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Purpose: Poor bioavailability may contribute to iron deficiency among children in high-resource countries, but iron bioavailability of Australian pre-schooler diets is unknown. This study aimed to estimate the bioavailability of Australian pre-schooler iron intakes across the day and by eating occasions to identify optimal timing for intervention, by using five previously developed algorithms, and to estimate the proportion of children with intakes of absorbable iron below the requirements. Methods: Dietary data of children aged 2 to < 6 y (n = 812) from the 2011–12 National Nutrition and Physical Activity Survey were collected via two 24-h recalls. Usual food and nutrient intakes were estimated via Multiple Source Method. Phytate, polyphenol, and heme iron values were sourced from international databases or the literature. Five previously published algorithms were applied to observed dietary data to estimate iron bioavailability and calculate the prevalence of children with intakes of absorbable iron below requirements. Results: Pre-schooler daily iron bioavailability was low (2.7–10.5%) and corresponded to intakes of 0.18–0.75 mg/d of absorbable iron. The proportion of children with inadequate intakes of absorbable iron ranged between 32 and 98%. For all eating occasions, dinner offered iron of the greatest bioavailability (4.2–16.4%), while iron consumed at breakfast was of the lowest bioavailability (1.2–5.6%). Conclusion: Future strategies are required to improve intakes of bioavailable iron for pre-schoolers to prevent the risk of deficiency. These strategies could include the encouragement of concomitant consumption of enhancers of iron absorption with iron-rich sources, particularly at breakfast. [ABSTRACT FROM AUTHOR]

Aims: Evidence is limited regarding the long-term impact of dietary iron intake on the development of hypertension. We investigated the association between dietary intakes of total, nonheme, and heme iron and hypertension risk in a large prospective cohort of Chinese populations over 26 years. Methods: A total of 16,122 adults (7810 men and 8312 women) who participated in the China Health and Nutrition Survey (1989–2015) were included. Dietary intake was repeatedly assessed by combining three consecutive 24‑h individual dietary recalls with household food inventory weighing at each survey round. Incident hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg, diagnosis by physicians, or current use of anti-hypertensive drugs. Results: During a median follow‑up of 11.1 years, 2863 men and 2532 women developed hypertension. After adjustment for non-dietary and dietary factors, a lower risk of hypertension was found in men and women with higher intakes of total, nonheme, or heme iron. The adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the highest vs. lowest quartiles were 0.76 (0.67, 0.87) in men and 0.85 (0.74, 0.97) in women for total iron intake, 0.77 (0.67, 0.87) in men and 0.85 (0.74, 0.98) in women for nonheme iron intake, and 0.73 (0.62, 0.87) in men and 0.69 (0.58, 0.82) in women for heme iron intake. Dose–response analyses further revealed a U-shaped association of total and nonheme iron intake and an L-shaped association of heme iron intake with hypertension risk in both men and women (all P for non-linearity < 0.001). Conclusions: Our findings emphasize the importance of maintaining moderate iron intake in the prevention of hypertension. Both insufficient and excess intake of iron might increase the risk of hypertension. [ABSTRACT FROM AUTHOR]

Objectives: The relationship of dietary iron intake with the risk of hypertension remains uncertain. We aimed to investigate the prospective association between dietary iron intake and new-onset hypertension among Chinese adults. Design: A nationwide cohort study. Setting: Using data from seven rounds of the China Health and Nutrition Survey (CHNS) from 1997 to 2015. Participants: A total of 12,245 participants without hypertension at baseline were included in this study. Exposures: Dietary intake was measured by three consecutive 24-h dietary recalls combined with a household weighing inventory. Measurements: The study outcome was new-onset hypertension, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg or diagnosed by physician or currently under antihypertensive treatment during the follow-up. Results: During a median follow-up of 6.1 years, 4,304 (35.1%) participants developed hypertension. Overall, there was a U-shaped association between dietary total iron intake and new-onset hypertension (P for nonlinearity <0.001), with the lowest risk observed at 18.2–<22.1 mg/day (quintile 2–3). Similarly, a U-shaped association between dietary nonheme iron intake and new-onset hypertension was found (P for nonlinearity <0.001), with the lowest risk at 17.4–<21.3 mg/day (quintile 2–3). However, the association between dietary heme iron intake and new-onset hypertension followed a L-shape (P for nonlinearity <0.001), and a significantly lower risk of new-onset hypertension was found in participants with quintile 2–5 of dietary heme iron intake (adjusted HR, 0.75; 95% CI: 0.68, 0.82), compared with those in quintile 1 (<0.25 mg/day). Conclusions: The association between dietary iron and new-onset hypertension was nonlinear in Chinese adults, following a U-shape for total or nonheme iron intake, and a L-shape for heme iron intake. [ABSTRACT FROM AUTHOR]

Purpose: Red and processed meats are recognized by the International Agency for Research on Cancer as probably carcinogenic and carcinogenic to humans, respectively. Heme iron has been proposed as a central factor responsible for this effect. Furthermore, anxiety affects the intestinal barrier function by increasing intestinal permeability. The objective of this work was to assess how anxiety modifies the association between red and processed meat consumption and cancer risk in the NutriNet-Santé prospective cohort (2009–2019). Methods: Using multi-adjusted Cox models in a sample of 101,269 subjects, we studied the associations between the consumption of red and processed meat, the amount of heme iron coming from these meats and overall, colorectal, prostate, and breast cancer risks, overall and separately among participants with and without anxiety. Results: An increase in red and processed meat consumption was associated with an increased risk of developing colorectal cancer in the total population (HR for an increase of 50 g/day = 1.18 (1.01–1.37), p = 0.03). After stratification on anxiety, the HR 50 g/day was 1.42 (1.03–1.94, p = 0.03) in anxious participants and 1.12 (0.94–1.33, p = 0.20) in other participants. Similar trends were observed for overall cancer risk. Analyses conducted with heme iron also provided similar results. Conclusions: Our results strengthen the existing body of evidence supporting that red and processed meat consumption and heme iron intake are associated with an increased risk of overall and more specifically colorectal cancer, and suggest that anxiety modifies these associations, with an increased risk in anxious participants. [ABSTRACT FROM AUTHOR]

Heme iron (Fe) release from alginate beads at in vitro simulated gastrointestinal conditions for potential use as oral heme Fe supplement was studied. Five beads at different ratios of sodium alginate (SA)-to-spray-dried bovine blood cells (SDBC) with weight ratios of 1:1.25, 1:2.5, 1:5, 1:10, and 1:15 ( w/ w) were prepared. Release characteristics of these beads were investigated at in vitro simulated gastrointestinal conditions. Release media pH strongly influenced the controlled Fe release from the beads. The heme Fe-beads in simulated gastric fluid (pH 2) remained in a shrinkage state and Fe release was low: 25.8, 21.1, 11.6, 12.1, and 12.0 % for 1:1.25, 1:2.5, 1:5, 1:10, and 1:15 ratios, respectively. Proportion and amount of Fe released by 1:1.25 and 1:2.5 ratios was higher than the other ratios. The heme Fe-beads swelled and dissociated in simulated intestinal fluid (pH 6), releasing three-fourths of the Fe in 200 min. The morphology studies showed that Fe release followed formation of pores in the alginate matrix, generating erosion of the beads and complete disintegration after 75 and 200 min of gastric and intestinal incubation, respectively. These results indicate that heme Fe-beads may be useful for oral delivery of heme Fe supplement. [ABSTRACT FROM AUTHOR]

The industrial by-product bovine blood was used to prepare heme iron. Obtained heme iron exhibited strong in vitro antioxidant activities. Heme iron exhibited a significantly ( p<0.05) higher DPPH radical scavenging activity than ascorbic acid at low concentrations. The effects of heme iron in iron deficient anemic rats were evaluated. Heme iron exhibited an effective restorative action by returning hemoglobin, red blood cell, hematocrit, mean corpuscular hemoglobin concentrations, and serum iron levels in iron-deficient animals to normal or better values. Rats in the medium dosage group (2 mg of Fe/kg of body weight) experienced better iron bioavailability than rats in other treatment groups. The activities of antioxidant enzymes were enhanced while malondialdehyde levels were reduced in iron deficient anemic rats. Heme iron obtained from bovine blood can be used as a safe and efficient new iron supplement. [ABSTRACT FROM AUTHOR]

Purpose: Heme iron may contribute to the development of atherosclerosis by catalyzing production of hydroxyl-free radicals and promoting low-density lipoprotein oxidation. However, epidemiologic findings regarding the association between heme iron intake and risk of coronary heart disease (CHD) are inconsistent. We aimed to investigate the association by carrying out a meta-analysis of prospective studies. Methods: Relevant studies were identified by using PubMed and EMBASE databases between January 1966 and April 2013 and also by manually reviewing the reference lists of retrieved publications. Summary relative risks (RRs) with corresponding 95 % confidence intervals (CIs) were computed using a random-effects model. Results: Six prospective studies, which contained a total of 131,553 participants and 2,459 CHD cases, met the inclusion criteria. Combined results indicated that participants with higher heme iron intake had a 31 % increased risk of CHD, compared with those with lower intake (RR = 1.31, 95 % CI 1.04-1.67), with significant heterogeneity ( P = 0.05, I = 55.0 %). Excluding the only study from Japan (limiting to Western studies) yielded a RR of 1.46 (95 % CI 1.21-1.76), with no study heterogeneity ( P = 0.44, I = 0.0 %). The dose-response RR of CHD for an increase in heme iron intake of 1 mg/day was 1.27 (95 % CI 1.10-1.47), with low heterogeneity ( P = 0.25, I = 25.8 %). We observed no significant publication bias. Conclusions: This meta-analysis suggests that heme iron intake was associated with an increased risk of CHD. [ABSTRACT FROM AUTHOR]

Background: Epidemiologic findings concerning the associations between intakes of heme iron and zinc and colorectal cancer (CRC) incidence yielded conflicting results. We aimed to investigate the associations by performing a meta-analysis of prospective studies. Methods: We conducted a literature search on PubMed and EMBASE databases up to December 2012 to identify the prospective studies that investigated the relationships between heme iron or zinc intake and risk of CRC. We also reviewed the bibliographies of the retrieved articles to identify additional studies. We used a random-effects model to calculate the summary relative risks (RRs) with 95 % confidence intervals (CIs). Results: Eight studies on heme iron intake and six studies on zinc intake met the inclusion criteria. The summary RR of CRC for the highest versus the lowest intake was 1.14 (95 % CI = 1.04-1.24) for heme iron and 0.83 (95 % CI = 0.72-0.94) for zinc, respectively. The observed associations were not significantly modified by subsites within the colorectum, sex, geographic area, study duration, the number of cases, or the range of intakes. In the dose-response analyses, the summary RR of CRC was 1.11 (95 % CI = 1.03-1.18) for heme iron intake of 1 mg/day, and 0.86 (95 % CI = 0.78-0.96) for zinc intake of 5 mg/day, respectively. There was little evidence of publication bias. Conclusion: This meta-analysis suggests a significant positive dose-response association of heme iron intake and a significant inverse dose-response association of zinc intake with risk of CRC. [ABSTRACT FROM AUTHOR]

In the human gastrointestinal tract, trypsin and mucin may affect the absorption of heme iron. However, these interactions have not been well-established. We determined the effect of trypsin and mucin on heme iron absorption in humans. Design: Twenty-eight apparently healthy females participated in two studies (14 per study). Study A evaluated the effect of trypsin on iron bioavailability. Subjects ingested 100 mg trypsin and 1.7 g mucin on 5 mg heme iron bioavailability on days 1, 2, 14, and 15, respectively. In study B, which assessed the effect of mucin on heme iron bioavailability, the subjects ingested hemin, hemin plus mucin, hemoglobin (Hb), and Hb plus mucin, on days 1, 2, 14, and 15, respectively. Results: In study A, the geometric means ± 1 SD of heme iron absorption were 5.1 % (3.1-8.3), 2.9 % (1.6-5.1), 7.3 % (4.1-13.1), and 6 % (2.7-13) for hemin, hemin plus trypsin, Hb plus trypsin, and Hb plus mucin plus trypsin, respectively. In study B, the geometric means ± 1 SD of heme iron absorption were 16.4 % (10.5-25.7), 13.1 % (9.0-18.9), 13.7 % (9.0-20.7), and 11.8 % (7.6-18.3) for hemin, hemin plus mucin, Hb, and Hb plus mucin, respectively. The ratio increased when Hb plus trypsin was ingested and decreased when hemin plus trypsin was ingested. There were no differences in other ratios with respect to the ratio on day 1 ( P < 0.05). Conclusion: Trypsin is the only human gastrointestinal protein that evaluated the affects of heme iron absorption. However, this effect depends on how heme iron is ingested. [ABSTRACT FROM AUTHOR]

Although laboratory studies linked zinc and heme iron to colorectal cancer, epidemiologic evidence is limited. We prospectively examined these associations in the Nurses' Health Study and Health Professionals Follow-up Study. We used Cox proportional hazards regression analyses to calculate cohort-specific relative risks (RRs) and pooled results using a fixed-effects model. We documented 2,114 incident colorectal cancer cases during up to 22 years of follow-up. Compared highest to lowest quintile of dietary zinc intake, the pooled multivariable RRs (95% CIs) were 0.86 (0.73, 1.02) for colorectal cancer, 0.92 (0.76, 1.11) for colon cancer, and 0.68 (0.47, 0.99) for rectal cancer. The significant inverse association between dietary zinc intake and risk of rectal cancer was mainly driven by data in women, although the difference in the sex-specific results was not statistically significant. For the same comparison, the pooled multivariable RRs (95% CIs) for heme iron were 1.10 (0.93, 1.30) for colorectal cancer, 1.06 (0.88, 1.29) for colon cancer, and 1.20 (0.83, 1.75) for rectal cancer. These associations were not significantly modified by alcohol consumption, body mass index, physical activity, menopausal status, or postmenopausal hormone use. Total zinc intake, total iron intake, dietary iron intake, and zinc or iron supplement uses were largely not associated with colorectal cancer risk. Our study does not support strong roles of zinc and heme iron intake in colorectal cancer risk; however, a suggestive inverse association of dietary zinc intake with rectal cancer risk in women requires further study. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the content of total iron (TFe), heme iron (HeFe), zinc (Zn), and copper (Cu) in different cuts of meat and viscera from rabbit. Five young New Zealand rabbits were used in the study. Samples in triplicate were obtained from three meat cuts (foreleg, hind leg, and loin) and from main viscera. TFe, Zn, and Cu concentrations from samples were determined by wet acid digestion followed by atomic absorption spectrophotometry (AAS), while HeFe was determined by acid extraction followed by AAS. Mean TFe, HeFe, Zn, and Cu in meat was 0.83 ± 0.09, 0.56 ± 0.11, 0.95 ± 0.35, and 0.08 ± 0.01 mg/100 g, respectively. TFe content was less than 1 mg/100 g in all meat cuts. Sixty-seven percent of iron content was HeFe. The cut of meat with highest Zn concentrations was the foreleg with 1.33 ± 0.12 mg/100 g. Cu content was low for all meat cuts. TFe, HeFe, Zn, and Cu content in viscera varied greatly. The spleen was the organ with the highest TFe and Zn concentrations (82.79 ± 9.22 mg/100 g and 3.49 ± 0.63 mg/100 g, respectively). Nevertheless, the lungs had the highest concentration of HeFe (5.79 ± 0.90 mg/100 g), accounting for 91% of the total iron. The liver had the highest Cu content (3.89 ± 0.89 mg/100 g). Rabbit meat has low TFe concentration, similar to that of poultry, and most of the iron is HeFe. The amount of minerals in viscera closely depends on their function. [ABSTRACT FROM AUTHOR]

comparative study of oxyhemoglobins from pig, rabbit, normal human and patients with blood system malignant diseases was performed using Mössbauer spectroscopy with a high velocity resolution at 90 K. Mössbauer spectra were fitted with the help of two models: using one quadrupole doublet (model of equivalent iron electronic structure in α- and β-subunits of hemoglobins) and superposition of two quadrupole doublets (model of non-equivalent iron electronic structure in α- and β-subunits of hemoglobins). The results obtained using both models demonstrated small variations of hyperfine parameters that were related to the heme iron state variation in different hemoglobins. These results were compared with structural and functional differences of the hemoglobins investigated. [ABSTRACT FROM AUTHOR]

Photosynthesis is a process occurring in certain species of bacteria, algae and higher plants. It transforms solar energy into various forms of energy-rich organic molecules. Photosystem II (PSII) is the “heart” of the photosynthetic apparatus because it delivers electrons and protons for further steps of the light-driven phases of photosynthesis. There are two enigmatic iron binding structures within the core of photosynthetic apparatus, which play an important role in the electron transfer within PSII. Many investigations focus on the determination of their function which is the key to the understanding of the molecular mechanism of the energy and electron transfer within PSII. Among many methods used in this research field, the Mössbauer spectroscopy is a unique one, which gives the possibility to study changes of the valence and spin states of those two iron sites and the dynamical properties of their protein matrix in the presence of various physiological and stress conditions. [ABSTRACT FROM AUTHOR]

In a cohort study of 49,654 Canadian women, we assessed the association of colorectal cancer with total iron and heme iron intake, excluding iron supplements. Among women aged 40-59 years, followed for an average of 16.4 years, we identified 617 incident colorectal cancer cases. Data from a food frequency questionnaire administered at baseline were used to calculate red meat intake and intake of total dietary iron, iron from meat, and heme iron. Analyses were carried out for all cases and for the proximal colon, distal colon, and rectum, using Cox proportional hazards models. We found no association of intake of iron, heme iron, or iron from meat with risk of colorectal cancer overall or with any of the subsites, nor was there effect modification by alcohol consumption or hormonal replacement therapy. [ABSTRACT FROM AUTHOR]

Recently, recommended dietary allowances (RDA) have been formulated by the Dutch Nutrition Council for minerals and trace elements, including iron (Fe). For some population groups in the Netherlands, it is questionable whether they easily meet the Fe recommendation. An increase in Fe intake is not always possible, but 'manipulation' of Fe bioavailability ultimately may result in better Fe utilization. Various factors are known to affect Fe bioavailability. Generally, much attention is paid to diet-related factors, such as inhibitors and enhancers of Fe availability for absorption. Factors such as pH, oxidation potential, structure of food, and time of digestion often are overlooked. Of the diet-related factors, heme Fe and ascorbic acid have a strong positive effect on Fe availability for absorption, whereas oxalate and polyphenols seem to be strong inhibitors of Fe availability. Because of the many interactions that may occur simultaneously, the net effect of the various combined factors in a meal is not equal to the sum of the individual factors. [ABSTRACT FROM AUTHOR]

A novel enzyme that catalyzes the disproportionation of chlorite into chloride and oxygen was purified from a gram-negative bacterium, strain GR-1 to homogeneity. A four-step purification procedure comprising Q-Sepharose, hydroxyapatite, and phenyl-Superose chromatography and ultrafiltration resulted in a 13.7-fold purified enzyme with a final specific activity of 2.0 mmol min (mg protein). The dismutase obeyed Michaelis-Menten kinetics. The V and K calculated for chlorite were 2,200 U (mg protein) and 170 μM, respectively. Dismutase activity was inhibited by hydroxylamine, cyanide, and azide, but not by 3-amino-1,2,4-triazole. Chlorite dismutase had a molecular mass of 140 kDa and consisted of four 32-kDa subunits. The enzyme was red-colored and had a Soret peak at 392 nm. Per subunit, it contained 0.9 molecule of protoheme IX and 0.7 molecule of iron. Chlorite dismutase displayed maxima for activity at pH 6.0 and 30° C. [ABSTRACT FROM AUTHOR]

Purpose Of Review: To examine the role of red meat consumption, especially heme iron intake, and risk for diabetes and its comorbidities.Recent Findings: Studies consistently show that consumption of red meat has been contributory to a multitude of chronic conditions such as diabetes, CVD, and malignancies. There are various emerging reasons that strengthen this link-from the basic constituents of red meat like the heme iron component, the metabolic reactions that take place after consumption, and finally to the methods used to cook it. The causative links show that even occasional use raises the risk of T2DM. Prior studies show how nitrites and nitrates in red meat can lead to increased insulin resistance, dysregulated blood glucose levels, and elevated oxidative stress all leading to chronic diseases. With the rise in these preventable chronic diseases, we examine how disease-causing links can be eliminated with appropriate lifestyle choices. [ABSTRACT FROM AUTHOR]