This study aimed to measure longitudinal quantities of the long chain fatty acids, their biologically active terminal metabolites and related intermediates (also called oxylipins) in preterm human milk expressed during the first month of lactation. In a prospective cohort, breast milk was collected throughout the first month of lactation in 30 women who delivered preterm infants. Eighteen bioactive lipids and their intermediates were quantified via solid phase extraction and LC-MS/MS. Analysis by GC-FID quantified the fatty acid precursors. Arachidonic acid (ARA) and docosahexaenoic acid (DHA) milk concentrations significantly declined throughout the first month. Oxylipin concentrations did not change during lactation. Positive associations existed between ARA and thromboxane B2, eicosapentaenoic acid and 18-hydroxyeicosapentaenoic acid, and between DHA and PDX and 14- and 17-hydroxydocosahexaenoic acids. DHA concentrations were 1.5 times higher and 14-HDHA was 1.7 times higher in milk from women taking DHA supplements. This investigation showed conditionally essential fatty acids, ARA and DHA, decreased in preterm milk, suggesting a need to supplement their intake for the breast milk-fed preterm infant. Positive associations between parent fatty acids, bioactive lipids and intermediates, as well as sensitivity of milk to maternal fatty acid intake, support consideration of a comprehensive approach to providing fatty acids for preterm infants through both maternal and infant supplementation.
Keywords: Breast milk; Lactation; Lipid mediators; Polyunsaturated fatty acids; Preterm infant; Supplementation.
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