[Dependency of human milk lipids on length of the lactation period, time of day, nursing and maternal diet]

Abstract

The dependency of the human milk lipids triglycerides (TG), cholesterol (Chol), phospholipids (PL), and the fatty acid composition of both TG and PL on the stage of lactation, the day time, the course of one nursing, and on the mother's diet was shown by analyzing more than 350 milk samples. In progressing lactation (day 1-36) TG increased from 1.9 to 3.9 g/100 ml. Chol decreased from 35 to 20 mg/100 ml, while PL remained with 40 mg/100 ml rather constant. The resulting decrease in the PL/TG- and Chol/TG-ratios indicates an increasing size of fat globules. During one nursing, TG and Chol increased four-fold and PL doubled. During the day lipids (TG, Chol, PL) of the milk of German mothers reached their peak values in the afternoon, whereas the ones of milks obtained from English mothers were found in the late evening. With 3 mothers (n = 3) carbohydrate-rich diets (65 cal%) led to an increase of the milk fat content. In contrast high fat diets (50 cal%) resulted in milks with low fat contents (2.6/4.1 g/100 ml). Chol (20.8/37.5 mg/100 ml) and PL (26.4/45.3 mg/100 ml) showed the same dependency. The fatty acid composition changed mainly dependent on the duration of the lactation and the mother's diet, but not during one single nursing and during the day. Long-chain polyunsaturated fatty acids were higher in early than in mature milks. The P/S-ratio of TG was found to remain constant in progressing lactation (0.32), whereas the one of PL increased from 0.6 to 0.71. Dependent on the regimen of the mother the P/S-ratios (n = 3) were found to be 0.27 (high carbohydrate diet) and 0.46 (high fat/high linoleic acid diet).