Triacylglycerol composition in colostrum, transitional and mature human milk

Objective: Milk triglycerides from colostrum, transitional and mature human milk, were analyzed and compared in order to determine the differences in triacylglycerol composition throughout lactation. Setting: Department of Food and Nutrition, University of Barcelona, Spain, and Neonatology Department of the University Hospital of Granada, Spain. Subjects: Twenty-two healthy lactating women aged 21-35. Design and interventions: The triacylglycerol profiles of 47 breast milk samples including colostrum (1-3 days), transitional milk (7-10 days) and mature milk (25-60 days) were analyzed by high-performance liquid chromatography (HPLC), with light-scattering detection (LSD). Results: Significant differences regarding several triglycerides were found between three milk classes when the Kruskal-Wallis nonparametric test was applied to 47 human milk samples that had been compared using the complete chromatographic triacylglycerol profile. The ANOVAS for each equivalent carbon number (ECN) group of triglycerides revealed significant differences between colostrum, transitional milk and mature milk. By the discriminant analysis of triacylglycerol percentages, in 19 colostrum samples, 14 transitional milk samples and 14 mature milk samples, three milk types were distinguished, and three triglycerides (peak no. 4, LnOO and SOO) were found to be the most predictive variables over all the triacylglycerol profile or ECN groups. Conclusions: Each state of lactation shows a specific profile of triacylglycerol composition in human milk. However the two most abundant triacylglycerides in colostrum, POO and POL, which account for more than 49% of the total, are also dominant in transitional (34%) and mature milk (42%).