Diet and genetic factors associated with iron status in middle-aged women

Decreased serum hepcidin concentration correlates with brain iron deposition in patients with HBV-related cirrhosis

Purpose

Excessive brain iron accumulation contributes to cognitive impairments in hepatitis B virus (HBV)-related cirrhotic patients. The underlying mechanism remains unclear. Hepcidin, a liver-produced, 25-aminoacid peptide, is the major regulator of systemic iron metabolism. Abnormal hepcidin level is a key factor in some body iron accumulation or deficiency disorders, especially in those associated with liver diseases. Our study was aimed to explore the relationship between brain iron content in patients with HBV-related cirrhosis and serum hepcidin level.

Methods

Seventy HBV-related cirrhotic patients and forty age- sex-matched healthy controls were enrolled. Brain iron content was quantified by susceptibility weighted phase imaging technique. Serum hepcidin as well as serum iron, serum transferrin, ferritin, soluble transferrin receptor, total iron binding capacity, and transferrin saturation were tested in thirty cirrhotic patients and nineteen healthy controls. Pearson correlation analysis was performed to investigate correlation between brain iron concentrations and serum hepcidin, or other iron parameters.

Results

Cirrhotic patients had increased brain iron accumulation compared to controls in the left red nuclear, the bilateral substantia nigra, the bilateral thalamus, the right caudate, and the right putamen. Cirrhotic patients had significantly decreased serum hepcidin concentration, as well as lower serum transferring level, lower total iron binding capacity and higher transferrin saturation, compared to controls. Serum hepcidin level negatively correlated with the iron content in the right caudate, while serum ferritin level positively correlated with the iron content in the bilateral putamen in cirrhotic patients.

Conclusions

Decreased serum hepcidin level correlated with excessive iron accumulation in the basal ganglia in HBV-related cirrhotic patients. Our results indicated that systemic iron overload underlined regional brain iron repletion. Serum hepcidin may be a clinical biomarker for brain iron deposition in cirrhotic patients, which may have therapeutic potential.

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.

Does hemochromatosis predispose to celiac disease? A study of 29,096 celiac disease patients

BACKGROUND AND AIM

Case reports suggest an association between hereditary hemochromatosis (HH) and celiac disease (CD), but estimates of association are lacking. We estimated the association between HH and CD in a population-based study.

MATERIAL AND METHODS

Case-control study. We identified 29,096 individuals with biopsy-verified CD (equal to villous atrophy, Marsh stage III) through biopsy reports from all 28 pathology departments in Sweden. We then investigated the risk of a clinical diagnosis of HH in CD and in 144,522 controls matched for age, sex, county and calendar year. Conditional logistic regression was used to calculate odds ratios (ORs) for CD in patients with HH.

RESULTS

HH was seen in 30 patients with CD and in 60 matched controls. HH was hence associated with an increased risk of CD (OR = 2.30; 95% CI = 1.53-3.45). Restricting HH to individuals with at least two records of HH, the OR for CD was 2.54 (95% CI = 1.57-4.11), with a similar risk estimate when we only looked at HH diagnosed before CD (and matched date in controls) (OR = 2.64; 95% CI = 1.24-5.60).

CONCLUSION

HH seems to be associated with an increased risk of CD.

Iron in relation to gastric cancer in the Alpha-tocopherol, Beta-carotene Cancer Prevention Study

BACKGROUND

Iron is an essential micronutrient that can have carcinogenic effects when at high or low concentrations. Previous studies of iron in relation to gastric cancer have not assessed subtype-specific relationships. We used the prospective Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study to assess whether iron metrics were associated with gastric cardia cancer (GCC) and gastric noncardia cancer (GNCC).

METHODS

We selected 341 incident gastric cancer cases (86 cardia, 172 noncardia, and 83 nonspecified), accrued during 22 years of follow-up, and 341 individually matched controls. We measured prediagnostic serum iron, ferritin, unsaturated iron binding capacity, and C-reactive protein. Total iron-binding capacity (TIBC) and transferrin saturation were estimated from these metrics. Dietary iron exposures were estimated from a food frequency questionnaire. Multivariable logistic regression was used for analysis.

RESULTS

Serum iron metrics were not associated with GCC, except for a potential "n"-shaped relationship with TIBC (global P = 0.038). GNCC was inversely associated with serum ferritin (global P = 0.024), serum iron (global P = 0.060) and, possibly, transferrin saturation. TIBC appeared to share a "u"-shaped relationship with GNCC (global P = 0.033). Dietary iron exposures were not associated with either subsite. Adjustment for Helicobacter pylori and gastric atrophy had little effect on observed associations.

CONCLUSIONS

We found little evidence for the involvement of iron exposure in the pathogenesis of GCC. GNCC was associated with an iron profile similar to that of iron deficiency.

IMPACT

Our findings indicate that inverse associations between iron metrics and gastric cancer are driven by associations with GNCC. Further elucidation of potential mechanisms is warranted.

Exploring the relationship between maternal iron status and offspring's blood pressure and adiposity: a Mendelian randomization study

Background

Iron deficiency is the most common micronutrient deficiency worldwide. Experimental animal studies suggest that mothers deficient in iron during pregnancy are more likely to have offspring who become obese with high blood pressure. C282Y mutation carriers are more likely to have higher iron stores.

Methods

We undertook an instrumental variable (IV) analysis, using maternal C282Y as an indicator for the mother’s iron status, to examine its association with offspring blood pressure (BP), waist circumference (WC), and body mass index (BMI), and compared the results to that of ordinary least squares (OLS) regression. Offspring of a sub-cohort of mothers from the UK Women’s Cohort Study (UKWCS) were recruited in 2009–2010 (n = 348, mean age = 41 years). Their blood pressure, height, and weight were measured at their local general medical practice, and they were asked to self-measure their waist circumference. About half were offspring of C282Y carriers. Maternal ferritin was used as a biomarker of maternal iron status.

Results

Maternal C282Y was strongly associated with maternal ferritin (mean difference per allele = 84 g/L, 95% confidence interval: 31–137, P = 0.002). Using IV analyses, maternal ferritin was not linked to offspring’s BP, BMI, or WC. The first stage F-statistic for the strength of the instrument was 10 (Kleibergen–Paap rk LM P = 0.009). Maternal ferritin was linked to offspring diastolic BP, WC, and BMI in univariable, but not in multivariable OLS analysis. There was no difference between the OLS and the IV models coefficients for any of the outcomes considered.

Conclusion

We found no association between maternal iron status and adult offspring’s BP and adiposity using both multivariable OLS and IV modeling. To our knowledge, this is the first study examining this relationship. Further exploration in larger studies that have genetic variation assessed in both mother and offspring should be considered.

Hepatic iron deposition does not predict extrahepatic iron loading in mouse models of hereditary hemochromatosis

Hereditary hemochromatosis is characterized by tissue iron loading and associated organ damage. However, the phenotype can be highly variable. The relationship between iron loading of different organs and the temporal nature of its deposition is still not well understood. We examined the progression of tissue iron loading in three mouse models to advance our understanding of the natural history of iron deposition in hereditary hemochromatosis. Wild-type, Hfe(-/-), Tfr2(-/-), and Hfe(-/-)/Tfr2(-/-) mice were analyzed at 3, 5, 10, 26, and 52 weeks, respectively. Hepatic, splenic, cardiac, and pancreatic iron concentrations were determined. Expression of both iron-regulatory and fibrosis genes was determined by quantitative real-time PCR in livers and hearts of 52-week-old mice. In all models, hepatic iron increased rapidly, plateauing before 10 weeks at different levels, depending on the genotype. Iron deposition in the pancreas and heart occurred after maximal iron loading of the liver was reached and was most marked in the Hfe(-/-)/Tfr2(-/-) mice. Although a significant positive correlation was identified between pancreatic and cardiac iron in all models at 52 weeks, there was no correlation between hepatic and either pancreatic or cardiac iron. There is variability in the timing and extent of tissue iron loading within a genotype, suggesting that hepatic iron levels in hereditary hemochromatosis may not accurately predict the iron content of other organs.

Dietary iron intake and serum ferritin concentration in 213 patients homozygous for the HFEC282Y hemochromatosis mutation

BACKGROUND

HFEC282Y homozygotes have an increased risk for developing increased iron stores and related disorders. It is controversial whether dietary iron restrictions should be recommended to such individuals.

OBJECTIVE

To determine whether dietary iron content influences iron stores in HFEC282Y homozygotes as assessed by serum ferritin concentration.

DESIGN

Serum ferritin concentration was measured and a dietary iron questionnaire was completed as part of the evaluation of 213 HFEC282Y homozygotes who were identified through screening of >100,000 primary care patients at five HEmochromatosis and IRon Overload Screening (HEIRS) Study Field Centers in the United States and Canada.

RESULTS

No significant relationships between serum ferritin concentration and dietary heme iron content, dietary nonheme iron content or reports of supplemental iron use were found.

CONCLUSION

These results do not support recommending dietary heme or nonheme iron restrictions for HFEC282Y homozygotes diagnosed through screening in North America.

The neglected significance of "antioxidative stress"

Oxidative stress arises when there is a marked imbalance between the production and removal of reactive oxygen species (ROS) in favor of the prooxidant balance, leading to potential oxidative damage. ROSs were considered traditionally to be only a toxic byproduct of aerobic metabolism. However, recently, it has become apparent that ROS might control many different physiological processes such as induction of stress response, pathogen defense, and systemic signaling. Thus, the imbalance of the increased antioxidant potential, the so-called antioxidative stress, should be as dangerous as well. Here, we synthesize increasing evidence on “antioxidative stress-induced” beneficial versus harmful roles on health, disease, and aging processes. Oxidative stress is not necessarily an un-wanted situation, since its consequences may be beneficial for many physiological reactions in cells. On the other hand, there are potentially harmful effects of “antioxidative stress,” especially in the cases of overconsumption of synthetic antioxidants. Antioxidants can neutralize ROS and decrease oxidative stress; however, this is not always beneficial in regard to disease formation or progression (of, e.g., cancer) or for delaying aging.

Review article: the iron overload syndromes

BACKGROUND

Iron overload syndromes encompass a wide range of hereditary and acquired conditions. Major developments in the field of genetics and the discovery of hepcidin as a central regulator of iron homeostasis have greatly increased our understanding of the pathophysiology of iron overload syndromes.

AIM

To review advances in iron regulation and iron overload syndrome with special emphasis on hereditary haemochromatosis, the prototype iron overload syndrome.

METHODS

A PubMed search using words such as 'iron overload', 'hemochromatosis', 'HFE', 'Non-HFE', 'secondary iron overload' was undertaken.

RESULTS

Iron overload is associated with significant morbidity and mortality. Sensitive diagnostic tests and effective therapy are widely available and can prevent complications associated with iron accumulation in end- organs. Therapeutic phlebotomy remains the cornerstone of therapy for removal of excess body iron, but novel therapeutic agents including oral iron chelators have been developed for iron overload associated with anaemia.

CONCLUSIONS

Iron overload disorders are common. Inexpensive screening tests as well as confirmatory diagnostic tests are widely available. Increased awareness of the causes and importance of early diagnosis and knowledge of the appropriate use of genetic testing are encouraged. The availability of novel treatments should increase therapeutic options for patients with iron overload disorders.

A comparison of levels of select minerals in scalp hair samples with estimated dietary intakes of these minerals in women of reproductive age

The objective of this study was to evaluate daily intake of minerals and concentrations of minerals in hair in women of reproductive age. The study included 77 menstruating women, aged 35.9 ± 9.7 years. Subjects were divided into three groups according to age. All women were healthy. Hair samples were taken from several points of the occipital scalp. The content of minerals in hair samples was determined by flame atomic absorption spectrometry. Dietary intake of the analysed minerals was assayed on the basis of dietary intake interviews from three preceding days and evaluated using the dietetic computer programme. It was shown that calcium and iron daily intake by the women was below the recommended value. Only few women had low concentrations (below reference values) of magnesium, copper and zinc in hair. Statistically significant differences were shown between age groups. Generally, the concentrations of minerals in hair in the younger (19-30 years) and the older women (41-50 years) were higher than in hair of middle-aged women (31-40 years). The content of calcium, magnesium, iron and zinc in daily diets of women correlated inversely with copper level in their hair. Food products with good bioavailability of iron and calcium should be recommended for women of childbearing age in all age groups.

Gestational diabetes mellitus in relation to maternal dietary heme iron and nonheme iron intake

OBJECTIVE

Higher heme iron intake is associated with increased type 2 diabetes risk. However, no previous study has evaluated gestational diabetes mellitus (GDM) risk in relation to heme iron intake during pregnancy. We investigated associations of maternal preconceptional and early pregnancy heme and nonheme iron intake with subsequent GDM risk.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study of 3,158 pregnant women. A food frequency questionnaire was used to assess maternal diet. Multivariable generalized linear regression models were used to derive estimates of relative risks (RRs) and 95% CIs.

RESULTS

Approximately 5.0% of the cohort developed GDM (n=158). Heme iron intake was positively and significantly associated with GDM risk (Ptrend=0.04). After adjusting for confounders, women reporting the highest heme iron intake levels (≥1.52 vs. <0.48 mg per day) experienced a 3.31-fold-increased GDM risk (95% CI 1.02-10.72). In fully adjusted models, we noted that a 1-mg per day increase in heme iron was associated with a 51% increased GDM risk (RR 1.51 [95% CI 0.99-2.36]). Nonheme iron was inversely, though not statistically significantly, associated with GDM risk, and the corresponding RRs were 1.00, 0.83, 0.62, and 0.61 across quartiles of nonheme iron intake (Ptrend=0.08).

CONCLUSIONS

High levels of dietary heme iron intake during the preconceptional and early pregnancy period may be associated with increased GDM risk. Associations of GDM risk with dietary nonheme iron intake are less clear. Confirmation of these findings by future studies is warranted.

How I treat hemochromatosis

Hemochromatosis is a common genetic disorder in which iron may progressively accumulate in the liver, heart, and other organs. The primary goal of therapy is iron depletion to normalize body iron stores and to prevent or decrease organ dysfunction. The primary therapy to normalize iron stores is phlebotomy. In this opinion article, we discuss the indications for and monitoring of phlebotomy therapy to achieve iron depletion, maintenance therapy, dietary and pharmacologic maneuvers that could reduce iron absorption, and the role of voluntary blood donation.

Dietary iron intake and risk of endometrial cancer: a population-based case-control study in Shanghai, China

Dietary red meat and animal fat have been linked to endometrial cancer (EC) risk, but the impact of bioavailable iron in animal-derived foods has been less well studied. Our objective was to investigate the effects of iron and fats on the risk of EC in a large, population-based, case-control study. The Shanghai Endometrial Cancer Study enrolled 1,204 EC cases and 1,212 controls who completed in-person interviews, including a food frequency questionnaire. Animal-derived iron and fat intakes were calculated from dietary intakes and food composition tables. Logistic regression models were used to evaluate independent and joint effects of iron and fat on EC risk. Animal-derived iron intake was positively associated with EC risk [adjusted OR = 1.9; 95% CI = 1.4-2.7, P(trend) < 0.01, highest vs. lowest quartile], predominantly after menopause (OR = 2.2; 95%CI = 1.4-3.4, P(trend) < 0.01) and in women with BMI >or= 25 kg/m(2)(OR = 3.2; 95% CI = 1.4-7.5 in postmenopausal obese women, P(trend) < 0.01). Animal-derived fat was also associated with postmenopausal EC risk (OR = 1.7; 95% CI = 1.2-2.5, P(trend) < 0.01). Multiplicative interactions between animal-derived iron and BMI or animal-derived fat intake were not observed. Animal-derived iron intake is associated with increased risk of EC after menopause and among obese women. Avoidance of animal-derived (heme) iron may reduce the risk of EC in these women.

High-protein diet promotes a moderate postpartum weight loss in a prospective cohort of Brazilian women

OBJECTIVE

Whether a high-protein (HP) diet promotes body weight loss (BWL) when compared with a low-protein (LP) diet is still unclear. Therefore, we evaluated the effects of an HP diet on BWL during postpartum.

METHODS

A food-frequency questionnaire with 81 items was applied at 6 mo after delivery to evaluate the diet of 430 postpartum women aged 18-45 y. Body weight was measured approximately at 0.5, 2, 6, and 9 mo after delivery. Body weight loss was modeled by comparing an HP diet (> or =1.2g . kg(-1) . d(-1)) with an LP diet (<1.2g . kg(-1) . d(-1)) using mixed-effects linear regression models adjusted for energy intake, percentage of body fat at baseline, stature, age, race, smoking, and schooling.

RESULTS

Usual energy intake was higher in the HP than in the LP diet group (2623 versus 1791kcal, P<0.0001). Daily mean protein intakes were 1.54+/-0.32g . kg(-1) . d(-1) for the HP group and 0.83+/-0.20g . kg(-1) . d(-1) for the LP group. A multivariate model showed that women in the HP group lost 316+/-0.062g of body weight more per month (P<0.01) when compared with the LP group.

CONCLUSION

A reported higher protein intake may improve moderate postpartum body weight loss. Further studies should evaluate the long-term consequences of an HP diet postpartum.

Phenotypic expression of hereditary hemochromatosis: what have we learned from the population studies?

Profound advances in our knowledge of hereditary hemochromatosis (HH) during the past 150 years have resulted in two distinct "iron ages": the pre-HFE gene era and the post-HFE gene era. During these periods, family studies, HLA association studies, and ultimately HFE gene studies in various populations informed us of the genotypic prevalence as well as the clinical and biochemical penetrance of HH. We learned that HH has a highly variable clinical penetrance in susceptible individuals of Northern European ancestry. Further, we now recognize that the natural history of HH is not as discrete as previously believed, because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical expression of HH.

Effects of C282Y, H63D, and S65C HFE gene mutations, diet, and life-style factors on iron status in a general Mediterranean population from Tarragona, Spain

Mutations in the HFE gene result in iron overload and can produce hereditary hemochromatosis (HH), a disorder of iron metabolism characterized by increased intestinal iron absorption. Dietary quality, alcoholism and other life-style factors can increase the risk of iron overload, especially among genetically at risk populations. Polymorphisms of the HFE gene (C282Y, H63D and S65C) were measured together with serum ferritin (SF), transferrin saturation (TS) and hemoglobin, to measure iron status, in randomly-selected healthy subjects living in the Spanish Mediterranean coast (n = 815; 425 females, 390 males), 18 to 75 years of age. The intake of dietary components that affect iron absorption was calculated from 3-day dietary records. The presence of C282Y/H63D compound heterozygote that had a prevalence of 2.8% in males and 1.2% in females was associated with an elevated TS and SF. No subject was homozygous for C282Y or S65C. The C282Y heterozygote, H63D heterozygote and homozygote and H63D/S65C compound heterozygote genotypes were associated with increased TS relative to the wild type in the general population. These genotypes together with the alcohol and iron intake increase the indicators of iron status, while calcium intake decreases them. We did not observe any affect of the S65C heterozygote genotype on these levels. All the HFE genotypes except for the S65C heterozygote together with the alcohol, iron and calcium intake affect the indicators of iron status. The C282Y/H63D compound heterozygote genotype has the higher phenotypic expression in our Spanish Mediterranean population.

Low total and nonheme iron intakes are associated with a greater risk of hypertension

The relationship between iron intake and blood pressure (BP) status has not been well established. Only 1 cross-sectional study has suggested an inverse association of dietary total iron intake and nonheme iron intake with BP. We investigated the relationship between total, heme, and nonheme iron intakes, markers of iron status, 5.4-y changes in BP, and the incidence of hypertension. A total of 2895 participants included in the Supplémentation en Vitamines et Minéraux Antioxydants cohort were followed up for 5.4 y. At least 3 repeated 24-h dietary records were performed at baseline and 5.4 y later. Hemoglobin and serum ferritin concentrations were assessed at baseline. Low nonheme iron intake at baseline was associated with a greater increase in systolic BP (SBP) and pulse pressure over time after adjustment for multiple possible confounding factors (P-trend = 0.002 and 0.0005, respectively). Conversely, participants in the 3rd tertile of nonheme iron intake at baseline had a 37% lower risk of hypertension after 5.4 y of follow-up compared with those in the first tertile (P-trend = 0.04). Heme iron intake was not associated with BP changes or risk of hypertension. Meat intake was positively associated with an increase in SBP (P-trend = 0.04). However, that relation became nonsignificant after adjusting for dietary pattern scores. Baseline hemoglobin and ferritin concentrations were not associated with changes in BP or incidental hypertension. Our data support a possible role of low nonheme iron intake, independent of heme iron intake, in the development of hypertension.

Determinants of ferritin and soluble transferrin receptors as iron status parameters in young adult women

Objective

To investigate associations between nutritional and non-nutritional variables and Fe status parameters, i.e. serum ferritin and soluble transferrin receptors (sTfR).

Design

Cross-sectional design. Fe status parameters were determined on a fasting venous blood sample. Nutritional variables were assessed using a 2 d food record and non-nutritional variables by a general questionnaire. A general linear model was used to investigate associations between the variables and Fe status parameters.

Setting

Region of Ghent, Dutch-speaking part of Belgium.

Subjects

Random sample of 788 women (aged 18–39 years).

Results

Median (interquartile range) ferritin and sTfR were 26·3 (15·9, 48·9) ng/ml and 1·11 (0·95, 1·30) mg/l, respectively. BMI and alcohol intake were positively associated and tea intake was negatively associated with serum ferritin. Women who used a non-hormonal intra-uterine device, who gave blood within the past year or who had been pregnant within the past year had lower serum ferritin values than their counterparts. Significant determinants of sTfR were smoking habit and pregnancy, with higher values for non-smokers and women who had been pregnant within the past year.

Conclusions

The present study indicates that contraceptive use, time since last blood donation, time since last pregnancy, BMI, alcohol and tea intake are determinants of Fe stores, whereas smoking habit and time since last pregnancy are determinants of tissue Fe needs. When developing strategies to improve Fe status, special attention should be given to women who use a non-hormonal intra-uterine device, gave blood within the past year and had been pregnant within the past year.

Iron intake does not significantly correlate with iron deficiency among young Japanese women: a cross-sectional study

Objectives

We evaluated the association of nutrient intake with Fe deficiency with regard to lifestyle factors and health condition in young Japanese women. Uniquely among developed countries, dietary habits render Japanese populations vulnerable to Fe deficiency, owing to their relatively low intake of Fe and high intake of Fe absorption inhibitors, such as green tea and soyabeans.

Design

A cross-sectional study.

Setting and subjects

The subjects were 1019 female Japanese dietetic students aged 18–25 years. Dietary habits during the preceding month were assessed using a previously validated, self-administered, diet history questionnaire. Blood analysis was performed to assess body Fe status. Subjects were categorized with Fe deficiency when their serum ferritin levels were <12 ng/ml. Twenty-nine dietary variables, i.e. intakes of energy, sixteen nutrients including Fe and twelve food groups, were analysed using multivariate logistic regression models adjusted for possible confounders.

Results

Of the subjects, 24·5 % were categorized with Fe deficiency. However, no dietary factors assessed were significantly associated with Fe deficiency. The risk of Fe deficiency was significantly lower in women with infrequent or no menstrual cycles than in those with regular cycles (OR = 0·58; 95 % CI 0·34, 1·00) and significantly higher in women with heavy menstrual flow than in women with average flow, albeit that these were self-reported (OR = 1·83; 95 % CI 1·35, 2·48).

Conclusions

These results suggest that dietary habits, including Fe intake, do not significantly correlate with Fe deficiency among young Japanese women.

The global burden of iron overload

There have been major developments in the field of iron metabolism in the past decade following the identification of the HFE gene and the mutation responsible for the C282Y substitution in the HFE protein. While HFE-associated hemochromatosis occurs predominantly in people of northern European extraction, other less-common mutations can lead to the same clinical syndrome and these may occur in other populations in the Asian-Pacific region. The most common of these is the mutation that leads to changes in the ferroportin molecule, the protein responsible for the transport of iron across the basolateral membrane of the enterocyte and from macrophages. Recent research has unraveled the molecular processes of iron transport and regulation of how these are disturbed in hemochromatosis and other iron-loading disorders. At the same time, at least one new oral iron chelating agent has been developed that shows promise in the therapy of hemochromatosis as well as thalassemia and other secondary causes of iron overload. It is pertinent therefore to examine the developments in the global field of iron overload that have provided insights into the pathogenesis, disease penetrance, comorbid factors, and management.

Genetics of hereditary hemochromatosis: a clinical perspective

Hereditary hemochromatosis due to homozygosity for the C282Y mutation in the HFE gene product is the most common autosomal recessive genetic disorder in populations of northern European descent, where it attains a maximum prevalence of approximately one in 200. Cross-sectional and longitudinal studies have revealed that clinically significant iron-overload disease develops in at least 28% of male and 1% of female HFE C282Y homozygotes. The relatively low clinical penetrance is largely unexplained. Current evidence suggests a limited role for digenic inheritance of mutations in iron homeostasis genes in modifying the penetrance of hemochromatosis. Male gender is a strong genetic factor, promoting expression of clinical disease. Dietary intake of alcohol and noncitrus fruit may also act as important environmental modifiers of penetrance. With genetic analyses becoming simpler to perform, new genetic modifiers of hepatic iron loading and liver fibrogenesis are likely to be forthcoming.

Plasma protein carbonyls and breast cancer risk in sisters discordant for breast cancer from the New York site of the Breast Cancer Family Registry

Reactive oxygen species are important in the pathogenesis of many diseases, including breast cancer. Several population-based case-control studies have shown that various biomarkers of oxidative stress are associated with an increase in breast cancer risk. We selected sisters discordant for breast cancer (n=645) from the New York site of the Breast Cancer Family Registry to explore factors that contribute to variation in plasma protein carbonyls, and to determine whether this biomarker is associated with an increase in breast cancer risk among those with a family history. Late age at menarche, hormone replacement therapy use, and Hispanic race were significantly associated with lower plasma protein carbonyl levels in unaffected sisters. Plasma protein carbonyls were associated with an increase in breast cancer risk [Q2 odds ratio (OR), 1.4; 95% confidence interval (CI), 0.8-2.7; Q3 OR, 2.4; 95% CI, 1.1-4.9; Q4 OR, 1.9; 95% CI, 0.8-4.2], although not in a dose-dependent manner. These data suggest that oxidative damage is a risk factor for breast cancer in high-risk women.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Modifying factors of the HFE hemochromatosis phenotype

C282Y homozygosity is the only common HFE genotype able to produce a complete hemochromatosis phenotype. However, its biochemical penetrance is incomplete (75% in men and 50% in women) and its clinical penetrance is low, especially in women (1 vs 25% in men). Environmental (e.g., diet, alcohol, drugs and metabolic syndrome) and genetic (digenism, common polymorphisms in the bone morphogenetic protein pathway involved in the regulation of hepcidin synthesis) explain a part of the variability of the C282Y homozygous phenotype. All other common HFE genotypes--including C282Y-H63D compound heterozygosity--are not associated with significant biochemical and clinical expression in the absence of comorbid factors (e.g., alcohol, diabetes or steatohepatitis). Better identification of acquired and genetic modifiers of iron burden and iron-related organ damage is needed to improve the preventive, diagnostic and therapeutic management of HFE hemochromatosis.

Relation of iron and red meat intake to blood pressure: cross sectional epidemiological study

OBJECTIVE

To investigate associations of dietary iron (total, haem, and non-haem), supplemental iron, and red meat with blood pressure.

DESIGN

Cross sectional epidemiological study.

SETTING

17 population samples from Japan, China, the United Kingdom, and the United States participating in the international collaborative study on macro-/micronutrients and blood pressure (INTERMAP).

PARTICIPANTS

4680 adults aged 40-59.

MAIN OUTCOME MEASURE

Average of eight blood pressure readings.

RESULTS

In multiple linear regression analyses dietary total iron and non-haem iron were consistently inversely associated with blood pressure. With adjustment for potential non-dietary and dietary confounders, dietary total iron intake higher by 4.20 mg/4.2 MJ (2 SD) was associated with -1.39 mm Hg (P<0.01) lower systolic blood pressure. Dietary non-haem iron intake higher by 4.13 mg/4.2 MJ (2 SD) was associated with -1.45 mm Hg (P<0.001) lower systolic blood pressure. Differences were smaller for diastolic blood pressure. In most models haem iron intake from food was positively, non-significantly associated with blood pressure. Iron intake from combined diet and supplements yielded smaller associations than dietary iron alone. Red meat intake was directly associated with blood pressure; 102.6 g/24 h (2 SD) higher intake was associated with 1.25 mm Hg higher systolic blood pressure. Associations between red meat and blood pressure persisted after adjustment for multiple confounders.

CONCLUSION

Non-haem iron has a possible role in the prevention and control of adverse blood pressure levels. An unfavourable effect of red meat on blood pressure was observed. These results need confirmation including in prospective studies, clinical trials, and from experimental evidence on possible mechanisms.

Blood loss is a stronger predictor of iron status in men than C282Y heterozygosity or diet

OBJECTIVE

To determine the relative importance of HFE gene, diet, lifestyle, and blood loss characteristics for predicting iron status in a sample of men aged 40 years or over.

DESIGN

Iron status (serum ferritin, transferrin saturation, soluble transferrin receptor) was measured in 44 C282Y heterozygote and 85 age- and BMI-matched wildtype men aged 40 years or over. Dietary intake of iron (total, heme and non-heme), and components known to influence iron bioavailability, was determined using a validated Meal-Based Intake Assessment Tool. Information on lifestyle and blood loss was obtained by questionnaire. Height and weight were measured to determine Quetelet's body mass index. Linear mixed models were used to determine the extent to which these variables predicted iron status.

RESULTS

C282Y heterozygosity was associated with 17% higher transferrin saturation (95% CI: 6%, 29%) but no difference in serum ferritin or soluble transferrin receptor concentrations. Blood donation was negatively associated with transferrin saturation (-13% (- 3%, -22%)) and serum ferritin (-58% (-44%, -68%)), and had a marginally significant positive association with soluble transferrin receptor concentration. Self-reported fecal blood loss was negatively associated with serum ferritin concentration (-35% (-54%, -7%)). Alcohol was the only dietary variable associated with iron status and was associated with all three of the iron status indices. Serum ferritin concentration was positively associated with body mass index (10% per unit increase (6%, 15%)).

CONCLUSIONS

Blood loss was a stronger predictor of iron status than either C282Y heterozygosity or diet in this population of men aged 40 years and over.

Iron and the liver: update 2008

The cross-talk which has taken place in recent years between clinicians and scientists has resulted in a greater understanding of iron metabolism with the discovery of new iron-related genes including the hepcidin gene which plays a critical role in regulating systemic iron homeostasis. Consequently, the distinction between (a) genetic iron-overload disorders including haemochromatosis related to mutations in the HFE, hemojuvelin, transferrin receptor 2 and hepcidin genes and (b) non-haemochromatotic conditions related to mutations in the ferroportin, ceruloplasmin, transferrin and di-metal transporter 1 genes, and (c) acquired iron-overload syndromes has become easier. However, major challenges still remain which include our understanding of the regulation of hepcidin production, the identification of environmental and genetic modifiers of iron burden and organ damage in iron-overload syndromes, especially HFE haemochromatosis, indications regarding the new oral chelator, deferasirox, and the development of new therapeutic tools interacting with the regulation of iron metabolism.

Relationship between iron status and dietary fruit and vegetables based on their vitamin C and fiber content

BACKGROUND

Dietary fruits and vegetables may enhance iron status because of their high vitamin C content. The potential association between iron status and intakes of specific fruits and vegetables, according to sex and menopausal status, must be investigated.

OBJECTIVE

The objective was to assess the relation between dietary fruits, vegetables, and juices (FVJ) according to their vitamin C and fiber contents and serum ferritin and hemoglobin concentrations.

DESIGN

A total of 4358 subjects, aged 35-60 y, of the Supplementation with Antioxidant Vitamins and Minerals (SU.VI.MAX) cohort were selected. Subjects had completed at least six 24-h-dietary records over 2 y. The relation between serum ferritin and hemoglobin, measured at inclusion, and dietary FVJ according to their vitamin C and fiber contents was assessed by multiple regression analysis.

RESULTS

In premenopausal women, serum ferritin was positively associated with intakes of fiber-poor FVJ (up to 10% higher serum ferritin in the third tertile compared with the first tertile). In the whole sample, hemoglobin was positively associated with fruits, vitamin C-rich FVJ, FVJ ascorbic acid, and fiber-poor FVJ categories (up to 1.5 g/L higher hemoglobin concentration).

CONCLUSIONS

Intakes of fiber-poor FVJ were associated with higher serum ferritin concentrations in premenopausal women and with higher hemoglobin concentrations in the whole sample. Our results suggest that the fiber content of fruits and vegetables influences iron stores in premenopausal women but has no influence in groups in whom nonheme-iron absorption is limited because of high iron stores. Other mechanisms are likely to be involved in the case of hemoglobin.

Noncitrus fruits as novel dietary environmental modifiers of iron stores in people with or without HFE gene mutations

OBJECTIVE

To investigate whether citrus fruit, noncitrus fruit, and other dietary factors act as environmental modifiers of iron status in the absence or presence of hemochromatotic HFE gene mutations.

PARTICIPANTS AND METHODS

Iron studies, HFE genotypic analyses, and dietary data from a survey conducted from March 21, 1994, through December 15, 1995, were analyzed for a group of 2232 residents (1105 men, 1127 women) aged 20 to 79 years recruited from the community electoral roll of Busselton in Western Australia. Data were analyzed by linear regression analysis and analysis of covariance.

RESULTS

Higher levels of fresh fruit intake (excluding citrus fruits and citrus juices) had a significant protective effect (P=.002) against high body iron status as gauged by ferritin levels in men, irrespective of HFE genotype. Consumption of 2 or more pieces of fruit per day on average reduced mean serum ferritin levels by 20% compared with average consumption of less than 1 piece of fruit per day. This effect was not observed in women. Consumption of citrus fruits and citrus juices had no significant effects in either sex. No protective effects were observed for tea consumption or any other dietary factors studied. Red meat and alcohol consumption correlated with high body iron stores (P<.05), consistent with previous studies, but did not interact with fruit with regard to effects on serum ferritin (P>.05).

CONCLUSION

Noncitrus fruits are environmental modifiers of iron status independent of HFE genotype. This could have important implications for the provision of evidence-based dietary advice to patients with other iron-storage disorders.

Current approach to hemochromatosis

Iron overload diseases of genetic origin are an ever changing world, due to major advances in genetics and molecular biology. Five major categories are now established: HFE-related or type1 hemochromatosis, frequently found in Caucasians, and four rarer diseases which are type 2 (A and B) hemochromatosis (juvenile hemochromatosis), type 3 hemochromatosis (transferrin receptor 2 hemochromatosis), type 4 (A and B) hemochromatosis (ferroportin disease), and a(hypo)ceruloplasminemia. Increased duodenal iron absorption and enhanced macrophagic iron recycling, both due to an impairment of hepcidin synthesis, account for the development of cellular excess in types 1, 2, 3, and 4B hemochromatosis whereas decreased cellular iron egress is involved in the main form of type 4A) hemochromatosis and in aceruloplasminemia. Non-transferrin bound iron plays an important role in cellular iron excess and damage. The combination of magnetic resonance imaging (for diagnosing visceral iron overload) and of genetic testing has drastically reduced the need for liver biopsy. Phlebotomies remain an essential therapeutic tool but the improved understanding of the intimate mechanisms underlying these diseases paves the road for innovative therapeutic approaches.

Roles of hormone replacement therapy and iron in proliferation of breast epithelial cells with different estrogen and progesterone receptor status

Estrogen and iron play critical roles in a female body development and were investigated in the present study in relation to in vitro cell proliferation. Prempro, a hormone replacement therapy drug, and 17beta-estradiol (E2) were shown to increase cell proliferations in estrogen receptor positive (ER+) cells independent of progesterone receptor (PR) status. For example, increased cell proliferation was observed in ER+/PR+ human breast cancer MCF-7, its matching non-cancerous human breast epithelial MCF-12A, and ER+/PR+ murine mammary cancer MXT+ cells, but not in ER-/PR- MDA-MB-231, its matching non-cancerous MCF-10A, and MXT- (ER-/PR+) cells. By mimicking post-menopausal conditions of high estrogen in local breast tissue and increased iron levels due to cessation of menstrual periods, E2 and iron were shown to exert synergistic effects on proliferation of MCF-7 cells and significantly increased Ki67 and proliferating cell nuclear antigen. Western blotting of E2-treated ER+ but not ER- cells showed that E2 also increased transferrin receptor (TfR). Further studies are needed to assess the mitogenic effects of iron and estrogen in normal post-menopausal breast.

Environmental and genetic modifiers of the progression to fibrosis and cirrhosis in hemochromatosis

Hereditary hemochromatosis is a genetic disorder of iron metabolism leading to inappropriate iron absorption and iron loading in various organs especially the liver. Despite the genetic mutation being relatively common in those of Anglo Celtic descent, cirrhosis of the liver occurs in only a small proportion of affected individuals. The risk of hepatic fibrosis and cirrhosis relates to the degree of iron loading with threshold hepatic iron concentrations being identified from population studies. However, other environmental and possibly genetic factors appear to modify this risk. Excess alcohol consumption appears to be one of the most important cofactors with steatosis and coexistent viral infection also implicated. Genetic polymorphisms in genes associated with fibrogenesis, antioxidant activity, and inflammation have been investigated in several different forms of chronic liver disease. The variability in the expression of these genes that predispose patients with hemochromatosis to increased risk of severe liver disease is the subject of ongoing investigations. Clearly the progression of iron loading to cirrhosis marks a crucial stage in the natural history of a patient's disease and therefore therapy and prognosis. This review explores recent developments in knowledge of environmental and genetic modifiers of this process.

Haem and non-haem iron intake through 17 years of adult life of a British Birth Cohort

An investigation was carried out to determine whether there were significant changes in the intake of haem and non-haem Fe of adult men and women in the UK from 1982 (aged 36 years) to 1999 (aged 53 years). The 1253 subjects studied were members of the Medical Research Council National Survey of Health and Development; a longitudinal study of a nationally representative cohort of births in 1946. Food intake was recorded in a 5-d diary at age 36 years in 1982, 43 years in 1989 and 53 years in 1999. Outcome measures were mean intakes of total Fe, haem and non-haem Fe, by year, gender and food source. There were significant changes in total Fe, haem Fe and non-haem Fe intake over the three time points. Total Fe intake was significantly higher in 1989 than in 1982 or 1999 for both men and women but haem Fe was significantly lower in 1999 mainly due to a 40% fall in haem Fe from beef during this period. Haem Fe from processed meats fell by more than 50% between 1989 and 1999 but that from poultry rose by more than 50%. Cereal foods remained the most important source of non-haem Fe and the contribution from breakfast cereals rose relative to that of bread over the 17 years. Several factors could be responsible for these changes, particularly the importance of the epidemic of BSE from 1990. The possible advantages of a lower haem Fe intake in older subjects are discussed.

Iron storage disease: facts, fiction and progress

There are many forms of iron storage disease, some hereditary and some acquired. The most common of the hereditary forms is HFE-associated hemochromatosis, and it is this disorder that is the main focus of this presentation. The body iron content is regulated by controlling absorption, and studies in the past decade have clarified, in part, how this regulation functions. A 25-amino-acid peptide hepcidin is up-regulated by iron and by inflammation, and it inhibits iron absorption and traps iron in macrophages by binding to and causing degradation of the iron transport protein ferroportin. Most forms of hemochromatosis results from dysregulation of hepcidin or defects of hepcidin or ferroportin themselves. Hereditary hemochromatosis was once considered to be very rare, but in the 1970s and 1980s, with the introduction of better diagnostic tests, it was considered the most common disease among Europeans. Controlled epidemiologic studies carried out in the last decade have shown, however, the disease itself actually is rare, and only its genotype and associated biochemical changes that are common. We do not understand why only a few homozygotes develop severe disease. It now seems unlikely that there are important modifying genes, and although alcohol is known to have some effect, excess drinking probably plays only a modest role in determining the hemochromatosis phenotype. Hereditary hemochromatosis is readily treated by phlebotomy. Secondary forms of the disease require chelation therapy, and the recent introduction of effective oral chelating agents is an important step forward in treating patients with disorders in which iron overload often proves to be fatal, such as thalassemia, myelodysplastic anemias, and dyserythropoietic anemias. While much has been learned about the regulation of iron homeostasis in the past decade, many mysteries remain and represent challenges that will keep us occupied for years to come.

Genetic variability in iron-related oxidative stress pathways (Nrf2, NQ01, NOS3, and HO-1), iron intake, and risk of postmenopausal breast cancer

Oxidative stress resulting from excess reactive oxygen species and/or deficiencies in antioxidant capabilities may play a role in breast cancer etiology. In a nested case-control study of postmenopausal women (505 cases and 502 controls) from the American Cancer Society Prevention II Nutrition Cohort, we examined relationships between breast cancer risk and genetic polymorphisms of enzymes involved in the generation and removal of iron-mediated reactive oxygen species. Using unconditional logistic regression, genetic variations in Nrf2 (11108C>T), NQO1 (609C>T), NOS3 (894G>T), and HO-1 [(GT)(n) dinucleotide length polymorphism] were not associated with breast cancer risk in a multivariate model. A significant dose trend (P trend = 0.04), however, was observed for total number of putative "at-risk" alleles (Nrf T, NQO1 T, NOS T, and HO-1 LL and LM genotypes), with those carrying three or more at-risk alleles having an odds ratio (OR) of 1.56 [95% confidence interval (95% CI), 0.97-2.51] compared with those having none. When examined in relation to iron, carriage of three or more high-risk alleles in the highest tertile of iron intake (OR, 2.27; 95% CI, 0.97-5.29; P trend = 0.02; P interaction = 0.30) or among users of supplemental iron (OR, 2.39; 95% CI, 1.09-5.26; P trend = 0.02; P interaction = 0.11) resulted in a greater than 2-fold increased risk compared with women with no high-risk alleles. Increased risk was also observed among supplement users with the HO-1 LL or LM genotypes (OR, 1.56; 95% CI, 1.01-2.41; P interaction = 0.32) compared with S allele carriers and MM genotypes combined. These results indicate that women with genotypes resulting in potentially higher levels of iron-generated oxidative stress may be at increased risk of breast cancer and that this association may be most relevant among women with high iron intake.

Heme iron from diet as a risk factor for coronary heart disease in women with type 2 diabetes

OBJECTIVE

Diabetes-related metabolic abnormality may aggravate the adverse effects of iron overload on cardiovascular health. However, little is known about whether iron consumption affects coronary heart disease (CHD) risk in diabetes.

RESEARCH DESIGN AND METHODS

We prospectively assessed the associations of long-term intakes of dietary iron and red meat with CHD risk among 6,161 women who reported a diagnosis of type 2 diabetes.

RESULTS

During 54,455 person-years of follow-up from 1980 through 2000, we documented 550 incident cases of CHD. After adjustment for age and BMI, high intakes of both heme iron and red meat were associated with a significantly increased risk of fatal CHD (P for trend = 0.003 and 0.018), coronary revascularization (P for trend = 0.02 and 0.06), and total CHD (P for trend = 0.0009 and 0.007). Women with the highest intake of heme iron had 50% (6-94%) increased risk of total CHD compared with those with the lowest intake. Further adjustment for other lifestyle and dietary factors did not appreciably change the associations. The positive association between heme iron and red meat intakes and CHD was more evident among postmenopausal women compared with premenopausal women.

CONCLUSIONS

Our data indicate that higher consumption of heme iron and red meat may increase CHD risk among women with type 2 diabetes.