Male-specific Association Between Fat-Free Mass Index and Fecal Microbiota in 2- to 3-Year-Old Australian Children

Exploring the Dynamic Relationship between the Gut Microbiome and Body Composition across the Human Lifespan: A Systematic Review

This systematic review aimed to identify different gut microbiome profiles across the human lifespan and to correlate such profiles with the body composition. PubMed, Scopus, and Cochrane were searched from inception to March 2022. Sixty studies were included in this systematic review. Overall, the gut microbiome composition in overweight participants exhibited decreased α-diversity, decreased levels of the phylum Bacteroidetes and its taxa, and increased levels of the phylum Firmicutes, its taxa, and the Firmicutes/Bacteroidetes ratio, in comparison to normal-weight participants. Other body composition parameters showed similar correlations. Fat mass and waist circumference were found to correlate positively with the Firmicutes taxa and negatively with the Bacteroidetes taxa. In contrast, lean body mass and muscle mass demonstrated a positive correlation with the Bacteroidetes taxa. Notably, these correlations were more pronounced in athletes than in obese and normal-weight individuals. The composition of the gut microbiome is evidently different in overweight individuals or athletes of all age groups, with the former tending towards decreased Bacteroidetes taxa and increased Firmicutes taxa, while a reversed relationship is observed concerning athletes. Further studies are needed to explore the dynamic relationship between energy intake, body composition, and the gut microbiome across the human lifespan.

Maturational patterns of the infant gut mycobiome are associated with early-life body mass index

Unlike the bacterial microbiome, the role of early-life gut fungi in host metabolism and childhood obesity development remains poorly characterized. To address this, we investigate the relationship between the gut mycobiome of 100 infants from the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study and body mass index Z scores (BMIz) in the first 5 years of life. An increase in fungal richness during the first year of life is linked to parental and infant BMI. The relationship between richness pattern and early-life BMIz is modified by maternal BMI, maternal diet, infant antibiotic exposure, and bacterial beta diversity. Further, the abundances of Saccharomyces, Rhodotorula, and Malassezia are differentially associated with early-life BMIz. Using structural equation modeling, we determine that the mycobiome's contribution to BMIz is likely mediated by the bacterial microbiome. This demonstrates that mycobiome maturation and infant growth trajectories are distinctly linked, advocating for inclusion of fungi in larger pediatric microbiome studies.

Personalized approach to childhood obesity: Lessons from gut microbiota and omics studies. Narrative review and insights from the 29th European childhood obesity congress

The traditional approach to childhood obesity prevention and treatment should fit most patients, but misdiagnosis and treatment failure could be observed in some cases that lie away from average as part of individual variation or misclassification. Here, we reflect on the contributions that high-throughput technologies such as next-generation sequencing, mass spectrometry-based metabolomics and microbiome analysis make towards a personalized medicine approach to childhood obesity. We hypothesize that diagnosing a child as someone with obesity captures only part of the phenotype; and that metabolomics, genomics, transcriptomics and analyses of the gut microbiome, could add precision to the term "obese," providing novel corresponding biomarkers. Identifying a cluster -omic signature in a given child can thus facilitate the development of personalized prognostic, diagnostic, and therapeutic approaches. It can also be applied to the monitoring of symptoms/signs evolution, treatment choices and efficacy, predisposition to drug-related side effects and potential relapse. This article is a narrative review of the literature and summary of the main observations, conclusions and perspectives raised during the annual meeting of the European Childhood Obesity Group. Authors discuss some recent advances and future perspectives on utilizing a systems approach to understanding and managing childhood obesity in the context of the existing omics data.

Microbiomes and Childhood Malnutrition: What Is the Evidence?

Both undernutrition and overnutrition continue to represent enduring global health crises, and with the growing implications of both forms of malnutrition occurring simultaneously in individuals and populations (referred to as the double burden of malnutrition), understanding their biological and environmental causes is a primary research and humanitarian necessity. There is growing evidence of a bidirectional association between variation in the gastrointestinal (GI) microbiome and risk of/resilience to malnutrition during early life. For example, studies of siblings who discordantly do or do not develop severe malnutrition show clear differences in the diversity and composition of fecal microbiomes. These differences are transiently lessened during refeeding but re-emerge thereafter. These findings have been somewhat recapitulated using animal models, but small sample sizes and limited range complicate interpretation of results and applicability to humans. Mechanisms driving these differences are currently unknown but likely involve a combination of inflammatory pathways (and perhaps antioxidant status of the host) and effects on nutrient availability, requirements, and utilization by both host and microbe. A less robust literature also suggests that variation in GI microbiome is associated with risk for obesity during childhood. The putative impact of GI microbiomes on malnutrition is likely modified by a variety of important variables such as genetics (likely driven, in part, by evolution), environmental pathogen exposure and its timing, dietary factors, and cultural/societal pattern (e.g., use of antibiotics). Given the growing double burden of malnutrition, this topic demands a focused interdisciplinary approach that expands from merely characterizing differences and longitudinal changes in fecal microbes to examining their functionality during early life. Understanding the complex composition of human milk and how its components impact establishment and maintenance of the recipient infant's GI microbiome will also undoubtedly shed important light on this topic.

Developmental origins of metabolic diseases

Almost 2 billion adults in the world are overweight, and more than half of them are classified as obese, while nearly one-third of children globally experience poor growth and development. Given the vast amount of knowledge that has been gleaned from decades of research on growth and development, a number of questions remain as to why the world is now in the midst of a global epidemic of obesity accompanied by the "double burden of malnutrition," where overweight coexists with underweight and micronutrient deficiencies. This challenge to the human condition can be attributed to nutritional and environmental exposures during pregnancy that may program a fetus to have a higher risk of chronic diseases in adulthood. To explore this concept, frequently called the developmental origins of health and disease (DOHaD), this review considers a host of factors and physiological mechanisms that drive a fetus or child toward a higher risk of obesity, fatty liver disease, hypertension, and/or type 2 diabetes (T2D). To that end, this review explores the epidemiology of DOHaD with discussions focused on adaptations to human energetics, placental development, dysmetabolism, and key environmental exposures that act to promote chronic diseases in adulthood. These areas are complementary and additive in understanding how providing the best conditions for optimal growth can create the best possible conditions for lifelong health. Moreover, understanding both physiological as well as epigenetic and molecular mechanisms for DOHaD is vital to most fully address the global issues of obesity and other chronic diseases.

Characterizing the Composition of the Pediatric Gut Microbiome: A Systematic Review

The consortium of trillions of microorganisms that live inside the human gut are integral to health. Little has been done to collate and characterize the microbiome of children. A systematic review was undertaken to address this gap (PROSPERO ID: CRD42018109599). MEDLINE and EMBASE were searched using the keywords: “healthy preadolescent children” and “gut microbiome” to 31 August 2018. Of the 815 journal articles, 42 met the inclusion criteria. The primary outcome was the relative abundance of bacteria at the phylum, family, and genus taxonomic ranks. α-diversity, short chain fatty acid concentrations, diet, 16S rRNA sequencing region, and geographical location were documented. The preadolescent gut microbiome is dominated at the phylum level by Firmicutes (weighted overall average relative abundance = 51.1%) and Bacteroidetes (36.0%); genus level by Bacteroides (16.0%), Prevotella (8.69%), Faecalibacterium (7.51%), and Bifidobacterium (5.47%). Geographic location and 16S rRNA sequencing region were independently associated with microbial proportions. There was limited consensus between studies that reported α-diversity and short chain fatty acids. Broadly speaking, participants from non-Western locations, who were less likely to follow a Westernized dietary pattern, had higher α-diversity and SCFA concentrations. Confirmatory studies will increase the understanding of the composition and functional capacity of the preadolescent gut microbiome.

Microbiota and Body Composition During the Period of Complementary Feeding

OBJECTIVES

This study aimed to explore the associations between food group intake, faecal microbiota profile, and body composition during the period of complementary feeding.

METHODS

Diet was assessed using a quantitative food frequency questionnaire, faecal microbiota profile was assessed using 16S rRNA gene sequencing, and body composition was assessed using bioelectrical impedance analysis and dual energy x-ray absorptiometry, in a cohort of 50 infants aged 6 to 24 months of age.

RESULTS

During this critical period of microbiota development, age was the strongest predictor of microbiota composition with network analysis revealing a cluster of genera positively associated with age. A separate cluster comprised genera associated with fat mass index with Bifidobacterium showing the strongest correlation with fat mass index (rho = 0.55, P = 0.001, false discovery rate [FDR] = 0.018). Dairy intake was both negatively correlated with Bacteroides (rho = -0.49, P < 0.001, FDR = 0.024) and positively correlated with lean mass index (rho = 0.44, P = 0.007, FDR = 0.024). Antibiotics use in the first month of life had the most striking influence on body composition and was associated with an increase in mean body mass index z score of 1.17 (P = 0.001) and body fat of 3.5% (P = 0.001).

CONCLUSIONS

Our results suggested that antibiotics use in the first month of life had the most striking influence on body composition in this cohort of infants aged 6 to 24 months, whereas dairy intake interacted with both microbiota and body composition in early life.

Antibiotic and acid-suppression medications during early childhood are associated with obesity

OBJECTIVE

Gut microbiota alterations are associated with obesity. Early exposure to medications, including acid suppressants and antibiotics, can alter gut biota and may increase the likelihood of developing obesity. We investigated the association of antibiotic, histamine-2 receptor antagonist (H2RA) and proton pump inhibitor (PPI) prescriptions during early childhood with a diagnosis of obesity.

DESIGN

We performed a cohort study of US Department of Defense TRICARE beneficiaries born from October 2006 to September 2013. Exposures were defined as having any dispensed prescription for antibiotic, H2RA or PPI medications in the first 2 years of life. A single event analysis of obesity was performed using Cox proportional hazards regression.

RESULTS

333 353 children met inclusion criteria, with 241 502 (72.4%) children prescribed an antibiotic, 39 488 (11.8%) an H2RA and 11 089 (3.3%) a PPI. Antibiotic prescriptions were associated with obesity (HR 1.26; 95% CI 1.23 to 1.28). This association persisted regardless of antibiotic class and strengthened with each additional class of antibiotic prescribed. H2RA and PPI prescriptions were also associated with obesity, with a stronger association for each 30-day supply prescribed. The HR increased commensurately with exposure to each additional medication group prescribed.

CONCLUSIONS

Antibiotics, acid suppressants and the combination of multiple medications in the first 2 years of life are associated with a diagnosis of childhood obesity. Microbiota-altering medications administered in early childhood may influence weight gain.

Dietary fat, the gut microbiota, and metabolic health - A systematic review conducted within the MyNewGut project

BACKGROUND AND AIMS

Studies indicate that dietary fat quantity and quality influence the gut microbiota composition which may as a consequence impact metabolic health. This systematic review aims to summarize the results of available studies in humans on dietary fat intake (quantity and quality), the intestinal microbiota composition and related cardiometabolic health outcomes.

METHODS

We performed a systematic review (CRD42018088685) following PRISMA guidelines and searched for literature in Medline, EMBASE, and Cochrane databases.

RESULTS

From 796 records, 765 records were excluded based on title or abstract. After screening of 31 full-text articles six randomized controlled trials (RCT) and nine cross-sectional observational studies were included. Our results of interventional trials do not suggest strong effects of different amounts and types of dietary fat on the intestinal microbiota composition or on metabolic health outcomes while observational studies indicate associations with the microbiota and health outcomes. High intake of fat and saturated fatty acids (SFA) may negatively affect microbiota richness and diversity and diets high in monounsaturated fatty acids (MUFA) may decrease total bacterial numbers whereas dietary polyunsaturated fatty acids (PUFA) had no effect on richness and diversity.

CONCLUSIONS

High fat and high SFA diets can exert unfavorable effects on the gut microbiota and are associated with an unhealthy metabolic state. Also high MUFA diets may negatively affect gut microbiota whereas PUFA do not seem to negatively affect the gut microbiota or metabolic health outcomes. However, data are not consistent and most RCT and observational studies showed risks of bias.

Growth and protein-rich food intake in infancy is associated with fat-free mass index at 2-3 years of age

AIM

The reduction of infant protein intake and associated growth velocity is a recommended public health strategy for reducing the risk of childhood obesity. This study tests the hypothesis that infants' growth and protein-rich food (dairy, meat, fish and egg) intake influences childhood body size and composition at 2-3 years of age.

METHODS

Thirty-six children were studied from the Feeding Queensland Babies Study Cohort, which prospectively collected data on infant growth and diet. Body composition was estimated using the deuterium oxide dilution technique at 2-3 years of age.

RESULTS

Fat-free mass index Z score at 2-3 years of age was positively associated with animal protein food (dairy, meat, fish and egg) intake at 12 months of age (r = 0.58, P = 0.002, false discovery rate corrected P value = 0.008) and negatively associated with weight-for-length growth velocity from 6 to 12 months of age (r = -0.75, P = 0.019, false discovery rate corrected P value = 0.038), which in turn was negatively associated with growth velocity from 0 to 6 months of age (r = -0.790, P = 0.007).

CONCLUSION

This study suggests that strategies to reduce protein intake and growth velocity in early life may limit fat-free mass growth, potentially predisposing to increased adiposity in later life.