Phospholipid Composition and Fat Globule Structure I: Comparison of Human Milk Fat from Different Gestational Ages, Lactation Stages, and Infant Formulas

We compared phospholipids (PLs), PL fatty acid (FA) composition, and milk fat globule size and structure in human milk (n = 120) from mothers of full-term and preterm infants during lactation (colostrum, transition, 1 mo, 2 mo, and 3 mo) and 8 brands of infant formulas. The absolute quantification of PLs was analyzed using P-31 NMR spectroscopy. Sphingomyelin was the dominant PLs (35.01 +/- 3.31%) in human milk, whereas phosphatidylcholine and phosphatidylethanolamine were the dominant PLs in infant formulas. The PL content in preterm milk increased during lactation, whereas that in term milk remained stable. Saturated FAs (mainly 16:0 and 18:0) were the most abundant (>60%) PL FA in both preterm and term milk and increased throughout lactation. The mean diameter of milk fat globules in infant formulas was much smaller than that found in human milk (200 nm vs 5.63 mu m). Significant differences were observed between human milk and infant formulas with regard to PLs, suggesting that more research is needed to mimic the PL profile in infant formulas.