Protein and energy digestibility in preterm infants fed fortified human milk

Objectives: The objective of the present study is to determine whether the apparent nutrient digestibility differs between very preterm infants fortified with bovine colostrum (BC) compared to those fortified with a conventional fortifier (CF), building on previous findings that BC was associated with looser stools and reduced need for laxatives in very preterm infants (VPI). Methods: We conducted a 24-h digestibility balance study in 10 VPIs to assess the retention of protein, energy, and wet-weight following the intake of fortified human milk and collection of faecal excretions. Infants (n = 5) were matched by gestational age and birthweight. Results: In the 10 infants, the mean gestational age and birthweight were 28 ± 1 weeks and 899 ± 182 g, respectively. Infants fortified with BC had a higher faecal energy loss compared with infants fortified with CF (BC: 178 [range 111–205] vs. CF: 153 [96–235] kJ/kg, p < 0.05). No differences (p > 0.05) were found for wet-weight intake (421 [360–427] vs. 494 [328–500] kJ/kg), relative absorption of protein (60 [33–75] vs. 50 [33–75]%) or absolute protein absorption (249 [159–310) vs. 281 [210–347]). Conclusion: Nutrient absorption was similar between groups although higher energy loss indicates reduced overall digestibility of BC versus CF, however, with a large variation within each group. Studies on more infants are required to confirm these results. A 24-h digestibility balance study can successfully be used to assess nutrient and energy retention in preterm infants.