Dietary iron depletion at weaning imprints low microbiome diversity and this is not recovered with oral Nano Fe(III)

The effects of iron deficient and high iron diets on SARS-CoV-2 lung infection and disease

Introduction

The severity of Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is often dictated by a range of comorbidities. A considerable literature suggests iron deficiency and iron overload may contribute to increased infection, inflammation and disease severity, although direct causal relationships have been difficult to establish.

Methods

Here we generate iron deficient and iron loaded C57BL/6 J mice by feeding standard low and high iron diets, with mice on a normal iron diet representing controls. All mice were infected with a primary SARS-CoV-2 omicron XBB isolate and lung inflammatory responses were analyzed by histology, immunohistochemistry and RNA-Seq.

Results

Compared with controls, iron deficient mice showed no significant changes in lung viral loads or histopathology, whereas, iron loaded mice showed slightly, but significantly, reduced lung viral loads and histopathology. Transcriptional changes were modest, but illustrated widespread dysregulation of inflammation signatures for both iron deficient vs. controls, and iron loaded vs. controls. Some of these changes could be associated with detrimental outcomes, whereas others would be viewed as beneficial.

Discussion

Diet-associated iron deficiency or overload thus induced modest modulations of inflammatory signatures, but no significant histopathologically detectable disease exacerbations.

Influence of supplementation with iron and probiotic bacteria Lactobacillus plantarum and Lactobacillus curvatus on selected parameters of inflammatory state in rats on a high-fat iron-deficient diet

BACKGROUND

A high-fat (HF) diet, diet iron deficiency and iron supplementation may affect inflammatory parameters. Probiotics influence both iron metabolism and inflammation. We compared the inflammatory state in rats on a HF iron-deficient diet receiving oral iron, Lactobacillus plantarum and Lactobacillus curvatus in different combinations.

METHODS

This was a two-stage experiment. In groups C (n = 8) and HF (n = 8), rats ate a control or HF diet, respectively, for 16 weeks. In the group HFDEF (n = 48), rats ate a HF iron-deficient diet for 8 weeks (first stage) and were subsequently divided into 6 groups (n = 8 each) receiving the following for a further 8 weeks (second stage): HFDEF - a HF iron-deficient diet; HFDEFFe - a HF iron-deficient diet with iron; HFDEFLp and HFDEFLc - a HF iron-deficient diet with L. plantarum or L. curvatus, respectively; and HFDEFFeLp and HFDEFFeLc - a HF iron-deficient diet with iron and L. plantarum or L. curvatus, respectively. Body composition analysis and blood sampling was performed. Markers of iron status and levels of total antioxidant status (TAS), C-reactive protein (CRP), tumour necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) were measured in the blood.

RESULTS

TAS was higher in the HFDEF group (756.57 ± 489.53 ng mL-1) versus the HFDEFLc group (187.04 ± 47.84 ng mL-1; P = 0.022). No more differences were found between groups, or in TAS, CRP, TNF-α and IL-6 concentrations. Also, no differences were found between groups for alanine and aspartate aminotransferases, glucose, total cholesterol, low- and high-density lipoproteins and triglycerides. TAS level was positively correlated with ferritin concentration, IL-6 with TAS and TNF-α with hepcidin level.

CONCLUSIONS

Supplementation with L. plantarum, L. curvatus and iron in combinations exerts no influence on inflammatory status, lipid profile, hepatic function and serum fasting glucose in rats on a HF iron-deficient diet. © 2024 Society of Chemical Industry.

Spotlight on iron overload and ferroptosis: Research progress in female infertility

Iron is an essential trace element for organisms. However, iron overload, which is common in haematological disorders (e.g. haemochromatosis, myelodysplastic syndromes, aplastic anaemia, and thalassaemia, blood transfusion-dependent or not), can promote reactive oxygen species generation and induce ferroptosis, a novel form of programmed cell death characterised by excess iron and lipid peroxidation, thus causing cell and tissue damage. Infertility is a global health concern. Recent evidence has indicated the emerging role of iron overload and ferroptosis in female infertility by inducing hypogonadism, causing ovary dysfunction, impairing preimplantation embryos, attenuating endometrial receptivity, and crosstalk between subfertility-related disorders, such as polycystic ovary syndrome and endometriosis. In addition, gut microbiota and their metabolites are involved in iron metabolism, ferroptosis, and female infertility. In this review, we systematically elaborate on the current research progress in female infertility with a novel focus on iron overload and ferroptosis and summarise promising therapies targeting iron overload and ferroptosis to recover fertility in women. In summary, our study provides new insights into female infertility and offers literature references for the clinical management of female infertility associated with iron overload and ferroptosis, which may be beneficial for females with haematopoietic disorders suffering from both iron overload and infertility.

Single-Cell Hemoprotein Diet Changes Adipose Tissue Distributions and Re-Shapes Gut Microbiota in High-Fat Diet-Induced Obese Mice

We have previously observed that feeding with single-cell hemoprotein (heme-SCP) in dogs (1 g/day for 6 days) and broiler chickens (1 ppm for 32 days) increased the proportion of lactic acid bacteria in the gut while reducing their body weights by approximately 1~2%. To define the roles of heme-SCP in modulating body weight and gut microbiota, obese C57BL/6N mice were administered varied heme-SCP concentrations (0, 0.05, and 0.5% heme-SCP in high fat diet) for 28 days. The heme-SCP diet seemed to restrain weight gain till day 14, but the mice gained weight again later, showing no significant differences in weight. However, the heme-SCP-fed mice had stiffer and oilier bodies compared with those of the control mice, which had flabby bodies and dull coats. When mice were dissected at day 10, the obese mice fed with heme-SCP exhibited a reduction in subcutaneous fat with an increase in muscle mass. The effect of heme-SCP on the obesity-associated dyslipidemia tended to be corroborated by the blood parameters (triglyceride, total cholesterol, and C-reactive protein) at day 10, though the correlation was not clear at day 28. Notably, the heme-SCP diet altered gut microbiota, leading to the proliferation of known anti-obesity biomarkers such as Akkermansia, Alistipes, Oscillibacter, Ruminococcus, Roseburia, and Faecalibacterium. This study suggests the potential of heme-SCP as an anti-obesity supplement, which modulates serum biochemistry and gut microbiota in high-fat diet-induced obese mice.

The effect of iron therapy on oxidative stress and intestinal microbiota in inflammatory bowel diseases: A review on the conundrum

One in five patients with Inflammatory Bowel Disease (IBD) suffers from anemia, most frequently caused by iron deficiency. Anemia and iron deficiency are associated with worse disease outcomes, reduced quality of life, decreased economic participation, and increased healthcare costs. International guidelines and consensus-based recommendations have emphasized the importance of treating anemia and iron deficiency. In this review, we draw attention to the rarely discussed effects of iron deficiency and iron therapy on the redox status, the intestinal microbiota, and the potential interplay between them, focusing on the clinical implications for patients with IBD. Current data are scarce, inconsistent, and do not provide definitive answers. Nevertheless, it is imperative to rule out infections and discern iron deficiency anemia from other types of anemia to prevent untargeted oral or intravenous iron supplementation and potential side effects, including oxidative stress. Further research is necessary to establish the clinical significance of changes in the redox status and the intestinal microbiota following iron supplementation.

Safe and effective delivery of supplemental iron to healthy adults: a two-phase, randomized, double-blind trial - the safe iron study

Introduction

The safety of novel forms of iron in healthy, iron-replete adults as might occur if used in population-based iron supplementation programs was examined. We tested the hypotheses that supplementation with nanoparticulate iron hydroxide adipate tartrate (IHAT), an iron-enriched Aspergillus oryzae product (ASP), or ferrous sulphate heptahydrate (FS) are safe as indicated by erythrocyte susceptibility to malarial infection, bacterial proliferation, and gut inflammation. Responses to FS administered daily or weekly, and with or without other micronutrients were compared.

Methods

Two phases of randomized, double-blinded trials were conducted in Boston, MA. Phase I randomized 160 volunteers to six treatments: placebo, IHAT, ASP, FS, and FS plus a micronutrient powder (MNP) administrated daily at 60 mg Fe/day; and FS administered as a single weekly dose of 420 mg Fe. Phase II randomized 86 volunteers to IHAT, ASP, or FS administered at 120 mg Fe/day. Completing these phases were 151 and 77 participants, respectively. The study was powered to detect effects on primary endpoints: susceptibility of participant erythrocytes to infection by Plasmodium falciparum, the proliferation potential of selected pathogenic bacteria in sera, and markers of gut inflammation. Secondary endpoints for which the study was not powered included indicators of iron status and gastrointestinal symptoms.

Results

Supplementation with any form of iron did not affect any primary endpoint. In Phase I, the frequency of gastrointestinal symptoms associated with FS was unaffected by dosing with MNP or weekly administration; but participants taking IHAT more frequently reported abdominal pain (27%, p < 0.008) and nausea (4%, p = 0.009) than those taking FS, while those taking ASP more frequently reported nausea (8%, p = 0.009). Surprisingly, only 9% of participants taking IHAT at 120 mg Fe/day (Phase II) reported abdominal pain and no other group reported that symptom.

Discussion

With respect to the primary endpoints, few differences were found when comparing these forms of iron, indicating that 28 days of 60 or 120 mg/day of IHAT, ASP, or FS may be safe for healthy, iron-replete adults. With respect to other endpoints, subjects receiving IHAT more frequently reported abdominal pain and nausea, suggesting the need for further study.

Clinical Trial Registration

ClinicalTrials.gov, NCT03212677; registered: 11 July 2017.

Effects of food-grade iron(III) oxide nanoparticles on cecal digesta- and mucosa-associated microbiota and short-chain fatty acids in rats

Although iron(III) oxide nanoparticles (IONPs) are widely used in diverse applications ranging from food to biomedicine, the effects of IONPs on different locations of gut microbiota and short-chain fatty acids (SCFAs) are unclear. So, a subacute repeated oral toxicity study on Sprague Dawley (SD) rats was performed, administering low (50 mg/kg·bw), medium (100 mg/kg·bw), and high (200 mg/kg·bw) doses of IONPs. In this study, we found that a high dose of IONPs increased animal weight, and 16S rRNA sequencing revealed that IONPs caused intestinal flora disorders in both the cecal digesta- and mucosa-associated microbiota. However, only high-dose IONP exposure changed the abundance and composition of the mucosa-associated microbiota. IONPs increased the relative abundances of Firmicutes, Ruminococcaceae_UCG-014, Ruminiclostridium_9, Romboutsia, and Bilophila and decreased the relative abundance of Bifidobacterium, and many of these microorganisms are associated with weight gain, obesity, inflammation, diabetes, and mucosal damage. Functional analysis showed that changes in the gut microbiota induced by a high dose of IONPs were mainly related to metabolism, infection, immune, and endocrine disease functions. IONPs significantly elevated the levels of valeric, isobutyric, and isovaleric acid, promoting the absorption of iron. This is the first description of intestinal microbiota dysbiosis in SD rats caused by IONPs, and the effects and mechanisms of action of IONPs on intestinal and host health need to be further studied and confirmed.

Effects of hemoglobin extracted from Tegillarca granosa on the gut microbiota in iron deficiency anemia mice

Iron deficiency anemia (IDA) is a serious threat to the health of humans around the world. Tegillarca granosa (T. granosa) is considered as an excellent source of iron due to its abundant iron-binding protein hemoglobin. This study aimed to investigate the effects of hemoglobin from T. granosa on the gut microbiota and iron bioavailability in IDA mice. Compared to normal mice, IDA mice showed reduced microbiota diversity and altered relative abundance (reduced Muribaculaceae and increased Bacteroides). After 4 weeks of administration, hemoglobin restored the dysbiosis of the intestinal microbiota induced by IDA and decreased the Firmicutes/Bacteroidota ratio and the abundance of Proteobacteria. Analysis of the hemoglobin regeneration efficiency of mice treated with hemoglobin confirmed that hemoglobin exhibited high iron bioavailability, particularly at low-dose administration, suggesting that a small amount of hemoglobin from T. granosa markedly elevated the blood hemoglobin level in mice. These findings suggested that IDA could be alleviated by administration of hemoglobin with excellent iron bioavailability, and its therapeutic mechanism may be partially attributed to the regulation of the intestinal microbiota composition and relative abundance. These results indicated that T. granosa hemoglobin may be a promising iron supplement to treat IDA and promote the utilization of aquatic-derived proteins.

A novel nano-iron supplement versus standard treatment for iron deficiency anaemia in children 6-35 months (IHAT-GUT trial): a double-blind, randomised, placebo-controlled non-inferiority phase II trial in The Gambia

BACKGROUND

Iron deficiency anaemia (IDA) is the leading cause of years lost to disability in most sub-Saharan African countries and is especially common in young children. The IHAT-GUT trial assessed the efficacy and safety of a novel nano iron supplement, which is a dietary ferritin analogue termed iron hydroxide adipate tartrate (IHAT), for the treatment of IDA in children under 3 years of age.

METHODS

In this single-country, randomised, double-blind, parallel, placebo-controlled, non-inferiority Phase II study in The Gambia, children 6-35 months with IDA (7≤Hb < 11 g/dL and ferritin<30 μg/L) were randomly assigned (1:1:1) to receive either IHAT, ferrous sulphate (FeSO₄) or placebo daily for 3 months (85 days). The daily iron dose was 12.5 mg Fe equivalent for FeSO₄ and the estimated dose with comparable iron-bioavailability for IHAT (20 mg Fe). The primary efficacy endpoint was the composite of haemoglobin response at day 85 and correction of iron deficiency. The non-inferiority margin was 0.1 absolute difference in response probability. The primary safety endpoint was moderate-severe diarrhoea analysed as incidence density and prevalence over the 3 months intervention. Secondary endpoints reported herein include hospitalisation, acute respiratory infection, malaria, treatment failures, iron handling markers, inflammatory markers, longitudinal prevalence of diarrhoea and incidence density of bloody diarrhoea. Main analyses were per-protocol (PP) and intention-to-treat (ITT) analyses. This trial is registered with clinicaltrials.gov (NCT02941081).

FINDINGS

Between Nov 2017 and Nov 2018, 642 children were randomised into the study (214 per group) and included in the ITT analysis, the PP population included 582 children. A total of 50/177 (28.2%) children in the IHAT group achieved the primary efficacy endpoint, as compared with 42/190 (22.1%) in the FeSO₄ group (OR 1.39, 80% CI 1.01-1.91, PP population) and with 2/186 (1.1%) in the placebo group. Diarrhoea prevalence was similar between groups, with 40/189 (21.2%) children in the IHAT group developing at least one episode of moderate-severe diarrhoea over the 85 days intervention, compared with 47/198 (23.7%) in the FeSO₄ group (OR 1.18, 80% CI 0.86-1.62) and 40/195 (20.5%) in the placebo group (OR 0.96, 80% CI 0.7-1.33, PP population). Incidence density of moderate-severe diarrhoea was 2.66 in the IHAT group and 3.42 in the FeSO₄ group (RR 0.76, 80% CI 0.59-0.99, CC-ITT population).There were 143/211 (67.8%) children with adverse events (AEs) in the IHAT group, 146/212 (68.9%) in the FeSO₄ group and 143/214 (66.8%) in the placebo group. There were overall 213 diarrhoea-related AEs; 35 (28.5%) cases reported in the IHAT group compared with 51 (41.5%) cases in the FeSO₄ group and 37 (30.1%) cases in the placebo group.

INTERPRETATION

In this first Phase II study conducted in young children with IDA, IHAT showed sufficient non-inferiority compared to standard-of-care FeSO₄, in terms of ID correction and haemoglobin response, to warrant a definitive Phase III trial. In addition, IHAT had lower incidence of moderate-severe diarrhoea than FeSO₄, with no increased adverse events in comparison with placebo.

FUNDING

The Bill & Melinda Gates Foundation (OPP1140952).

Effect of Diets Varying in Iron and Saturated Fat on the Gut Microbiota and Intestinal Inflammation: A Crossover Feeding Study among Older Females with Obesity

Obesity is considered an independent risk factor for colorectal cancer (CRC). Altered nutrient metabolism, particularly changes to digestion and intestinal absorption, may play an important role in the development of CRC. Iron can promote the formation of tissue-damaging and immune-modulating reactive oxygen species. We conducted a crossover, controlled feeding study to examine the effect of three, 3-week diets varying in iron and saturated fat content on the colonic milieu and systemic markers among older females with obesity. Anthropometrics, fasting venous blood and stool were collected before and after each diet. There was a minimum 3-week washout period between diets. Eighteen participants consumed the three diets (72% Black; mean age 60.4 years; mean body mass index 35.7 kg/m2). Results showed no effect of the diets on intestinal inflammation (fecal calprotectin) or circulating iron, inflammation, and metabolic markers. Pairwise comparisons revealed less community diversity between samples (beta diversity, calculated from 16S rRNA amplicon sequences) among participants when consuming a diet low in iron and high in saturated fat vs. when consuming a diet high in iron and saturated fat. More studies are needed to investigate if dietary iron represents a salient target for CRC prevention among individuals with obesity.

Gastrointestinal side effects of iron supplements: potential effects on gut microbiota

Iron deficiency anemia remains a significant problem in pediatric practice with its prevalence of 6–40% in the Russian Federation. Oral iron supplementation is the most common first-line treatment especially in outpatient setting. Despite adequate efficacy of oral supplementation, the problem of its side effects and, primarily, gastrointestinal toxicity remains. This review examines the issue of the potential effect of iron supplementation on gut microbiota composition, presents data from studies in animal models and in clinical studies. 

The whole food beef matrix is more than the sum of its parts

Foods are not simply a delivery vehicle for nutrients; they consist of a matrix in which nutrients and non-nutrient compounds are presented that induce physiologic effects different from isolated nutrients. Dietary guidance is often based on effects of single nutrients that are considered unhealthy, such as saturated fat in beef. The purpose of this paper is to propose a working definition of the whole food beef matrix whose consumption has health effects distinct from those of isolated nutrients. The beef matrix can be defined as: the collective nutritive and non-nutritive components of the beef food structure and their unique chemical and physical interactions that may be important for human health which are distinguishable from those of the single components in isolation. Background information supporting this approach is summarized on multiple components provided by beef, temporal changes in beef consumption, dietary guidance that restricts beef, and how the background diet determines healthfulness rather than a single food. Examples of research are provided on other whole foods that differ from their constitutive nutrients and lay the groundwork for studies of beef as part of a healthy dietary pattern.

Influence of multistrain probiotic and iron supplementation on iron status in rats

OBJECTIVE

The impact of multistrain probiotics on iron (Fe) metabolism under Fe-deficient diet conditions remains unknown. The study aimed to compare the effect of 6 weeks simultaneous and exclusive oral multistrain probiotic and iron supplementation on selected parameters of Fe metabolism in rats on an Fe-deficient diet.

METHODS

Forty rats were assigned to five groups, with eight animals in each, and for 6 weeks received: the CC group- a standard diet, the DD group- an Fe-deficient diet, the DPB group- an Fe-deficient with a multispecies probiotic, the DFE group- an Fe-deficient diet supplemented with iron, the DPBFE group- an Fe-deficient diet with iron and a multispecies probiotic. The Fe content in blood and tissues; serum concentration of erythroferrone, ferritin (Ft), homocysteine, hepcidin (HEPC) and lactoferrin; liver content of divalent metal transporter 1 (DMT1), transferrin receptor protein 1 (TfR1) and 2 (TfR2) and ZRT/IRT-like protein 14 (ZIP14) and faecal microbiota were assessed.

RESULTS

In DPBFE group, unlike in DPB and DFE groups, duodenal Fe content was higher compared to DD group. Similarly, serum Ft level was higher in DPBFE group, but not in DPB and DFE groups, compared to DD group.

CONCLUSIONS

Six weeks simultaneous oral multistrain probiotic and Fe supplementation, but not exclusive probiotic or Fe intake, increases duodenal Fe absorption in rats and presents higher effectiveness in increasing tissue Fe stores.

Supplementation with Sucrosomial® iron leads to favourable changes in the intestinal microbiome when compared to ferrous sulfate in mice

Iron deficiency is one of the most common nutritional deficiencies worldwide and is often treated with oral iron supplements. However, commonly used supplements, including those based on ferrous iron salts, are associated with gastrointestinal side effects and unfavorable changes in the intestinal microbiome. Sucrosomial® iron is a novel iron formulation that is effective at treating iron deficiency, and with fewer gastrointestinal side effects, yet its effect on the gut microbiome has not been examined previously. Thus, we treated mice for two weeks with diets containing either Sucrosomial® iron or ferrous sulfate as the sole iron source and examined bacterial communities in the intestine using 16S Microbial Profiling of DNA extracted from feces collected both prior to and following dietary treatment. Mice treated with Sucrosomial® iron showed an increase in Shannon diversity over the course of the study. This was associated with a decrease in the abundance of the phylum Proteobacteria, which contains many pathogenic species, and an increase in short chain fatty acid producing bacteria such as Lachnospiraceae, Oscillibacter and Faecalibaculum. None of these changes were observed in mice treated with ferrous sulfate. These results suggest that Sucrosomial® iron may have a beneficial effect on the intestinal microbiome when compared to ferrous sulfate and that this form of iron is a promising alternative to ferrous iron salts for the treatment of iron deficiency.

Comparative Evaluation of Sucrosomial Iron and Iron Oxide Nanoparticles as Oral Supplements in Iron Deficiency Anemia in Piglets

Iron deficiency is the most common mammalian nutritional disorder. However, among mammalian species iron deficiency anemia (IDA), occurs regularly only in pigs. To cure IDA, piglets are routinely injected with high amounts of iron dextran (FeDex), which can lead to perturbations in iron homeostasis. Here, we evaluate the therapeutic efficacy of non-invasive supplementation with Sucrosomial iron (SI), a highly bioavailable iron supplement preventing IDA in humans and mice and various iron oxide nanoparticles (IONPs). Analysis of red blood cell indices and plasma iron parameters shows that not all iron preparations used in the study efficiently counteracted IDA comparable to FeDex-based supplementation. We found no signs of iron toxicity of any tested iron compounds, as evaluated based on the measurement of several toxicological markers that could indicate the occurrence of oxidative stress or inflammation. Neither SI nor IONPs increased hepcidin expression with alterations in ferroportin (FPN) protein level. Finally, the analysis of the piglet gut microbiota indicates the individual pattern of bacterial diversity across taxonomic levels, independent of the type of supplementation. In light of our results, SI but not IONPs used in the experiment emerges as a promising nutritional iron supplement, with a high potential to correct IDA in piglets.

Imbalanced dietary intake alters the colonic microbial profile in growing rats

An imbalanced dietary intake is associated with alteration of intestinal ecosystem. We investigated the impact of imbalanced diets on colonic microbiota, concentrations of short chain fatty acid in colonic digesta and serum immunoglobulins (Igs) of growing rats. Compared to the control diet, consuming diets high in fat, sucrose, or processed meat, or low in iron, increased the abundance of the pathogenic bacteria such as Clostridium, Escherichia coli, and Salmonella species, and decreased the beneficial bacteria, like Bifidobacteria, Lactobacillus, Akkermansia, Phascolarctobacterium, Alistipes, and butyrate producing species of bacteria in the colon of growing rats. The heatmap of metagenomics indicated that each group was separated into distinct clusters, and the ID group in particular, showed significantly (P < 0.01) reduced alpha diversity of colonic microbiota in comparison to the control group. All experimental groups showed significantly (P < 0.05 or P < 0.01) decreased concentration of acetate and butyrate in the colonic digesta and lower levels of serum IgG or IgA, compared to the control. These results indicated that the imbalanced dietary intake negatively altered intestinal ecosystem and immunity.

Oral iron supplementation in patients with chronic kidney disease: Can it be harmful to the gut microbiota?

Patients with chronic kidney disease (CKD) have several pathophysiological alterations, including anemia, one of the first changes in CKD patients. More recently, researchers have observed that the intestinal microbiota alterations are also another complication in these patients. The most common treatment for anemia is oral (mainly ferrous sulfate) or intravenous iron supplementation. Despite being a necessary treatment, recent studies have reported that supplementation with oral iron may increase its availability in the intestine, leading to disturbance in the gut microbiota and also to oxidative stress in the enterocytes, which may change the permeability and the microbiota profile. Although it is a therapy routinely used in patients with CKD, supplementation with oral iron on the gut microbiota has been rarely studied in these patients. Thus, this review will discuss the relationship between iron and the gut microbiota and the possible effects of oral iron supplementation on gut microbiota in patients with CKD.

Nanoparticles in the Food Industry and Their Impact on Human Gut Microbiome and Diseases

The use of inorganic nanoparticles (NPs) has expanded into various industries including food manufacturing, agriculture, cosmetics, and construction. This has allowed NPs access to the human gastrointestinal tract, yet little is known about how they may impact human health. As the gut microbiome continues to be increasingly implicated in various diseases of unknown etiology, researchers have begun studying the potentially toxic effects of these NPs on the gut microbiome. Unfortunately, conflicting results have limited researcher’s ability to evaluate the true impact of NPs on the gut microbiome in relation to health. This review focuses on the impact of five inorganic NPs (silver, iron oxide, zinc oxide, titanium dioxide, and silicon dioxide) on the gut microbiome and gastrointestinal tract with consideration for various methodological differences within the literature. This is important as NP-induced changes to the gut could lead to various gut-related diseases. These include irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), celiac disease, and colorectal cancer. Research in this area is necessary as the use of NPs in various industries continues to grow along with the number of people suffering from chronic gastrointestinal diseases.

Safe and effective delivery of supplemental iron to healthy older adults: The double-blind, randomized, placebo-controlled trial protocol of the Safe Iron Study

The forms of iron currently available to correct iron deficiency have adverse effects, including infectious diarrhea, increased susceptibility to malaria, inflammation and detrimental changes to the gut microbiome. These adverse effects limit their use such that the growing burden of iron deficiency has not abated in recent decades. Here, we summarize the protocol of the "Safe Iron Study", the first clinical study examining the safety and efficacy of novel forms of iron in healthy, iron-replete adults. The Safe Iron Study is a double-blind, randomized, placebo-controlled trial conducted in Boston, MA, USA. This study compares ferrous sulfate heptahydrate (FeSO 4·H 2O) with two novel forms of iron supplements (iron hydroxide adipate tartrate (IHAT) and organic fungal iron metabolite (Aspiron™ Natural Koji Iron)). In Phase I, we will compare each source of iron administrated at a low dose (60 mg Fe/day). We will also determine the effect of FeSO 4 co-administrated with a multiple micronutrient powder and weekly administration of FeSO 4. The forms of iron found to produce no adverse effects, or adverse effects no greater than FeSO 4 in Phase I, Phase II will evaluate a higher, i.e., a therapeutic dose (120 mg Fe/day). The primary outcomes of this study include ex vivo malaria ( Plasmodium falciparum) infectivity of host erythrocytes, ex vivo bacterial proliferation (of selected species) in presence of host plasma and intestinal inflammation assessed by fecal calprotectin. This study will test the hypotheses that the novel forms of iron, administered at equivalent doses to FeSO 4, will produce similar increases in iron status in iron-replete subjects, yet lower increases in ex vivo malaria infectivity, ex vivo bacterial proliferation, gut inflammation. Ultimately, this study seeks to contribute to development of safe and effective forms of supplemental iron to address the global burden of iron deficiency and anemia. Registration: ClinicalTrials.gov identifier: NCT03212677; registered: 11 July 2017.

Iron homeostasis in host and gut bacteria - a complex interrelationship

Iron deficiency is the most frequent nutritional deficiency in the world with an estimated 1.4 billion people affected. The usual way to fight iron deficiency is iron fortification, but this approach is not always effective and can have undesirable side effects including an increase in the growth and virulence of gut bacterial pathogens responsible for diarrhea and gut inflammation. Iron is mainly absorbed in the duodenum and is tightly regulated in mammals. Unabsorbed iron enters the colonic lumen where many microorganisms, referred to as gut microbiota, reside. Iron is essential for these bacteria, and its availability consequently affects this microbial ecosystem. The aim of this review is to provide further insights into the complex relationship between iron and gut microbiota. Given that overcoming anemia caused by iron deficiency is still a challenge today, gut microbiota could help identify more efficient ways to tackle this public health problem.

Comparative Gut Microbiome Differences between Ferric Citrate and Calcium Carbonate Phosphate Binders in Patients with End-Stage Kidney Disease

Gut dysbiosis in patients with chronic kidney disease (CKD) may induce chronic inflammation and increase morbidity. Phosphate-binding agents, generally used in patients with CKD, may potentially change the composition of the gut microbiota. This study aimed to compare the microbiota composition in hemodialysis patients treated with ferric citrate or calcium carbonate. The stool microbiota was investigated in hemodialysis patients treated with ferric citrate (n = 8) and calcium carbonate (n = 46) using 16S rRNA gene amplicon sequencing profiling using linear discriminant analysis of effect size. Further predictive functional profiling of microbial communities was obtained with Tax4Fun in R. Hemodialysis patients treated with calcium carbonate had a significantly reduced microbial species diversity (Shannon index and Simpson index) and an increased microbial alteration ratio compared with patients treated with ferric citrate. A distinct microbial community structure was found in patients treated with ferric citrate, with an increased abundance of the Bacteroidetes phylum and a decreased abundance of the phylum Firmicutes. Members of the order Lactobacillales were enriched in patients treated with calcium carbonate, whereas taxa of the genera Ruminococcaceae UCG-004, Flavonifractor, and Cronobacter were enriched in patients treated with ferric citrate phosphate binder. In conclusion, Ferric citrate therapy results in a more diverse microbiome community compared to calcium carbonate therapy in hemodialysis patients with phosphate binder treatment. The gut microbiome reflects the phosphate binder choice in hemodialysis patients, further affecting the physiological environment in the gastrointestinal tract.

The Impact of Low-Level Iron Supplements on the Faecal Microbiota of Irritable Bowel Syndrome and Healthy Donors Using In Vitro Batch Cultures

Ferrous iron supplementation has been reported to adversely alter the gut microbiota in infants. To date, the impact of iron on the adult microbiota is limited, particularly at low supplementary concentrations. The aim of this research was to explore the impact of low-level iron supplementation on the gut microbiota of healthy and Irritable Bowel Syndrome (IBS) volunteers. Anaerobic, pH-controlled in vitro batch cultures were inoculated with faeces from healthy or IBS donors along with iron (ferrous sulphate, nanoparticulate iron and pea ferritin (50 μmol⁻¹ iron)). The microbiota were explored by fluorescence in situ hybridisation coupled with flow cytometry. Furthermore, metabolite production was assessed by gas chromatography. IBS volunteers had different starting microbial profiles to healthy controls. The sources of iron did not negatively impact the microbial population, with results of pea ferritin supplementation being similar to nanoparticulate iron, whilst ferrous sulphate led to enhanced Bacteroides spp. The metabolite data suggested no shift to potentially negative proteolysis. The results indicate that low doses of iron from the three sources were not detrimental to the gut microbiota. This is the first time that pea ferritin fermentation has been tested and indicates that low dose supplementation of iron is unlikely to be detrimental to the gut microbiota.

The Effects of Iron Supplementation and Fortification on the Gut Microbiota: A Review

Iron supplementation and fortification are used to treat iron deficiency, which is often associated with gastrointestinal conditions, such as inflammatory bowel disease and colorectal cancer. Within the gut, commensal bacteria contribute to maintaining systemic iron homeostasis. Disturbances that lead to excess iron promote the replication and virulence of enteric pathogens. Consequently, research has been interested in better understanding the effects of iron supplementation and fortification on gut bacterial composition and overall gut health. While animal and human trials have shown seemingly conflicting results, these studies emphasize how numerous factors influence gut microbial composition. Understanding how different iron formulations and doses impact specific bacteria will improve the outcomes of iron supplementation and fortification in humans. Furthermore, discerning the nuances of iron supplementation and fortification will benefit subpopulations that currently do not respond well to treatment.

Effect of sucroferric oxyhydroxide on gastrointestinal microbiome and uremic toxins in patients with chronic kidney disease undergoing hemodialysis

BACKGROUND

In patients with chronic kidney disease (CKD), dysbiosis in the gastrointestinal microbiome is thought to be associated with increased production of uremic toxins, such as indoxyl sulfate (IS) and p-cresyl sulfate (PCS). Sucroferric oxyhydroxide (SFO), an iron-based phosphate binder, may affect the gastrointestinal microbiome and the production of uremic toxins. We aimed to examine whether SFO administration affected distribution of gastrointestinal microbiome and serum uremic toxin levels in CKD patients undergoing hemodialysis.

METHODS

In this single-center, open-label, interventional study, 18 maintenance hemodialysis patients with hyperphosphatemia were prescribed with SFO. We collected serum samples before and after 3 months of administration, and serum levels of IS and PCS were measured. A control group of 20 hemodialysis patients without SFO was evaluated. We evaluated gastrointestinal microbiome of patients pre- and post-SFO administration by 16S rDNA sequencing and bioinformatics analysis.

RESULTS

Serum IS and PCS levels were significantly elevated after administration of SFO (IS before 2.52 ± 1.60 mg/dl vs. after 3.13 ± 1.51 mg/dl, P = 0.008; PCS before 2.32 ± 2.44 mg/dl vs. after 3.45 ± 2.11 mg/dl, P = 0.002), while serum IS and PCS levels did not change in the control group. Microbiome analysis in the SFO group showed no significant change in diversity and major components in phylum, class, order, family, gene, and species.

CONCLUSION

Administration of SFO increased the serum levels of IS and PCS with no change of major components of gastrointestinal microbiome.

Hepcidin and Erythroferrone Correlate with Hepatic Iron Transporters in Rats Supplemented with Multispecies Probiotics

The influence of probiotic supplementation on iron metabolism remains poorly investigated. However, a range of studies, especially on Lactobacillus plantarum 299v (Lp229v), have indicated a possible positive impact of probiotics on iron absorption. The aim of the study was to determine the effect of multistrain probiotic supply on iron balance. Thirty Wistar rats were randomized into three groups: placebo (KK group), and multistrain probiotic per os in a daily dose of 2.5 × 10⁹ colony forming units (CFU) (PA group) or 1 × 10¹⁰ CFU (PB group). Multistrain probiotic consisted of nine bacterial strains: Bifidobacterium bifidum W23, B. lactis W51, B. lactis W52, Lactobacillus acidophilus W37, L. brevis W63, L. casei W56, L. salivarius W24, Lactococcus lactis W19, and Lc. lactis W58, in equal proportions. After six weeks, blood and organ samples were collected. No differences were found between the three groups in terms of serum concentrations of hepcidin (HEPC), lactoferrin (LTF), homocysteine (HCY), ferritin (Ft), or erythroferrone (ErFe), or in liver content of divalent metal transporter 1 (DMT1), transferrin receptors 1 and 2 (TfR), or ZRT/IRT-like protein 14 (ZIP14) proteins. In the overall sample, positive correlations were noted between the serum concentrations of hepcidin and lactoferrin, and hepcidin and ferritin; serum concentration of hepcidin and DMT1 and TfR1 in the liver; and serum concentration of erythroferrone and TfR2 in the liver. The correlations of serum hepcidin and erythroferrone with liver DMT1 and TfR represent significant mechanisms of Fe homeostasis. Our study has shown that multistrain probiotic supplementation used in the experiment did not disrupt the biochemical and hepatic regulatory processes of Fe balance and did not demonstrate significant influence on selected parameters of Fe metabolism.

The Effect of Multispecies Probiotic Supplementation on Iron Status in Rats

A range of interactions between gut microbiota and iron (Fe) metabolism is described. Oral probiotics ameliorate host's iron status. However, this has been proven for single-strain probiotic supplements. Dose-dependence of beneficial probiotic supplementation effect on iron turnover remains unexplored. Our study aimed to investigate the effects of oral multispecies probiotic supplementation in two doses on iron status in rats. Thirty rats were randomized into three groups receiving multispecies probiotic supplement at a daily dose of 2.5 × 10⁹ CFU (PA group, n = 10) and 1 × 10¹⁰ CFU (PB group, n = 10) or placebo (KK group, n = 10). After 6 weeks, rats were sacrificed for analysis, blood samples, and organs (the liver, heart, kidneys, spleen, pancreas, femur, testicles, duodenum, and hair) were collected. The total fecal bacteria content was higher in the PB group vs. PA group. Unsaturated iron-binding capacity was higher in the PB group vs. KK group. Serum Fe was lower in both PA and PB vs. KK group. Iron content in the liver was higher in the PB group vs. KK group; in the pancreas, this was higher in the PB group vs. the KK and PA group, and in the duodenum, it was higher in both supplemented groups vs. the KK group. A range of alterations in zinc and copper status and correlations between analyzed parameters were found. Oral multispecies probiotic supplementation exerts dose-independent and beneficial effect on iron bioavailability and duodenal iron absorption in the rat model, induces a dose-independent iron shift from serum and intensifies dose-dependent pancreatic and liver iron uptake.

Early-Life Iron Deficiency and Subsequent Repletion Alters Development of the Colonic Microbiota in the Pig

Background: Iron deficiency is the most prevalent micronutrient deficiency worldwide, affecting over two billion people. Early-life iron deficiency may alter the developing microbiota, which may or may not be reversible with subsequent dietary iron repletion. Thus, the aim of this study was to determine whether early-life iron deficiency and subsequent repletion alter colonic microbial composition and fermentation end-product concentrations in pigs. Methods: Forty-two male pigs received either control (CONT, 21.3 mg Fe/L) or iron-deficient (ID, 2.72 mg Fe/L) milk replacer treatments from postnatal day (PND) 2 to 32. Subsequently, 20 pigs continued through a series of age-appropriate, iron-adequate diets from PND 33 to 61. Contents from the ascending colon (AC) and rectum (feces) were collected at PND 32 and/or 61. Assessments included microbiota composition by 16S rRNA sequencing and volatile fatty acid (VFA) concentrations by gas chromatography methods. Data were analyzed using a 1-way ANOVA and PERMANOVA to assess the main effects of early-life iron status on all outcomes. Results: In AC samples, 15 genera differed (P < 0.05) between ID and CONT pigs, while 27 genera differed (P < 0.05) in fecal samples at PND 32. Early-life ID pigs had higher (P = 0.012) relative abundance of Lactobacillus in AC samples compared with CONT pigs. In feces, ID pigs had lower (P < 0.05) relative abundances of Bacteroides and Clostridium from the families of Clostridiaceae, Lachnospiraceae, and Ruminococcaceae. At PND 61, only two genera differed between treatment groups in AC samples, with ID pigs having a higher (P = 0.043) relative abundance of Bifidobacterium and lower (P = 0.047) relative abundance of Prevotella. Beta diversity differed at PND 32 in both AC and feces between CONT and ID pigs but no differences remained at PND 61. At PND 32, the total VFA concentration was higher in ID pigs compared with CONT pigs in both AC (P = 0.003) and feces (P = 0.001), but no differences in VFA concentrations persisted to PND 61. Conclusion: Early-life iron status influenced microbial composition and VFA concentrations within the large intestine, but these differences were largely normalized following subsequent dietary iron repletion.

Safe and effective delivery of supplemental iron to healthy older adults: The double-blind, randomized, placebo-controlled trial protocol of the Safe Iron Study

The forms of iron currently available to correct iron deficiency have adverse effects, including infectious diarrhea, increased susceptibility to malaria, inflammation and detrimental changes to the gut microbiome. These adverse effects limit their use such that the growing burden of iron deficiency has not abated in recent decades. Here, we summarize the protocol of the "Safe Iron Study", the first clinical study examining the safety and efficacy of novel forms of iron in healthy, iron-replete adults. The Safe Iron Study is a double-blind, randomized, placebo-controlled trial conducted in Boston, MA, USA. This study compares ferrous sulfate heptahydrate (FeSO 4·H 2O) with two novel forms of iron supplements (iron hydroxide adipate tartrate (IHAT) and organic fungal iron metabolite (Aspiron™ Natural Koji Iron)). In Phase I, we will compare each source of iron administrated at a low dose (60 mg Fe/day). We will also determine the effect of FeSO 4 co-administrated with a multiple micronutrient powder and weekly administration of FeSO 4. The forms of iron found to produce no adverse effects or adverse effects no greater than FeSO 4 in Phase I, Phase II will evaluate a higher, i.e., a therapeutic dose (120 mg Fe/day). The primary outcomes of this study include ex vivo malaria ( Plasmodium falciparum) infectivity of host erythrocytes, ex vivo bacterial proliferation (of selected species) in presence of host plasma and intestinal inflammation assessed by fecal calprotectin. This study will test the hypotheses that the novel forms of iron, administered at equivalent doses to FeSO 4, will produce similar increases in iron status in iron-replete subjects, yet lower increases in ex vivo malaria infectivity, ex vivo bacterial proliferation, gut inflammation. Ultimately, this study seeks to contribute to development of safe and effective forms of supplemental iron to address the global burden of iron deficiency and anemia. Registration: ClinicalTrials.gov identifier: NCT03212677; registered: 11 July 2017.

Dietary iron variably modulates assembly of the intestinal microbiota in colitis-resistant and colitis-susceptible mice

Iron deficiency, a common comorbidity of gastrointestinal inflammatory disorders such as inflammatory bowel diseases (IBD), is often treated with oral iron supplementation. However, the safety of oral iron supplementation remains controversial because of its association with exacerbated disease activity in a subset of IBD patients. Because iron modulates bacterial growth and function, one possible mechanism by which iron may exacerbate inflammation in susceptible hosts is by modulating the intestinal microbiota. We, therefore, investigated the impact of dietary iron on the intestinal microbiota, utilizing the conventionalization of germ-free mice as a model of a microbial community in compositional flux to recapitulate the instability of the IBD-associated intestinal microbiota. Our findings demonstrate that altering intestinal iron availability during community assembly modulated the microbiota in non-inflamed wild type (WT) and colitis-susceptible interleukin-10-deficient (Il10^-/-) mice. Depletion of luminal iron availability promoted luminal compositional changes associated with dysbiotic states irrespective of host genotype, including an expansion of Enterobacteriaceae such as Escherichia coli. Mechanistic in vitro growth competitions confirmed that high-affinity iron acquisition systems in E. coli enhance its abundance over other bacteria in iron-restricted conditions, thereby enabling pathobiont iron scavenging during dietary iron restriction. In contrast, distinct luminal community assembly was observed with dietary iron supplementation in WT versus Il10^-/- mice, suggesting that the effects of increased iron on the microbiota differ with host inflammation status. Taken together, shifts in dietary iron intake during community assembly modulate the ecological structure of the intestinal microbiota and is dependent on host genotype and inflammation status.

Impact of Micronutrients on the Immune Response of Animals

Vitamins and minerals (micronutrients) play an important role in regulating and shaping an immune response. Deficiencies generally result in inadequate or dysregulated cellular activity and cytokine expression, thereby affecting the immune response. Decreased levels of natural killer, granulocyte, and phagocytic cell activity and T and B cell proliferation and trafficking are associated with inadequate levels of micronutrients, as well as increased susceptibility to various adverse health conditions, including inflammatory disorders, infection, and altered vaccine efficacy. In addition, most studies of micronutrient modulation of immune responses have been done in rodents and humans, thus limiting application to the health and well-being of livestock and companion animals. This exploratory review elucidates the role of vitamins and minerals on immune function and inflammatory responses in animals (pigs, dogs, cats, horses, goats, sheep, and cattle), with reference to rodents and humans.

A novel nano-iron supplement to safely combat iron deficiency and anaemia in young children: The IHAT-GUT double-blind, randomised, placebo-controlled trial protocol

Background: Iron deficiency and its associated anaemia (IDA) are the leading forms of micronutrient malnutrition worldwide. Here we describe the rationale and design of the first clinical trial evaluating the efficacy and safety of an innovative nano iron supplement, iron hydroxide adipate tartrate (IHAT), for the treatment of IDA in young children (IHAT-GUT trial). Oral iron is often ineffective due to poor absorption and/or gastrointestinal adverse effects. IHAT is novel since it is effectively absorbed whilst remaining nanoparticulate in the gut, therefore should enable supplementation with fewer symptoms. Methods: IHAT-GUT is a three-arm, double-blind, randomised, placebo-controlled phase II trial conducted in Gambian children 6-35 months of age. The intervention consists of a 12-week supplementation with either IHAT, ferrous sulphate (both at doses bioequivalent to 12.5 mg Fe/day) or placebo. The trial aims to include 705 children with IDA who will be randomly assigned (1:1:1) to each arm. The primary objectives are to test non-inferiority of IHAT in relation to ferrous sulphate at treating IDA, and to test superiority of IHAT in relation to ferrous sulphate and non-inferiority in relation to placebo in terms of diarrhoea incidence and prevalence. Secondary objectives are mechanistic assessments, to test whether IHAT reduces the burden of enteric pathogens, morbidity, and intestinal inflammation, and that it does not cause detrimental changes to the gut microbiome, particularly in relation to Lactobacillaceae, Bifidobacteriaceae and Enterobacteriaceae. Discussion: This trial will test the hypothesis that supplementation with IHAT eliminates iron deficiency and improves haemoglobin levels without inducing gastrointestinal adverse effects. If shown to be the case, this would open the possibility for further testing and use of IHAT as a novel iron source for micronutrient intervention strategies in resource-poor countries, with the ultimate aim to help reduce the IDA global burden. Registration: This trial is registered at clinicaltrials.gov ( NCT02941081).

A novel nano-iron supplement to safely combat iron deficiency and anaemia in young children: The IHAT-GUT double-blind, randomised, placebo-controlled trial protocol

Background: Iron deficiency and its associated anaemia (IDA) are the leading forms of micronutrient malnutrition worldwide. Here we describe the rationale and design of the first clinical trial evaluating the efficacy and safety of an innovative nano iron supplement, iron hydroxide adipate tartrate (IHAT), for the treatment of IDA in young children (IHAT-GUT trial). Oral iron is often ineffective due to poor absorption and/or gastrointestinal adverse effects. IHAT is novel since it is effectively absorbed whilst remaining nanoparticulate in the gut, therefore should enable supplementation with fewer symptoms. Methods: IHAT-GUT is a three-arm, double-blind, randomised, placebo-controlled phase II trial conducted in Gambian children 6-35 months of age. The intervention consists of a 12-week supplementation with either IHAT, ferrous sulphate (both at doses bioequivalent to 12.5 mg _Fe/day) or placebo. The trial aims to include 705 children with IDA who will be randomly assigned (1:1:1) to each arm. The primary objectives are to test non-inferiority of IHAT in relation to ferrous sulphate at treating IDA, and to test superiority of IHAT in relation to ferrous sulphate and non-inferiority in relation to placebo in terms of diarrhoea incidence and prevalence. Secondary objectives are mechanistic assessments, to test whether IHAT reduces the burden of enteric pathogens, morbidity, and intestinal inflammation, and that it does not cause detrimental changes to the gut microbiome, particularly in relation to Lactobacillaceae, Bifidobacteriaceae and Enterobacteriaceae. Discussion: This trial will test the hypothesis that supplementation with IHAT eliminates iron deficiency and improves haemoglobin levels without inducing gastrointestinal adverse effects. If shown to be the case, this would open the possibility for further testing and use of IHAT as a novel iron source for micronutrient intervention strategies in resource-poor countries, with the ultimate aim to help reduce the IDA global burden. Registration: This trial is registered at clinicaltrials.gov ( NCT02941081).

Iron deficiency anaemia: experiences and challenges

Iron deficiency remains the largest nutritional deficiency worldwide and the main cause of anaemia. Severe iron deficiency leads to anaemia known as iron deficiency anaemia (IDA), which affects a total of 1·24 billion people, the majority of whom are children and women from resource-poor countries. In sub-Saharan Africa, iron deficiency is frequently exacerbated by concomitant parasitic and bacterial infections and contributes to over 120 000 maternal deaths a year, while it irreparably limits the cognitive development of children and leads to poor outcomes in pregnancy.Currently available iron compounds are cheap and readily available, but constitute a non-physiological approach to providing iron that leads to significant side effects. Consequently, iron deficiency and IDA remain without an effective treatment, particularly in populations with high burden of infectious diseases. So far, despite considerable investment in the past 25 years in nutrition interventions with iron supplementation and fortification, we have been unable to significantly decrease the burden of this disease in resource-poor countries.If we are to eliminate this condition in the future, it is imperative to look beyond the strategies used until now and we should make an effort to combine community engagement and social science approaches to optimise supplementation and fortification programmes.

Impact of Iron-Enriched Aspergillus oryzae on Iron Bioavailability, Safety, and Gut Microbiota in Rats

Iron deficiency is a leading global nutritional problem. Ferrous sulfate (FeSO₄) is the most common iron source used for supplementation. Because of many side effects associated with its consumption, it is important to identify new forms of iron. The objectives of this study were to assess the bioavailability of iron-enriched Aspergillus oryzae, Aspiron (ASP), evaluate the toxicity of high-dose iron supplementation with ASP, and determine the ASP impact on gut microbiota in rats. In this study, we investigated iron bioavailability using the hemoglobin repletion test. Aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen levels were determined to evaluate the effect on liver and kidney functions. Protein carbonyls were measured to assess oxidative damage to proteins. Fecal samples at the end of the 14 day repletion period were used for 16S rRNA sequencing for gut microbiota analysis. The slope ratio method using a common intercept linear regression model was used to compare the bioavailability of ASP to FeSO₄. Iron repletion increased hemoglobin concentrations with both ASP and FeSO₄ treatments compared to the control group, except in the lowest ASP group. The slope ratio indicated that relative iron bioavailability of ASP was 60% of that of FeSO₄ when hemoglobin change was compared to iron in the diet. Similar results were obtained when absolute iron intake was compared on the basis of food consumption. In comparison to the control, protein carbonyl concentrations were significantly ( p < 0.05) higher in the FeSO₄ group but not with the ASP group. Supplementation with both sources of iron reduced the Enterobacteriaceae population in the gut microbiota of the rats. A higher relative abundance of bacteria from the phylum Verrucomicrobia was also observed with the highest dose of ASP. Iron-enriched A. oryzae with 60% relative bioavailability of FeSO₄ did not show any signs of adverse effects after 14 days of iron supplementation. Future human studies are needed to understand the ASP detailed effect on gut microbiota.

Association between the gut microbiota and mineral metabolism

The aim of this review is to present the most recent scientific evidence of interactions between the intestinal microbiota and minerals, and the effect of this interaction on the health of the host. The Web of Science database from the years 2013-2017 on this topic was reviewed. Numerous in vitro studies have shown that iron significantly affects the intestinal microbiota. However, Bifidobacteriaceae are capable of binding iron in the large intestine, thereby limiting the formation of free radicals synthesized in the presence of iron, and thus reducing the risk of colorectal cancer. Animal studies have revealed that supplementation with probiotics, prebiotics and synbiotics has a significant effect on bone calcium, phosphate and bone metabolism. The dynamic interaction between microbiota and zinc was shown. Human studies have provided evidence of the influence of probiotic bacteria on parathormone, calcium and phosphate levels and thus on bone resorption. Recent studies have produced new information mainly on the impact of the intestinal bacteria on the metabolism of calcium and iron. From a scientific perspective, the most urgent fields that remain to be investigated are the identification of all human gut microbes and new therapies targeting the interaction between intestinal bacteria and minerals. © 2017 Society of Chemical Industry.

Nanomaterial–microbe cross-talk: physicochemical principles and (patho)biological consequences

NPs’ characteristics impact their spontaneous binding to microbes, which may affect the (patho)biological identity of both NP and microbes.

Iron Supplements Modulate Colon Microbiota Composition and Potentiate the Protective Effects of Probiotics in Dextran Sodium Sulfate-induced Colitis

BACKGROUND

Iron is an important nutrient for both the host and colonizing bacteria. Oral iron supplementation may impact the composition of the microbiota and can be particularly damaging to patients suffering from inflammatory bowel disease (IBD). However, patients with IBD may require iron supplementation to treat their anemia.

METHODS

We fed mice with diets supplemented with ferrous sulfate at different doses (5, 50, and 500 mg of iron/kg chow) and with different iron formulations (ferrous sulfate, ferrous bisglycinate and ferric ethylenediaminetetraacetic acid [FEDTA]), and analyzed the effects on the composition of the gut microbiota by 16S ribosomal RNA gene sequencing. Using the dextran sodium sulfate (DSS)-induced colitis mouse model, we investigated the effects of iron supplementation in colitis severity, as well as the use of the probiotic Escherichia coli Nissle 1917 (EcN) in combination with iron supplementation.

RESULTS

Iron supplementation at different doses induced shifts in the gut microbial communities and inferred metabolic pathways. However, depending on the iron formulation used in the diets, iron supplementation during dextran sodium sulfate-induced colitis was either beneficial (ferrous bisglycinate) or highly detrimental (FEDTA). Finally, the beneficial effect of the probiotic EcN in the dextran sodium sulfate-induced colitis model was potentiated by oral iron supplementation with ferrous sulfate.

CONCLUSIONS

These results show that the iron formulations used to treat iron deficiency influence the gut microbiota and colitis in mice and suggest that distinct iron compounds may be of particular relevance to patients with IBD. In addition, the beneficial action of probiotics in IBD may be enhanced by oral iron supplementation.

Bioavailability of iron multi-amino acid chelate preparation in mice and human duodenal HuTu 80 cells

Strategies for preventing Fe deficiency include Fe supplementation and Fe fortification of foods. The absorption, metabolism and chemical characteristics of Fe multi-amino acid chelate (IMAAC) are not known. Absorption of IMAAC was compared with FeSO4in Fe-depleted mice andin vitrochemical studies of the Fe supplement was performed in HuTu 80 cells. Hb repletion study was carried out in Fe-deficient CD1 mice that were fed for 10 d a diet supplemented with ferrous IMAAC or FeSO4. A control group of Fe-replete mice was fed a diet with adequate Fe concentrations throughout the study. Tissues were collected from the mice, and the expression of Fe-related genes was determined by quantitative PCR. Ferric reductase and Fe uptake were evaluated in HuTu 80 cells. Supplementation of the diet with FeSO4or IMAAC significantly increased Hb levels (P<0·001) in Fe-deficient mice from initial 93·9 (SD10·8) or 116·2 (SD9·1) to 191 (SD0·7) or 200 (SD0·5) g/l, respectively. Initial and final Hb for the Fe-deficient control group were 87·4 (SD6·7) and 111 (SD11·7) g/l, respectively. Furthermore, the liver non-haem Fe of both supplement groups increased significantly (P<0·001). IMAAC was more effective at restoring Fe in the spleen compared with FeSO4(P<0·005). Gene expression showed the IMAAC supplement absorption is regulated by the body’s Fe status as it significantly up-regulated hepcidin (P<0·001) and down-regulated duodenal cytochrome b mRNA (P<0·005), similar to the effects seen with FeSO4. A significant proportion of Fe in IMAAC is reduced by ascorbic acid. Fe absorption in mice and cells was similar for both IMAAC and FeSO4and both compounds induce and regulate Fe metabolism genes similarly in the maintenance of homeostasis in mice.

Siderophore-mediated iron acquisition and modulation of host-bacterial interactions

Iron is an essential micronutrient for most life forms including the majority of resident bacteria of the microbiota and their mammalian hosts. Bacteria have evolved numerous mechanisms to competitively acquire iron within host environments, such as the secretion of small molecules known as siderophores that can solubilize iron for bacterial use. However, siderophore biosynthesis and acquisition is not a capability equally harbored by all resident bacteria. Moreover, the structural diversity of siderophores creates variability in the susceptibility to host mechanisms that serve to counteract siderophore-mediated iron acquisition and limit bacterial growth. As a result, the differential capabilities to acquire iron among members of a complex microbial community carry important implications for the growth and function of resident bacteria. Siderophores can also directly influence host function by modulating cellular iron homeostasis, further providing a mechanism by which resident bacteria may influence their local environment at the host-microbial interface. This review will explore the putative mechanisms by which siderophore production by resident bacteria in the intestines may influence microbial community dynamics and host-bacterial interactions with important implications for pathogen- and microbiota-driven diseases including infection, inflammatory bowel diseases and colorectal cancer.

Oral iron supplementation: Potential implications for the gut microbiome and metabolome in patients with CKD

Patients with chronic kidney disease (CKD) and loss of kidney function are at increased risk for morbidity and mortality. The risks of CKD are attributed to "uremia," an increased concentration of uremic retention solutes (toxins) in the plasma. Recently, a colo-renal axis became clearly apparent and uremia has been associated with an altered gut microbiome composition and metabolism. There is a high prevalence of anemia in patients with CKD, for which patients are often treated with oral or intravenous iron. Recent in vivo and in vitro studies have reported adverse effects of oral iron supplementation on the gut microbiota composition, gut metabolome, and intestinal health, which in turn may result in an increased production of uremic toxins. It may also affect circulating levels of other microbe-derived molecules, that can act as mediators of immune regulation. Changes in body iron levels have also been reported to exert subtle effects on host immune function by modulating immune cell proliferation and differentiation, and by directly regulating cytokine formation and antimicrobial immune effector mechanisms. Based on the foregoing it is conceivable that oral iron supplementation in iron deficient predialysis CKD patients adversely changes gut microbiota composition, the gut and systemic metabolome, and host immunity and infection. Future studies are needed to confirm these hypotheses and to assess whether, compared to IV iron supplementation, oral iron supplementation negatively impacts on morbidity of CKD, and whether these adverse effects depend on the iron bioavailability of the iron formulation to the microbiota.

Effect of Vitamin E With Therapeutic Iron Supplementation on Iron Repletion and Gut Microbiome in US Iron Deficient Infants and Toddlers

BACKGROUND

Iron therapy induces inflammation, which could decrease iron absorption. Increased exposure of iron in the gut could also alter microbiome file. Providing antioxidants such as vitamin E with iron therapy has been associated with reduced oxidative potential.

OBJECTIVE

The aim of the present study was to test the efficacy of adding vitamin E to therapeutic iron therapy on iron repletion, inflammation markers, and gut microbiome in iron-deficient infants and toddlers.

DESIGN

This was a randomized, double-blind, control trial in which infants and toddlers (Denver, CO metro area) who were at risk of iron deficiency were screened. Eligible participants were randomized to receive iron therapy (6 mg · kg · day) plus placebo (n = 22) or iron (6 mg · kg · day) and vitamin E (18 mg/day, n = 14) for 8 weeks. Iron and inflammation status, and gut microbiome (16S sequencing) were analyzed in all participants before and after the treatment.

RESULTS

After 8 weeks of treatment, average serum ferritin level returned to normal for both iron + placebo and iron + vitamin E groups at 33.3 ± 20.2 and 33.5 ± 21.5 μg/L, respectively. Serum vitamin E concentration increased in iron + vitamin E group. No change over time was observed regarding serum interleukin-4, tumor necrosis factor-α, or fecal calprotectin. The relative abundance of the genus Roseburia (phylum Firmicutes), a butyrate producer, increased in the Fe + E group (Δ1.3%, P < 0.01). Also at the genus level, the genus Escherichia decreased by 1.2% on average among all participants (effect of time P = 0.01).

CONCLUSIONS

Using a therapeutic iron dose of 6 mg · kg · day is effective in treating iron deficiency during an 8-week period, without inducing persistent inflammatory response. Changes of the gut microbiome raised the possibility that antioxidant therapy in conjunction with therapeutic iron supplementation could potentially improve microbial community profiles in the intestinal tract.