Lactational changes of fatty acids and fat-soluble antioxidants in human milk from healthy Chinese mothers

Human milk fat is specially tailored to supply the developing infant with adequate and balanced nutrients. The present study aimed to quantify the composition of fatty acids, tocopherols and carotenoids in human milk, with special emphasis on the lactational changes. Colostrum, transitional and mature milk samples were collected longitudinally from the same forty-two healthy, well-nourished Chinese mothers. Fatty acids were quantified by GC with carotenoids (carotenes and xanthophylls) and tocopherols (alpha-, gamma-tocopherol) determined by HPLC. Total fatty acid (TFA) content increased from 15 center dot 09 g/l in colostrum to 32 center dot 57 g/l in mature milk with the percentages of DHA and arachidonic acid (ARA) decreased. The ratio of n-6:n-3 PUFA and ARA:DHA remained constant during lactation at about 11:1 and 1 center dot 3:1, respectively. Both alpha-tocopherol and gamma-tocopherol decreased over lactation with the ratio of alpha-:gamma-tocopherol declined significantly from 7 center dot 21:1 to 4 center dot 21:1 (P < 0 center dot 001). Carotenoids all dropped from colostrum to mature milk as the less polar carotenes dropped by 88 center dot 67 %, while xanthophylls only dropped by 35 center dot 92 %. Lutein was predominated in both transitional and mature milk carotenoids (51 center dot 64-52 center dot 49 %), while colostrum carotenoids were mainly composed of lycopene (32 center dot 83 %) and beta-carotene (30 center dot 78 %). The concentrations of tocopherols and xanthophylls but not carotenes were positively associated with TFA content in milk. These results suggested that colostrum and mature milk contained divergent lipid profiles and selective transfer mechanisms related to polarity might be involved. The present outcomes provide new insights for future breast-feeding studies, which also add in scientific evidences for the design of both initial and follow-on infant formulas.