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

The Effect of Iron Supplements on the Gut Microbiome of Females of Reproductive Age: A Randomized Controlled Trial

BACKGROUND

Iron deficiency is the most common nutritional deficiency worldwide, particularly for young children and females of reproductive age. Although oral iron supplements are routinely recommended and generally considered safe, iron supplementation has been shown to alter the fecal microbiota in low-income countries. Little is known about the effect of iron supplementation on the fecal microbiota in high-income settings.

OBJECTIVES

To assess the effect of oral iron supplementation compared with placebo on the gut microbiome in nonpregnant females of reproductive age in a high-income country.

METHODS

A 21-d prospective parallel design double-blind, randomized control trial conducted in South Australia, Australia. Females (18-45 y) were randomly assigned to either iron (65.7 mg ferrous fumarate) or placebo. Fecal samples were collected prior to commencing supplements and after 21 d of supplementation. The primary outcome was microbiota β-diversity (paired-sample weighted unique fraction metric dissimilarity) between treatment and placebo groups after 21 d of supplementation. Exploratory outcomes included changes in the relative abundance of bacterial taxa.

RESULTS

Of 82 females randomly assigned, 80 completed the trial. There was no significant difference between the groups for weighted unique fraction metric dissimilarity (mean difference: 0.003; 95% confidence interval: -0.007, 0.014; P = 0.52) or relative abundance of common bacterial taxa or Escherichia-Shigella (q > 0.05).

CONCLUSIONS

Iron supplementation did not affect the microbiome of nonpregnant females of reproductive age in Australia. This trial was registered at clinicaltrials.gov as NCT05033483.

The Effect of Oral Iron Supplementation/Fortification on the Gut Microbiota in Infancy: A Systematic Review and Meta-Analysis

(1) Background: Iron is an essential metal for the proper growth and neurodevelopment of infants. To prevent and treat iron deficiency, iron supplementation or fortification is often required. It has been shown, though, that it affects the synthesis of gut microbiota. (2) Methods: This paper is a systematic review and meta-analysis of the effect of oral iron supplementation/fortification on the gut microbiota in infancy. Studies in healthy neonates and infants who received per os iron with existing data on gut microbiota were included. Three databases were searched: PUBMED, Scopus, and Google Scholar. Randomized controlled trials (RCTs) were included. Quality appraisal was assessed using the ROB2Tool. (3) Results: A total of six RCTs met inclusion criteria for a systematic review, and four of them were included in the meta-analysis using both the fixed and random effects methods. Our results showed that there is very good heterogeneity in the iron group (I2 = 62%), and excellent heterogeneity in the non-iron group (I2 = 98%). According to the meta-analysis outcomes, there is a 10.3% (95% CI: -15.0--5.55%) reduction in the bifidobacteria population in the iron group and a -2.96% reduction for the non-iron group. There is a confirmed difference (p = 0.02) in the aggregated outcomes between iron and non-iron supplement, indicative that the bifidobacteria population is reduced when iron supplementation is given (total reduction 6.37%, 95%CI: 10.16-25.8%). (4) Conclusions: The abundance of bifidobacteria decreases when iron supplementation or fortification is given to infants.

Vitamin E and conflicting understandings in noncommunicable diseases: Is it worth supplementing?

Vitamin E is a lipid-soluble nutrient found mainly in vegetable oils and oilseeds. It is divided into eight homologous compounds; however, only α-tocopherol exhibits vitamin activity. Many advantages are related to these compounds, including cellular protection through antioxidant and anti-inflammatory activity, and improving lipid metabolism. Physiopathology of many diseases incepts with reduced antioxidant defense, characterized by an increased reactive oxygen species production and activation of transcription factors involved in inflammation, such as nuclear factor-kappa B (NF-κB), that can be linked to oxidative stress. Moreover, disorders of lipid metabolism can increase the risk of cardiovascular diseases. In addition, intestinal dysbiosis plays a vital role in developing chronic non-communicable diseases. In this regard, vitamin E can be considered to mitigate those disorders, but data still needs to be more conclusive. This narrative review aims to elucidate the mechanisms of action of vitamin E and if supplementation can be beneficial in a disease scenario regarding non-communicable diseases.

Vitamin E stabilizes iron and mitochondrial metabolism in pulmonary fibrosis

Introduction: Pulmonary fibrosis (PF) is a fatal chronic lung disease that causes structural damage and decreased lung function and has a poor prognosis. Currently, there is no medicine that can truly cure PF. Vitamin E (VE) is a group of natural antioxidants with anticancer and antimutagenic properties. There have been a few reports about the attenuation of PF by VE in experimental animals, but the molecular mechanisms are not fully understood. Methods: Bleomycin-induced PF (BLM-PF) mouse model, and cultured mouse primary lung fibroblasts and MLE 12 cells were utilized. Pathological examination of lung sections, immunoblotting, immunofluorescent staining, and real-time PCR were conducted in this study. Results: We confirmed that VE significantly delayed the progression of BLM-PF and increased the survival rates of experimental mice with PF. VE suppressed the pathological activation and fibrotic differentiation of lung fibroblasts and epithelial-mesenchymal transition and alleviated the inflammatory response in BLM-induced fibrotic lungs and pulmonary epithelial cells in vitro. Importantly, VE reduced BLM-induced ferritin expression in fibrotic lungs, whereas VE did not exhibit iron chelation properties in fibroblasts or epithelial cells in vitro. Furthermore, VE protected against mitochondrial dysmorphology and normalized mitochondrial protein expression in BLM-PF lungs. Consistently, VE suppressed apoptosis in BLM-PF lungs and pulmonary epithelial cells in vitro. Discussion: Collectively, VE markedly inhibited BLM-induced PF through a complex mechanism, including improving iron metabolism and mitochondrial structure and function, mitigating inflammation, and decreasing the fibrotic functions of fibroblasts and epithelial cells. Therefore, VE presents a highly potential therapeutic against PF due to its multiple protective effects with few side effects.

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.

Maternal Supplementation of Vitamin E or Its Combination with Hydroxytyrosol Increases the Gut Health and Short Chain Fatty Acids of Piglets at Weaning

An adequate intestinal environment before weaning may contribute to diarrhea predisposition and piglet development. This study evaluates how the dietary supplementation of vitamin E (VE) (100 mg/kg), hydroxytyrosol (HXT) (1.5 mg/kg) or the combined administration (VE + HXT) given to Iberian sows from gestation affects the piglet's faecal characteristics, short chain fatty acids (SCFAs), fatty acid profile or intestinal morphology as indicators of gut health; and quantify the contribution of the oxidative status and colostrum/milk composition to the piglet's SCFAs content and intestinal health. Dietary VE increased isobutyric acid (iC4), butyric acid (C4), isovaleric acid (iC5), and ∑SCFAs, whereas HXT increased iC4 and tended to decrease ∑SCFAs of faeces. Piglets from HXT-supplemented sows also tended to have higher faecal C20:4n-6/C20:2 ratio C22:6 proportion and showed lower occludin gene expression in the duodenum. The combination of both antioxidants had a positive effect on iC4 and iC5 levels. Correlation analyses and regression equations indicate that faecal SCFAs were related to oxidative status (mainly plasma VE) and colostrum and milk composition (mainly C20:2, C20:3, C20:4 n-6). This study would confirm the superiority of VE over HXT supplementation to improve intestinal homeostasis, gut health, and, consequently piglet growth.

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.

Regulation of gut microbiota by vitamin C, vitamin E and β-carotene

Vitamin C (VC), vitamin E (VE) and β-carotene (βC) are representative dietary antioxidants, which exist in daily diet and can increase the antioxidant capacity of body fluids, cells and tissues. The health benefits of vitamins like VC, VE and βC are widely demonstrated. Given that the strong associations between the gut microbiota and host health or a range of diseases has been extensively reported, it is important to explore the modulatory effects of known vitamins on the gut microbiota. Herein, this article reviews the effects of VC, VE and βC on the gut microbiota. Totally, 19 studies were included, of which eight were related to VC, nine to VE, and six to βC. Overall, VC, VE and βC can provide health benefits to the host by modulating the composition and metabolic activity of the gut microbiota, improving intestinal barrier function and maintaining the normal function of the immune system. Two perspectives are proposed for future studies: i) roles of known antioxidant activity of vitamins in regulating the gut microbiota and its molecular mechanism need to be further studied; ii) causal relationships between the regulatory effects of vitamins on gut microbiota and host health still remains to be further verified.

The intersection of undernutrition, microbiome, and child development in the first years of life

Undernutrition affects about one out of five children worldwide. It is associated with impaired growth, neurodevelopment deficits, and increased infectious morbidity and mortality. Undernutrition, however, cannot be solely attributed to a lack of food or nutrient deficiency but rather results from a complex mix of biological and environmental factors. Recent research has shown that the gut microbiome is intimately involved in the metabolism of dietary components, in growth, in the training of the immune system, and in healthy development. In this review, we look at these features in the first three years of life, which is a critical window for both microbiome establishment and maturation and child development. We also discuss the potential of the microbiome in undernutrition interventions, which could increase efficacy and improve child health outcomes.

The roles of dietary lipids and lipidomics in gut-brain axis in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM), one of the main types of Noncommunicable diseases (NCDs), is a systemic inflammatory disease characterized by dysfunctional pancreatic β-cells and/or peripheral insulin resistance, resulting in impaired glucose and lipid metabolism. Genetic, metabolic, multiple lifestyle, and sociodemographic factors are known as related to high T2DM risk. Dietary lipids and lipid metabolism are significant metabolic modulators in T2DM and T2DM-related complications. Besides, accumulated evidence suggests that altered gut microbiota which plays an important role in the metabolic health of the host contributes significantly to T2DM involving impaired or improved glucose and lipid metabolism. At this point, dietary lipids may affect host physiology and health via interaction with the gut microbiota. Besides, increasing evidence in the literature suggests that lipidomics as novel parameters detected with holistic analytical techniques have important roles in the pathogenesis and progression of T2DM, through various mechanisms of action including gut-brain axis modulation. A better understanding of the roles of some nutrients and lipidomics in T2DM through gut microbiota interactions will help develop new strategies for the prevention and treatment of T2DM. However, this issue has not yet been entirely discussed in the literature. The present review provides up-to-date knowledge on the roles of dietary lipids and lipidomics in gut-brain axis in T2DM and some nutritional strategies in T2DM considering lipids- lipidomics and gut microbiota interactions are given.

Arsenic and iron bioavailability in Caco-2 cells: The influence of their co-existence and concentration

Arsenic (As) exposure in humans is primarily caused through food and drinking water. Iron (Fe) is one of the most common element of the human and can influence the toxicity and bioavailability of As. However, information on the interaction between As and Fe when present together is limited. In this study, the interaction effects of Fe(III) (0, 3, and 10 mg/L) and As (As(III) at 0, 0.05, 0.1 mg/L, and As(V) at 0, 0.1, and 2 mg/L, respectively) on their absorption and bioavailability in Caco-2 cells were analyzed. As(III) absorption significantly decreased with the addition of Fe, while Fe absorption significantly increased. Compared with 0.1 mg/L As(III) addition alone, 3 and 10 mg/L Fe(III) addition significantly reduced the As(III) absorption by 8.6 and 11 μg/L, respectively. The absorption of As and Fe(III) and the bioavailability of Fe(III) significantly increased with the addition of As(III/V). Compared with 10 mg/L Fe(III) alone, the absorption of As(III) was significantly increased by 1 and 1.3 mg/L with 0.05 and 0.1 mg/L As(III) addition, respectively. Furthermore, the absorption and bioavailability of Fe(III) were significantly increased by 1.2 mg/L and 8% and 1.2 mg/L and 8.2%, respectively, after adding 0.1 and 2 mg/L As(V).

Vitamin E protective effects on genomic and cellular damage caused by paediatric preventive supplementation for anaemia: an experimental model

Iron deficiency is the leading cause of anaemia. In Argentina, the prevalence of anaemia and iron deficiency is very high; for that reason, the Argentine Society of Pediatrics recommends daily ferrous sulphate supplementation as a preventive treatment strategy. Alternatively, weekly ferrous sulphate supplementation has also been shown to be effective for anaemia prevention. Excess iron could be related to oxidative stress, which may in turn cause cytomolecular damage. Both can be prevented with vitamin E supplementation. We evaluated the effect of both daily and weekly ferrous sulphate supplementation combined with two doses of vitamin E on cell viability, oxidative stress and cytomolecular damage in peripheral blood cultured in vitro. The experimental design included the following groups: untreated negative control, two vitamin E controls (8·3 and 16·6 µg/ml), weekly ferrous sulphate supplementation (0·55 mg/ml) with each vitamin E dose, daily ferrous sulphate supplementation (0·14 mg/ml) with each vitamin E dose and a positive control. Daily ferrous sulphate supplementation decreased cell viability and increased the levels of reactive oxygen species, lipid peroxidation and cytomolecular damage (P < 0·5) compared with the weekly supplementation, probably due to the excess iron observed in the former. Vitamin E seemed to reduce ferrous sulphate-induced oxidative stress and genomic damage.

Iron in infectious diseases friend or foe?: The role of gut microbiota

Iron is a trace element involved in metabolic functions for all organisms, from microorganisms to mammalians. Iron deficiency is a prevalent health problem that affects billions of people worldwide, and iron overload could have some hazardous effect. The complex microbial community in the human body, also called microbiota, influences the host immune defence against infections. An imbalance in gut microbiota, dysbiosis, changes the host's susceptibility to infections by regulating the immune system. In recent years, the number of studies on the relationship between infectious diseases and microbiota has increased. Gut microbiota is affected by different parameters, including mode of delivery, hygiene habits, diet, drugs, and plasma iron levels during the lifetime. Gut microbiota may influence iron levels in the body, and iron overload and deficiency can also affect gut microbiota composition. Novel researches on microbiota shed light on the fact that the bidirectional interactions between gut microbiota and iron play a role in the pathogenesis of many diseases, especially infections. A better understanding of these interactions may help us to comprehend the pathogenesis of many infectious and metabolic diseases affecting people worldwide and following the development of more effective preventive and/or therapeutic strategies. In this review, we aimed to present the iron-mediated host-gut microbiota interactions, susceptibility to bacterial infections, and iron-targeted therapy approaches for infections.

The Role of Nutrition on Meta-inflammation: Insights and Potential Targets in Communicable and Chronic Disease Management

PURPOSE OF REVIEW

Chronic low-grade inflammation may contribute to the onset and progression of communicable and chronic diseases. This review examined the effects and eventual mediation roles of different nutritional factors on inflammation.

RECENT FINDINGS

Potential nutritional compounds influencing inflammation processes include macro and micronutrients, bioactive molecules (polyphenols), specific food components, and culinary ingredients as well as standardized dietary patterns, eating habits, and chrononutrition features. Therefore, research in this field is still required, taking into account critical aspects of heterogeneity including type of population, minimum and maximum intakes and adverse effects, cooking methods, physiopathological status, and times of intervention. Moreover, the integrative analysis of traditional variables (age, sex, metabolic profile, clinical history, body phenotype, habitual dietary intake, physical activity levels, and lifestyle) together with individualized issues (genetic background, epigenetic signatures, microbiota composition, gene expression profiles, and metabolomic fingerprints) may contribute to the knowledge and prescription of more personalized treatments aimed to improving the precision medical management of inflammation as well as the design of anti-inflammatory diets in chronic and communicable diseases.

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. 

Interactions between Dietary Micronutrients, Composition of the Microbiome and Efficacy of Immunotherapy in Cancer Patients

The effectiveness of immunotherapy in cancer patients depends on the activity of the host's immune system. The intestinal microbiome is a proven immune system modulator, which plays an important role in the development of many cancers and may affect the effectiveness of anti-cancer therapy. The richness of certain bacteria in the gut microbiome (e.g., Bifidobacterium spp., Akkermanisa muciniphila and Enterococcus hire) improves anti-tumor specific immunity and the response to anti-PD-1 or anti-PD-L1 immunotherapy by activating antigen-presenting cells and cytotoxic T cells within the tumor. Moreover, micronutrients affect directly the activities of the immune system or regulate their function by influencing the composition of the microbiome. Therefore, micronutrients can significantly influence the effectiveness of immunotherapy and the development of immunorelated adverse events. In this review, we describe the relationship between the supply of microelements and the abundance of various bacteria in the intestinal microbiome and the effectiveness of immunotherapy in cancer patients. We also point to the function of the immune system in the case of shifts in the composition of the microbiome and disturbances in the supply of microelements. This may in the future become a therapeutic target supporting the effects of immunotherapy in cancer patients.

Manipulation of the diet-microbiota-brain axis in Alzheimer's disease

Several studies investigating the pathogenesis of Alzheimer's disease have identified various interdependent constituents contributing to the exacerbation of the disease, including Aβ plaque formation, tau protein hyperphosphorylation, neurofibrillary tangle accumulation, glial inflammation, and the eventual loss of proper neural plasticity. Recently, using various models and human patients, another key factor has been established as an influential determinant in brain homeostasis: the gut-brain axis. The implications of a rapidly aging population and the absence of a definitive cure for Alzheimer's disease have prompted a search for non-pharmaceutical tools, of which gut-modulatory therapies targeting the gut-brain axis have shown promise. Yet multiple recent studies examining changes in human gut flora in response to various probiotics and environmental factors are limited and difficult to generalize; whether the state of the gut microbiota in Alzheimer's disease is a cause of the disease, a result of the disease, or both through numerous feedback loops in the gut-brain axis, remains unclear. However, preliminary findings of longitudinal studies conducted over the past decades have highlighted dietary interventions, especially Mediterranean diets, as preventative measures for Alzheimer's disease by reversing neuroinflammation, modifying the intestinal and blood-brain barrier (BBB), and addressing gut dysbiosis. Conversely, the consumption of Western diets intensifies the progression of Alzheimer's disease through genetic alterations, impaired barrier function, and chronic inflammation. This review aims to support the growing body of experimental and clinical data highlighting specific probiotic strains and particular dietary components in preventing Alzheimer's disease via the gut-brain axis.

Colloidal delivery of vitamin E into solid lipid nanoparticles as a potential complement for the adverse effects of anemia treatment

Vitamin E (VitE) is one of the most important antioxidants and plays a key role in decreasing the inflammatory effects of oxidative stress caused by recurrent doses of iron administration in anemia treatment. However, VitE is poorly soluble in aqueous environments. Here, VitE encapsulation into solid lipid nanoparticles (SLN) composed of myristil myristate to improve its bioavailability was proposed. A 99.9 ± 0.1% encapsulation efficiency with a drug/lipid ratio of 500 µg/mg and 478 higher VitE solubility was obtained. The antioxidant properties of VitE after encapsulation were maintained. SLN-VitE showed a 228.2 nm mean diameter with low polidispersitivity (0.335), and negative Z potential (ζ ≈ -9.0 mV). The SLN were well-dispersed, displayed spherical and homogeneous morphology by TEM. A controlled release of VitE from SLN was found. The XRD and FTIR analyses revealed the presence of a nanostructured architecture of SLN after VitE incorporation. We probed the safety of SLN-VitE after contact with three in vitro cell models: erythrocytes, lymphocytes and HepG2 cells. The cell viability in presence of SLN, SLN-VitE, and their combinations with iron was not affected. The comet assay demonstrated that the DNA damage caused by iron administration was decrease in presence of SLN-VitE.

Daily iron intake and BMI for age but not for daily tannin intake increase hemoglobin levels in young females at Karanganyar Regency, Central Java, Indonesia

Abstract.

Iron Supplementation at the Crossroads of Nutrition and Gut Microbiota: The State of the Art

Gut microbiota has received significant attention owing to its decisive role in human health and disease. Diet exerts a significant influence on the variety and number of bacteria residing in the intestinal epithelium. On the other hand, as iron is a key micronutrient for blood formation and oxygen supply, its deficiency is highly prevalent worldwide. In fact, it is the most common cause of anemia and thus, iron supplementation is widespread. However, there is concern due to some potential risks linked to iron supplementation. Therefore, we have reviewed the available evidence of the effects that iron supplementation exerts on the gut microbiota as well as its potential benefits and risks. The compiled information suggests that iron supplementation is potentially harmful for gut microbiota. Therefore, it should be performed with caution, and by principle, recommended only to individuals with proven iron deficiency or iron-deficiency anemia to avoid potential adverse effects. In any case, large and long-term population studies are urgently needed to confirm or refute these results, mainly focused on vulnerable populations.

Effects of colon-targeted vitamins on the composition and metabolic activity of the human gut microbiome- a pilot study

An increasing body of evidence has shown that gut microbiota imbalances are linked to diseases. Currently, the possibility of regulating gut microbiota to reverse these perturbations by developing novel therapeutic and preventive strategies is being extensively investigated. The modulatory effect of vitamins on the gut microbiome and related host health benefits remain largely unclear. We investigated the effects of colon-delivered vitamins A, B2, C, D, and E on the gut microbiota using a human clinical study and batch fermentation experiments, in combination with cell models for the assessment of barrier and immune functions. Vitamins C, B2, and D may modulate the human gut microbiome in terms of metabolic activity and bacterial composition. The most distinct effect was that of vitamin C, which significantly increased microbial alpha diversity and fecal short-chain fatty acids compared to the placebo. The remaining vitamins tested showed similar effects on microbial diversity, composition, and/or metabolic activity in vitro, but in varying degrees. Here, we showed that vitamins may modulate the human gut microbiome. Follow-up studies investigating targeted delivery of vitamins to the colon may help clarify the clinical significance of this novel concept for treating and preventing dysbiotic microbiota-related human diseases. Trial registration: ClinicalTrials.gov, NCT03668964. Registered 13 September 2018 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03668964.

Vitamins, the gut microbiome and gastrointestinal health in humans

The gut microbiome plays important roles in the maintenance of host health and the pathogenesis of many diseases. Diet is a key modulator of the gut microbiome. There is increasing evidence that nutrients other than fermentable fiber affect the gut microbial composition. In this review, we discuss the effects of vitamins on the gut microbiome, and related gastrointestinal health, based on in vitro, animal and human studies. Some vitamins, when provided in large doses or when delivered to the large intestine, have been shown to beneficially modulate the gut microbiome by increasing the abundance of presumed commensals (vitamins A, B₂, D, E, and beta-carotene), increasing or maintaining microbial diversity (vitamins A, B₂, B₃, C, K) and richness (vitamin D), increasing short chain fatty acid production (vitamin C), or increasing the abundance of short chain fatty acid producers (vitamins B₂, E). Others, such as vitamins A and D, modulate the gut immune response or barrier function, thus, indirectly influencing gastrointestinal health or the microbiome. Future research is needed to explore these potential effects and to elucidate the underlying mechanisms and host health benefits.

Dietary Micronutrients from Zygote to Senility: Updated Review of Minerals' Role and Orchestration in Human Nutrition throughout Life Cycle with Sex Differences

Micronutrients such as selenium, fluoride, zinc, iron, and manganese are minerals that are crucial for many body homeostatic processes supplied at low levels. The importance of these micronutrients starts early in the human life cycle and continues across its different stages. Several studies have emphasized the critical role of a well-balanced micronutrient intake. However, the majority of studies looked into or examined such issues in relation to a specific element or life stage, with the majority merely reporting the effect of either excess or deficiency. Herein, in this review, we will look in depth at the orchestration of the main element requirements across the human life cycle beginning from fertility and pregnancy, passing through infancy, childhood, adolescence, and reaching adulthood and senility, with insight on the interactions among them and underlying action mechanisms. Emphasis is given towards approaches to the role of the different minerals in the life cycle, associated symptoms for under- or overdoses, and typical management for each element, with future perspectives. The effect of sex is also discussed for each micronutrient for each life stage as literature suffice to highlight the different daily requirements and or effects.

Nurturing the Early Life Gut Microbiome and Immune Maturation for Long Term Health

Early life is characterized by developmental milestones such as holding up the head, turning over, sitting up and walking that are typically achieved sequentially in specific time windows. Similarly, the early gut microbiome maturation can be characterized by specific temporal microorganism acquisition, colonization and selection with differential functional features over time. This orchestrated microbial sequence occurs from birth during the first years of age before the microbiome reaches an adult-like composition and function between 3 and 5 years of age. Increasingly, these different steps of microbiome development are recognized as crucial windows of opportunity for long term health, primarily linked to appropriate immune and metabolic development. For instance, microbiome disruptors such as preterm and Cesarean-section birth, malnutrition and antibiotic use are associated with increased risk to negatively affect long-term immune and metabolic health. Different age discriminant microbiome taxa and functionalities are used to describe age-appropriate microbiome development, and advanced modelling techniques enable an understanding and visualization of an optimal microbiome maturation trajectory. Specific microbiome features can be related to later health conditions, however, whether such features have a causal relationship is the topic of intense research. Early life nutrition is an important microbiome modulator, and 'Mother Nature' provides the model with breast milk as the sole source of nutrition for the early postnatal period, while dietary choices during the prenatal and weaning period are to a large extent guided by tradition and culture. Increasing evidence suggests prenatal maternal diet and infant and child nutrition impact the infant microbiome trajectory and immune competence development. The lack of a universal feeding reference for such phases represents a knowledge gap, but also a great opportunity to provide adequate nutritional guidance to maintain an age-appropriate microbiome for long term health. Here, we provide a narrative review and perspective on our current understanding of age-appropriate microbiome maturation, its relation to long term health and how nutrition shapes and influences this relationship.

Nutritional Interventions and the Gut Microbiome in Children

The gut microbiome plays an integral role in health and disease, and diet is a major driver of its composition, diversity, and functional capacity. Given the dynamic development of the gut microbiome in infants and children, it is critical to address two major questions: (a) Can diet modify the composition, diversity, or function of the gut microbiome, and (b) will such modification affect functional/clinical outcomes including immune function, cognitive development, and overall health? We synthesize the evidence on the effect of nutritional interventions on the gut microbiome in infants and children across 26 studies. Findings indicate the need to study older children, assess the whole intestinal tract, and harmonize methods and interpretation of findings, which are critical for informing meaningful clinical and public health practice. These findings are relevant for precision health, may help identify windows of opportunity for intervention, and may inform the design and delivery of such interventions. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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.

Early Nutrition and Risk of Type 1 Diabetes: The Role of Gut Microbiota

Type 1 diabetes (T1D) appears most frequently in childhood, with an alarming increasing incidence in the last decades. Although the genetic predisposition is a major risk factor, it cannot solely explain the complex etiology of T1D which is still not fully understood. In this paper, we reviewed the most recent findings on the role of early nutrition and the involvement of the gut microbiota in the etiopathogenesis of T1D. The main conclusions that are withdrawn from the current literature regarding alleviating the risk of developing T1D through nutrition are the encouragement of long-term breast-feeding for at least the first 6 months of life and the avoidance of early complementary foods and gluten introduction (before 4 months of age) as well as cow milk introduction before 12 months of life. These detrimental feeding habits create a gut microbiota dysbiotic state that can contribute to the onset of T1D in infancy. Finally, we discussed the possibility to introduce probiotics, prebiotics and post-biotics in the prevention of T1D.

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.

Effects of Complementary Feeding With Different Protein-Rich Foods on Infant Growth and Gut Health: Study Protocol

Background: An urgent need exists for evidence-based dietary guidance early in life, particularly regarding protein intake. However, a significant knowledge gap exists in the effects of protein-rich foods on growth and development during early complementary feeding. Methods: This is a randomized controlled trial of infant growth and gut health (primary outcomes). We directly compare the effects of dietary patterns with common protein-rich foods (meat, dairy, plant) on infant growth trajectories and gut microbiota development (monthly assessments) during early complementary feeding in both breast- and formula-fed infants. Five-month-old infants (up to n = 300) are randomized to a meat-, dairy-, plant-based complementary diet or a reference group (standard of care) from 5 to 12 months of age, with a 24-month follow-up assessment. Infants are matched for sex, mode of delivery and mode of feeding using stratified randomization. Growth assessments include length, weight, head circumference and body composition. Gut microbiota assessments include both 16S rRNA profiling and metagenomics sequencing. The primary analyses will evaluate the longitudinal effects of the different diets on both anthropometric measures and gut microbiota. The secondary analysis will evaluate the potential associations between gut microbiota and infant growth. Discussion: Findings are expected to have significant scientific and health implications for identifying beneficial gut microbial changes and dietary patterns and for informing dietary interventions to prevent the risk of overweight and later obesity, and promote optimal health. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT05012930.

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 effect of vitamin E supplementation on selected inflammatory biomarkers in adults: a systematic review and meta-analysis of randomized clinical trials

The previous meta-analysis of clinical trials revealed a beneficial effect of vitamin E supplementation on serum C-reactive protein (CRP) concentrations; however, it is unknown whether this vitamin has the same influence on other inflammatory biomarkers. Also, several clinical trials have been published since the release of earlier meta-analysis. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the effects of vitamin E supplementation on inflammatory biomarkers in adults. We searched the online databases using relevant keywords up to November 2019. Randomized clinical trials (RCTs) investigating the effect of vitamin E, compared with the placebo, on serum concentrations of inflammatory cytokines were included. Overall, we included 33 trials with a total sample size of 2102 individuals, aged from 20 to 70 years. Based on 36 effect sizes from 26 RCTs on serum concentrations of CRP, we found a significant reduction following supplementation with vitamin E (− 0.52, 95% CI − 0.80, − 0.23 mg/L, P < 0.001). Although the overall effect of vitamin E supplementation on serum concentrations of interleukin-6 (IL-6) was not significant, a significant reduction in this cytokine was seen in studies that used α-tocopherol and those trials that included patients with disorders related to insulin resistance. Moreover, we found a significant reducing effect of vitamin E supplementation on tumor necrosis factor-α (TNF-α) concentrations at high dosages of vitamin E; such that based on dose–response analysis, serum TNF-α concentrations were reduced significantly at the dosages of ≥ 700 mg/day vitamin E (P_{non-linearity} = 0.001). Considering different chemical forms of vitamin E, α-tocopherol, unlike other forms, had a reducing effect on serum levels of CRP and IL-6. In conclusion, our findings revealed a beneficial effect of vitamin E supplementation, particularly in the form of α-tocopherol, on subclinical inflammation in adults. Future high-quality RCTs should be conducted to translate this anti-inflammatory effect of vitamin E to the clinical setting.

Host Factors of Favorable Intestinal Microbial Colonization

Gut microbial colonization starts with birth and initiates a complex process between the host and the microbiota. Successful co-development of both establishes a symbiotic mutual relationship and functional homeostasis, while alterations thereof predispose the individual life-long to inflammatory and metabolic diseases. Multiple data have been provided how colonizing microbes induce a reprogramming and maturation of immunity by providing crucial instructing information to the newborn immune system. Less is known about what host factors have influence on the interplay between intestinal immunity and the composition of the gut microbial ecology. Here we review existing evidence regarding host factors that contribute to a favorable development of the gut microbiome and thereby successful maturation of gut mucosal immunity.

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.

Nutrition and the Gut Microbiota in 10- to 18-Month-Old Children Living in Urban Slums of Mumbai, India

In this cross-sectional study, we describe the composition and diversity of the gut microbiota among undernourished children living in urban slums of Mumbai, India, and determine how nutritional status, including anthropometric measurements, dietary intakes from complementary foods, feeding practices, and micronutrient concentrations, is associated with their gut microbiota. We collected rectal swabs from children aged 10 to 18 months living in urban slums of Mumbai participating in a randomized controlled feeding trial and conducted 16S rRNA sequencing to determine the composition of the gut microbiota. Across the study cohort, Proteobacteria dominated the gut microbiota at over 80% relative abundance, with Actinobacteria representation at <4%, suggesting immaturity of the gut. Increased microbial α-diversity was associated with current breastfeeding, greater head circumference, higher fat intake, and lower hemoglobin concentration and weight-for-length Z-score. In redundancy analyses, 47% of the variation in Faith's phylogenetic diversity (Faith's PD) could be accounted for by age and by iron and polyunsaturated fatty acid intakes. Differences in community structure (β-diversity) of the microbiota were observed among those consuming fats and oils the previous day compared to those not consuming fats and oils the previous day. Our findings suggest that growth, diet, and feeding practices are associated with gut microbiota metrics in undernourished children, whose gut microbiota were comprised mainly of Proteobacteria, a phylum containing many potentially pathogenic taxa.IMPORTANCE The impact of comprehensive nutritional status, defined as growth, nutritional blood biomarkers, dietary intakes, and feeding practices, on the gut microbiome in children living in low-resource settings has remained underreported in microbiome research. Among undernourished children living in urban slums of Mumbai, India, we observed a high relative abundance of Proteobacteria, a phylum including many potentially pathogenic species similar to the composition in preterm infants, suggesting immaturity of the gut, or potentially a high inflammatory burden. We found head circumference, fat and iron intake, and current breastfeeding were positively associated with microbial diversity, while hemoglobin and weight for length were associated with lower diversity. Findings suggest that examining comprehensive nutrition is critical to gain more understanding of how nutrition and the gut microbiota are linked, particularly in vulnerable populations such as children in urban slum settings.

Role of Dietary Nutrients in the Modulation of Gut Microbiota: A Narrative Review

Understanding how dietary nutrients modulate the gut microbiome is of great interest for the development of food products and eating patterns for combatting the global burden of non-communicable diseases. In this narrative review we assess scientific studies published from 2005 to 2019 that evaluated the effect of micro- and macro-nutrients on the composition of the gut microbiome using in vitro and in vivo models, and human clinical trials. The clinical evidence for micronutrients is less clear and generally lacking. However, preclinical evidence suggests that red wine- and tea-derived polyphenols and vitamin D can modulate potentially beneficial bacteria. Current research shows consistent clinical evidence that dietary fibers, including arabinoxylans, galacto-oligosaccharides, inulin, and oligofructose, promote a range of beneficial bacteria and suppress potentially detrimental species. The preclinical evidence suggests that both the quantity and type of fat modulate both beneficial and potentially detrimental microbes, as well as the Firmicutes/Bacteroides ratio in the gut. Clinical and preclinical studies suggest that the type and amount of proteins in the diet has substantial and differential effects on the gut microbiota. Further clinical investigation of the effect of micronutrients and macronutrients on the microbiome and metabolome is warranted, along with understanding how this influences host health.

The Benefits and Risks of Iron Supplementation in Pregnancy and Childhood

Iron deficiency is the most common micronutrient deficiency in the world and disproportionately affects pregnant women and young children. Iron deficiency has negative effects on pregnancy outcomes in women and on immune function and neurodevelopment in children. Iron supplementation programs have been successful in reducing this health burden. However, iron supplementation of iron-sufficient individuals is likely not necessary and may carry health risks for iron-sufficient and potentially some iron-deficient populations. This review considers the physiology of iron as a nutrient and how this physiology informs decision-making about weighing the benefits and risks of iron supplementation in iron-deficient, iron-sufficient, and iron-overloaded pregnant women and children.

The Role of Diet, Micronutrients and the Gut Microbiota in Age-Related Macular Degeneration: New Perspectives from the Gut⁻Retina Axis

Age-related macular degeneration (AMD) is a complex multifactorial disease and the primary cause of legal and irreversible blindness among individuals aged ≥65 years in developed countries. Globally, it affects 30–50 million individuals, with an estimated increase of approximately 200 million by 2020 and approximately 300 million by 2040. Currently, the neovascular form may be able to be treated with the use of anti-VEGF drugs, while no effective treatments are available for the dry form. Many studies, such as the randomized controlled trials (RCTs) Age-Related Eye Disease Study (AREDS) and AREDS 2, have shown a potential role of micronutrient supplementation in lowering the risk of progression of the early stages of AMD. Recently, low-grade inflammation, sustained by dysbiosis and a leaky gut, has been shown to contribute to the development of AMD. Given the ascertained influence of the gut microbiota in systemic low-grade inflammation and its potential modulation by macro- and micro-nutrients, a potential role of diet in AMD has been proposed. This review discusses the role of the gut microbiota in the development of AMD. Using PubMed, Web of Science and Scopus, we searched for recent scientific evidence discussing the impact of dietary habits (high-fat and high-glucose or -fructose diets), micronutrients (vitamins C, E, and D, zinc, beta-carotene, lutein and zeaxanthin) and omega-3 fatty acids on the modulation of the gut microbiota and their relationship with AMD risk and progression.

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).

Ursodeoxycholic acid improves liver function via phenylalanine/tyrosine pathway and microbiome remodelling in patients with liver dysfunction

Ursodeoxycholic acid (UDCA) is a metabolic by-product of intestinal bacteria, showing hepatoprotective effects. However, its underlying molecular mechanisms remain unclear. The purpose of this study was to elucidate the action mechanisms underlying the protective effects of UDCA and vitamin E against liver dysfunction using metabolomics and metagenomic analysis. In this study, we analysed blood and urine samples from patients with obesity and liver dysfunction. Nine patients were randomly assigned to receive UDCA (300 mg twice daily), and 10 subjects received vitamin E (400 IU twice daily) for 8 weeks. UDCA significantly improved the liver function scores after 4 weeks of treatment and effectively reduced hepatic deoxycholic acid and serum microRNA-122 levels. To better understand its protective mechanism, a global metabolomics study was conducted, and we found that UDCA regulated uremic toxins (hippuric acid, p-cresol sulphate, and indole-derived metabolites), antioxidants (ascorbate sulphate and N-acetyl-L-cysteine), and the phenylalanine/tyrosine pathway. Furthermore, microbiome involvement, particularly of Lactobacillus and Bifidobacterium, was demonstrated through metagenomic analysis of bacteria-derived extracellular vesicles. Meanwhile, vitamin E treatment did not result in such alterations, except that it reduced uremic toxins and liver dysfunction. Our findings suggested that both treatments were effective in improving liver function, albeit via different mechanisms.

Excess iron intake as a factor in growth, infections, and development of infants and young children

The provision of iron via supplementation or the fortification of foods has been shown to be effective in preventing and treating iron deficiency and iron deficiency anemia in infants and young children. However, iron is a pro-oxidative element and can have negative effects on biological systems even at moderate amounts. An increasing number of studies have reported adverse effects of iron that was given to infants and young-children populations who initially were iron replete. These effects include decreased growth (both linear growth and weight), increased illness (usually diarrhea), interactions with other trace elements such as copper and zinc, altered gut microbiota to more pathogenic bacteria, increased inflammatory markers, and impaired cognitive and motor development. If these results can be confirmed by larger and well-controlled studies, it may have considerable programmatic implications (e.g., the necessity to screen for iron status before interventions to exclude iron-replete individuals). A lack of understanding of the mechanisms underlying these adverse outcomes limits our ability to modify present supplementation and fortification strategies. This review summarizes studies on the adverse effects of iron on various outcomes; suggests possible mechanisms that may explain these observations, which are usually made in clinical studies and intervention trials; and gives examples from animal models and in vitro studies. With a better understanding of these mechanisms, it may be possible to find novel ways of providing iron in a form that causes fewer or no adverse effects even when subjects are iron replete. However, it is apparent that our understanding is limited, and research in this area is urgently needed.

Maternal modifiers of the infant gut microbiota: metabolic consequences

Transmission of metabolic diseases from mother to child is multifactorial and includes genetic, epigenetic and environmental influences. Evidence in rodents, humans and non-human primates support the scientific premise that exposure to maternal obesity or high-fat diet during pregnancy creates a long-lasting metabolic signature on the infant innate immune system and the juvenile microbiota, which predisposes the offspring to obesity and metabolic diseases. In neonates, gastrointestinal microbes introduced through the mother are noted for their ability to serve as direct inducers/regulators of the infant immune system. Neonates have a limited capacity to initiate an immune response. Thus, disruption of microbial colonization during the early neonatal period results in disrupted postnatal immune responses that highlight the neonatal period as a critical developmental window. Although the mechanisms are poorly understood, increasing evidence suggests that maternal obesity or poor diet influences the development and modulation of the infant liver and other end organs through direct communication via the portal system, metabolite production, alterations in gut barrier integrity and the hematopoietic immune cell axis. This review will focus on how maternal obesity and dietary intake influence the composition of the infant gut microbiota and how an imbalance or maladaptation in the microbiota, including changes in early pioneering microbes, might contribute to the programming of offspring metabolism with special emphasis on mechanisms that promote chronic inflammation in the liver. Comprehension of these pathways and mechanisms will elucidate our understanding of developmental programming and may expand the avenue of opportunities for novel therapeutics.

Iron in Micronutrient Powder Promotes an Unfavorable Gut Microbiota in Kenyan Infants

Iron supplementation may have adverse health effects in infants, probably through manipulation of the gut microbiome. Previous research in low-resource settings have focused primarily on anemic infants. This was a double blind, randomized, controlled trial of home fortification comparing multiple micronutrient powder (MNP) with and without iron. Six-month-old, non- or mildly anemic, predominantly-breastfed Kenyan infants in a rural malaria-endemic area were randomized to consume: (1) MNP containing 12.5 mg iron (MNP+Fe, n = 13); (2) MNP containing no iron (MNP-Fe, n = 13); or (3) Placebo (CONTROL, n = 7), from 6-9 months of age. Fecal microbiota were profiled by high-throughput bacterial 16S rRNA gene sequencing. Markers of inflammation in serum and stool samples were also measured. At baseline, the most abundant phylum was Proteobacteria (37.6% of rRNA sequences). The proteobacterial genus Escherichia was the most abundant genus across all phyla (30.1% of sequences). At the end of the intervention, the relative abundance of Escherichia significantly decreased in MNP-Fe (-16.05 ± 6.9%, p = 0.05) and CONTROL (-19.75 ± 4.5%, p = 0.01), but not in the MNP+Fe group (-6.23 ± 9%, p = 0.41). The second most abundant genus at baseline was Bifidobacterium (17.3%), the relative abundance of which significantly decreased in MNP+Fe (-6.38 ± 2.5%, p = 0.02) and CONTROL (-8.05 ± 1.46%, p = 0.01), but not in MNP-Fe (-4.27 ± 5%, p = 0.4445). Clostridium increased in MNP-Fe only (1.9 ± 0.5%, p = 0.02). No significant differences were observed in inflammation markers, except for IL-8, which decreased in CONTROL. MNP fortification over three months in non- or mildly anemic Kenyan infants can potentially alter the gut microbiome. Consistent with previous research, addition of iron to the MNP may adversely affect the colonization of potential beneficial microbes and attenuate the decrease of potential pathogens.