Background: Gastric lipase has an important compensatory function in neonatal fat digestion. The activity level of pepsin and its role in protein digestion is less well understood. We have, therefore, studied the ontogeny of lipase and pepsin in the ferret, a species with a neonatal fat digestion pattern similar to that of humans.
Methods: Gastric lipase and pepsin activities were quantified from the late fetal period throughout lactation, and were compared with those of the adult.
Results: The data show earlier ontogeny and much more rapid rise of lipase activity than of pepsin. Lipase activity was present during the last week of fetal development, whereas pepsin was detected only postnatally. Lipase activity was 72.8% +/- 14.2% and 153% +/- 9.95% and pepsin activity was 11.6% +/- 1.3% and 30.1% +/- 1.3% of the adult level at 2 and 4 wk of age, respectively.
Conclusions: We conclude that lipase activity develops early and exceeds adult activity during the suckling period, when fat intake is very high. The low pepsin activity and high postprandial pH probably limit gastric proteolysis, thereby contributing to the structural and functional stability of milk proteins, many with protective or bioactive function in the gastrointestinal tract of the newborn.