EFFECT OF HUMAN-MILK OR FORMULA ON GASTRIC FUNCTION AND FAT DIGESTIONIN THE PREMATURE-INFANT

The effect of diet, human milk or formula, on gastric function (lipase and pepsin activity, pH, and volume) and intragastric digestion of fa t was assessed in 28 appropriate for gestational age preterm infants ( gestational age, 28.9 +/- 1.4, 29.1 +/- 0.9, 29.5 +/- 0.6 wk; birth we ight, 1.00 +/- 0.14 to 1.18 +/- 0.07 kg). The infants were fed either human milk (n = 11), SMA Super Preemie formula (n = 9), or Similac, Sp ecial Care formula (n = 8). Fasting and postprandial activity of diges tive enzymes, pH, and gastric volume (measured before or during 50 min after gavage feeding) did not differ as a function of diet among the three groups of infants. Gastric lipase output, 23.1 +/- 5.1, 28.3 +/- 6.6, and 22.5 +/- 6.4 (U/kg of body weight) in human milk-, SMA SP-, or Similac SC-fed infants was comparable to the gastric lipase output of healthy adults fed a high fat diet (22.6 +/- 3.0). Pepsin output wa s, however, significantly lower (597 +/- 77, 743 +/- 97, and 639 +/- 1 42 U/kg of body weight) in human milk-, SMA SP-, and Similac SC-fed in fants) than in healthy adults (3352 +/- 753 U/kg). The hydrolysis of d ietary fat was 1.7-2.5-fold higher (p < 0.01) in human milk-fed infant s than in infants fed either formula. We conclude that differences in type of feeding, i.e. different fatty acid profiles (long chain or med ium chain triglycerides), different emulsions (natural or artificial), and different fat particle sizes do not affect the level of activity of gastric enzymes. However, the triglyceride within milk fat globules appears to be more accessible to gastric lipase than that within form ula fat particles. We suggest that the contribution of gastric lipase to overall fat digestion might be greater in the newborn (a period of pancreatic insufficiency) than in the adult.