A pilot study of maternal vitamin D status and its association with breast milk and infant gut metabolites.

Human milk contains multiple bioactive components, many of which are influenced by the mother's nutritional status. To identify the impact of maternal vitamin D status on neuroactive compounds, we conducted a post hoc analysis of breast milk and matched infant stool samples from mothers categorized as sufficient or deficient for vitamin D. Neuroactive metabolites were quantified using both targeted and nontargeted liquid chromatography with tandem mass spectrometry (LC-MS/MS). Our findings revealed that breast milk from mothers with sufficient vitamin D levels contained significantly higher concentrations of tryptophan, phenylalanine, and tyrosine compared to milk from mothers with lower vitamin D levels. No significant differences were observed in tryptamine, kynurenine, kynurenic acid, anthranilic acid, quinolinic acid, tyramine, dopamine, epinephrine, or norepinephrine between the two groups. Among SCFAs and other acids, only hexanoic acid was significantly elevated in the breast milk of mothers with sufficient vitamin D. A nontargeted metabolomics analysis of infant stool identified distinct metabolite profiles, where oleamide, vaccenic acid, lacto-N-triaose, and N-acetyl-D-glucosamine varied according to maternal vitamin D levels, indicating that maternal nutrient status may influence the infant gut metabolome. These findings suggest that maternal vitamin D status is associated with neurotransmitter precursor levels in breast milk and a distinct metabolomic profile of infant stool.