INTRODUCTIONDietary fats must be digested into fatty acids and monoacylglycerols prior to absorption. In adults, colipase-dependent pancreatic triglyceride lipase (PTL) contributes significantly to fat digestion. In newborn rodents and humans, the pancreas expresses low levels of PTL. In rodents, a homologue of PTL, pancreatic lipase related protein 2 (PLRP2) and carboxyl ester lipase (CEL) compensate for the lack of PTL. In human newborns, the role for PLRP2 in dietary fat digestion is unclear. To clarify the potential of human PLRP2 to influence dietary fat digestion in newborns, we determined PLRP2 activity against human milk and infant formula.METHODSThe activity of purified recombinant PLRP2, gastric lipase and CEL against fats in human milk and formula was measured with each lipase alone and in combination with a standard pH-stat assay.RESULTSColipase added to human milk stimulated fat digestion. PLRP2 and CEL had activity against human milk and formula. Pre-digestion with gastric lipase increased PLRP2 activity against both substrates. Together, CEL and PLRP2 activity was additive with formula and synergistic with human milk.CONCLUSIONSPLRP2 can digest fats in human milk and formula. PLRP2 acts in concert with CEL and gastric lipase to digest fats in human milk in vitro.

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