Quantification of Human Milk Phospholipids: the Effect of Gestational and Lactational Age on Phospholipid Composition

Abstract

Human milk (HM) provides infants with macro- and micronutrients needed for growth and development. Milk phospholipids are important sources of bioactive components, such as long-chain polyunsaturated fatty acids (LC-PUFA) and choline, crucial for neural and visual development. Milk from mothers who have delivered prematurely (<37 weeks) might not meet the nutritional requirements for optimal development and growth. Using liquid chromatography tandem-mass spectrometry, 31 phospholipid (PL) species were quantified for colostrum (<5 days postpartum), transitional (≥5 days and ≤2 weeks) and mature milk (>2 weeks and ≤15 weeks) samples from mothers who had delivered preterm (n = 57) and term infants (n = 22), respectively. Both gestational age and age postpartum affected the PL composition of HM. Significantly higher concentrations (p < 0.05) of phosphatidylcholine (PC), sphingomyelin (SM) and total PL were found in preterm milk throughout lactation, as well as significantly higher concentrations (p < 0.002) of several phosphatidylethanolamine (PE), PC and SM species. Multivariate analysis revealed that PLs containing LC-PUFA contributed highly to the differences in the PL composition of preterm and term colostrum. Differences related to gestation decreased as the milk matured. Thus, gestational age may impact the PL content of colostrum, however this effect of gestation might subside in mature milk.

Keywords: Human Milk; Lipidomics; Milk Fat Globule Membrane; Phospholipids; Preterm infant.

Figure 1

Percentage distribution of phosphatidylethanolamine (PE), phosphatidylcholine (PC) and sphingomyelin (SM) in term (T; vertically striped bars) and preterm (P; dotted bars) colostrum, transitional and mature milk.

Figure 2

(A) PCA score scatter plot of preterm milk (squares) and term milk (circles) expressed between day 1 and 15 weeks post-partum. Score colours indicate day postpartum at which the samples were expressed. (B) Corresponding loading scatter plot containing the 31 phospholipid species quantified in human milk belonging to the phospholipid classes phosphatidylethanolamine (red circles), phosphatidylcholine (orange circles) and sphingomyelin (green circles). Details about the numbering of phospholipid species can be found in Table 2.

Figure 3

Concentration (mg/100 mL) of phosphatidylcholine (PC) and sphingomyelin (SM) species in preterm (blue circle) and term (red square) milk in colostrum (<5 days), transitional milk (≥5 days and ≤2 weeks) and mature milk (>2 weeks and ≤15 weeks).