Metallomics Reviews
Gut Microbiome Composition and Childhood Stunting: LMIC data
Clinical Overview
This systematic review synthesizes 14 microbiome studies (n=20–691 per study) of children under 5 years in low- and middle-income countries, comparing gut communities in stunted versus non-stunted children using 16S rRNA and shotgun metagenomic sequencing of stool, duodenal, and gastric samples. Across Asia, Africa, and South America, alpha diversity was usually similar, but several studies showed higher beta diversity in stunted children. Stunting was consistently associated with enrichment of putative pathobionts (Escherichia/Shigella, Campylobacter, Desulfovibrio, Neisseria) and depletion of butyrate producers (Faecalibacterium, Megasphaera, Blautia, Bifidobacterium), plus duodenal overgrowth of oropharyngeal-like taxa and growth-linked metabolic pathways (B-vitamin, purine/pyrimidine, carbohydrate and amino acid metabolism).
What was reviewed and who was studied
The review includes observational and case–control cohorts of under-five children from Bangladesh, India, Indonesia, Malawi, Zimbabwe, Madagascar, the Central African Republic, and Peru. Stunting was defined either as LAZ/HAZ < −2 or by negative growth velocity. The primary matrix was stool, with duodenal and gastric aspirates in two studies, analyzed by 16S rRNA gene sequencing (various variable regions) or shotgun metagenomics and, in two studies, virome profiling.
Major findings
| Domain | Summary of findings |
|---|---|
| Diversity | Most studies reported no difference in alpha diversity (Shannon); two metagenomic studies found lower diversity in stunted children. A meta-analysis of five datasets showed no significant Shannon difference but very high heterogeneity (I² = 97%). |
| Community structure | Several studies reported higher beta diversity in stunted children by weighted or unweighted UniFrac and Bray–Curtis, indicating compositional instability rather than simple richness loss. |
| Phylum-level shifts | In Asian cohorts, stunted children often had higher Bacillota, Bacteroidota, and Pseudomonadota; e.g., one study reported Bacillota 45.7% vs 39.8% in stunted vs non-stunted children (p = 5.89×10⁻⁴). Other studies showed no consistent phylum-level differences. |
| Genus-level taxa | Stunting was repeatedly associated with increased Escherichia/Shigella, Campylobacter, Desulfovibrio, Veillonella, Streptococcus, Aggregatibacter, and decreased Faecalibacterium, Megasphaera, Blautia, Bifidobacterium, and some Bacteroides/Parabacteroides. |
| Duodenal ecology | Duodenal aspirates from stunted children showed marked overrepresentation of oropharyngeal-associated genera (Veillonella, Gemella, Neisseria, Haemophilus, Rothia, Actinomyces) and similar taxa in stool, interpreted as “decompartmentalization” of the gastrointestinal tract. |
| Virome and pathways | Phage diversity and richness tracked bacterial diversity and were lower or not growth-associated in stunted children. One Zimbabwean cohort found B-vitamin, lipid, purine/pyrimidine, and carbohydrate/amino-acid pathways predicted LAZ at different ages. |
Implications for Microbial Metallomics
Gut community structure and metabolic pathway capacity in these cohorts are tightly linked to linear growth, suggesting that microbially mediated nutrient and cofactor handling—including vitamins and associated redox chemistry—may be central to stunting biology, even though metals were not directly measured.
| Concept | Implication |
|---|---|
| Enrichment of Escherichia/Shigella, Campylobacter, Desulfovibrio, Neisseria | These inflammatory pathobionts plausibly drive chronic enteropathy, diverting host resources from growth to immune responses and altering local redox conditions in ways likely to affect micronutrient and cofactor availability. |
| Depletion of Faecalibacterium, Megasphaera, Blautia, Bifidobacterium | Loss of butyrate producers and beneficial commensals may compromise epithelial energy supply, barrier integrity, and nutrient absorption, a key context for interpreting trace-nutrient and cofactor flux in stunting. |
| Higher beta diversity without consistent alpha shifts | Compositional instability rather than simple diversity loss suggests that functional (metabolic) and possibly metal/cofactor-linked resilience markers may be more informative than bulk diversity metrics. |
| Duodenal overgrowth of oropharyngeal taxa | “Decompartmentalization” of the upper gut indicates mucosal colonization by atypical communities in the main absorptive region, where micronutrient—including metal—uptake occurs, highlighting this niche as a critical sampling and intervention target. |
| Growth-predictive B-vitamin and nucleotide pathways | Pathway-based signatures of LAZ suggest that functional profiling (metagenomics, metabolomics) could outperform taxonomic profiling for identifying stunting-related disturbances in nutrient and cofactor metabolism. |
| Virome–bacteriome coupling | Reduced phage diversity parallel to reduced bacterial diversity in poorer growth trajectories hints that phage-mediated control of bacterial functions (including nutrient metabolism) could influence therapeutic attempts to reshape the gut ecosystem. |
Limitations
The review aggregates small, heterogeneous studies with varying definitions of stunting, age ranges (birth to 5 years), and study designs. Many cohorts lacked adjustment for diet, antibiotic exposure, and other key confounders. Most sequencing used 16S rRNA with different variable regions and pipelines, limiting taxonomic resolution and comparability. Duodenal sampling lacked healthy controls, and observational designs preclude causal inference.
Future perspectives
The authors highlight the need for larger, harmonized longitudinal studies using standardized stunting definitions and dense sampling across early life. Next steps logically include combining high-resolution metagenomics with metabolomics and transcriptomics to move from descriptive taxonomies to mechanistic pathway maps, especially around B-vitamin, carbohydrate, amino acid, and inflammatory pathways. Less invasive small-intestinal sampling would refine localization of dysbiosis. Mechanistic work and interventional trials (for example, microbiota-directed complementary foods) should target the specific taxa and pathways here linked to linear growth.
Key takeaways for Researchers and Clinicians
This review evaluates under-five children in LMICs, showing that stunting is less about simple loss of gut diversity and more about distinct patterns: enrichment of inflammatory Proteobacteria (Escherichia/Shigella, Campylobacter, Desulfovibrio, Neisseria), depletion of butyrate producers (Faecalibacterium, Megasphaera, Blautia, Bifidobacterium), and duodenal colonization by oropharyngeal taxa. Phylum-level shifts are inconsistent, but community structure and specific genera, together with growth-associated metabolic pathways (B-vitamin, nucleotide, carbohydrate, amino-acid metabolism), emerge as the clearest signatures.
Methodologically, 16S rRNA sequencing of stool alone is insufficient; targeted small-intestinal sampling and pathway-level metagenomics give more clinically relevant signals. Clinically, these data support a view of stunting as a chronic enteropathy linked to microbiome composition and function, not just caloric deficit. The translational hook for microbial metallomics is that the same taxa and pathways that shape energy harvest and B-vitamin metabolism likely intersect with trace nutrient and cofactor handling, offering future diagnostic and therapeutic entry points.
Citation
Chibuye M, Mende DR, Spijker R, et al. Systematic review of associations between gut microbiome composition and stunting in under-five children. npj Biofilms and Microbiomes. 2024;10:46. doi:10.1038/s41522-024-00517-5