Metallomics Reviews
Prenatal Acetaminophen, Microbiome Change and Cognition
Clinical Overview
This prospective birth cohort study from Sherbrooke, Canada evaluated whether in utero and mid-childhood exposure to acetaminophen and caffeine, quantified in meconium and stool (ng/g, wet weight), relate to the gut microbiome and cognition at 6–7 years. In 49 children with meconium and 85 with stool, prenatal acetaminophen detection was associated with lower bacterial alpha diversity and altered phylum composition, including reduced Firmicutes and increased Actinobacteria. Functional shifts included higher potential for succinate fermentation to butanoate. Proteobacteria abundance modified associations between both drugs and Wechsler IQ subtests, weakening small benefits of acetaminophen and amplifying adverse caffeine–cognition relationships.
What was reviewed and who was studied
The investigators analysed the GESTation and Environment (GESTE) cohort, focusing on 49 children with meconium for prenatal exposure assessment and 85 with stool at 6–7 years for cross-sectional exposure and metagenomic profiling, relating fecal acetaminophen and caffeine to gut microbial composition, functional pathways, and WISC-IV and QTAC neurodevelopmental measures.
Major Findings
Quantitative analyses centred on bacterial alpha and beta diversity, phylum-level composition, species and MetaCyc pathways, and on effect modification of drug–cognition relationships by microbial features. Prenatal and concurrent exposures were analysed separately, with models adjusted for sex, breastfeeding history, mode of delivery, and family income, and multiple-testing handled by false discovery-rate control.
| Exposure / Microbiome feature (matrix, basis) | Main result (effect estimate or qualitative outcome) |
|---|---|
| Prenatal acetaminophen detected vs undetected (meconium, ng/g) and alpha diversity | Associated with a 0.17-unit lower Shannon Index in childhood stool [95% CI −0.31 to −0.04; q=0.044], with similar direction for Pielou evenness, suggesting reduced bacterial diversity. |
| Prenatal acetaminophen and phylum composition | Trend toward lower Firmicutes relative abundance [β = −0.09, 95% CI −0.16 to −0.03; q=0.062] and higher Actinobacteria [β = 0.183, 95% CI 0.03 to 0.34; q=0.085] in childhood stool. |
| Prenatal acetaminophen and functional pathways | Higher relative abundance of genes in the succinate fermentation to butanoate pathway (MetaCyc PWY-5677) [β = 0.33, 95% CI 0.17 to 0.49; q=0.072]. |
| Prenatal caffeine (meconium, log2-transformed ng/g) | No statistically significant associations with childhood alpha diversity, phylum or species composition, functional pathways, or beta diversity. |
| Childhood stool caffeine (ng/g) and pathways | Per log2-doubling in stool caffeine, higher relative abundance of pathways for L-methionine biosynthesis (PWY-5345) [β = 0.24, 95% CI 0.12 to 0.35; q=0.018], assimilatory sulfate reduction (SO4ASSIM-PWY) [β = 0.24, 95% CI 0.12 to 0.36; q=0.018], and sulfate assimilation and cysteine synthesis (SULFATE-CYS-PWY) [β = 0.24, 95% CI 0.12 to 0.35; q=0.018]. |
| Proteobacteria and neurocognition | Higher childhood Proteobacteria relative abundance weakened small positive associations of prenatal acetaminophen with several WISC-IV subtests and strengthened inverse associations of prenatal caffeine with digit span, information, and WISC summary scores. |
Implications for Microbial Metallomics
Across this cohort, xenobiotic exposure–linked changes in microbial diversity and sulfur- and short-chain-fatty-acid–related pathways position the gut “metallome-adjacent” metabolome as a modifier of neurodevelopmental risk.
| Concept | Implication |
|---|---|
| Prenatal acetaminophen linked to lower diversity and a Firmicutes↓/Actinobacteria↑ profile | Early exposure to a non-metal xenobiotic can durably shift gut community structure, potentially mimicking delayed maturation patterns; microbial resilience to later environmental metal or metalloid exposures may be altered by such baseline configurations. |
| Increased succinate-to-butanoate fermentation genes with prenatal acetaminophen | Functional reprogramming of energy-harvesting and fermentation pathways in childhood may represent a lasting microbial “memory” of in utero drug exposure, offering a pathway-level readout complementary to elemental measurements. |
| Caffeine-associated enrichment of methionine synthesis and sulfate reduction/assimilation pathways | Sulfur-handling and one-carbon–related microbial functions respond measurably to stool caffeine, suggesting that, in future metallomics work, sulfur-containing metabolites and redox-active sulfur species could serve as sensitive reporters of drug–microbe interactions. |
| Proteobacteria amplification of adverse caffeine–cognition associations | A Proteobacteria-enriched state appears to increase neurocognitive susceptibility to common over-the-counter chemicals, supporting the idea that microbiome structure can stratify host response to xenobiotics, alongside metal exposures. |
| Lack of detectable prenatal caffeine effects on composition | Not all pervasive exposures leave a strong taxonomic footprint; this underscores the value of pairing metallomic, xenobiotic, and functional microbial data rather than relying solely on community composition. |
| Meconium and stool as exposure matrices for microbiome studies | Measuring parent acetaminophen and caffeine directly in feces provides a practical template for integrating drug and, by extension, metal/metalloid body burdens with high-resolution microbiome and neurodevelopmental phenotyping. |
Limitations
Key limitations include the small sample (49 with prenatal and 85 with cross-sectional fecal measurements), restricting power and confounder adjustment; reliance on a socioeconomically homogeneous French-Canadian cohort, which may limit generalisability; single time-point stool sampling at 6–7 years; measurement of only parent acetaminophen and caffeine but not metabolites; and concurrent assessment of stool and cognition, raising potential for reverse causation in cross-sectional analyses.
Future perspectives
Next studies should enlarge and diversify cohorts while repeating fecal sampling from pregnancy through childhood to map exposure-linked trajectories in microbial taxa, Proteobacteria specifically, and functional pathways. Parallel metabolomic or metatranscriptomic assays could test whether increased succinate-to-butanoate and sulfur amino-acid pathways translate into altered microbial function. Designs incorporating additional neurodevelopmental phenotypes and finer exposure timing, including dosing and indications for acetaminophen use, could clarify windows of susceptibility. Experimental models mirroring meconium versus stool exposure could directly probe how early-life xenobiotic contact conditions the gut ecosystem that later interacts with cognitive outcomes.
Key takeaways for Researchers and Clinicians
This prospective analysis of the Sherbrooke-based GESTE cohort examined 49 children with meconium and 85 with childhood stool to link fetal and mid-childhood exposure to acetaminophen and caffeine, the 6–7-year gut microbiome, and cognition. Acetaminophen and caffeine were quantified in feces (ng/g wet weight), and childhood stool underwent shotgun metagenomic profiling alongside WISC-IV and QTAC assessments.
Prenatal acetaminophen, treated dichotomously, was the dominant driver of microbial differences, with exposed children showing a 0.17-unit lower Shannon diversity index and shifts toward lower Firmicutes and higher Actinobacteria, plus increased representation of succinate-to-butanoate fermentation genes. In contrast, prenatal caffeine showed no clear compositional effects, while higher concurrent stool caffeine was associated with greater relative abundance of methionine synthesis and assimilatory sulfate reduction and cysteine synthesis pathways. Proteobacteria abundance consistently modified neurocognitive associations: higher Proteobacteria attenuated small positive relationships between prenatal acetaminophen and specific WISC-IV subtests, and amplified inverse associations of prenatal caffeine with memory-related scores.
Methodologically, the work demonstrates the feasibility and interpretive value of quantifying xenobiotics directly in meconium and stool as exposure proxies for the gut ecosystem, then integrating metagenomic taxonomic and pathway data with neuropsychological outcomes. Clinically, the findings suggest that prenatal acetaminophen use may leave a lasting microbial imprint and that children with Proteobacteria-enriched microbiomes could be more vulnerable to neurocognitive impacts of common over-the-counter drugs. A concise translational hook is that early-life drug exposures may sculpt a gut microbiome state that later interacts with host neurodevelopment, making the microbiome a potential target for stratifying risk and designing adjunctive interventions.
Citation
Laue HE, Shen Y, Bloomquist TR, Wu H, Brennan KJM, Cassoulet R, et al. In Utero Exposure to Caffeine and Acetaminophen, the Gut Microbiome, and Neurodevelopmental Outcomes: A Prospective Birth Cohort Study. Int J Environ Res Public Health. 2022;19(15):9357