Fatty acid positional distribution in colostrum and mature milk of women living in Inner Mongolia, North Jiangsu and Guangxi of China.

In order to investigate the fatty acid composition and distribution in colostrum and mature milk, breast milk samples and 24 h food records were obtained from 65 lactating women across three regions in China (Inner Mongolia, North Jiangsu and Guangxi). Fatty acid methyl esters were prepared by standard methods and separated and identified by gas chromatography. Compared with the Chinese breast milk fatty acid data 10 years ago, SFA and trans fatty acids (TFA) in breast milk decreased, while PUFA increased in the present study. Most SFA (C16:0, C15:0, C14:0), cis-C16:1 and several LC-PUFA (C22:5n-3 and C22:6n-3) were predominantly acylated at the sn-2 position. The cis-C17:1 and C22:6n-3 were distributed equally in three positions of triacylglycerol (TAG). Whereas, TFA, conjugated linoleic acids (CLA), cis-C18:1, C18:2n-6, C18:3n-3 and C20:5n-3 were acylated at the sn-1, 3 positions of TAG in human milk. The composition of fatty acids in breast milk was closely related to the diet of lactating mothers. PUFA in breast milk was negatively correlated with the intake of protein, fat and meat, but positively correlated with the intake of carbohydrates. MUFA of human milk was negatively correlated with the intake of dairy products, eggs, fish and shrimp. SFA in breast milk was positively correlated with the maternal intake of meat. In addition, the present results showed that the composition of total fatty acids and sn-2 fatty acids in breast milk varied with the lactation period and the geographical regions in China; however, the regiospecific fatty acid profile seemed not to be affected by the lactation time and regions, although the quantities at each position could be changed.