The natural occurring RRR-α-Tocopherol and synthetic α-Tocopherol stereoisomers in maternal plasma, cord plasma and breast milk among six regions of China.

The study aimed to investigate RRR-α-Tocopherol and synthetic α-Tocopherol stereoisomers in maternal plasma, cord plasma and breast milk from different regions of China, providing a reference for further guidance on maternal diet and the potential need to supplement mothers with vitamin E. Two hundred and twenty-one sample sets from maternal plasma, cord plasma and three stages of milk (colostrum: 1-5 d after delivery; transitional milk: 10-15 d; mature milk: 40-45 d) were collected longitudinally in six regions of Shanghai, Guangzhou, Tianjin, Chengdu, Lanzhou and Changchun. α-Tocopherol and the stereoisomers were determined by HPLC with a fluorescence detector. The RRR configuration accounted for more than 80 % of α-Tocopherol in maternal plasma, cord plasma and breast milk. Overall, there were regional differences both in α-Tocopherol and RRR. There were significant correlations between α-Tocopherol and RRR in maternal plasma, cord plasma and milk (P < 0.001). As well as negative correlations among α-Tocopherol, RRR and weight-related indicators, which refer to pre-gestation weight and BMI, pre-delivery weight and BMI and pregnancy weight gain, in almost all of samples. This study suggested that RRR-α-Tocopherol was the dominant configuration of α-Tocopherol and the main active form of vitamin E in the early life, guiding the rational supplement of pregnant women and the addition of α-Tocopherol in infant formula milk powder.

[Contents and isomers distribution of vitamin E in human mature breast milk from six regions of China in 2018-2019].

OBJECTIVE: The study aimed to investigate the contents and isomer composition of vitamin E in mature milk in different regions of China. METHODS: Simultaneously recruited 604 lactating mothers aged(29.58±3.43) from Shanghai, Guangzhou, Tianjin, Chengdu, Lanzhou and Changchun cities. They were mainly primiparas with good education background. A total number of 604 mature milk samples was collected. The contents of α-, γ-, δ-tocopherols and the stereoisomers of α-tocopherol were determined by high performance liquid chromatography(HPLC). RESULTS: The M(P25, P75) concentrations of α-tocopherol, RRR-α-tocopherol, γ-tocopherol and δ-tocopherol in Chinese mature milk were 3.16(2.29, 4.16)mg/L, 2.57(1.77, 3.48)mg/L, 0.89(0.58, 1.27)mg/L and 0.17(0.09, 0.27)mg/L, respectively. The total α-TE level was 3.09(2.22, 4.10)mg/L with statistically regional differences(P<0.001). RRR-α-tocopherol was the predominated stereoisomers of α-tocopherol, accounting for 83.17%(76.36%, 88.43%). The proportion of RRR in Tianjin mature milk was significantly lower than that in Lanzhou(77.11% vs. 86.16%, P<0.001) while breast milk samples from other regions had similar RRR-α-tocopherol proportions(82.82%-85.39%). CONCLUSION: Vitamin E content in mature milk was mainly composed of α-tocopherol. Even though the contents of tocopherols have large regional differences, RRR-α-tocopherol was predominated form in all breast milk samples. It is suggested that RRR-α-tocopherol was the main active form of vitamin E in the early stage of life.

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 (α-, γ-tocopherol) determined by HPLC. Total fatty acid (TFA) content increased from 15·09 g/l in colostrum to 32·57 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 1·3:1, respectively. Both α-tocopherol and γ-tocopherol decreased over lactation with the ratio of α-:γ-tocopherol declined significantly from 7·21:1 to 4·21:1 (P < 0·001). Carotenoids all dropped from colostrum to mature milk as the less polar carotenes dropped by 88·67 %, while xanthophylls only dropped by 35·92 %. Lutein was predominated in both transitional and mature milk carotenoids (51·64-52·49 %), while colostrum carotenoids were mainly composed of lycopene (32·83 %) and ß-carotene (30·78 %). 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.