(P17-023-23) Human Milk Metabolites Associated With Linear Growth of Infants From 3 to 6 Months in Rural Bangladesh

Objectives: Despite known benefits of breastfeeding, human milk constituents associated with infant growth require elucidation, especially where both breastfeeding and stunting are common. Using high-throughput, untargeted metabolomics, we identified putative milk metabolic biomarkers of linear growth from 3 to 6 months (mo) of age, as change in length-for-age Z-scores (ΔLAZ), in rural Bangladeshi infants.

Methods: Human milk collected from 752 Bangladeshi women at 3mo postpartum, 80% of whom were exclusively breastfeeding, underwent tandem mass spectrometry (MS/MS) to quantify the milk metabolome (Sapient Bioanalytics). Associations between metabolite abundances and ΔLAZ were determined with higher-criticism thresholding applied to Spearman correlations, followed by sparse Partial Least Squares regression (sPLS) with parameters optimized by 10-fold cross-validation. For metabolites associated with ΔLAZ, we used the Mummichog pipeline with KEGG pathway enrichment analysis to predict metabolite identifications. Pathway enrichment was performed with Fisher’s Exact Test at α < 0.05.

Results: Mean±SD LAZ was -1.3±1.1 and -1.4±1.0, at 3 and 6mo, respectively, and ΔLAZ was 0.1±0.7. Of >60,000 metabolites, 945 were associated with ΔLAZ; 113 were identified by Mummichog. Metabolites associated with ΔLAZ suggested activation of pathways for xenobiotics degradation, amino acid and carbohydrate metabolism. Specifically, metabolites involved in xenobiotics degradation of aflatoxin B1 (AFQ1, AFB1-diol, and AFB1-endo-8,9-epoxide), and 1-nitronaphthalene (1-nitronaphthalene-1,6,-oxide, 1-nitronaphthalene-7,8-oxide and 1-dihydro-5-nitro-1,2-naphthalenediol), and metabolites involved in the kynurenine pathway of tryptophan metabolism (4-(2-Aminophenyl)-2,4-dioxobutanoate and 2-aminomuconate) were inversely associated with ΔLAZ. Metabolites involved in the citric acid cycle and glyoxylate and dicarboxylate metabolism (malate, citrate, isocitrate, and oxalosuccinate) were positively associated with ΔLAZ.

Conclusions: Metabolites that emerged as associated with infant growth suggest links to maternal exposure to toxins, increased inflammation, and energy metabolism, as reflected in human milk. These hypotheses require testing with targeted biomarker approaches.

Funding Sources: Bill and Melinda Gates Foundation