Changes in fatty acid composition of human milk over lactation stages and relationship with dietary intake in Chinese women.

Breast milk samples and 24-hour food records were obtained from lactating mothers on day 1 (colostrum), day 14 (transitional milk) and day 42 (mature milk) from Hangzhou (n = 202), Lanzhou (n = 133) and Beijing (n = 142), China. Fatty acid methyl esters were prepared by standard methods, separated and quantified by gas chromatography. We aimed to investigate the fatty acid composition (% of total fatty acid) in human milk of three lactating stages from three regions in China and the relationship with maternal dietary intake during lactation. Present results showed that the fatty acid composition of breast milk varied with lactating period and geographical regions in China. In all the milk samples, the total saturated fatty acid (SFA) remained stable. However, C10:0 and C12:0 increased over the lactation period, total monounsaturated fatty acid (MUFA) significantly increased from colostrum (34.50%) to transitional milk (37.06%), and total polyunsaturated fatty acid (PUFA) showed its highest percentage in colostrum (29.58%). In particular, C22:6n-3 and C22:5n-3 were lowest in mature milk (0.38% and 0.41%, respectively), and C18:3n-3 (1.83%) was lowest in colostrum. There were significant differences among the three regions in total MUFA and PUFA in breast milk. The Hangzhou samples had the lowest C18:1n-9 and highest C22:6n-3. Additionally, C22:6n-3, total PUFA and n-3 PUFA were lowest in the Lanzhou samples. Different dietary habits were largely the drivers behind the different fatty acid profiles among the three regions.

Retinol and α-tocopherol in human milk and their relationship with dietary intake during lactation.

Human milk is considered as an optimal nutrition source for neonates, and vitamins A and E improve oxidative stress in offspring through breast milk. We aim to determine α-tocopherol and retinol contents in breast milk obtained over the course of lactation stages from mothers in three regions in China, and to investigate their correlation with maternal dietary intake during lactation. Human milk samples and 24 hour food records were obtained from mothers in Hangzhou (n = 34), Lanzhou (n = 34) and Beijing (n = 34) on day 1 (colostrum), day 14 (transitional milk) and day 42 (mature milk) postpartum. Concentrations of α-tocopherol and retinol in breast milk samples were measured by high-performance liquid chromatography. The breast milk concentrations of α-tocopherol and retinol decreased over progress of lactation stages (P < 0.001). The retinol content of transitional milk from Hangzhou was higher than that in Lanzhou (P = 0.019) and Beijing (P < 0.001), and the α-tocopherol content in colostrum from Hangzhou showed a lower concentration than that from Lanzhou (P = 0.001). There was a significantly positive correlation between retinol and α-tocopherol contents in colostrum (r = 0.37, P = 0.002), transitional (r = 0.41, P < 0.001) and mature milk (r = 0.53, P < 0.001). No significant correlation was found between any dietary constituents (grain, fruit, vegetable, dairy, egg and meat, oil and bean products) and either retinol or α-tocopherol.