Serum metabolome indicators of early childhood development in the Brazilian National Survey on Child Nutrition (ENANI-2019)

Background: The role of circulating metabolites on child development is understudied. We investigated associations between children’s serum metabolome and early childhood development (ECD). Methods: Untargeted metabolomics was performed on serum samples of 5,004 children aged 6-59 months, a subset of participants from the Brazilian National Survey on Child Nutrition (ENANI-2019). ECD was assessed using the Survey of Well-being of Young Children’s milestones questionnaire. The graded response model was used to estimate developmental age. Developmental quotient (DQ) was calculated as the developmental age divided by chronological age. Partial least square regression was used to select metabolites with a variable importance projection ≥ 1. Results: Twenty-eight top-ranked metabolites were included in linear regression models adjusted for child’s nutritional status, diet quality and age. Interaction between these metabolites and child age was tested. Cresol sulfate (β = -0.07; adjusted-p < 0.001), hippuric acid (β = -0.06; adjusted-p < 0.001), phenylacetylglutamine (β = -0.06; adjusted-p < 0.001), and trimethylamine- N -oxide (β = -0.05; adjusted-p = 0.002) showed inverse associations with DQ. We observed opposite directions in the association of DQ for creatinine (for children aged -1 SD: β = -0.05; p =0.01; +1 SD: β = 0.05; p =0.02) and methylhistidine (-1 SD: β = - 0.04; p =0.04; +1 SD: β = 0.04; p =0.03). Conclusion: Serum biomarkers, including dietary and microbial derived metabolites involved in the gut-brain axis, may potentially be used to track children at risk for developmental delays. Funding: Supported by the Brazilian Ministry of Health and Brazilian National Research Council. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The study has been funded by the Brazilian Ministry of Health through a grant from the The National Council for Scientific and Technological Development (CNPq) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ENANI-2019 was approved by the Research Ethics Committee of the Clementino Fraga Filho University Hospital of the Federal University of Rio de Janeiro (UFRJ). It was registered under the number CAAE 89798718.7.0000.5257. Data were collected after a parent or caregiver of the child authorized participation in the study through an informed consent form, and all the principles of good clinical practice of the Declaration of Helsinki were respected. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data is available upon reques