Iron status in association with cardiovascular disease risk in 3 controlled feeding studies

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.

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.

Effect of Oral Iron on Markers of Oxidative Stress and Antioxidant Status in Children with Iron Deficiency Anaemia

INTRODUCTION

Conflicting reports are available on the relationship of Iron Deficiency Anaemia (IDA) and iron therapy with oxidative stress.

AIM

To study the levels of markers of oxidative stress and anti-oxidant status in children with IDA and to assess the effect of iron therapy on the same.

MATERIALS AND METHODS

This prospective, single centre, hospital based study was a sub-study of a randomized controlled trial conducted in the Department of Paediatrics, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh in collaboration with the Department of Biochemistry (of the same institution) between October 2009 to February 2011. The sub-study was conducted in two parts: in the first part, levels of a biomarker of oxidative stress {Malondialdehyde (MDA)} and anti-oxidant enzymes {Superoxide Dismutase (SOD), Catalase (CAT), Glutathione Peroxidase (GPx)} were assessed and compared between 67 children with IDA and 31 non-anaemic controls; in the second part, the effect of oral iron (6mg/kg/day) for eight weeks on these markers was studied in a subset of 35 children with IDA. The Bivariate correlations procedure was used to compute pair wise associations for a set of variables. T-tests (Independent samples t-test/Paired sample t-test) and Non-parametric tests (Mann-Whitney test/Wilcoxon signed-rank test) were applied as applicable for normally and non-normally distributed data, respectively.

RESULTS

Levels of anti-oxidant enzymes were significantly lower (p<0.001) in children with IDA as compared to controls, viz., SOD {median, 8.63 (IQR, 8.60-8.66) vs. 9.46 (IQR, 9.14-9.62) units/mg protein}, CAT {median, 8.49 (IQR, 8.46-8.50) vs. 9.10 (IQR, 9.04-9.14) μmol H₂O₂/min/mg protein} and GPx {median, 49.19 (IQR, 48.99-49.60) vs. 56.94(IQR, 56.80-57.14) mol NADPH oxidized /min/ mg protein}. Whereas, levels of MDA were significantly higher (p<0.001) in IDA group {median, 1.50 (IQR, 1.48-1.52) vs. 1.24 (IQR, 1.20-1.27) moles/ml of serum}. Levels of Haemoglobin (Hb) and markers of iron status (serum iron, transferrin saturation and ferritin) had a very strong, highly significant positive correlation (p<0.001) with levels of anti-oxidant enzymes (SOD, CAT, and GPx) but a very strong, highly significant negative correlation (p<0.001) with MDA. Total Iron Binding Capacity (TIBC) on the other hand, had a strong, highly significant (p<0.001) negative correlation with SOD, CAT, and GPx but a strong, highly significant positive correlation (p<0.001) with MDA. After eight weeks of daily iron therapy, a highly significant rise (p<0.001) from baseline was observed in levels of SOD, CAT, and GPx in subjects with IDA. On the other hand, MDA levels declined significantly (p<0.001).

CONCLUSION

Lipid peroxidation is increased and anti-oxidant defenses lowered in IDA. These changes, however, may be mitigated effectively with oral iron therapy.

Increased iron levels and lipid peroxidation in a Mediterranean population of Spain

BACKGROUND

Many chronic diseases are adversely affected by elevated iron levels. It has been speculated that this relationship is mediated by increased oxidative stress, due to the ability of iron to generate reactive oxygen species. The aim of this study was to assess the relationship between elevated iron levels and lipid peroxidation in Caucasian adults residing in the north-eastern Mediterranean region of Spain.

MATERIALS AND METHODS

This cross-sectional case-control study included 300 subjects: 150 adults displaying elevated iron levels (cases) selected from a representative sample of our general population and 150 age- and sex-matched adults exhibiting normal iron levels (controls). Dietary assessment (3-day food records), iron biomarkers (serum iron, ferritin and transferrin saturation) and lipid profile were determined. Elevated iron levels were defined by high serum ferritin (SF>110 μg/L in women and>200 μg/L in men) and/or transferrin saturation (TS)>45%. Oxidized low-density lipoprotein (oxLDL) plasma levels were measured, and oxLDL/LDL-cholesterol ratio was calculated to estimate lipid peroxidation. Multiple linear regression (MLR) models were applied.

RESULTS

Individuals with elevated serum iron levels showed increased oxLDL/LDL ratio, but not oxLDL levels, compared to control subjects (20·92 ± 4·89 U/mmol vs. 19·72 ± 3·573 U/mmol, P = 0·028). These results were further confirmed by the regression models adjusted for demographic characteristics, diet, lipid profile and inflammation. Importantly, higher serum levels of triglycerides, LDL-cholesterol and lower intake of Vitamin E increased lipid peroxidation.

CONCLUSIONS

In our general population, we have observed that higher circulating levels of iron, measured by serum ferritin and/or TS, increased lipid peroxidation (measured by oxLDL/LDL ratio).

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.

Anthropometric indices added the predictive ability of iron status in prognosis of atherosclerosis

BACKGROUND

Abnormal homeostasis of iron such as deficiency or overload is associated with the pathogenesis of cardiovascular disease (CVD). Another risk factor for CVD is obesity whose added predictive ability to iron status has been assessed by few study. This study aimed to eva¬luate the effect of adding anthropometric indices to a model based on iron status as risk factors of CVD.

METHODS

This cross-sectional study included 140 adult women aged 18-50 years randomly se-lected from Sheikhorrais Clinic that is one of the Tabriz University sub-specialized clinics in 2011. Anthropometric indices, carotid intima-media thickness (CIMT) and body iron status were measured by standard protocol, non-invasive ultrasound and concentrations of serum iron, ferri¬tin, TIBC (Total iron Binding Capacity) and complete blood cell counts (CBC), respectively. In¬tegrated discriminatory improvement index (IDI) and net reclassification improvement index (NRI) were used as the measures of added predictive ability of anthropometric measures to the iron statues.

RESULTS

IDI (SE) after adding Waist Circumference (WC), Waist to Heap Ratio (WHR), Waist to Height Ratio (WHtR), Body Mass Index (BMI) and Body fat (%) to base model was 0.12 (0.028), 0.09 (0.026), 0.12 (0.028), 0.07 (0.022) and 0.10 (0.026) respectively. The NRI (SE) was 0.10 (0.065) for WC, 0.03 (0.058) for WHR, 0.07 (0.067) for WHtR, 0.05 (0.067) for BMI, and 0.08 (0.064) for Body fat.

CONCLUSIONS

Anthropometric indices could significantly add to the predictive ability of the iron statues, with highest IDI when WC and WHtR were added to the base model. It suggests that by adding WC and WHtR to the iron status lead us to a more optimal model for predicting the ini¬tial stage of atherosclerosis.

Iron intake and associated factors in general Japanese population: NIPPON DATA80, NIPPON DATA90 and national nutrition monitoring

OBJECTIVE

The purpose of this study was to investigate the dietary iron intake and associated other dietary factors and clinical characteristics among a representative sample cohort of Japanese population.

METHODS

We obtained data from NIPPON DATA80 and 90 that were conducted with the National Nutrition Surveys in 1980 and in 1990. Then we estimated nutrient and food intakes of individuals in the National Nutrition Survey of 1980 and that of 1990, which were adjusted on the basis of data of the National Nutrition Survey of 1995. Finally, we analyzed data for the 10,422 participants (4585 men and 5837 women) in NIPPON DATA80 and 8342 participants (3488 men and 4854 women) in NIPPON DATA90 having dietary iron intake information.

RESULTS

In NIPPON DATA80 and 90, there was a significant relationship between the dietary iron intake and age for both men and women. Dietary protein intake was associated with iron intake where as dietary fat intake did not show any association. Regarding the minerals, significant relationships were observed between the different minerals and dietary iron intake. Apart from the food group of milk and dairy products, there were significant differences in other food groups according to quintiles of iron intakes for men and women.

CONCLUSIONS

We described the mean dietary iron intake and its relation with other dietary factors and clinical characteristics in Japanese adults as the baseline data in NIPPON DATA80 and in NIPPON DATA90.

Association of oxidative stress, iron, and centralized fat mass in healthy postmenopausal women

OBJECTIVE

Centralized adiposity, insulin resistance, excess iron, and elevated oxidative stress place postmenopausal women at risk for atherosclerotic cardiovascular disease (CVD). The objective of this study was to determine the relationship among excess iron, oxidative stress, and centralized fat mass in healthy postmenopausal women.

METHODS

The parent project recruited healthy women for a randomized, double-blind, clinical trial designed to examine the effect of soy isoflavones on bone. At baseline (n = 122), we measured three antioxidant enzymes, iron status indices (serum ferritin among others), oxidative stress indices (oxidized low-density lipoprotein [oxLDL], urinary isoprostanes [PGF(2alpha)], protein carbonyls, DNA damage), and waist, hip, and thigh fat mass using dual-energy x-ray absorptiometry (DXA). We calculated insulin resistance using the homeostasis model assessment (HOMA). Multiple regression analysis was used to determine the CVD risk factors that contributed to oxidative stress and centralized fat mass (waist + hip/thigh = AndGynFM ratio).

RESULTS

Almost 14% (p < 0.0005) of the variability in oxLDL was accounted for by AndGynFM ratio (6.1%, p < 0.0005), age (4.0%, p = 0.012), and serum iron (2.8%, p = 0.053). Similarly, 16% (p < 0.0001) of the variability in PGF(2alpha) was accounted for by the AndGynFM ratio (4.8%, p = 0.011), HOMA (3.9%, p = 0.021), and serum iron (2.7%, p = 0.054). We accounted for 33% (p

CONCLUSIONS

Our study suggests that reducing centralized fat mass and maintaining a favorable lipid profile, antioxidant status, and iron status all may be important in protecting postmenopausal women from atherosclerotic CVD.

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Key Words Collapse

MESH Headings

• Aged
• Biomarkers/blood
• Body Fat Distribution/adverse effects
• Body Mass Index
• Bone Density/drug effects
• Bone and Bones/drug effects
• Coronary Artery Disease/blood
• Coronary Artery Disease/etiology
• Coronary Artery Disease/prevention & control
• Double-Blind Method
• Female
• Ferritins/blood
• Folic Acid/blood
• Humans
• Iron/metabolism
• Middle Aged
• Oxidative Stress/drug effects
• Postmenopause/blood
• Reference Values
• Soybean Proteins/administration & dosage
• Soybean Proteins/pharmacology
• Waist-Hip Ratio

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Grants

• R01 AR046922-01A2 NIAMS NIH HHS
• R01 AR046922 A2 NIAMS NIH HHS
• P01 ES012020 NIEHS NIH HHS
• 95P50AT004155 NCCIH NIH HHS

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Affiliation(s)

Betsy L. Crist Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa
D. Lee Alekel Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa Nutrition and Wellness Research Center, Iowa State University, Ames, Iowa
Laura M. Ritland Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa
Laura N. Hanson Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa
Ulrike Genschel Department of Statistics, Iowa State University, Ames, Iowa
Manju B. Reddy Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa

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Daily Supplementation with Iron Increases Lipid Peroxidation in Young Women with Low Iron Stores

The aim of this study was to determine whether women with low iron stores (plasma ferritin ≤ 20 μg/L) receiving a daily iron supplement for 8 wks at a level commonly used to treat poor iron status develop increased lipid peroxidation as measured by ethane exhalation rates and plasma malondialdehyde. The women served as their own control as pre- and post-supplementation periods were compared. Twelve women participated in the study for a 70-day period and consumed daily iron supplements (98 mg of iron as ferrous sulfate) from day 14 to day 70. Baseline blood and expired air samples were obtained on days 1 and 14; measurements during supplementation were performed on days 56 and 70, that is at 6 and 8 weeks of supplementation. Iron status improved during the iron supplementation period; biochemical indicators of lipid peroxidation also increased. After 6 wks of iron supplementation, serum ferritin almost doubled and body iron more than doubled. Hemoglobin levels increased slightly and other indicators of iron status became normal. However, plasma malondialdehyde (MDA) and breath ethane exhalation rates (BEER) increased by more than 40% between baseline and 6 wks of supplementation; these increases correlated significantly with plasma iron and ferritin levels. MDA was positively correlated with BEER. BEER increased further after 8 wks of iron supplementation. The increased indicators of lipid peroxidation with duration of supplementation and as iron status improved suggest that providing daily nearly 100 mg iron may not be a totally innocuous regimen for correcting iron depletion in women.

A very-low-fat vegan diet increases intake of protective dietary factors and decreases intake of pathogenic dietary factors

There is increasing evidence that dietary factors in plant-based diets are important in the prevention of chronic disease. This study examined protective (eg, antioxidant vitamins, carotenoids, and fiber) and pathogenic (eg, saturated fatty acids and cholesterol) dietary factors in a very-low-fat vegan diet. Ninety-three early-stage prostate cancer patients participated in a randomized controlled trial and were assigned to a very-low-fat (10% fat) vegan diet supplemented with soy protein and lifestyle changes or to usual care. Three-day food records were collected at baseline (n=42 intervention, n=43 control) and after 1 year (n=37 in each group). Analyses of changes in dietary intake of macronutrients, vitamins, minerals, carotenoids, and isoflavones from baseline to 1 year showed significantly increased intake of most protective dietary factors (eg, fiber increased from a mean of 31 to 59 g/day, lycopene increased from 8,693 to 34,464 mug/day) and significantly decreased intake of most pathogenic dietary factors (eg, saturated fatty acids decreased from 20 to 5 g/day, cholesterol decreased from 200 to 10 mg/day) in the intervention group compared to controls. These results suggest that a very-low-fat vegan diet can be useful in increasing intake of protective nutrients and phytochemicals and minimizing intake of dietary factors implicated in several chronic diseases.

Non-transferrin-bound iron is associated with plasma level of soluble intercellular adhesion molecule-1 but not with in vivo low-density lipoprotein oxidation

BACKGROUND

Excess body iron is associated with increased cardiovascular disease risk, possibly via non-transferrin-bound iron (NTBI)-mediated enhancement of inflammation and oxidation of low-density lipoprotein (LDL).

METHODS

We assessed this proposed atherosclerotic mechanism of body iron by determining the relationship of levels of serum iron parameters, including NTBI, with plasma markers of inflammation and LDL oxidation in 232 subjects who visited the outpatient clinic for hemochromatosis family screening.

RESULTS

Plasma level of soluble intercellular adhesion molecule-1 (sICAM-1) was positively related to ferritin (standardized beta coefficient 0.16) and to NTBI (0.185) and negatively to total iron-binding capacity (TIBC, -0.166). Significant higher levels of sICAM-1 were found for subjects in the highest quartile of NTBI compared to the lowest quartile of NTBI (122 microg/L (107-141) and 106 microg/L (89-125), median (interquartile range), p<0.001). Odds ratio of subjects having sICAM-1 level above 134 microg/L (75th percentile) in the highest and lowest quartile of NTBI amounted 2.3. White blood cell count was positively related to ferritin (0.149). High-sensitivity C-reactive protein, interleukin-6, interleukin-8, oxidized LDL, oxidized LDL/apolipoprotein B and IgG and IgM antibodies to oxidized LDL were not related to any of the markers of iron status.

CONCLUSION

Excess body iron, reflected by elevated serum ferritin and NTBI and decreased TIBC, is associated with increased plasma level of sICAM-1 but not with markers of in vivo LDL oxidation.

Serum non-transferrin-bound iron and low-density lipoprotein oxidation in heterozygous hemochromatosis

Non-transferrin-bound iron (NTBI) is implicated in lipid peroxidation but the relation with oxidative modification of low-density lipoprotein (LDL) is not known. We assessed variables reflecting in vitro and in vivo LDL oxidation in two age- and sex-matched groups (n=23) of hereditary hemochromatosis heterozygotes (C282Y), characterized by a clear difference in mean serum NTBI (1.55+/-0.57 micromol/L vs 3.70+/-0.96 micromol/L). Plasma level of oxidized LDL (absolute and relative to plasma apolipoprotein B), and IgG and IgM antibodies to oxidized LDL, markers of in vivo LDL oxidation, did not differ between the groups with low and high serum NTBI. Mean lag-phase of in vitro LDL oxidation was also not significantly different between both study groups.

CONCLUSION

these findings do not support the hypothesis that NTBI promotes oxidative modification of plasma LDL.

Non–Transferrin-Bound Iron and Risk of Coronary Heart Disease in Postmenopausal Women

Background— Epidemiological studies aimed at correlating coronary heart disease (CHD) with serum ferritin levels have thus far yielded inconsistent results. We hypothesized that a labile iron component associated with non–transferrin-bound iron (NTBI) that appears in individuals with overt or cryptic iron overload might be more suitable for establishing correlations with CHD.

Methods and Results— We investigated the relation of NTBI, serum iron, transferrin saturation, and serum ferritin with risk of CHD and acute myocardial infarction (AMI). The cohort used comprised a population-based sample of 11 471 postmenopausal women aged 49 to 70 years at enrollment in 1993 to 1997. During a median follow-up of 4.3 years (quartile limits Q1 to Q3: 3.3 to 5.4), 185 CHD events were identified, including 66 AMI events. We conducted a case-cohort study using all CHD cases and a random sample from the baseline cohort (n=1134). A weighted Cox proportional hazards model was used to estimate hazard ratios for tertiles of iron variables in relation to CHD and AMI. Adjusted hazard ratios of women in the highest NTBI tertile (range 0.38 to 3.51) compared with the lowest (range −2.06 to −0.32) were 0.84 (95% confidence interval 0.61 to 1.16) for CHD and 0.47 (95% confidence interval 0.31 to 0.71) for AMI. The results were similar for serum iron, transferrin saturation, and serum ferritin.

Conclusions— Our results show no excess risk of CHD or AMI within the highest NTBI tertile compared with the lowest but rather seem to demonstrate a decreased risk. Additional studies are warranted to confirm our findings.

Role of dietary iron restriction in a mouse model of Parkinson's disease

There is a growing body of evidence suggesting that iron chelation may be a useful therapy in the treatment of Parkinson's Disease (PD). Experiments were designed to test the impact of dietary iron availability on the pathogenic process and functional outcome in a mouse model of PD. Mice were fed diets containing low (4 ppm) or adequate (48 ppm) amounts of iron for 6 weeks before the administration of MPTP, a mitochondrial toxin that damages nigrostriatal dopaminergic neurons and induces Parkinson-like symptoms. Low dietary iron increased serum total iron binding capacity (P < 0.001). Consistent with neuronal protection, iron restriction increased sphingomyelin C16:0 and decreased ceramide C16:0. However, there was a 35% decrease in striatal dopamine (DA) in iron-restricted mice. Motor behavior was also impaired in these animals. In vitro studies suggested that severe iron restriction could lead to p53-mediated neuronal apoptosis. Administration of MPTP reduced striatal DA (P < 0.01) and impaired motor behavior in iron-adequate mice. However, in iron-restricted mice, striatal dopamine levels and motor behavior were unchanged compared to saline-treated mice. Thus, while reduced iron may provide protection against PD-inducing insults such as MPTP, the role of iron in the synthesis of DA and neuronal survival should be considered, particularly in the development of iron-chelating agents to be used chronically in the clinical setting.

Iron, oxidative stress, and disease risk

Based on epidemiologic evidence citing excess iron as a risk factor for many diseases, and oxidative stress as an underlying cause for those diseases, iron-induced oxidative stress has recently gained attention. Although iron can participate in oxidative reactions to generate free radicals under in vitro conditions, its involvement in vivo in the cause or progression of diseases is questionable.

Is blood donation induced low iron status associated with favourable levels of OxLDL, s-ICAM-1, sVCAM-1 and vWF-antigen in healthy men

The potential effect of iron depletion by blood donation and its relevance to cardiovascular diseases are still under debate. Markers of vascular integrity are increasingly applied in investigations of atherothrombotic diseases. In this study, we investigated whether a lower iron status through blood donation was associated with markers of vascular integrity (circulating oxidised LDL, sICAM-1, sVCAM-1 and vWF-antigen) by comparing healthy male voluntary donors to non-donors, taking into account differences in baseline characteristics. Two fasting blood samples were collected within 1 week from 41 donors and 39 non-donors. The iron status was estimated by measuring the concentration of plasma iron, ferritin, haemoglobin and hematocrit. The markers of iron status were all significantly lower in donors compared to non-donors, especially for ferritin concentrations. However, the lower iron status by blood donation was not reflected in the concentrations of OxLDL, sICAM-1, sVCAM-1 and vWF-antigen in men after adjustment for BMI and ratio total/HDL cholesterol. In order to avoid possible selection-bias related to donorship, we have additionally investigated the difference in marker concentrations within the non-donors, comparing low- and high-ferritin concentrations. This analysis suggests that ferritin concentration is not associated with in vivo LDL oxidation.

Iron supplementation does not affect the susceptibility of LDL to oxidative modification in women with low iron status

Elevated iron stores may or may not promote atherogenesis by increasing free radical formation and oxidative stress, but controlled diet and supplement trials are lacking. We tested the hypothesis that iron supplementation does not increase the susceptibility of LDL to undergo oxidative modification in women with low iron status. A randomized, double-blind, 2-period crossover study design (n=26) was used to examine the effects of the following diets on measures of LDL oxidation: average American diet (AAD) [36% of energy as fat; 15% saturated fatty acids (SFA)], and a Step 2 diet (26% fat; 7% SFA). In addition, subjects received either a supplement containing 160 mg of ferrous sulfate (50 mg elemental iron) or a placebo twice daily [supplement group received a total of 320 mg ferrous sulfate (100 mg elemental iron) daily]. After supplementation, serum ferritin differed between the supplement and placebo groups (P=0.008). Measures of LDL oxidation were not affected by supplement intake; however, they were affected by diet. Lag time was shorter after the women consumed the AAD diet than after the Step 2 diet (P<0.0001). The diets did not affect the rate of oxidation or total dienes. Although iron status was improved by aggressive iron supplementation, LDL oxidative susceptibility was not affected. As expected, lag time was increased after the women consumed the low fat, low SFA diet. Therefore, the results of this study do not support a relationship between iron status and LDL oxidation.