Fat digestion in the neonate.

Fats are essential components of the diet, and have a critical role in the growth and development of the neonate. Far from being simply compact sources of energy (providing 40-50% of calorie requirements), they are also integral constituents of neural and retinal tissues. 2 Dietary fats come in three forms: triacylglycerols; phospholipids; and cholesterol esters, all of which contain fatty acids esterified to alcohols. The infant consumes fats largely as triacylglycerols, which need to be broken down by enzymes in the upper gastrointestinal tract before absorption. Compared with adults, however, the newborn infant’s exocrine pancreas is “immature,” secreting only small amounts of lipase even in response to secretagogues. 4 How the neonate digests fats, and what part they play in neurodevelopment is of growing importance, particularly when preterm infants of ever shorter gestation are surviving into adulthood.