Effect of dietary triacylglycerol fatty acid positional distribution on plasma lipid classes and their fatty acid composition in preterm infants.

Seven premature infants were each fed, for 1 wk in a crossover design. The beta formula contained triacylglycerols resembling the stereoisomeric structure of human milk fat (25.4% by wt 16:0, 76.1% of which is at the sn-2 position), whereas in the alpha formula 87.3% of total 16:0 (25.7% by wt was at the sn-1,3 positions. Plasma lipids and their fatty acid compositions were determined at the end of each 1 wk study period. Infants fed with the beta formula had higher percentages of palmitic acid in plasma sterol esters, triacylglycerols, and free fatty acids, and lower linoleic acid in triacylglycerols than with the alpha formula. Premature infants fed formulas with triacylglycerols 16:0 predominantly in the sn-2 rather than the sn-1,3 positions had alterations in their plasma fatty acids consistent with enhanced absorption of 16:0 from the sn-2 compared with the sn-1,3 positions.