Abstract 1707 Human Milk Poster Symposium, Sunday, 5/2

Although mineral supplementation of human milk for premature infants is recognized, we have shown that infants receiving FHM (mother's own milk plus Enfamil Human Milk Fortifier, Mead Johnson, Evansville, IN) have significantly lower fat absorption than similar infants fed preterm formula (PF, Enfamil Premature Formula), 62 vs 91%, respectively, and that there is a positive relationship between fat absorption and rate of weight gain. The objective of this study was to determine whether the addition of fortifier reduced fat absorption by promoting the binding of minerals to fatty acids over time. We measured the content of total fat, free fatty acids (FFA), and mineral-bound fatty acids (MBFA) in the milk and in the feces of premature infants, 26 to 29 wk gestation. Milk was collected by electric breast pumps directly into glass bottles for storage at -20°C. After thawing in warm water for 30 min, 0, 2, or 4 packets of fortifier were added to 100 ml of milk, which was then stored at 4°C for 24 h. To simulate the use of FHM in nursery conditions, aliquots were removed at 0, 20, and 24 h, warmed to room temperature, then stored at -70°C for analyses. Feces were collected for 72 h into plastic bags adherent to the buttocks at 6 to 9 wk from premature infants fed either FHM or PF. Total fat was determined by gravimetry, FFA by microtitration, and calcium (Ca) by atomic absorption spectrophometry. In addition, to determine, by difference, the quantity of fecal MBFA, fecal analyses were repeated without the usual addition of acid. Although milk stored at -20°C had 30% FFA, there were no differences in milk FFA over time. Significant differences (*p<0.02) in FFA, %MBFA, and Ca were noted between unfortified and FHM (Table, mean ± SEM). Fecal fat was significantly greater in infants (n=36) fed FHM (5.7 ± 0.4 g/100 g) than those (n=34) fed PF (3.1 ± 0.2 g/100 g), p < 0.001. Fecal MBFA were significantly greater in infants fed FHM vs PF, 2.4 ± 0.2 vs 1.3 ± 0.1 g/100 g, respectively, p < 0.001. In conclusion, we found that there was no change in the total fat, FFA, and Ca content of milk as used under routine nursery conditions for 24 h. However, there was a rapid decrease in milk FFA after fortification, which was significantly associated with the amount of fortifier added. This decrease in FFA suggests a very strong binding of MBFA. The data further suggest that conditions within the gastrointestinal tract preserve MBFA which would not be absorbed, resulting in the higher fat excretion in infants fed FHM.

Table 1 No caption available
Full size table

Supported in part by NIH RO1-HD28140 and Mead Johnson Research Fund