Dietary triacyglycerols rich in sn-2 palmitate alter post-prandial lipoprotein and unesterified fatty acids in term infants

Human milk TAG contain 20-25% 16:0, with over 70% of the 16:0 at the TAG sn-2 position. The benefits of TAG sn-2 16:0 have been ascribed to reducing 16:0 excretion as insoluble fatty acid soaps. This study builds on knowledge that infants conserve milk TG sn-2 16:0 post-absorption. Comparison of plasma lipids from 120 day old infants fed formula containing 25-27% 16:0 with 29% 16:0 or 5% 16:0 at the TAG sn-2 position showed higher formula sn-2 16:0 led to lower 18:1n-9, but higher 18:2n-6 and 22:6n-3 in the infant plasma unesterified fatty acids, higher 18:0 in LDL TAG, and higher apo B and lower apo A-1. TAG-sn-2 16:0 may provide 16:0 in remnant particles for hepatic elongation to 18:0, needed for plasma and tissue phospholipids. We suggest attention to the plasma unesterified fatty acids as possible sources of fatty acids for membrane phospholipid synthesis.