Lipid-based Nutrient Supplements Do Not Affect Gut Bifidobacterium Microbiota in Malawian Infants: A Randomized Trial

The infant gut microbiome and cognitive development in malnutrition

Malnutrition affects 195 million children under the age of five worldwide with long term effects that include impaired cognitive development. Brain development occurs rapidly over the first 36 months of life. Whilst seemingly independent, changes to the brain and gut microbiome are linked by metabolites, hormones, and neurotransmitters as part of the gut-brain axis. In the context of severe malnutrition, the composition of the gut microbiome and the repertoire of biochemicals exchanged via the gut-brain axis vary when compared to healthy individuals. These effects are primarily due to the recognized interacting determinants, macro- and micronutrient deficiencies, infection, infestations and toxins related to poor sanitation, and a dearth of psycho-social stimulation. The standard of care for the treatment of severe acute malnutrition is focused on nutritional repletion and weight restoration through the provision of macro- and micronutrients, the latter usually in excess of recommended dietary allowances (RDA). However, existing formulations and supplements have not been designed to specifically address key recovery requirements for brain and gut microbiome development. Animal model studies indicate that treatments targeting the gut microbiome could improve brain development. Despite this, research on humans targeting the gut microbiome with the aim of restoring brain functionality are scarce. We conclude that there is a need for assessment of cognition and the use of various tools that permit visualization of the brain anatomy and function (e.g., Magnetic resonance imaging (MRI), functional near-infrared spectroscopy (fNIRS), electroencephalogram (EEG)) to understand how interventions targeting the gut microbiome impact brain development.

Gut Microbiome-Targeted Nutrition Interventions and Growth among Children in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Background

Childhood malnutrition is a public health challenge of much interest and concern globally. However, a perturbed gut microbiome (GM) may limit some nutrition interventions' effects among healthy children with undernutrition.

Objectives

This review aimed to evaluate the effects of GM-targeted nutrition interventions on growth outcomes among children (0-59 mo) using published studies in low- and middle-income countries.

Methods

The methods were guided by the Cochrane methodology. The literature search was conducted to include articles published from inception to July 2023 in PubMed, Google Scholar, and Cochrane Databases. We identified and included 35 studies among 11,047 children. The analysis was conducted considering various growth parameters in the qualitative synthesis and weight gain (kg) in the meta-analysis.

Results

In the qualitative synthesis, 55.6% of prebiotics, 66.7% of probiotics, 71.4% of synbiotics, and 28.6% of "microbiome complementary feed" studies had significant effects on growth outcomes. Also, prebiotics had more studies with significant effects among healthy children, whereas probiotics, synbiotics, and "microbiome complementary feeds" had more studies with significant effects among children with undernutrition. Nineteen studies were included in the meta-analyses, of which 7 (36.8%) measured GM outcomes. The meta-analysis showed that prebiotics exhibited heterogeneity but had significant effects on weight in the intervention as compared with the control (mean difference [MD]: 0.14 kg; 95% CI: 0.02, 0.25; I2 = 63%, P = 0.02; 4 studies, n = 932). Probiotics had significant effects on weight in the intervention (MD: 0.15 kg; 95% CI: 0.06, 0.25; I2 = 42%, P = 0.05; 8 studies, n = 2437) as compared to the control. However, synbiotics (MD: 0.26 kg; 95% CI: -0.04, 0.56; I2 = 41%, P = 0.17; 4 studies, n = 1896] and "microbiome complementary feed" (MD: -0.03 kg; 95% CI: -0.18, 0.11; I2 = 0%, P = 0.60; 3 studies, n = 733] had no significant effects on weight in the intervention as compared with control.

Conclusions

Although probiotics and synbiotics may be effective at enhancing growth among children, the selection of interventions should be contingent upon health status.This trial was registered at www.crd.york.ac.uk/prospero/ as CRD42023434109.

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.

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.

A Scoping Review Evaluating the Current State of Gut Microbiota Research in Africa

The gut microbiota has emerged as a key human health and disease determinant. However, there is a significant knowledge gap regarding the composition, diversity, and function of the gut microbiota, specifically in the African population. This scoping review aims to examine the existing literature on gut microbiota research conducted in Africa, providing an overview of the current knowledge and identifying research gaps. A comprehensive search strategy was employed to identify relevant studies. Databases including MEDLINE (PubMed), African Index Medicus (AIM), CINAHL (EBSCOhost), Science Citation index (Web of Science), Embase (Ovid), Scopus (Elsevier), WHO International Clinical Trials Registry Platform (ICTRP), and Google Scholar were searched for relevant articles. Studies investigating the gut microbiota in African populations of all age groups were included. The initial screening included a total of 2136 articles, of which 154 were included in this scoping review. The current scoping review revealed a limited number of studies investigating diseases of public health significance in relation to the gut microbiota. Among these studies, HIV (14.3%), colorectal cancer (5.2%), and diabetes mellitus (3.9%) received the most attention. The top five countries that contributed to gut microbiota research were South Africa (16.2%), Malawi (10.4%), Egypt (9.7%), Kenya (7.1%), and Nigeria (6.5%). The high number (n = 66) of studies that did not study any specific disease in relation to the gut microbiota remains a gap that needs to be filled. This scoping review brings attention to the prevalent utilization of observational study types (38.3%) in the studies analysed and emphasizes the importance of conducting more experimental studies. Furthermore, the findings reflect the need for more disease-focused, comprehensive, and population-specific gut microbiota studies across diverse African regions and ethnic groups to better understand the factors shaping gut microbiota composition and its implications for health and disease. Such knowledge has the potential to inform targeted interventions and personalized approaches for improving health outcomes in African populations.

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.

Gut Microbiota-Targeted Nutritional Interventions Improving Child Growth in Low- and Middle-Income Countries: A Systematic Review

The objective of this systematic literature review was to evaluate the efficacy of probiotic, prebiotic, and synbiotic interventions compared with control on improving growth outcomes of children living in low- and middle-income countries (LMICs). Probiotics had a beneficial effect on ≥1 of the growth outcomes in 5 out of the 11 included studies. Of these, 3 studies were conducted in undernourished children, 1 in healthy children, and 1 in children without a described health status. No effect of prebiotics on growth outcomes was seen in the 4 included studies. Synbiotics had a beneficial effect on growth outcomes in 3 out of 4 studies. Although a limited number of studies with high heterogeneity indicate that probiotics and synbiotics may have the potential to improve the growth of both undernourished and healthy children living in LMICs, more research is needed to confirm the observed effects. This review was registered at www.crd.york.ac.uk/prospero/ as CRD42020212998.

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.

Provision of Lipid-Based Nutrient Supplements to Mothers During Pregnancy and 6 Months Postpartum and to Their Infants from 6 to 18 Months Promotes Infant Gut Microbiota Diversity at 18 Months of Age but Not Microbiota Maturation in a Rural Malawian Setting: Secondary Outcomes of a Randomized Trial

BACKGROUND

Diet may alter the configuration of gut microbiota, but the impact of prenatal and postnatal nutritional interventions on infant gut microbiota has not been investigated.

OBJECTIVE

We evaluated whether providing lipid-based nutrient supplements (LNSs) to mother-infant dyads promotes a more diverse and mature infant gut microbiota, compared to maternal supplementation with multiple micronutrients (MMN) or iron and folic acid (IFA).

METHODS

We enrolled 869 pregnant women in a randomized trial in Malawi. There were 3 study groups, with women receiving 1 MMN capsule daily during pregnancy and 6 mo postpartum, or 1 LNS sachet (20 g) daily during pregnancy and 6 mo postpartum, or 1 IFA capsule daily (during pregnancy) then a placebo daily (postpartum). Infants in the LNS group received LNS from 6 to 18 mo; infants in the other groups did not receive supplements. The infants' fecal microbiota were characterized by PCR amplification and sequencing of the bacterial 16S rRNA gene (variable region 4). The primary outcomes were microbiota α diversity and maturation [as microbiota-for-age z score (MAZ)]. Specific associations of taxa with intervention were established with indicator species analysis (ISA).

RESULTS

Primary outcomes did not differ between IFA and MMN groups, so these groups were combined (IFA + MMN). Mean ± SD α diversity was higher in the LNS group at 18 mo for Shannon index [3.01 ± 0.57 (LNS) compared with 2.91 ± 0.60 (IFA + MMN), P = 0.032] and Pielou's evenness index [0.61 ± 0.08 (LNS) compared with 0.60 ± 0.09 (IFA + MMN), P = 0.043]; no significant differences were observed at 1, 6, 12, or 30 mo. MAZ and β diversity did not differ at any age. We found 10 and 3 operational taxonomic units (OTUs) positively associated with LNS and IFA + MMN, respectively; however, these associations became nonsignificant following false discovery rate correction at 10%.

CONCLUSIONS

Prenatal and postnatal LNS intake promoted infant gut microbiota diversity at 18 mo, after 12 mo of child supplementation, but did not alter microbiota maturation. This trial was registered at clinicaltrials.gov as NCT01239693.

Surveying Gut Microbiome Research in Africans: Toward Improved Diversity and Representation

Descriptive and translational investigations into the human gut microbiome (GM) are rapidly expanding; however, studies are largely restricted to industrialized populations in the USA and Europe. Little is known about microbial variability and its implications for health and disease in other parts of the world. Populations in Africa are particularly underrepresented. What limited research has been performed has focused on a few subject domains, including the impact of long-term lifestyle and dietary factors on GM ecology, its maturation during infancy, and the interrelationships between the microbiome, infectious disease, and undernutrition. Recently, international consortia have laid the groundwork for large-scale genomics and microbiome studies on the continent, with a particular interest in the epidemiologic transition to noncommunicable disease. Here, we survey the current landscape of GM scholarship in Africa and propose actionable recommendations to improve research capacity and output.

Preventive lipid-based nutrient supplements given with complementary foods to infants and young children 6 to 23 months of age for health, nutrition, and developmental outcomes

BACKGROUND

One nutritional intervention advocated to prevent malnutrition among children is lipid-based nutrient supplements (LNS). LNS provide a range of vitamins and minerals, but unlike most other micronutrient supplements, LNS also provide energy, protein and essential fatty acids. Alternative recipes and formulations to LNS include fortified blended foods (FBF), which are foods fortified with vitamins and minerals, and micronutrient powders (MNP), which are a combination of vitamins and minerals, OBJECTIVES: To assess the effects and safety of preventive LNS given with complementary foods on health, nutrition and developmental outcomes of non-hospitalised infants and children six to 23 months of age, and whether or not they are more effective than other foods (including FBF or MNP).This review did not assess the effects of LNS as supplementary foods or therapeutic foods in the management of moderate and severe acute malnutrition.

SEARCH METHODS

In October 2018, we searched CENTRAL, MEDLINE, Embase, 21 other databases and two trials registers for relevant studies. We also checked the reference lists of included studies and relevant reviews and contacted the authors of studies and other experts in the area for any ongoing and unpublished studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs that evaluated the impact of LNS plus complementary foods given at point-of-use (for any dose, frequency, duration) to non-hospitalised infants and young children aged six to 23 months in stable or emergency settings and compared to no intervention, other supplementary foods (i.e. FBF), nutrition counselling or multiple micronutrient supplements or powders for point-of-use fortification of complementary foods.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for relevance and, for those studies included in the review, extracted data, assessed risk of bias and rated the quality of the evidence using the GRADE approach. We carried out statistical analysis using Review Manager software. We used a random-effects meta-analysis for combining data as the interventions differed significantly. We set out the main findings of the review in 'Summary of findings' tables,.

MAIN RESULTS

Our search identified a total of 8124 records, from which we included 17 studies (54 papers) with 23,200 children in the review. The included studies reported on one or more of the pre-specified primary outcomes, and five studies included multiple comparison groups.Overall, the majority of trials were at low risk of bias for random sequence generation, allocation concealment, blinding of outcome assessment, incomplete outcome data, selective reporting and other sources of bias, but at high risk of bias for blinding of participants and personnel due to the nature of the intervention. Using the GRADE approach, we judged the quality of the evidence for most outcomes as low or moderate.LNS+complementary feeding compared with no intervention Thirteen studies compared LNS plus complementary feeding with no intervention. LNS plus complementary feeding reduced the prevalence of moderate stunting by 7% (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.88 to 0.98; nine studies, 13,372 participants; moderate-quality evidence), severe stunting by 15% (RR 0.85, 95% CI 0.74 to 0.98; five studies, 6151 participants; moderate-quality evidence), moderate wasting by 18% (RR 0.82, 95% CI 0.74 to 0.91; eight studies; 13,172 participants; moderate-quality evidence), moderate underweight by 15% (RR 0.85, 95% CI 0.80 to 0.91; eight studies, 13,073 participants; moderate-quality evidence), and anaemia by 21% (RR 0.79, 95% CI 0.69 to 0.90; five studies, 2332 participants; low-quality evidence). There was no impact of LNS plus complementary feeding on severe wasting (RR 1.27, 95% CI 0.66 to 2.46; three studies, 2329 participants) and severe underweight (RR 0.78, 95%CI 0.54 to 1.13; two studies, 1729 participants). Adverse effects did not differ between the groups (RR 0.86, 95% CI 0.74 to 1.01; three studies, 3382 participants).LNS+complementary feeding compared with FBF Five studies compared LNS plus complementary feeding with other FBF, including corn soy blend and UNIMIX. We pooled four of the five studies in meta-analyses and found that, when compared to other FBF, LNS plus complementary feeding significantly reduced the prevalence of moderate stunting (RR 0.89, 95% CI 0.82 to 0.97; three studies, 2828 participants; moderate-quality evidence), moderate wasting (RR 0.79, 95% CI 0.65 to 0.97; two studies, 2290 participants; moderate-quality evidence), and moderate underweight (RR 0.81, 95% CI 0.73 to 0.91; two studies, 2280 participants; moderate-quality evidence). We found no difference between LNS plus complementary feeding and FBF for severe stunting (RR 0.41, 95% CI 0.12 to 1.42; two studies, 729 participants; low-quality evidence), severe wasting (RR 0.64, 95% CI 0.19 to 2.81; two studies, 735 participants; moderate-quality evidence), and severe underweight (RR 1.23, 95% CI 0.67 to 2.25; one study, 173 participants; low-quality evidence).LNS+complementary feeding compared with MNP Four studies compared LNS plus complementary feeding with MNP. We pooled data from three of the four studies in meta-analyses and found that compared to MNP, LNS plus complementary feeding significantly reduced the prevalence of moderate underweight (RR 0.88, 95% CI 0.78 to 0.99; two studies, 2004 participants; moderate-quality evidence) and anaemia (RR 0.38, 95% CI 0.21 to 0.68; two studies, 557 participants; low-quality evidence). There was no difference between LNS plus complementary feeding and MNP for moderate stunting (RR 0.92, 95% CI 0.82 to 1.02; three studies, 2365 participants) and moderate wasting (RR 0.97, 95% CI 0.77 to 1.23; two studies, 2004 participants).

AUTHORS' CONCLUSIONS

The findings of this review suggest that LNS plus complementary feeding compared to no intervention is effective at improving growth outcomes and anaemia without adverse effects among children aged six to 23 months in low- and middle-income countries (LMIC) in Asia and Africa, and more effective if provided over a longer duration of time (over 12 months). Limited evidence also suggests that LNS plus complementary feeding is more effective than FBF and MNP at improving growth outcomes.