Iron stores and cardiovascular disease risk factors in women of reproductive age in the United States

The complementary roles of iron and estrogen in menopausal differences in cardiometabolic outcomes

Biological hormonal changes are frequently cited as an explanatory factor of sex and menopause differences in cardiometabolic diseases (CMD) and its associated risk factors. However, iron metabolism which varies between sexes and among women of different reproductive stages could also play a role. Recent evidence suggest that iron may contribute to CMD risk by modulating oxidative stress pathways and inflammatory responses, offering insights into the mechanistic interplay between iron and CMD development. In the current review, we provide a critical appraisal of the existing evidence on sex and menopausal differences in CMD, discuss the pitfall of current estrogen hypothesis as sole explanation, and the emerging role of iron in CMD as complementary pathway. Prior to menopause, body iron stores are lower in females as compared to males, but the increase during and after menopause, is tandem with an increased CMD risk. Importantly, basic science experiments show that an increased iron status is related to the development of type 2 diabetes (T2D), and different cardiovascular diseases (CVD). While epidemiological studies have consistently reported associations between heme iron intake and some iron biomarkers such as ferritin and transferrin saturation with the risk of T2D, the evidence regarding their connection to CVD remains controversial. We delve into the factors contributing to this inconsistency, and the limitation of relying on observational evidence, as it does not necessarily imply causation. In conclusion, we provide recommendations for future studies on evaluating the potential role of iron in elucidating the sex and menopausal differences observed in CMD.

Preconception Micronutrient Supplementation Affects Maternal BMI and Body Composition Postpartum: A Randomized Controlled Trial in Vietnam

BACKGROUND

Although there is growing evidence on the role of preconception nutrition for birth outcomes, limited evidence exists for its effects on maternal health.

OBJECTIVES

This study evaluates the impact of preconception micronutrient supplementation on maternal BMI (kg/m2) and body composition at 6 to 7 y postpartum (PP).

METHODS

We followed females who participated in a randomized controlled trial of preconception supplementation in Vietnam and delivered live offspring (n = 1599). Females received weekly supplements containing either 2800 μg folic acid (FA) only, 60 mg iron and 2800 μg FA (IFA), or multiple micronutrients (MMs) (15 micronutrients including IFA) from baseline until conception followed by daily prenatal IFA supplements until delivery. Height, weight, mid-upper arm circumference, triceps skinfold, and waist-hip circumference were measured at recruitment and at 1, 2, and 6 to 7 y PP. Body fat was assessed using bioelectric impedance at 6 to 7 y PP (n = 867). Group comparisons were made using analysis of variance or chi-square tests and general linear models for adjusted models.

RESULTS

At 6 to 7 y PP, we found significant differences (P < 0.05) by treatment group for mean percent fat (MM: 29.2%; IFA: 27.6%; FA: 27.8%), absolute fat mass (MM: 15.1 kg; IFA: 14.0 kg; FA: 14.3 kg), and prevalence of underweight based on BMI < 18.5 (MM: 5.8%; IFA: 10.3%; FA: 14.3%). Mean BMI and triceps skinfold thickness were higher in the MM group, but these differences were not statistically significant; the differences in absolute fat mass were also attenuated after controlling for body weight. No differences were observed for fat-free mass, prevalence of overweight (BMI >23), or other anthropometric measurements.

CONCLUSIONS

Preconception MM supplementation was associated with lower prevalence of underweight and higher percent fat when compared with IFA and/or FA only. Preconception micronutrient interventions may have long-term effects on maternal health and merit further examination. This trial was registered at clinicaltrials.gov as NCT01665378.

Increased Levels of Circulating Iron-Albumin Complexes in Peripheral Arterial Disease Patients

Under physiological conditions, extracellular iron circulates in the blood bound to transferrin. As a consequence of several pathologies, the circulating level of a Non-Transferrin Bound pool of Iron (NTBI) increases. The NTBI pool is biologically heterogeneous and represented by iron chelated either by small metabolites (citrate, amino acids, or cofactors) or by serum proteins. By promoting reactive oxygen species (ROS) and reactive nitrogen species (RNS) formation, NTBI causes oxidative stress and alteration of membrane lipids, seriously compromising the healthy state of organs and tissues. While NTBI involvement in several pathologies has been clarified, its contribution to vascular diseases remains to be investigated. Here we measure and analyze the pool of NTBI in the serum of a small group of peripheral arterial disease (PAD) patients. We show that: (i) the NTBI pool shifts from low molecular complexes to high-molecular ones in PAD patients compared to healthy controls; (ii) most of this NTBI is bound to the serum protein Albumin; (iii) this NTBI-Albumin complex can be isolated and quantitated following a simple immunoisolation procedure amenable to automation and suitable for clinical screening purposes.

Associations of iron status with breast cancer risk factors in adult women: Findings from National Health and Nutrition Examination Survey 2017-2018

OBJECTIVE

This study examined the association between iron status and a set of breast cancer risk factors among U.S. adult women aged 20-80 years.

METHODS

Data from National Health and Nutrition Examination Survey (2017-2018) were used to examine the relation between serum ferritin, serum iron and transferrin saturation with a set of breast cancer risk factors [body mass index (BMI), waist circumference, glycosylated hemoglobin (HbA1c), fasting plasma glucose, insulin and HOMA-IR]. The multivariable linear regressions were used controlling for age, race/ethnicity, menopause status, education level, smoking status, alcohol consumption, physical activity, high-sensitivity C-reactive protein (hsCRP) and total energy intake.

RESULTS

HbA1c, BMI and waist circumference data were available for 1902 women with a fasting sample (n = 913) for fasting plasma glucose, insulin and HOMA-IR. Transferrin saturation had significant, inverse associations with BMI, waist circumference and HbA1c. The size of difference observed were that participants in the fourth quartile of transferrin saturation had a 4.50 kg/m² smaller BMI, a 9.36 cm smaller waist circumference and a 0.1 % lower HbA1c level than participants in the first quartile. Similarly, serum iron concentrations were inversely associated with BMI and waist circumference. In addition, serum iron had significant, inverse associations with insulin and HOMA-IR. Sensitivity analyses among men gave similar results. For serum ferritin, there was a trend towards a positive association between waist circumference, HbA1c and fasting plasma glucose with serum ferritin. However, the associations did not reach statistical significance among women.

CONCLUSIONS

Iron status may impact breast cancer risk via effects on adiposity or glucose metabolism. The findings should be confirmed with further prospective data.

Dietary iron to total energy intake ratio and type 2 diabetes incidence in a longitudinal 12-year analysis of the Korean Genome and Epidemiology Cohort Study

PURPOSE

Recent study found iron consumption has been associated with an increased risk of type 2 diabetes (T2DM). Even though, high iron intake is correlated with total caloric intake, most studies have evaluated the individual effect of iron and total caloric intake. The aim of this study was to investigate the effect of iron intake, in conjunction with total energy intake, on developing T2DM. We also investigated the interactions between dietary iron and energy ratios (IERs) and iron-related single nucleotide polymorphisms (SNPs) in the development of T2DM.

METHODS

The study was carried out in Ansan and Ansung, Korea, between March 2001 and December 2014. A total of 6413 participants (3073 men and 3340 women), aged 40-69 years, were enrolled in this study. The mean follow-up period was 8.4 years. The study population was divided into quartiles based on IERs with cut-off points at 4.54, 5.41, and 6.29. The odds ratios (ORs) for new-onset T2DM were calculated across each quartile of IERs and a random forest model was constructed using the default settings to predict new-onset T2DM. To confirm the interaction among IERs, SNPs, and the incidence of T2DM, we measured the predictive power of new-onset T2DM using IER and six SNPs in genes related to iron metabolism [rs855791 (TPMRSS6), rs38116479 (TF), rs1799852 (TF), rs2280673, rs1799945 (HFT), rs180562 (HFE)].

RESULTS

The prevalence of T2DM was 762 (11.8%). IERs showed a positive association with T2DM. The ORs were 1.30 (95% CI 1.02-1.67), 1.20 (95% CI 0.94-1.56), and 1.43 (95% CI 1.11-1.86) across the IER quartiles after adjusting for non-dietary and dietary metabolic risk factors. When the IER was 1.89-fold higher than the reference group, the risk of developing T2DM increased by 43% (OR 1.43; 95% CI 1.11-1.86).

CONCLUSION

A higher IER was positively associated with developing T2DM independent of dietary or non-dietary risk factors. We also found the possible interactions between the identified SNPs and iron intake in relations to T2DM.

Effects of alpha lipoic acid on iron overload, lipid profile and oxidative stress indices in β-thalassemia major patients: A cross-over randomised controlled clinical trial

AIMS

β-Thalassemia major (β-TM) is associated with iron overload, abnormal lipid levels and oxidative stress. Alpha lipoic acid (ALA) showed anti-oxidant and iron chelating properties, but its effect in β-TM patients is unclear. We investigated the effects of ALA on iron levels, lipid profile and oxidative stress.

METHODS

In this cross-over randomised clinical trial, 26 β-TM patients were assigned to receive 600 mg/d ALA or placebo (corn starch), for 8 weeks with a 21-days washout period. Serum ferritin, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C, total antioxidant capacity, malondialdehyde (MDA) and MDA/LDL-C were assessed at baseline and the end of each intervention phase.

RESULTS

Twenty-two patients completed the study. Serum ferritin (P = .004), MDA (P = .025) and MDA/LDL-C ratio (P =.002) were decreased and HDL-C (P =.035) increased significantly during ALA consumption. In comparison with placebo, ALA decreased the serum ferritin significantly (P = .02). Also, the changes in serum ferritin between ALA and placebo (-123.1 ± 40.0 vs -34.3 ± 21.0, P =.03) was significant in women subgroup. ALA had no significant effects on the other biomarkers.

CONCLUSION

The results of this study indicated that supplementation with 600 mg/d ALA may decrease serum ferritin in β-TM. Further studies are needed to confirm the findings.

Difference in iron metabolism may partly explain sex-related variability in the manifestation of Wilson's disease

BACKGROUND/AIM

Wilson's disease (WD) is a hereditary disorder characterized by abnormal metabolism of copper. For unknown reasons, the clinical picture of this disease appears to be sex-dependent. Because the metabolism of copper and iron is interrelated, we aimed to evaluate whether the variability in the clinical picture of WD could be explained by the sex difference in iron metabolism.

METHODS

A total of 138 WD patients were examined in this study: 39 newly diagnosed, treatment naive patients and 99 individuals already treated with decoppering drugs. The serum concentration of ceruloplasmin (Cp) and copper were measured using an enzymatic colorimetric assay and by atomic absorption spectroscopy, respectively. The parameters of iron metabolism were determined by using standard laboratory methods and enzyme immunoassays.

RESULTS

In the treatment naive group men had a higher median serum concentration of ferritin (290.5 vs. 81.0 ng/mL, p < 10^-4), and hepcidin (Hepc) (55.4 vs. 22.8 ng/mL, p < 10^-3) compared to women, and tended to have higher concentration of iron, hemoglobin (HGB) and number of red blood cells (RBC). In the treated group men had higher median ferritin (122.0 vs. 46.0 ng/mL, p < 10^-4), Hepc (23.5 vs. 10.8 ng/mL, p < 10^-4), iron (102.5 vs. 68.0 μg/dL, p < 10^-4), HGB (15.0 vs. 13.2 g/dL, p < 10^-4), and RBC (5.0 vs. 4.5 M/L, p < 10^-4) than women.

CONCLUSION

Iron metabolism differs between men and women with WD, which may partly explain the sex difference noted in the disease manifestation.

The Effects of Dietary Polyphenols on Circulating Cardiovascular Disease Biomarkers and Iron Status: A Systematic Review

The prevalence of cardiovascular disease (CVD) is rising worldwide, remaining the major cause of death in developed countries. Polyphenols have been shown to have cardioprotective properties; however, their impact on iron bioavailability and potential impact on other aspects of health is unclear. A systematic review was undertaken to evaluate the current status of the relationship between habitual polyphenol consumption, iron status, and circulating biomarkers of CVD. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines, searches were performed across 5 electronic databases (PubMed, Cochrane Library, Scopus, Web of Science, and CINAHL) to identify randomized controlled trials which investigated the effects of polyphenol consumption on inflammatory markers, serum lipid profile, and iron absorption and bioavailability. In total, 1174 records were identified, with only 7 studies meeting the inclusion criteria. The selected studies involved 133 participants and used a variety of foods and supplements, including olive oil and cherries, rich in polyphenols including hydroxytyrosol, quercetin, and resveratrol, as well as catechin enriched drinks. The duration of the studies ranged from between 56 and 145 days, with total polyphenolic content of the food items and supplements ranging from 45 to 1015 mg (per 100 g). Polyphenols did not appear to interfere with iron status, and most studies reported improvements in inflammatory markers and lipid profile. While these results are promising, the limited number of studies and considerable heterogeneity across the interventions support the need for more extensive trials assessing the relationship between polyphenol intake, iron bioavailability, and CVD risk.

Plasma ferritin, C-reactive protein, and risk of incident type 2 diabetes in Singapore Chinese men and women

AIMS

Ferritin is postulated to be involved in diabetogenesis as a marker of iron stores. We prospectively examined the association between ferritin levels and type 2 diabetes (T2D) risk in a Chinese population.

METHODS

Plasma ferritin concentrations were assayed among 485 diabetes cases and 485 controls nested within the Singapore Chinese Health Study. Cases and controls were matched on age, gender, date of blood collection, and dialect group. Participants were free of diagnosed diabetes, cardiovascular disease, and cancer at blood collection (1999-2004). Incident self-reported T2D cases were identified at follow-up II interview (2006-2010). Multivariable conditional logistic regression models were used to compute the odds ratio (OR) and the corresponding 95% confidence intervals (CIs).

RESULTS

After adjusting for T2D risk factors, including high-sensitivity C-reactive protein (hs-CRP), adiponectin, triglycerides, HDL cholesterol and alanine aminotransferase, the OR comparing the highest versus lowest quartile of ferritin levels was 1.87 (95% CI 1.10-3.19) (P-trend=0.004). When the analysis was limited to participants with hs-CRP<1.5mg/L (below median; n=482), the OR comparing extreme quartiles of ferritin levels was 1.16 (95% CI 0.62-2.16; P-trend=0.63); while the corresponding OR was 2.51 (95% CI 1.31-4.79; P-trend<0.001) when confined to those with hs-CRP≥1.5mg/L (n=488; P-interaction=0.022). Compared to participants with both ferritin and hs-CRP levels below median, those with both levels above median had markedly increased T2D risk (P-interaction for multiplicative scale=0.037).

CONCLUSIONS

The elevation of blood ferritin levels, in the presence of raised hs-CRP, was significantly associated with increased risk of T2D.

Females Are Protected From Iron-Overload Cardiomyopathy Independent of Iron Metabolism: Key Role of Oxidative Stress

Background

Sex‐related differences in cardiac function and iron metabolism exist in humans and experimental animals. Male patients and preclinical animal models are more susceptible to cardiomyopathies and heart failure. However, whether similar differences are seen in iron‐overload cardiomyopathy is poorly understood.

Methods and Results

Male and female wild‐type and hemojuvelin‐null mice were injected and fed with a high‐iron diet, respectively, to develop secondary iron overload and genetic hemochromatosis. Female mice were completely protected from iron‐overload cardiomyopathy, whereas iron overload resulted in marked diastolic dysfunction in male iron‐overloaded mice based on echocardiographic and invasive pressure‐volume analyses. Female mice demonstrated a marked suppression of iron‐mediated oxidative stress and a lack of myocardial fibrosis despite an equivalent degree of myocardial iron deposition. Ovariectomized female mice with iron overload exhibited essential pathophysiological features of iron‐overload cardiomyopathy showing distinct diastolic and systolic dysfunction, severe myocardial fibrosis, increased myocardial oxidative stress, and increased expression of cardiac disease markers. Ovariectomy prevented iron‐induced upregulation of ferritin, decreased myocardial SERCA2a levels, and increased NCX1 levels. 17β‐Estradiol therapy rescued the iron‐overload cardiomyopathy in male wild‐type mice. The responses in wild‐type and hemojuvelin‐null female mice were remarkably similar, highlighting a conserved mechanism of sex‐dependent protection from iron‐overload‐mediated cardiac injury.

Conclusions

Male and female mice respond differently to iron‐overload‐mediated effects on heart structure and function, and females are markedly protected from iron‐overload cardiomyopathy. Ovariectomy in female mice exacerbated iron‐induced myocardial injury and precipitated severe cardiac dysfunction during iron‐overload conditions, whereas 17β‐estradiol therapy was protective in male iron‐overloaded mice.

High fat diet induced atherosclerosis is accompanied with low colonic bacterial diversity and altered abundances that correlates with plaque size, plasma A-FABP and cholesterol: a pilot study of high fat diet and its intervention with Lactobacillus rhamnosus GG (LGG) or telmisartan in ApoE-/- mice

BACKGROUND

Atherosclerosis appears to have multifactorial causes - microbial component like lipopolysaccharides (LPS) and other pathogen associated molecular patterns may be plausible factors. The gut microbiota is an ample source of such stimulants, and its dependent metabolites and altered gut metagenome has been an established link to atherosclerosis. In this exploratory pilot study, we aimed to elucidate whether microbial intervention with probiotics L. rhamnosus GG (LGG) or pharmaceuticals telmisartan (TLM) could improve atherosclerosis in a gut microbiota associated manner.

METHODS

Atherosclerotic phenotype was established by 12 weeks feeding of high fat (HF) diet as opposed to normal chow diet (ND) in apolipoprotein E knockout (ApoE^-/-) mice. LGG or TLM supplementation to HF diet was studied.

RESULTS

Both LGG and TLM significantly reduced atherosclerotic plaque size and improved various biomarkers including endotoxin to different extents. Colonial microbiota analysis revealed that TLM restored HF diet induced increase in Firmicutes/Bacteroidetes ratio and decrease in alpha diversity; and led to a more distinct microbial clustering closer to ND in PCoA plot. Eubacteria, Anaeroplasma, Roseburia, Oscillospira and Dehalobacteria appeared to be protective against atherosclerosis and showed significant negative correlation with atherosclerotic plaque size and plasma adipocyte - fatty acid binding protein (A-FABP) and cholesterol.

CONCLUSION

LGG and TLM improved atherosclerosis with TLM having a more distinct alteration in the colonic gut microbiota. Altered bacteria genera and reduced alpha diversity had significant correlations to atherosclerotic plaque size, plasma A-FABP and cholesterol. Future studies on such bacterial functional influence in lipid metabolism will be warranted.

Altered Concentrations of Copper, Zinc, and Iron are Associated With Increased Levels of Glycated Hemoglobin in Patients With Type 2 Diabetes Mellitus and Their First-Degree Relatives

BACKGROUND

The altered levels of some essential trace elements and antioxidant minerals have been observed in diabetic patients.

OBJECTIVES

The aim of the present study was to compare the concentrations of essential trace elements, copper (Cu), zinc (Zn), and iron (Fe) in the serum of patients who have type 2 diabetes mellitus (T2DM) with those of their non-diabetic first-degree relatives (FDR) and control subjects. The association between glycated hemoglobin (HbA1c) and levels of metals was also evaluated.

PATIENTS AND METHODS

We studied 46 subjects with T2DM, 46 FDR, and 50 control subjects matched for age and sex. Serum concentrations of Cu, Zn, and Fe were measured by colorimetric kit. Fasting blood glucose (FBG) and HbA1c were assayed using the standard kit.

RESULTS

An imbalance in the levels of the studied metals was observed in both patients with T2DM and FDR. We found significantly decreased levels of Zn and higher levels of Cu and Fe in the patients with T2DM and FDR when compared with the control subjects (P < 0.05). HbA1c levels were positively correlated with Cu and Fe and inversely correlated with Zn in the patients with T2DM and FDR (P < 0.05).

CONCLUSIONS

The patients with T2DM and FDR had altered contents of Cu, Zn, and Fe that might be a predisposing factor to the development of diabetes in future or vice versa the result of diabetes development. Impaired metabolism of these elements may contribute to the augmented risk of developing type 2 diabetes mellitus later in the life of their first-degree relatives.

Serum ferritin is associated with arterial stiffness in hemodialysis patients: results of a 3-year follow-up study

BACKGROUND

Iron may contribute to vascular injury through reactive oxygen species. Hemodialysis patients frequently receive iron supply for correction of anemia and are at a high risk of cardiovascular disease. We tested the relationship between iron status and change in arterial stiffness in hemodialysis patients.

PATIENTS AND METHODS

We measured iron status in 53 hemodialysis patients and studied the association with clinical, biochemical, and arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV) over 3 years. The blood pressure was controlled to below 140/90 mmHg by anti-hypertensive drugs.

RESULTS

Median and interquartile range of baseline baPWV, baPWV at 3 years, and ΔbaPWV (difference between 3-year baPWV and baseline baPWV) were following: 17.6 (14.8-18.9), 16.9 (15.3-19.9), and 0.2 (-1.2 to 2.7) m/s. At baseline, baPWV was positively correlated with age, serum ferritin, and systolic blood pressure in univariate analysis. However, in multivariate analysis, only age and serum ferritin remained the significant determinants of baseline baPWV. After 3 years, ΔbaPWV was negatively correlated with age and positively with 3-year averaged serum ferritin in univariate analysis. Then, in multivariate analysis, only 3-year averaged serum ferritin was the important determinant of ΔbaPWV. ΔbaPWV was significantly increased in patients with 3-year averaged serum ferritin >500 ng/mL compared to patients with 3-year averaged serum ferritin ≤500 ng/mL.

CONCLUSIONS

In hemodialysis patients, serum ferritin associates with the progressive arterial stiffness, especially when serum ferritin >500 ng/mL.

Predisposing factors associated with uncomplicated type 2 diabetes among adults in a diabetic clinic, Enugu State, Nigeria

BACKGROUND

The role of micronutrients and other predisposing factors associated with the aetiology of type 2 diabetes in Nigeria is not well established. The objectives of this study were to investigate predisposing factors associated with uncomplicated type 2 diabetes among a Nigerian adult population.

METHODS

Predisposing factors associated with uncomplicated type 2 diabetes were investigated in 60 Igbo (a major tribe in Eastern Nigeria) adults aged 30-90 years. This study was carried out at the Diabetic Clinic, University of Nigeria Teaching Hospital (UNTH) Ituku-Ozalla, Enugu. Packed cell volume (PCV), serum ferrtin and some anthropometric parameters were measured alongside fasting blood sugar (FBS).

RESULTS

PCV recorded a statistically significant lower (p<0.001) mean value at 32.94±0.61% in the patients when compared with the control group with a mean value of 39.06±1.02%. Serum ferritin revealed a statistically significant higher (p<0.01; 110.20±15.17 ng/ml) mean value in the patients when compared with the control group (20.4±5.64 ng/ml). However, PCV (32.00±0.88%) and body mass index (BMI) (31.99±1.12 Kg/m(2)) recorded a statistically significant lower (p<0.05) mean value in female patients when compared with their corresponding males. There was no significant correlation (p>0.05) between serum iron ferritin, FBS and all other anthropometric predictors of incidence of type 2 diabetes.

CONCLUSION

Type 2 diabetes is not associated with elevated levels of serum iron ferritin. Hence, serum ferritin may not be a better predictor of type 2 diabetes, especially in uncomplicated cases.

Association between serum ferritin and microalbuminuria in Type 2 diabetes in Taiwan

AIMS

Serum ferritin has been found closely related with diabetes and glucose metabolism, but its impact on diabetic nephropathy remains unknown. This study aimed to explore the association between serum ferritin and microalbuminuria in Type 2 diabetes.

METHODS

Eight hundred and fifty-one subjects with Type 2 diabetes were selected from a cohort participating in a glycaemic control study in Taiwan in 2008. We used urine albumin:creatinine ratio to define microalbuminuria; serum ferritin was divided into quartiles for analysis. Logistic regression and trend tests were used to delineate the association between serum ferritin and microalbuminuria.

RESULTS

Subjects with diabetes with higher ferritin tended to have more metabolic disorders, higher high-sensitivity C-reactive protein and higher prevalence of microalbuminuria. Compared with those in the lowest quartile, subjects with diabetes in the highest ferritin quartile were 55% (P = 0.029) more likely to have microalbuminuria. After controlling for demographics, metabolic profiles and other inflammatory markers, the association between serum ferritin levels and microalbuminuria remained significant (P for trend < 0.001). This independent relationship was not changed either for those who had better glycaemic control or those who had not used an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker.

CONCLUSIONS

The current study shows hyperferritinemia may be an independent risk factor of nephropathy in patients with Type 2 diabetes.

Ferritin levels and risk of type 2 diabetes mellitus: an updated systematic review and meta-analysis of prospective evidence

BACKGROUND

Emerging evidence suggests that a strong link that exists between elevated baseline body iron stores and high risk of incident type 2 diabetes mellitus (T2DM) in general populations, but the precise magnitude of the associations remains uncertain.

METHODS

We conducted a systematic review and meta-analysis of published prospective studies evaluating the associations of baseline ferritin (a biomarker of body iron stores) levels with risk of T2DM in general populations. A subsidiary review of dietary heme iron status and T2DM risk associations was also conducted. Studies were identified in a literature search of PubMed, EMBASE, and Web of Science up to October 2012.

RESULTS

Of the 730 studies reviewed for eligibility, 12 published studies involving 185 462 participants and 11 079 incident T2DM events were included in the analyses. Nine studies assessed associations between ferritin levels and T2DM with heterogeneous findings (I(2)  = 58%, 12-80%, p = 0.014). The pooled fully adjusted relative risk (RR) with (95% confidence interval) for T2DM was 1.73 (1.35-2.22) in a comparison of extreme fifths of baseline ferritin levels. Three studies evaluated associations between dietary heme iron status and T2DM with a corresponding RR for T2DM of 1.28 (1.16-1.41). In dose-response analyses, the pooled RRs for an increment of 5 ng/mL in ferritin levels and 5 mg/day in dietary heme iron were, respectively, 1.01 (0.99-1.02) and 3.24 (2.05-5.10).

CONCLUSION

Elevated levels of ferritin may help identify individuals at high risk of T2DM. Further research is warranted to establish causality of these associations and to ascertain which patients are likely to benefit from lifestyle or therapeutic interventions.

Long-term stability of biomarkers of the iron status in human serum and plasma

CONTEXT

In epidemiological research, it is very important to test the stability of biomarkers as function of both storage time and temperature.

OBJECTIVE

In this study, the stability of biomarkers of the iron status was tested up to 1 year of storage.

MATERIALS AND METHODS

The biomarkers include total iron, unsaturated iron binding capacity, ferritin, transferrin, soluble transferrin receptor, ceruloplasmin and haptoglobin.

RESULTS

The concentrations of all biomarkers tested remain constant upon storage at -20, -70 and -196 °C.

CONCLUSION

All biomarkers of the iron status were stable at the temperatures tested for 1 year.

Sex differences in the association between serum ferritin and fasting glucose in type 2 diabetes among South Asian Surinamese, African Surinamese, and ethnic Dutch: the population-based SUNSET study

OBJECTIVE

Moderately elevated iron stores below the levels commonly associated with hemochromatosis have been implicated in the etiology of diabetes. Studies suggest that iron status (measured by serum ferritin) differs significantly according to sex, but inconsistent findings have been reported. Our aim is to test the association between serum ferritin and the prevalence of type 2 diabetes and fasting glucose concentrations in a population-based, multiethnic, cross-sectional study including men and women of African Surinamese, South Asian Surinamese, and ethnic Dutch origin.

RESEARCH DESIGN AND METHODS

We analyzed data on 508 ethnic Dutch, 597 African Surinamese, and 339 South Asian Surinamese aged 35-60 years. Type 2 diabetes was defined as a fasting plasma glucose level ≥7.0 mmol/L or a self-reported diagnosis.

RESULTS

Serum ferritin was positively associated with type 2 diabetes and fasting glucose, but differences in the associations according to sex were observed. Serum ferritin concentration was positively associated with type 2 diabetes among women in all ethnic groups (odds ratio [OR] ethnic Dutch: 1.07 [95% CI 1.01-1.13]; OR South Asian Surinamese: 1.05 [1.00-1.10]; OR African Surinamese: 1.05 [1.01-1.10]), but not among men. Serum ferritin was also more strongly associated with fasting glucose in women than in men. Moreover, the magnitude of sex differences in the association between serum ferritin and fasting glucose, but not type 2 diabetes, was more pronounced in the African Surinamese group than in the other ethnic groups (P for interaction ≤0.0001).

CONCLUSIONS

We found a positive association between serum ferritin and type 2 diabetes and fasting glucose in our multiethnic population, which appeared stronger among women than men. Further evaluation of the variation in sex differences between ethnic groups is warranted, particularly among the African Surinamese, to understand the mechanisms behind these sex differences.

Iron homeostasis in the metabolic syndrome

The metabolic syndrome (MetS) affects iron homeostasis in a many-faceted fashion. On the one side, hyperferritinaemia with normal or mildly elevated transferrin saturation is observed in approximately one-third of patients with non-alcoholic fatty liver disease (NAFLD) or the MetS. This constellation has been named the 'dysmetabolic iron overload syndrome (DIOS)'. Current evidence suggests that elevated body iron stores exert a detrimental effect on the clinical course of obesity-related conditions and that iron removal improves insulin sensitivity and delays the onset of T2DM. On the other side, iron deficiency is a frequent finding in more progressed stages of obesity. The mechanisms underlying the DIOS and obesity-related iron deficiency appear strikingly similar as elevated hepcidin concentrations, low expression of duodenal ferroportin (FPN) and impaired iron absorption are found in both conditions. This review summarizes the current knowledge about the dysregulation of iron homeostasis in the MetS and particularly in its hepatic manifestation NAFLD.

eNOS Gene Variant in Patients with Coronary Artery Disease

Subject & Aim. Endothelial nitric oxide synthase (eNOS) is one of the most important candidate genes in CAD. A functional polymorphism within eNOS gene is a 27 bp VNTR on its intron 4 which has been shown to be associated with various diseases. In this study we investigated eNOS VNTR polymorphism in addition to eNOS gene expression profile in patients with CAD. Material and Methods. The study comprised patients with angiographically confirmed CAD (CAD⁺) and individuals with normal coronary as CAD⁻. eNOS VNTR polymorphism frequencies were determined in both groups. In addition eNOS gene expression profile was examined using a quantitative real-time PCR. Results. We have found that aa genotype was significantly increasing the risk of CAD in our patients (aa versus ab + bb, P = 0.02, OR = 3.5; 95% CI: = 0.98 to 16.2). The differences in eNOS expression were not significant between patients and normal group; however in CAD⁺ patients eNOS expression was higher than the expression level of patients carrying other genotypes (P = 0.16). Conclusion. We have observed that eNOS gene polymorphism was associated with CAD in angiography-confirmed patients. However, the difference in eNOS gene expression was not statistically significant between patients and control which might be due to the contribution of other confounding factors which require further investigations.

Body iron stores and risk of type 2 diabetes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study

AIMS/HYPOTHESIS

The aim of this study was to prospectively examine the association between body iron stores and risk of type 2 diabetes.

METHODS

We designed a case-cohort study among 27,548 individuals within the population-based European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study. During 7 years of follow-up, 849 incident cases of type 2 diabetes were identified. Of these, 607 remained for analyses after exclusion of participants with missing data or abnormal glucose levels at baseline. A sub-cohort of 2,500 individuals was randomly selected from the full cohort, comprising 1,969 individuals after applying the same exclusion criteria.

RESULTS

After adjustment for age, sex, BMI, waist circumference, sports activity, bicycling, education, occupational activity, smoking habit, alcohol consumption and circulating levels of γ-glutamyltransferase, alanine aminotransferase, fetuin-A, high-sensitivity C-reactive protein, adiponectin, HDL-cholesterol and triacylglycerol, higher serum ferritin concentrations were associated with a higher risk of type 2 diabetes (RR in the highest vs lowest quintile, 1.73; 95% CI 1.15, 2.61; p(trend) = 0.002). No significant association was observed for soluble transferrin receptor (RR 1.33; 95% CI 0.85, 2.09; p(trend) = 0.50). The soluble transferrin receptor-to-ferritin ratio was significantly inversely related to risk (RR 0.61; 95% CI 0.41, 0.91; p(trend) = 0.02).

CONCLUSIONS/INTERPRETATION

High ferritin levels are associated with higher risk of type 2 diabetes independently of established diabetes risk factors and a range of diabetes biomarkers whereas soluble transferrin receptor concentrations are not related to risk. These results support the hypothesis that higher iron stores below the level of haemochromatosis are associated with risk of type 2 diabetes.

Non transferrin bound iron: nature, manifestations and analytical approaches for estimation

Iron is an essential trace element and plays a number of vital roles in biological system. It also leads the chains of pathological actions if present in excess and/or present in free form. Major portion of iron in circulation is associated with transferrin, a classical iron transporter, which prevent the existence of free iron. The fraction of iron which is free of transferrin is known as "non transferrin bound iron". Along with the incidence in iron over loaded patient non transferrin bound iron has been indicated in patients without iron overload. It has been suggested as cause as well as consequence in a number of pathological conditions. The major organs influenced by iron toxicity are heart, pancreas, kidney, organs involved in hematopoiesis etc. The most commonly suggested way for iron mediated pathogenesis is through increased oxidative stress and their secondary effects. Generation of free oxygen radicals by iron has been well documented in Fenton chemistry and Haber-Weiss reaction. Non transferrin bound iron has obvious chance to generate the free reactive radicals as it is not been shielded by the protective carrier protein apo transferrin. The nature of non transferrin bound iron is not clear at present time but it is definitely a group of heterogenous iron forms free from transferrin and ferritin. A variety of analytical approaches like colorimetry, chromatography, fluorimetry etc. have been experimented in different research laboratories for estimation of non transferrin bound iron. However the universally accepted gold standard method which can be operated in pathological laboratories is still to be developed.

Transition metals and mitochondrial metabolism in the heart

Transition metals are essential to many biological processes in almost all organisms from bacteria to humans. Their versatility, which arises from an ability to undergo reduction-oxidation chemistry, enables them to act as critical cofactors of enzymes throughout the cell. Accumulation of metals, however, can also lead to oxidative stress and cellular damage. The importance of metals to both enzymatic reactions and oxidative stress makes them key players in mitochondria. Mitochondria are the primary energy-generating organelles of the cell that produce ATP through a chain of enzymatic complexes that require transition metals, and are highly sensitive to oxidative damage. Moreover, the heart is one of the most mitochondrially-rich tissues in the body, making metals of particular importance to cardiac function. In this review, we focus on the current knowledge about the role of transition metals (specifically iron, copper, and manganese) in mitochondrial metabolism in the heart. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".

Serum ferritin levels associated with increased risk for developing CHD in a low-income urban population

OBJECTIVE

The present study examined the association of serum ferritin with CHD risk using the Framingham Heart Study's 10-year risk algorithm.

DESIGN

Ordinal logistic regression modelling was used to interpret risk. Proportional odds modelling assessed four divisions of ranked CHD risk (4, high; 3, increased; 2, slight; 1, minimal), separately by sex.

SETTING

Baltimore, MD, USA.

SUBJECTS

African-American and white participants (n 1823) from baseline of the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study, aged 30-64 years.

RESULTS

For men, there was a 0·5 % increase in risk for every 10-unit rise in serum ferritin (pmol/l). Other significant predictors included increased BMI, white race, unemployment and C-reactive protein ≥9·5 mg/l. For women, there was a 1·5 % [corrected] increase in risk per 10-unit rise in serum ferritin (pmol/l). Other significant predictors included increased BMI, lower education, unemployment and C-reactive protein ≥9·5 mg/l.

CONCLUSIONS

Serum ferritin is a significant predictor of 10-year hard CHD risk for HANDLS study participants, a low-income, urban population. Serum ferritin, independent of elevated C-reactive protein, was associated with increased 10-year CHD risk for HANDLS participants. To our knowledge, these data provide the first evidence of the role of serum ferritin as a risk factor for hard CHD in African-American and white postmenopausal women in the USA. Future research on cardiovascular events from this prospective study may confirm the association.

Serum ferritin concentration in gestational diabetes mellitus and risk of subsequent development of early postpartum diabetes mellitus

PURPOSE

To compare the serum ferritin concentrations of normal pregnant women with those having gestational diabetes mellitus (GDM) and to determine the possible role of ferritin in predicting pregnancy outcome and early development of postpartum glucose intolerance and diabetes mellitus.

METHOD

This case-control study consisted of 128 pregnant women (64 women with GDM and 64 age-matched healthy pregnant women) seen at a university hospital in Zanjan, Iran. Anthropometric measurements were determined, and serum ferritin, C-reactive protein, insulin, glycosylated hemoglobin (HbA(1c)), and hemoglobin levels were measured. Pregnancy outcomes were recorded in all subjects. In the women with GDM, a diagnostic oral glucose tolerance test was performed eight weeks after delivery.

RESULTS

Women with GDM had a higher concentration of serum ferritin (112 ± 28.4 pmol/L in GDM versus 65 ± 16.9 pmol/L in controls, P < 0.001). A positive correlation was found between serum ferritin level and mid-pregnancy fasting plasma glucose and HbA(lc) levels. Although women in the highest quartile of serum ferritin had a greater than two-fold increased risk of GDM, no significant correlation was found between ferritin levels and early postpartum oral glucose tolerance test results.

CONCLUSIONS

Elevated serum ferritin concentrations in mid-pregnancy are associated with an increased risk of GDM independent of C-reactive protein and body mass index. Ferritin levels in GDM cannot be used as an indicator to predict subsequent glucose concentration in early postpartum oral glucose tolerance test.

One size does not fit all: an examination of low birthweight disparities among a diverse set of racial/ethnic groups

To examine disparities in low birthweight using a diverse set of racial/ethnic categories and a nationally representative sample. This research explored the degree to which sociodemographic characteristics, health care access, maternal health status, and health behaviors influence birthweight disparities among seven racial/ethnic groups. Binary logistic regression models were estimated using a nationally representative sample of singleton, normal for gestational age births from 2001 using the ECLS-B, which has an approximate sample size of 7,800 infants. The multiple variable models examine disparities in low birthweight (LBW) for seven racial/ethnic groups, including non-Hispanic white, non-Hispanic black, U.S.-born Mexican-origin Hispanic, foreign-born Mexican-origin Hispanic, other Hispanic, Native American, and Asian mothers. Race-stratified logistic regression models were also examined. In the full sample models, only non-Hispanic black mothers have a LBW disadvantage compared to non-Hispanic white mothers. Maternal WIC usage was protective against LBW in the full models. No prenatal care and adequate plus prenatal care increase the odds of LBW. In the race-stratified models, prenatal care adequacy and high maternal health risks are the only variables that influence LBW for all racial/ethnic groups. The race-stratified models highlight the different mechanism important across the racial/ethnic groups in determining LBW. Differences in the distribution of maternal sociodemographic, health care access, health status, and behavior characteristics by race/ethnicity demonstrate that a single empirical framework may distort associations with LBW for certain racial and ethnic groups. More attention must be given to the specific mechanisms linking maternal risk factors to poor birth outcomes for specific racial/ethnic groups.

Biomarkers of body iron stores and risk of developing type 2 diabetes

AIM

Iron may contribute to the pathogenesis of type 2 diabetes mellitus (DM) by inducing oxidative stress and interfering with insulin secretion. Elevated ferritin levels are associated with increased DM risk among healthy individuals. However, it is yet unknown if ferritin predicts DM incidence among high-risk individuals with impaired glucose tolerance (IGT). Furthermore, the association between soluble transferrin receptors (sTfR), a novel marker of iron status, and DM risk has not yet been prospectively investigated in these individuals. We conducted this study to evaluate the association between baseline levels of ferritin and sTfR and the risk of developing DM among overweight and obese individuals at high risk of DM.

METHODS

This nested case-control study (280 cases and 280 matched controls) was conducted within the placebo arm of the Diabetes Prevention Program, is a clinical trial conducted among overweight/obese individuals with IGT. Ferritin and sTfR levels were measured by immunoturbidimetric assays. Incident DM was ascertained by annual 75-g oral glucose tolerance test and semi-annual fasting glucose.

RESULTS

Compared with controls, cases had higher sTfR levels (3.50 +/- 0.07 vs. 3.30 +/- 0.06 mg/l; p = 0.03), but ferritin levels were not statistically different. The multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for DM incidence comparing highest with the lowest quartiles of sTfR was 2.26 (1.37-4.01) (p-trend: 0.008).

CONCLUSIONS

Modestly elevated sTfR levels are associated with increased DM risk among overweight and obese individuals with IGT. Future studies should evaluate factors determining sTfR levels and examine if interventions that lower body iron stores reduce DM incidence.

The role of iron in type 2 diabetes in humans

The role of micronutrients in the etiology of type 2 diabetes is not well established. Several lines of evidence suggest that iron play may a role in the pathogenesis of type 2 diabetes. Iron is a strong pro-oxidant and high body iron levels are associated with increased level of oxidative stress that may elevate the risk of type 2 diabetes. Several epidemiological studies have reported a positive association between high body iron stores, as measured by circulating ferritin level, and the risk of type 2 diabetes and of other insulin resistant states such as the metabolic syndrome, gestational diabetes and polycystic ovarian syndrome. In addition, increased dietary intake of iron, especially that of heme iron, is associated with risk of type 2 diabetes in apparently healthy populations. Results from studies that have evaluated the association between genetic mutations related to iron metabolism have been inconsistent. Further, several clinical trials have suggested that phlebotomy induced reduction in body iron levels may improve insulin sensitivity in humans. However, no interventional studies have yet directly evaluated the effect of reducing iron intake or body iron levels on the risk of developing type 2 diabetes. Such studies are required to prove the causal relationship between moderate iron overload and diabetes risk.

Gender differences in correlations between the content of elements in rain water and the frequency of hospitalization for arterial hypertension, chronic obstructive pulmonary disease, and psoriasis in Opole Voivodship, Poland, during 2000-2002

The aim of this work is to show and give a plausible explanation to gender-dependent differences in correlations between the content of selected elements in rainwater and the frequency of hospitalization by reason of arterial hypertension, chronic obstructive pulmonary disease (COPD), and psoriasis in the area of Opolskie Voivodeship, Poland, during the period 2000-2002. The elements analyzed were sodium, potassium, calcium, magnesium, manganese, iron, total phosphorus, total nitrogen, ammonium nitrogen, zinc, copper, lead, cadmium, nickel, chromium, chloride, nitrate, and sulfate. Hospitalization due to arterial hypertension was more frequent in women, whereas those for COPD and psoriasis were more frequent in men. In the case of women hospitalized for arterial hypertension, the correlations were low, except for zinc (r = 0.47) and for cadmium (r = 0.43). In men hospitalized for COPD, all of the correlation coefficients were higher than 0.4, except for phosphorus. The coefficients for nickel, ammonia nitrogen, and total nitrogen ranged from 0.5 to 0.6 and the remaining elements from 0.6 to 0.7. In women, the correlation was limited to five elements where the coefficient was r > 0.4 for chloride, calcium, nitrate, phosphorus, and chromium. In cases of hospitalization for psoriasis, the correlation in men was between 0.4 and 0.5 for chloride, phosphorus, copper, lead, and total nitrogen and greater than 5 for sulfate, potassium, calcium, iron, manganese, nitrate, and ammonium nitrogen. The correlation in women was between 0.48 and 0.5 for ammonium nitrogen and phosphorus.

Pregravid body mass index is negatively associated with diet quality during pregnancy

OBJECTIVE

To investigate the association between pregravid weight status and diet quality.

DESIGN

Institute of Medicine body mass index (BMI) cut-off points of 26.0-29.0 kg m- 2 for overweight and >29 kg m- 2 for obese were used to categorise women's weight status. Dietary information was obtained by self-report at 26-28 weeks' gestation using a modified Block food-frequency questionnaire. The Diet Quality Index for Pregnancy (DQI-P) included: servings of grains, vegetables and fruits, folate, iron and calcium intake, percentage calories from fat, and meal pattern score. Multinomial logistic regression models were used to estimate the association between weight status and tertiles of DQI-P controlling for potential individual confounders.

SETTING

A clinical-based population recruited through four prenatal clinics in central North Carolina.

SUBJECTS

A total of 2394 women from the Pregnancy, Infection and Nutrition study were included in this analysis.

RESULTS

Evidence of a dose-response relationship was found between BMI and inadequate servings of grains and vegetables, and iron and folate intake. Pregravid obesity was associated with 76% increased odds of falling into the lowest diet quality tertile compared with underweight women after controlling for potential confounders.

CONCLUSION

A modest association was found between pregravid weight status and diet quality. If corroborated, these findings suggest that overweight pregnant women should be targeted for nutrition counselling interventions aimed to improve diet quality.

Iron intake and the risk of type 2 diabetes in women: a prospective cohort study

OBJECTIVE

Epidemiological studies suggest that high body iron stores are associated with insulin resistance and type 2 diabetes. The aim of this study was to evaluate the association between dietary intake of iron and the risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study within the Nurses' Health Study. We followed 85,031 healthy women aged 34-59 years from 1980 to 2000. Dietary data were collected every 4 years, and data on medical history and lifestyle factors were updated biennially.

RESULTS

During the 20 years of follow-up, we documented 4,599 incident cases of type 2 diabetes. We found no association between total, dietary, supplemental, or nonheme iron and the risk of type 2 diabetes. However, heme iron intake (derived from animal products) was positively associated with risk; relative risks (RRs) across increasing quintiles of cumulative intake were 1.00, 1.08 (95% CI 0.97-1.19), 1.20 (1.09-1.33), 1.27 (1.14-1.41), and 1.28 (1.14-1.45) (P(trend) < 0.0001) after controlling for age, BMI, and other nondietary and dietary risk factors. In addition, when we modeled heme iron in seven categories, the multivariate RR comparing women who consumed > or =2.25 mg/day and those with intake <0.75 mg/day was 1.52 (1.22-1.88). The association between heme iron and the risk of diabetes was significant in both overweight and lean women.

CONCLUSIONS

This large cohort study suggests that higher heme iron intake is associated with a significantly increased risk of type 2 diabetes.

Association of elevated serum ferritin levels and the risk of gestational diabetes mellitus in pregnant women: The Camden study

OBJECTIVE- We examined the influence of a moderately elevated serum ferritin level at entry to care on the risk of gestational diabetes mellitus (GDM) and a possible mechanism (increased iron stores versus inflammation). RESEARCH DESIGN AND METHODS- In a prospective observational study with 1,456 healthy pregnant women in Camden, New Jersey, serum ferritin and anthropometric measurements were determined. Serum C-reactive protein (CRP) concentration was measured in a nested case-control study of 172 subjects. RESULTS- Women who developed GDM had a higher concentration of serum ferritin than women who did not develop GDM (P < 0.001). Elevated serum ferritin level (highest quintile) was significantly and positively correlated with prepregnant BMI and skinfold measurements. Women in the highest quintile of serum ferritin had a twofold increased risk of developing GDM adjusted for several known risk factors (adjusted odds ratio, 2.02 [95% CI 1.04-3.92], P < 0.05). Similar results were obtained with a nested case-control study, in which women in the highest tertile of serum ferritin (2.35 [1.06-5.22], P < 0.05) or CRP (2.67 [1.16-6.17], P < 0.001) had a greater than twofold increased risk of GDM. However, these effects were modified and became nonstatistically significant after additional adjustment for prepregnant BMI. CONCLUSIONS- Elevated serum ferritin concentrations early in gestation are associated with an increased risk of GDM. The association, at least in part, is mediated by the maternal fat mass and obesity. These data suggest a possible link between elevated serum ferritin and low-grade inflammation.

Evaluation of Iron Overload in Healthy Adult Residents of Mexico City

BACKGROUND

We described the effects of age, gender and body mass index (BMI) on the prevalence of iron overload (IO) in blood donors from Mexico City.

METHODS

A cross-sectional study of clinically healthy adults was performed. We evaluated serum ferritin (SF) concentration to allow us to establish groups with normal iron stores (SF >30 microg/L) and with IO (SF >200 microg/L and >300 microg/L for women and men), in the following ages groups: 18-29 years, 30-49 years, and 50-64 years, divided by gender.

RESULTS

The study included 1757 subjects. Prevalence of IO was 12% in men and 4.8% in women, and prevalence increased in parallel with increasing age (15.6, 25.0 and 29.9% and 3.5, 5.2 and 9.6%, for men and women, respectively). Regression analysis showed that in men there was a significant association of SF and IO with age, BMI and recent blood donation (p <0.01). In women, no differences were seen for BMI and recent blood donation.

CONCLUSIONS

IO is highly prevalent in blood donors residing in Mexico City, more so in men than in women. Age, gender and BMI had a positive association with iron stores. This report is the initial contribution towards the study of IO in the Mexican population.

Is serum ferritin an additional cardiovascular risk factor for all postmenopausal women?

BACKGROUND

Most of the studies on cardiovascular disease (CVD) risk factors in menopause have focused on serum lipid(lipoprotein) abnormalities and were conducted in populations which were not well controlled for several important influential factors.

METHODS

Two homogenous groups of 30 apparently healthy Caucasian premenopausal women and 3-5 years postmenopausal women who were nonobese, nonsmoking and not using estrogen were compared in a well-controlled cross-sectional design. Fasting serum ferritin and plasma total homocysteine (tHcy) were evaluated concomitantly to classical serum lipid(lipoprotein) risk factors. Relationships between risk factors and the influence of other contributing variables such as diet and body weight were also examined.

RESULTS

Serum total cholesterol (p < 0.01), low-density lipoproteins (LDL; p < 0.05) and triglycerides (p < 0.05) of postmenopausal women were greater than that of their menstruating counterparts, even though they ate a CVD-preventive diet, had similar body weight and body fat distribution. Their serum ferritin was almost 3-fold greater (p < 0.0001) but was still within normal limits, except for the 38.5% of postmenopausal women who exhibited values above the 80 mug/l limit that has been associated with sharp increases in the rate of heart disease in either gender. Serum ferritin was low in one third of the postmenopausal group (as low as in the premenopausal control group, whose dietary iron intake was slightly below the nutritional recommendation). The mean plasma tHcy of the postmenopausal group was almost twice as elevated (p < 0.0001). Both ferritin and tHcy were found to be linked to serum cholesterol. The correlation between tHcy and triglycerides was also significant.

CONCLUSION

Early menopause is not associated with blood iron overload and CVD risk factor in an important proportion of women.