Brown fat-activating lipokine 12,13-diHOME in human milk is associated with infant adiposity.

Context Little is known about the specific breastmilk components responsible for protective effects on infant obesity. Whether 12,13-diHOME, an oxidized linoleic acid metabolite and activator of brown fat metabolism, is present in human milk, or linked to infant adiposity, is unknown. Objective To examine associations between concentrations of 12,13-diHOME in human milk and infant adiposity. Design Prospective cohort study between 2015-2019, following participants from birth to 6-months. Setting Academic medical centers. Participants Volunteer sample of 58 exclusively breastfeeding mother-infant pairs; exclusion criteria included smoking, gestational diabetes, and health conditions with the potential to influence maternal or infant weight gain. Main outcome measures Infant anthropometric measures including weight, length, BMI, and body composition at birth and at 1, 3 and 6 months postpartum. Results We report for the first time that 12,13-diHOME is present in human milk. Higher milk 12,13-diHOME was associated with increased weight-for-length (WFL) Z-score at birth (β=0.5742, p=0.0008), lower infant fat mass at 1-month (p=0.021), and reduced gain in body mass index (BMI) Z-score from 0 to 6-months (β=-0.3997, p=0.025). We observed similar associations between infant adiposity and milk abundance of related oxidized linoleic acid metabolites 12,13-epOME and 9,10-diHOME, and metabolites linked to thermogenesis including succinate and lyso-phosphatidylglycerol 18:0. Milk abundance of 12,13-diHOME was not associated with maternal BMI, but was positively associated with maternal height, milk glucose concentration, and was significantly increased after a bout of moderate exercise. Conclusions We report novel associations between milk abundance of 12,13-diHOME and adiposity during infancy.