Assessment of maternal diet inflammatory status and inflammatory markers in human breast milk

Human breast milk is a complex bioactive fluid containing multi-functional components that support many infant physiological functions. Maternal diet has been demonstrated to influence human milk components; however, how maternal diet impacts inflammatory markers in human milk remains unclear. This study investigated the association between maternal dietary inflammatory status, assessed using the Dietary Inflammatory Index (DII), and the profile of inflammatory markers in breast milk from healthy lactating women, quantified using cytometric bead array. Dietary intake of lactating mothers (n = 101) was assessed using a 24-hr food recall and categorised using the DII as either pro-inflammatory (score > 0) or anti-inflammatory (score < 0). Thirteen inflammatory markers were quantified in breast milk by flow cytometric bead array (13-plex panel: IL-4, IL-2, IP-10, IL-1β, TNF-α, MCP-1, IL-17A, IL-6, IL-10, IFN-γ, IL-12p70, IL-8, free active TGF-β1). All participant diets were categorised as anti-inflammatory diets (DII score range -4.83 to -1.22). Participants' food intake aligned with dietary guidelines (AUSNUT 2023) for lactating women, with most analysed food parameters classified as anti-inflammatory (19/27). Inflammatory marker analysis revealed a chemokine-dominant profile in breast milk with IP-10, MCP-1 and IL-8 present at the highest concentrations and detected in > 96% of participant human milk samples MCP-1 concentration was weakly associated with DII score (p = 0.025, r2 -0.23, Spearman correlation). This study is the first to investigate the inflammatory index of maternal diets in lactating mothers and characterise inflammatory markers in human milk. Further research is required to fully elucidate the relationship between dietary inflammatory status and inflammatory markers in breast milk and their potential impact on infant health, especially of a more diverse cohort.