Imbalance of ω3 and ω6 Fatty Acids in Breast Milk of Overweight/Obese Women

<b>Background/Objectives</b>: Studies demonstrate better health outcomes for infants consuming milk with higher concentrations of ω3 (ALA and DHA) and negative health outcomes associated with higher ω6 (LA and AA) PUFAs. We studied the relationship between maternal BMI and PUFA levels in maternal plasma and breast milk. <b>Methods</b>: Women at 7-8 weeks postpartum were grouped according to normal BMI (18-24.9 kg/m²) and overweight/obese (OW/OB; ≥25 kg/m²). Maternal blood and continuous breast milk samples obtained from foremilk to hindmilk were analyzed for lipidomics. <b>Results</b>: The plasma levels of ω3 and ω6 PUFA were significantly lower in OW/OB subjects, with a total ω3 and ω6 FA level of 50% for women with normal BMI. Conversely, breastmilk levels of total ω3 and ω6, including their respective precursors of LCFAs (ALA and LA), were significantly increased in both foremilk and hindmilk samples of OW/OB. Despite this, DHA (ω3 PUFA) levels in OW/OB women were similar in foremilk and significantly decreased in hindmilk samples as compared to normal BMI women. Consequently, the ratio of DHA/Total ω3 significantly decreased in foremilk and hindmilk samples of OW/OB women. However, proinflammatory AA (ω6 PUFA) levels increased, resulting in an increased ratio of AA/DHA in OW/OB women. Breast milk DHA was positively correlated, whereas AA was negatively correlated with maternal plasma. <b>Conclusions</b>: Marked differences in maternal plasma and breast milk ω3 and ω6 FA concentrations among women with OW/OB indicate significant differences in nutritional exposures for their infants. Reduced milk DHA may be a consequence of reduced mammary peroxisomal conversion of ALA to DHA due to increased insulin/reactive species within the maternal obese environment. The imbalance of ω3 and ω6 FAs suggests that DHA supplementation and approaches to limit plasma to breast milk AA transfer in OW/OB subjects may be of value.