Western blot. Measurement of oxidative stress markers (8-iso-prostaglandin F2α, advanced glycation end products, and protein carbonyl content) was conducted with ELISA kits.

RESULTS

Different subtypes of human GCs exposed to RES or DFO were protected as evidenced by the lack of cell death, enhanced mitosis, induction of protective autophagy, reduction of oxidative stress markers, and reduced expression of LOX-1, TLR4, CD36, and heat-shock protein 60. Importantly, RES could restore steroid biosynthesis in cytokeratin-positive GCs, which exhibited significant induction of steroidogenic acute regulatory protein.

CONCLUSIONS

RES and DFO exert a protective effect on human GCs. Thus, RES and DFO may help improve the treatment of obese women or polycystic ovarian syndrome patients undergoing in vitro fertilization therapy.

Obesity does not influence hepcidin and hemojuvelin levels in hemodialysis patients

BACKGROUND/AIMS

Clinical studies have shown increased levels of hepcidin causing functional iron deficiency in obese individuals. This study examined whether obesity contributes to increased hepcidin and hemojuvelin levels in adult hemodialysis patients.

METHODS

In a case-control design, 37 obese [body mass index (BMI) >30 kg/m(2)] stable hemodialysis patients and 37 patients with normal BMI (20-25 kg/m(2)), matched for age, gender and race, who fulfilled a strict set of inclusion and exclusion criteria were included in the study. Serum hepcidin and hemojuvelin, markers of iron status and inflammation, and routine hematological and biochemical variables were measured on samples obtained prior to the midweek hemodialysis session.

RESULTS

Obese and nonobese patients (BMI 35.1 ± 3.4 vs. 22.8 ± 1.4 kg/m(2); p < 0.001) were similar with regard to basic comorbidities and use of erythropoietin and iron. Levels of hemoglobin, hypochromic red cells and reticulocytes were similar in the two groups. Serum iron and transferrin saturation levels were on the low side and not different between obese and lean individuals; total iron-binding capacity showed a trend towards higher levels in obese patients (48.4 ± 8.3 vs. 44.9 ± 7.4 μmol/l; p = 0.065). Levels of serum ferritin (651 ± 302 vs. 705 ± 327 μg/l; p = 0.46), hepcidin (118.3 ± 67.7 vs. 119.3 ± 78.0 ng/ml; p = 0.95) and hemojuvelin (1.90 ± 1.11 vs. 1.94 ± 1.24 mg/l; p = 0.90) were high but similar between the two groups. Serum hepcidin showed a significant correlation only with ferritin (r = 0.287, p = 0.013).

CONCLUSIONS

Hepcidin and hemojuvelin levels are already considerably elevated in dialysis patients, but obesity does not have an additional impact. Further studies should examine whether increased weight contributes towards hepcidin elevation in predialysis individuals, in whom there is a lesser burden of systemic inflammation.

The relation between body iron stores and adipose tissue function in patients with manifest vascular disease

BACKGROUND

We investigated whether plasma ferritin levels through the pro-inflammatory effects of free iron are associated with adipose tissue dysfunction in a relevant population of patients with manifest vascular disease who would potentially benefit the most from further aetiological insights.

MATERIALS AND METHODS

In a cohort of 355 patients with vascular diseases, the association between plasma ferritin and adiponectin levels was quantified using linear regression analysis. Interleukin-6 and adiponectin levels were measured in medium from pre-adipocytes and adipocytes after incubation with increasing concentrations of Fe(III)-citrate and after co-incubation with iron chelators or radical scavengers.

RESULTS

Increasing ferritin plasma concentrations were not related to plasma adiponectin levels in patients without (β -0·13; 95% CI -0·30 to 0·04) or with the metabolic syndrome (β -0·04; 95% CI -0·17 to 0·10). Similar results were found in patients who developed a new cardiovascular event in the follow-up period. In vitro, incubation with increasing concentrations of Fe(III)-citrate-induced inflammation in pre-adipocyte cultures as witnessed by increased IL-6 secretion at 30 μm Fe(III)-citrate vs. control (500 ± 98 pg/mL vs. 194 ± 31 pg/mL, P = 0·03). Co-incubation of pre-adipocytes with iron chelators or radical scavengers prevented this inflammatory response. Incubation of adipocytes with 30 μm Fe(III)-citrate did not influence adiponectin secretion compared with control.

CONCLUSIONS

In patients with vascular disease, there is no association between plasma ferritin and adiponectin levels. In vitro, free iron induces an inflammatory response in pre-adipocytes, but not in adipocytes. This response was blocked by co-incubation with iron chelators or radical scavengers. Adiponectin secretion by adipocytes was not influenced by free iron.

Diet-induced obese rats have higher iron requirements and are more vulnerable to iron deficiency

PURPOSE

Since obesity is associated with poorer iron status, the effects of diet-induced obesity on iron status and iron-regulatory pathways were examined.

METHODS

Weanling male diet-induced obese sensitive (n = 12/diet group) and resistant (n = 12/diet group) rats were fed one of four high-fat, high-energy diets supplemented with 5 (5Fe, low), 15 (15Fe, marginal), 35 (35Fe, normal) or 70 (70Fe, high) mg iron/kg diet for 12 weeks. At the end of the study, rats in each diet group were categorised as obese (>19 %) or lean (<17 %) based on percentage body fat.

RESULTS

Obese rats gained more weight, had larger total lean mass, consumed more food and showed greater feed efficiency compared with lean rats. Obese rats fed the 5Fe and 15Fe diets had poorer iron status than lean rats fed the same diet. Obese 5Fe rats had lower serum iron and more severe iron-deficiency anaemia. Obese 15Fe rats had lower mean corpuscular haemoglobin and liver iron concentrations. Hepcidin mRNA expression in liver and adipose tissue was similar for obese and lean rats. Iron concentration and content of the iron transporters divalent metal transporter 1 and ferroportin 1 in duodenal mucosa were also similar.

CONCLUSIONS

Obese rats that were larger, regardless of adiposity, had higher iron requirements compared with lean rats that appeared independent of hepcidin, inflammation and intestinal iron absorption. Higher iron requirements may have resulted from larger accretion of body mass and blood volume. Greater food consumption did not compensate for the higher iron needs, indicating increased susceptibility to iron deficiency.

Being overweight or obese is associated with lower prevalence of anemia among Colombian women of reproductive age

Overweight and micronutrient deficiencies have manifested in the same individuals. This study investigated the association among iron deficiency (ID), anemia, and weight status among nonpregnant Colombian females aged 13-49 y (n = 3267). Data from the 2005 National Survey of the Nutrition Situation were used. The prevalence of ID (plasma ferritin <12.0 μg/L; individuals with CRP >0.012 g/L excluded) and anemia (altitude-adjusted hemoglobin <120 g/L) was estimated separately. The likelihood of having ID or anemia was tested as a function of overweight (BMI-age Z-score 1-1.9 SD for 13-17 y, BMI 25.0-29.9 kg/m² for 18-49 y) and obesity (≥2 SD for 13-17 y, ≥30 kg/m² for 18-49 y) using multivariate logistic regressions accounting for survey design. Additionally, demographic predictors of combined overweight/obesity with ID or anemia were identified. The prevalence of overweight and obesity was 29.2 and 13.1%, respectively, whereas that of ID and anemia was 16.1 and 32.5%, respectively. Contrary to previous reports, overweight and obese women had a lower likelihood of anemia [OR (95% CI) = 0.8 (0.7, 0.9) and 0.8 (0.6, 1.0), respectively] than normal-weight women. Overweight/obesity combined with ID or anemia was present among 6.3 and 12.8% of women, respectively. Although overweight and obesity were associated with a lower likelihood of anemia, a sizeable group of women was identified as experiencing both over- and undernutrition. Because of the potential for exacerbated health problems in the presence of over- and undernutrition, these conditions should continue to be monitored.

The double burden of obesity and iron deficiency on children and adolescents in Greece: the Healthy Growth Study

BACKGROUND

Some small cohort studies have noted that obesity co-exists with lower serum iron levels. The present study aimed to examine the association between being overweight and iron deficiency (ID) in a large cohort of Greek children and adolescents.

METHODS

A representative sample of 2492 primary schoolchildren aged 9-13 years old was examined. Anthropometric, biochemical, clinical, dietary intake and physical activity data were collected.

RESULTS

The prevalence of ID and iron deficiency anaemia (IDA) was higher in obese boys and girls compared to their normal-weight peers (P < 0.05). Serum ferritin was higher in obese compared to normal-weight boys (P = 0.024) and higher in obese compared to normal-weight and overweight girls (P = 0.001). By contrast, a negative association was found between transferrin saturation and adiposity in both boys and girls (P = 0.001 and P = 0.005). Furthermore, obese girls had significantly higher fibre intake than normal-weight girls (P = 0.048) and also overweight and obese boys and girls recorded significantly fewer pedometer steps than their normal-weight peers (P < 0.001). Finally, obesity more than doubled the likelihood of ID in both boys (odds ratio = 2.83; 95% confidence inteval = 1.65-4.85) and girls (odds ratio = 2.03; 95% confidence interval = 1.08-3.81) after controlling for certain lifestyle and clinical indices as potential confounders.

CONCLUSIONS

The present study shows that obese children and adolescents were at greater risk for ID and IDA than their normal-weight peers. Low grade inflammation induced by excessive adiposity may be a reason for the observed low iron levels. This is also strengthened by the elevated serum ferritin levels, comprising an acute phase protein that is plausibly increased in inflammation.

Short-term effects of sibutramine on mineral status and selected biochemical parameters in obese women

The aim of this study was to assess the effect of sibutramine on mineral status and selected biochemical parameters in obese women. The study was conducted on 24 patients who received 15 mg daily doses of sibutramine for 12 weeks, and on 20 patients who received placebo. At the baseline, after the sixth and twelfth weeks of treatment, body weight and blood pressure were measured, the BMI was calculated, and samples of blood and of first morning urine were collected. Serum lipid profiles, glucose levels, and nitric oxide levels were determined. The iron (Fe), copper (Cu), zinc (Zn), calcium (Ca), and magnesium (Mg) present in the serum and urine samples were assessed. The erythrocyte hemolysate of the patients was use to assay the activity of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). No changes were observed in BMI, blood pressure, or nitric oxide during the study. After 12 weeks of treatment, a decrease was observed in total cholesterol, LDL cholesterol, triglyceride, glucose, and ferritin levels. GSH-Px and SOD activity increased after 12 weeks of sibutramine treatment. The Mg and Cu increases was observed in serum after the sixth and twelfth weeks of treatment. It was found that the Zn level decreased in serum after the twelfth week. The elimination of Ca, Mg, Fe, Zn, and Cu in urine also declined in the twelfth week. No differences were found in the women taking the placebo. In conclusion, we found that sibutramine had a positive effect on lipid and glucose status in obese women. However, the drug disturbed the balance of minerals, especially Zn and Mg, in the subjects.