Low Iron Bioavailability Research Articles

Chlamydomonas cells transition through distinct Fe nutrition stages within 48h of transfer to Fe-free medium.

Low iron (Fe) bioavailability can limit the biosynthesis of Fe-containing proteins, which are especially abundant in photosynthetic organisms, thus negatively affecting global primary productivity. Understanding cellular coping mechanisms under Fe limitation is therefore of great interest. We surveyed the temporal responses of Chlamydomonas (Chlamydomonas reinhardtii) cells transitioning from an Fe-rich to an Fe-free medium to document their short and long-term adjustments. While slower growth, chlorosis and lower photosynthetic parameters are evident only after one or more days in Fe-free medium, the abundance of some transcripts, such as those for genes encoding transporters and enzymes involved in Fe assimilation, change within minutes, before changes in intracellular Fe content are noticeable, suggestive of a sensitive mechanism for sensing Fe. Promoter reporter constructs indicate a transcriptional component to this immediate primary response. With acetate provided as a source of reduced carbon, transcripts encoding respiratory components are maintained relative to transcripts encoding components of photosynthesis and tetrapyrrole biosynthesis, indicating metabolic prioritization of respiration over photosynthesis. In contrast to the loss of chlorophyll, carotenoid content is maintained under Fe limitation despite a decrease in the transcripts for carotenoid biosynthesis genes, indicating carotenoid stability. These changes occur more slowly, only after the intracellular Fe quota responds, indicating a phased response in Chlamydomonas, involving both primary and secondary responses during acclimation to poor Fe nutrition.

Nutrient and anti-nutrient composition of durum, soft and red wheat landraces: Implications for nutrition and mineral bioavailability

Morocco possesses a significant genetic diversity of wheat cultivars in the form of landraces conserved by local farmers in several regions. This study aimed to investigate the nutritional and antinutritional composition of 75 flour samples of durum, soft, and red wheat landraces cultivated in Morocco in order to determine their nutritional value. The analysis concerned the quantification of total carbohydrates, starch, lipid, fatty acids, protein, amino acids, minerals, and dietary fibers using AOAC standards, and phytic acid and polyphenols using spectrophotometric assays. The antiradical activity was evaluated using a DPPH assay based on the chelating properties of the free radicals against minerals. The bioavailability of minerals was also estimated using molar ratios. On a dry weight basis, soft wheat flour contains higher amounts of carbohydrates (80.307 ± 0.634 g/100 g), while durum (14.007 ± 0.569 g/100 g) and red (16.452 ± 0.141 g/100 g) wheat flours contain more proteins, predominantly represented by glutamic acid and leucine. The mineral analysis revealed the abundance of iron, zinc, and calcium in soft, red, and durum wheat flours. Concerning lipids, the flour samples showed relatively low concentrations with a distinct predominance of oleic, linoleic, and palmitic acids. The quantification of antinutrients revealed the richness of red wheat flour in dietary fibers (1.763 ± 0.103 g/100 g), total polyphenols (301.609 ± 0.169 μg GAE/g), and flavonoids (80.091 ± 0.121 μg QE/g), while durum and soft wheat flours contain more tannins (60.138 ± 0.751 μg CE/g) and phytic acid (9.182 ± 0.391 mg/g), respectively. The phenolic extract derived from red wheat flour demonstrated significant antiradical activity against DPPH, with an IC50 value of 121.683 ± 0.229 μg/mL. The calculated (PA:Fe), (PA:Zn), and (PA:Ca) were below the critical values, indicating a low bioavailability of iron, zinc, and calcium in the wheat flour samples. The results showed significant differences (p < 0.05) in the amounts of nutrients and antinutrients among the studied wheat cultivars, leading to variations in the bioavailability of their mineral contents. These quantitative differences could be used to more accurately guide dietary recommendations and develop focused strategies for optimizing the bioavailability of minerals in wheat flour-based products.

Preparation, characterization, and bioavailability evaluation of antioxidant phosvitin peptide-ferrous complex.

Iron deficiency anemia (IDA) is one of the commonest global nutritional deficiency diseases, and the low bioavailability of iron is a key contributing factor. The peptide-iron complex could be used as a novel iron supplement to improve iron bioavailability. In this study, antioxidant low molecular weight (<3 kDa) phosvitin peptide (named PP-4) was separated to prepare a phosvitin peptide-ferrous complex (named PP-4-Fe); then the structural conformation of PP-4-Fe was characterized and its bioavailability by in vitro digestion was evaluated. The results showed that PP-4 had good ferrous-binding activity with 96.14 ± 2.86 μg Fe2+ mg-1 , and had a strong antioxidant effect with 995.61 ± 79.75 μmol TE mg-1 in 2,2'-azinobis'3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 62.3 ± 3.95 μmol FeSO4 mg-1 in ferric ion reducing antioxidant power (FRAP). After ferrous binding, the FRAP activity of PP-4-Fe, enhanced by 1.8 times, formed a more ordered structure with an increase in α-helix and decrease in γ-random coil. The ferrous binding sites of PP-4 involved were the amino, carboxyl, imidazole, and phosphate groups. The PP-4-Fe complex displayed excellent gastrointestinal stability and antioxidant effects during digestion. The iron dialysis percentage of PP-4-Fe was 74.59% ± 0.68%, and increased to 81.10% ± 0.89% with the addition of 0.25 times vitamin C (VC). This indicated that PP-4-Fe displayed excellent bioavailability and VC in sufficient quantities had a synergistic effect on improving bioavailability. This study demonstrated that antioxidant phosvitin peptide was an efficient delivery system to protect ferrous ions and suggested that the phosvitin peptide-ferrous complex has strong potential as a ferrous supplement. © 2023 Society of Chemical Industry.

Effect of dissolved iron (II) and temperature on growth of the Southern Ocean phytoplankton species Fragilariopsis cylindrus and Phaeocystis antarctica

Low bioavailability of the vital element iron (Fe) limits primary production in large regions of the Southern Ocean, thus impacting phytoplankton community structures. Primary productivity seems to be particularly sensitive to the reduced form of iron (Fe(II)), which is thought to be the most readily bioavailable redox form of Fe in the ocean. Here, we investigated the impact of temperature (3 °C, 5 °C and 7 °C) and Fe(II) additions (+ 5 nM) on growth of two Southern Ocean phytoplankton species Fragilariopsis cylindrus and Phaeocystis antarctica in coastal and open ocean water. At all tested temperatures, growth rates of P. antarctica were significantly higher with added iron, compared to the treatments without added iron in both waters. Temperature only had a significant effect on the growth rate of this species when it was raised to 7 °C in all treatments. For F. cylindrus, growth rates only significantly increased with iron addition at 7 °C in both water types. Temperature did not affect the growth rate of F. cylindrus except for a significant reduction without iron addition at 7 °C in coastal water. These results highlight the complex interactions between Fe bioavailability and temperature on Southern Ocean phytoplankton growth. Thus, certain Southern Ocean phytoplankton species may have higher growth rates in regions of the ocean that will warm the most and possibly experience greater Fe supply under future climate conditions, such as coastal regions. This may result in changes in phytoplankton community structures with implications for carbon sequestration efficiency under future climate conditions.

Plant-based alternative proteins-are they nutritionally more advantageous?

The transition towards sustainable nutrition as well as the exploration of alternative sources of protein have been at the forefront of thinking in the 21st century. However, further research is required to ascertain if a diet composed of alternative plant-based proteins has similar nutritional advantages to a plant-based diet. This study aims to model the replacement of a diet consisting of animal-based proteins with plant-based alternatives (PBA), in a group of Asians. A 4-day food record was collected from 50 individuals residing in Singapore and nutrient profiles were generated for each individual. Food records were analysed, and meat, dairy, and seafood ingredients were substituted gram-for-gram with their PBA. The original and replaced nutrient profiles were compared against each other and the differences in macro and micronutrients were analysed. A significant increase in carbohydrates, dietary fibre, as well as in micronutrients such as sodium and calcium was observed. Conversely, there was a significant decreased intake in overall energy, protein and fat (p < 0.005). The significant nutritional impact of substituting animal-based proteins for PBA may present benefits for bone health and individuals on a caloric restriction diet. However, higher sodium levels may be undesirable for individuals with cardiovascular conditions and hypertension, and the low bioavailability of iron in plant-based sources may present issues for iron deficient populations. Bearing some of these key findings in mind, researchers and manufacturers need to consider these when developing alternative protein products to meet consumer demands for palatable and nutritious plant-based products.

Low bioavailability of dietary iron among Brazilian children: Study in a representative sample from the Northeast, Southeast, and South regions.

Despite all efforts, iron deficiency anemia remains a serious public health problem among Brazilian children. To evaluate dietary iron intake and dietary practices that interfere with the absorption of this nutrient from three regions of Brazil. Brazil Kids Nutrition and Health Study is a cross-sectional dietary intake study in children aged 4-13.9 years old designed to investigate nutrient intakes and gaps of Brazilian children in a representative sample of households from Northeast, Southeast and South regions. Nutrient intake was assessed based on multiple-pass 24-h dietary recall and U.S. National Cancer Institute method was used to estimate usual micronutrients intakes and compliance with Dietary Reference Intakes. Five hundred sixteen individuals participated in the study (52.3% male). The top three most consumed food sources of iron were products of plant origin. Food sources of animal origin contributed with <20% of the total iron intake. Vitamin C intake was adequate, but the concomitant consumption of food sources of vitamin C with plant food sources of iron was not common. On the other hand, the concomitant intake of plant food sources of iron with food sources of iron chelators (e.g., coffee and teas) was frequent. Adequate iron intake was observed in all three regions in Brazil. Children's diet showed low iron bioavailability and insufficient consumption of food sources of iron absorption stimulants. Frequent presence of iron chelators and inhibitors of iron absorption might help to explain the high prevalence of iron deficiency in the country.

Fluxograma para diagnóstico precoce, tratamento e monitorização da deficiência de ferro na criança

Iron deficiency anemia is defined as a hemoglobin concentration less than a second standard deviation from the distribution mean for a population of the same sex and age. It is the last event in a progression of negative iron balance, with the stages: negative balance, iron deficiency, and iron deficiency anemia. It is the most common hematologic alteration in the world, especially in developing countries. The main source of iron in the body comes from the red blood cell recycling system, while a smaller portion comes from the diet. Despite this, nutritional deficiency is the main etiology of iron deficiency anemia and iron deficiency in childhood. Iron is essential for several physiological functions and its deficiency, especially in childhood, can compromise mental and physical development. Clinical manifestations usually become detectable in severe deficiency. For this reason, the early diagnosis of iron deficiency is through laboratory tests. It should be performed through screening at 12 months of life. Treatment should be started promptly after diagnosis. Diet is of little value in correcting iron owing to the low bioavailability of iron in most foods. However, preparations containing iron are easily absorbed by the body. Given the severity of this condition, treatment should be monitored using laboratory parameters. This study aims to develop a protocol for screening and monitoring the treatment of iron deficiency anemia to systematize and organize care, bringing better results for the childs development.

FLUXOGRAMA PARA DIAGNÓSTICO PRECOCE, TRATAMENTO E MONITORIZAÇÃO DA DEFICIÊNCIA DE FERRO NA CRIANÇA

Iron deficiency anemia is defined as a hemoglobin concentration less than a second standard deviation from the distribution mean for a population of the same sex and age. It is the last event in a progression of negative iron balance, with the stages: negative balance, iron deficiency, and iron deficiency anemia. It is the most common hematologic alteration in the world, especially in developing countries. The main source of iron in the body comes from the red blood cell recycling system, while a smaller portion comes from the diet. Despite this, nutritional deficiency is the main etiology of iron deficiency anemia and iron deficiency in childhood. Iron is essential for several physiological functions and its deficiency, especially in childhood, can compromise mental and physical development. Clinical manifestations usually become detectable in severe deficiency. For this reason, the early diagnosis of iron deficiency is through laboratory tests. It should be performed through screening at 12 months of life. Treatment should be started promptly after diagnosis. Diet is of little value in correcting iron owing to the low bioavailability of iron in most foods. However, preparations containing iron are easily absorbed by the body. Given the severity of this condition, treatment should be monitored using laboratory parameters. This study aims to develop a protocol for screening and monitoring the treatment of iron deficiency anemia to systematize and organize care, bringing better results for the childs development.

Association of anemia with BMI in paramedical students of the remote and rural high land of Mid-Western Nepal

Background and Objectives: Anemia is a widespread public health issue. It impairs immune systems and is linked to an increase in morbidity. Additional factors linked to lower hemoglobin (Hb) levels in adolescents include lack of awareness, low educational status, poor dietary practices, and unhealthy eating habits, low iron bioavailability of the diet, decreased physical activity, malaria, and parasite infestations. Studies on the incidence and severity of anemia among Nepali college students are extremely rare. The significance of research on the prevalence of anemia among college students cannot be underestimated. The study's objective was to evaluate the relationship between anemia and BMI in paramedical students from the isolated, rural highlands of Midwestern Nepal. Materials and Methods: A quantitative cross-sectional study was conducted among the paramedical students of KAHS. A total of 96 students from paramedical students were participated in this study. Before collecting the data, the consent was taken from students. Data were collected from a semi-structured questionnaire and analyze by using SPSS software (20.0 Version). A chi square test was used to show the relationship between demographic variables and anemia. Results: The prevalence of anemia was 20.8% (male=6.1% and female=53.3%) among the 96 students. There was no significant association between anemia and BMI (P&gt;0.05). Conclusion: The anemic status of students was significantly associated with gender but BMI and age where not the factors of anemic status in this Therefore, there should be adequate diet and nutritional status needs to be emphasized for paramedical students who are well educated and well oriented about nutrition and its ill effect on health.

Diversity and Evolution of Iron Uptake Pathways in Marine Cyanobacteria from the Perspective of the Coastal Strain Synechococcus sp. Strain PCC 7002.

Marine cyanobacteria contribute to approximately half of the ocean primary production, and their biomass is limited by low iron (Fe) bioavailability in many regions of the open seas. The mechanisms by which marine cyanobacteria overcome Fe limitation remain unclear. In this study, multiple Fe uptake pathways have been identified in a coastal strain of Synechococcus sp. strain PCC 7002. A total of 49 mutants were obtained by gene knockout methods, and 10 mutants were found to have significantly decreased growth rates compared to the wild type (WT). The genes related to active Fe transport pathways such as TonB-dependent transporters and the synthesis and secretion of siderophores are found to be essential for the adaptation of Fe limitation in Synechococcus sp. PCC 7002. By comparing the Fe uptake pathways of this coastal strain with other open-ocean cyanobacterial strains, it can be concluded that the Fe uptake strategies from different cyanobacteria have a strong relationship with the Fe bioavailability in their habitats. The evolution and adaptation of cyanobacterial iron acquisition strategies with the change of iron environments from ancient oceans to modern oceans are discussed. This study provides new insights into the diversified strategies of marine cyanobacteria in different habitats from temporal and spatial scales. IMPORTANCE Iron (Fe) is an important limiting factor of marine primary productivity. Cyanobacteria, the oldest photosynthetic oxygen-evolving organisms on the earth, play crucial roles in marine primary productivity, especially in the oligotrophic ocean. How they overcome Fe limitation during the long-term evolution process has not been fully revealed. Fe uptake mechanisms of cyanobacteria have been partially studied in freshwater cyanobacteria but are largely unknown in marine cyanobacterial species. In this paper, the characteristics of Fe uptake mechanisms in a coastal model cyanobacterium, Synechococcus sp. PCC 7002, were studied. Furthermore, the relationship between Fe uptake strategies and Fe environments of cyanobacterial habitats has been revealed from temporal and spatial scales, which provides a good case for marine microorganisms adapting to changes in the marine environment.

Low source-inherited iron solubility limits fertilization potential of South American dust

Where atmospheric processing is weak due to low anthropogenic emissions, fertilization of iron-limited oceans by non-volcanic mineral dust aerosols strongly depends on iron solubility at the sources. Southern South America (SSA) is a pristine environment and the main dust supplier to the southern oceans, the most sensitive to iron fertilization. Thus, the present-day lack of SSA dust fertilization of the southern oceans is hypothesized to reflect low source-inherited iron bioavailability. However, a dearth of geochemical studies on SSA dust prevents testing this hypothesis. To remedy this, we conducted the first systematic sampling of SSA dust sources. Iron leaching experiments showed fractional solubilities of close-to-source dust (bulk) and dust-emitting surface sediments (<63 µm) in pure water (0.05 ± 0.05%), seawater (0.03 ± 0.04%) and 1% nitric acid (5 ± 6%) that imply a low mass-normalized fertilization potential of SSA dust compared to dust from other regions. Based on grain size, size-resolved mineralogy, elemental chemistry and iron speciation determinations, we found that variability in labile iron is enhanced by high clay contents, small grain size and higher proportions of paramagnetic versus non-paramagnetic iron, irrespective of oxidation state. The independence of the most labile, water-soluble iron on grain size and its strong negative correlation to the Chemical Index of Alteration may imply that we currently underestimate the role of coarse glaciogenic dust as a supplier of bioavailable iron during drier-than-present ice ages when continental chemical weathering was reduced, and during which enhanced supply of dust-borne bioavailable iron to the southern oceans is observed.

An In Vitro Analysis and In Vivo Trial Demonstrating the Improved Iron Bioavailability of White Beans (Phaseolus vulgaris L.) After Processing Into Pasta

Abstract Objectives The cotyledon cell wall of the common bean can be a factor in Fe bioavailability. This study evaluated the iron bioavailability of two bean varieties (white or black) either boiled (intact cell walls) or extruded into pasta formulated from heat treated bean flour as the major ingredient (100% bean flour; broken cell walls). Methods In vitro Fe bioavailability was determined via the Caco-2 Cell Bioassay. In vivo Fe bioavailability was measured by the capacity of a bean-based or bean pasta-based diet to generate and maintain total body hemoglobin iron (Hb-Fe) during a 6 week poultry feeding trial. Results The iron and phytate concentrations of the bean-based and bean pasta-based diets consisting of tomato paste, carrot, cabbage, milk, potato and corn oil were not significantly different. The Caco-2 cell bioassay predicted that the white bean pasta diet would have the highest Fe bioavailability, closely followed by the white bean diet. The bioassay predicted the black bean diet and the black bean pasta diet would have significantly lower Fe bioavailability. For the in vivo studies, animals fed the white bean pasta diet (broken cell walls) had significantly (p ≤ 0.05) higher hemoglobin, Hb-Fe and hemoglobin maintenance efficiencies than animals fed a white bean, black bean or black bean pasta-based diet. Although cotyledon cells were broken, the iron bioavailability of the black bean pasta was not improved after processing into pasta. The low iron bioavailability of black beans was associated with their high concentrations of seed coat procyanidin, cinnamtannin and anthocyanidin compounds that have a negative impact on the absorption of iron. Conclusions This study shows that white colored dry bean possesses a combination of traits that result in improved iron bioavailability after processing into pasta. The enhanced Fe bioavailability from the white bean pasta is likely due to the breakage of the cotyledon cell wall during processing, thus allowing enhanced bioaccessibility of the intracellular Fe. In the black bean pasta diet, this enhancement was not observed due to the presence of the seed coat polyphenols which interacted with the released intracellular Fe and prevented Fe absorption. Funding Sources Funded by the United States Department of Agriculture, Agricultural Research Service.

Preparation of iron-loaded water-in-oil-in-water (W1/O/W2) double emulsions: optimization using response surface methodology

Iron deficiency anemia is a major public health problem caused by low iron intake or bioavailability. To overcome the problem of anemia, iron fortification of a variety of food products is being tested worldwide. Ferric sodium EDTA is a desirable iron source for food fortification due to its high bioavailability and ability to prevent binding of iron to phytates during absorption. This study investigated the application of double emulsions for encapsulation and controlled delivery of ferric sodium EDTA stabilized by the lipophilic Span®80 and hydrophilic complex of sodium alginate and sodium caseinate emulsifiers. The influence of factors such as the ratio of internal water to the oil phase, concentrations of alginate or Span®80 and the ratio of water-in-oil emulsion to the external water on internal (din ) and external emulsion droplet sizes (dout ) was studied by response surface methodology. The feasible range for selection of factors for achieving target values of din and dout was proposed by the response optimizer confirmed by the results of experiments. The results indicate that double emulsion systems may be useful for iron fortification of food products.

A new perspective of copper-iron effects on bloom-forming algae in a highly impacted environment

Relatively little work has been done on the role of micronutrients in influencing development and progression of harmful algal blooms, yet micronutrients are ineluctably required for growth. Relatively small changes in micronutrient status have wide-ranging consequences. Here, we report results from mesocosm experiments with Microcystis and Desmodesmus spp., in mono- and mixed-cultures, to probe questions of how copper, iron, and copper-iron amendments affect growth, short-term assemblage progression, and production of siderophore, chalkophore, and microcystin in lake water from a large, hypereutrophic lake (Taihu, China). Our approach offers an entirely new perspective to understanding micronutrient dynamics in aqueous environments, as this is the first work to systematically screen for chalkophores and siderophores separately, as a function of copper/iron amendment, and using community trajectory analysis. Singular findings are summarized as follows: 1) unlike lab-based studies, in our work we observe neither dramatic copper-modulation of iron demand, nor evidence of an iron-protective effect from copper toxicity. 2) The interplay between chalkophore/siderophore production supports a concept model wherein Microcystis spp. varies behavior to individually and uniquely manage copper/iron requirements in a phased manner. In being able to specifically screen for chalkophores, we observe a previously unreported link between chalkophore and microcystin production that may relate to iron-limitation. 3) Regarding harmful algal bloom (HAB) persistance, the lake water itself influences mesocosm changes; differentiated effects for iron regarding growth indicators and/or reduction of Fe-limitation stress were found at an HAB-free field station (Xukou Bay), likely a consequence of low bioavailability of iron in this station as compared to HAB-impacted stations (half the initial dissolved iron concentration, persisting throughout experiments). The low dissolved iron accompanies more intense chalkophore/siderophore community trajectories.

Blood Lead Level in a Paediatric Population of South-Eastern Spain and Associated Risk Factors.

Objective: To determine blood lead levels (BLL) in a healthy paediatric population and to analyse related sociodemographic, dietary and haematological factors. Methods: A cross-sectional study was made of 1427 healthy subjects aged 1–16 years from the city of Almería (south-eastern Spain). BLL, iron parameters and erythropoietin were determined, and sociodemographic and dietary data obtained. The study paramateters was analyses in BLL toxic and BLL no toxic group by multiple logistic regression. Results: The mean BLL was 1.98 ± 1.1 µg/dL (95% CI:1.91–2.04). For 5.7% of the population, mean BLL was 2–5 µg/dL, for 2.1% it was >5 µg/dL and for 0.15% it was >10 µg/dL. Multivariate analysis showed that immigrant origin (OR:11.9; p < 0.0001), low level of parental education (OR:4.6; p < 0.02) and low dietary iron bioavailability (OR: 3.2; p < 0.02) were all risk factors for toxic BLL. Subjects with toxic and non-toxic BLL presented similar iron and erythropoiesis-related parameters, except erythrocyte protoporphyrin, which was significantly higher in the BLL >5 µg/dL group. Conclusions: BLL and the prevalence of toxic BLL in healthy subjects aged 1–16 years living in south-eastern Spain are low and similar to those found in other developed countries. The factors associated with toxic BLL are immigrant origin, low level of parental education and dietary iron deficiency. The toxicity of BLL was not related to changes in the analytical parameters studied.

Fighting Iron-Deficiency Anemia: Innovations in Food Fortificants and Biofortification Strategies.

Iron deficiency remains one of the main nutritional disorders worldwide and low iron intake and/or bioavailability are currently the major causes of anemia. To fight this public health problem, the scientific challenge is to find an iron form with sufficient bioavailability to increase its levels in humans through food fortification. In turn, biofortification appears as a comparatively advantageous and bearable strategy for the delivery of vitamins and other micronutrients for people without access to a healthy and diverse diet. This approach relies on plant breeding, transgenic techniques, or agronomic practices to obtain a final food product with a higher iron content. It is also known that certain food constituents are able to favor or inhibit iron absorption. The management of these compounds can thus successfully improve the absorption of dietary iron and, ultimately, contribute to fight this disorder present all over the world. This review describes the main causes/manifestations of iron-deficiency anemia, forms of disease prevention and treatment, and the importance of a balanced and preventive diet. A special focus was given to innovative food fortification and biofortification procedures used to improve the iron content in staple food crops.

Catalytic effects of photogenerated Fe(II) on the ligand-controlled dissolution of Iron(hydr)oxides by EDTA and DFOB

Low bioavailability of iron due to poor solubility of iron(hydr)oxides limits the growth of microorganisms and plants in soils and aquatic environments. Previous studies described accelerated dissolution of iron(hydr)oxides under continuous illumination, but did not distinguish between photoreductive dissolution and non-reductive processes in which photogenerated Fe(II) catalyzes ligand-controlled dissolution. Here we show that short illuminations (5–15 min) accelerate the dissolution of iron(hydr)oxides by ligands during subsequent dark periods under anoxic conditions. Suspensions of lepidocrocite (Lp) and goethite (Gt) (1.13 mM) with 50 μM EDTA or DFOB were illuminated with UV-A light of comparable intensity to sunlight (pH 7.0, bicarbonate-CO2 buffered solutions). During illumination, the rate of Fe(II) production was highest with Gt-EDTA; followed by Lp-EDTA > Lp-DFOB > Lp > Gt-DFOB > Gt. Under anoxic conditions, photochemically produced Fe(II) increased dissolution rates during subsequent dark periods by factors of 10–40 and dissolved Fe(III) reached 50 μM with DFOB and EDTA. Under oxic conditions, dissolution rates increased by factors of 3–5 only during illumination. With DFOB dissolved Fe(III) reached 35 μM after 10 h of illumination, while with EDTA it peaked at 15 μM and then decreased to below 2 μM. The observations are explained and discussed based on a kinetic model. The results suggest that in anoxic bottom water of ponds and lakes, or in microenvironments of algal blooms, short illuminations can dramatically increase the bioavailability of iron by Fe(II)-catalyzed ligand-controlled dissolution. In oxic environments, photostable ligands such as DFOB can maintain Fe(III) in solution during extended illumination.

Salivary Cystatin SN Is a Factor Predicting Iron Bioavailability in Phytic Acid Rich Meals

Abstract Objectives Phytic acid is an inhibitor of iron bioavailability, but recent research has suggested that individuals may adapt to phytic acid, and that the salivary protein, cystatin SN, may play a role. Study objectives were: 1) to assess the relationship between cystatin SN levels and iron bioavailability during a phytic acid rich meal, and 2) whether cystatin SN would differ among participants with greater vs. lower iron bioavailability overall. Methods Three groups of ten women received meals with: 1) 500 mg phytic acid powder sprinkles 2) 500 mg phytic acid capsules, or 3) no phytic acid. Meals included 18 mg iron. Pre-meal, hemoglobin, iron, ferritin, total iron binding capacity, transferrin saturation, and C - reactive protein were measured from venous blood. Iron bioavailability was measured by the mealtime percentage of maximum iron recovery (% max iron absorption); cystatin SN was measured pre-and post-meal by enzyme-linked immunosorbent assay. All participants completed 3–24 hour dietary recalls. Data were analyzed by multifactor regression analysis and ANOVA. Results There were no significant differences in group dietary intake (P &amp;gt; 0.05). The % max iron absorption was not different among groups; after adjustment, there was significantly greater % max iron absorption in Groups 2 and 3, compared to 1 (P = 0.03, P = 0.004, respectively). Unadjusted pre-to-post meal cystatin SN levels were significantly and positively correlated with improved iron bioavailability in Group 1 (P = 0.046, R2 = 0.4), but not Groups 2 or 3. After adjusted modeling, pre-to-post meal cystatin SN was significantly associated with improved % max iron absorption in Groups 1 and 2 (P's &amp;lt; 0.0001). Overall, there were significantly greater pre-to-post meal cystatin SN levels in participants with % max iron absorption greater, compared to less than 12% (10.2 ± 20.6 vs. −20.5 ± 13.5, respectively, P = 0.01). Conclusions There was a significant relationship between improved iron bioavailability and pre-to-post meal Cystatin SN levels with phytic acid rich meals. Overall, participants with greater meal iron bioavailability had significantly greater pre-to-post meal cystatin SN recovery. Cystatin SN may be a physiological factor in predicting iron bioavailability with phytic acid rich meals. Funding Sources Funded by Wichita State University's School of Nursing.

Prevalence of iron deficiency and related factors in Spanish adolescents.

Iron deficiency anaemia continues to be the world's most important cause of years lived with disability in children and adolescents. Assessment of iron deficiency traditionally depended on laboratory parameters that may be modified by inflammation states, including obesity, which is nowadays a current condition in adolescent population of high-income countries. The present study ascertains the prevalence of iron deficiency and its related factors in adolescents, using the serum transferrin receptor and the reticulocyte haemoglobin content, in order to avoid this confusing effect of classical parameters. A cross-sectional study was conducted on a population-based representative sample for teenagers in Almería (Spain), of 405 subjects aged 12 to 16years. Iron deficiency was present in 13.3% of adolescents, but iron deficiency anaemia only in 1.2%. Multivariate logistic regression analyses showed that being part of an immigrant family, a low iron bioavailability diet, meat consumption below four times a week and fish consumption below twice a week, were independent risk factors for iron deficiency.Conclusion: This study provides an estimate iron deficiency prevalence of 13.3% in Spanish healthy adolescents, avoiding potential confounding factors through the use of new iron status parameters, based on a wide representative sample of adolescents from the city of Almería. What is Known: • For children and adolescents, iron deficiency anaemia continues to be the world's most important cause of years lived with disability. • Assessment of iron deficiency has traditionally depended on laboratory parameters that may be modified by inflammatory states, including obesity. What is New: • Iron deficiency prevalence and their related factors were analysed in Spanish adolescents, avoiding potential confounding factors through the use of sTfR and CHr. • Being part of an immigrant family and consuming a low iron bioavailability diet are independent risk factors for iron deficiency.

Bovine plasma hydrolysates' iron chelating capacity and its potentiating effect on ferritin synthesis in Caco-2 cells.

The low bioavailability of iron is one factor that contributes to its deficiency in the human diet. For this reason, it is necessary to find compounds that can form iron chelates so that these can be added to foods that contain iron to improve its bioavailability at the intracellular level. In this study, we assessed the relationship between bovine plasma hydrolysates' iron chelating ability and their degree of hydrolysis. The hydrolysate with the highest chelating capacity was fractionated and each fraction's chelating capacity was subsequently assessed. Each fraction's effect on ferritin synthesis in Caco-2 cells was also determined. The results showed that bovine plasma hydrolysates with a degree of hydrolysis of 19.1% have an iron chelating capacity of 38.5 ± 0.4% and increase the synthesis of ferritin in Caco-2 cells five-fold compared to the control. This may be due to the fact that these hydrolysates contain amino acids such as Leu, Lys, Glu, Ala, Asp, Val, Thr, Cys and Phe, which may be responsible for binding iron to the hydrolysate, increasing its solubility and the consequent uptake by Caco-2 cells.