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United States Department of Agriculture

Agricultural Research Service

Title: The Effects of Nutrient Fortification and Varying Storage Conditions on Host Defense Properties of Human Milk

Authors
item Jocson, Maria - BAYLOR COLL OF MEDICINE
item Mason, Edward - BAYLOR COLL OF MEDICINE
item Schanler, Richard

Submitted to: Pediatrics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 1996
Publication Date: N/A

Interpretive Summary: Human milk is preferred for feeding premature infants due to its nutritional value and immune protection. To meet the special growth needs of the premature infant, human milk often is fortified with proteins, vitamins, and minerals. Little is known about how fortification affects the stored milk's immune protection. We tested unfortified and fortified human milk that had been frozen, thawed, and kept at room or refrigerator temperature for up to 72 hours. We also tested samples under conditions representing standard nursery practice by thawing, refrigerating, and warming for 4 hours. Bacterial counts were significantly lower in unfortified human milk, but the count increased similarly in unfortified and fortified milk, whether fresh or frozen. Our findings support current recommendations to use fortified milk within 24 hours of fortification. We also showed that fortified refrigerated milk that was warmed and incubated for 4 hours, to resemble usual nursery practice, had a significant increas in bacterial count. Although this is a concern, the increase after 4 hours of incubation was no greater than the original baseline. These data suggest current handling of fortified human milk is adequate.

Technical Abstract: Objective. Data are scarce regarding the effects of nutrient fortification and storage on the immunoprotective properties of human milk, important considerations when feeding premature infants. We hypothesized that total bacterial colony counts (TBCC) and IgA concentration were not affected by the addition of fortifier even when tested under extreme storage conditions sand that osmolality of fortified human milk does not increase with storage Methods. Ten frozen and 5 fresh milk samples from mothers of premature infants were divided into fortified and unfortified milk, and stored for 72h at either room or refrigerator temperature. Aliquots were obtained at 0 to 72h for TBCC, osmolality, and IgA. Results. TBCC at 0, 24, 48, and 72h were significantly greater in fortified vs unfortified milk respectively, p=0.017; both increased with storage, p0.001. Osmolality was greater in fortified than unfortified milk; both increased similarly, by approximately y4%, p=0.012. IgA was similar between milks and with storage. In Part B of the study, frozen samples were thawed, fortified, and refrigerated for 20h, warmed in a 400C laboratory incubator for 20 min, and placed in a 340C infant incubator for 4h to simulate routine use of milk in the Neonatal Intensive Care Unit (NICU). Samples for TBCC were obtained at 0, 20, and 24h. TBCC in fortified, refrigerated milk did not change over 20h storage but increased during the simulated 4h usage p<0.01. Conclusions. These findings may warrant consideration when using human milk in the NICU but support recommendations to use commercially fortified human milk within 24h.

Last Modified: 12/19/2014
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