24 ± 0.31 (median = 0.18); in thawed milk offered by gavage and continuous infusion, this difference was 0.26 ± 0.17 (median = 0.17). Fat loss caused by thawing was similar for both routes of administration (p = 0.853). The difference in fat content between natural

and thawed milk was 0.3 g/100 mL for continuous infusion and 0.2 g/100 mL for gavage. The analysis of the influence of human milk handling on macronutrients, from its expression to the final offer to the newborn, is of great importance when considering the effects of proper nutrition on growth and development of preterm newborns.2 This study demonstrated that the choice of administration by continuous infusion selleck screening library significantly impairs the concentration of fat, both in natural and thawed human milk. Fat loss is generally attributed to its adherence to the container, to lipolysis, or to lipid peroxidation.10 The reduction of fat content in thawed human milk has also been observed

in other studies,11 and 12 and it has been suggested that lipolysis would still occur in frozen milk.13 and 14 When at rest, the fat easily separates and adheres to the container, tubes, and syringes, which reduces its supply to the newborn. Although the effect of freezing/thawing was not statistically significant in the two forms of infusion, the association between thawing and continuous infusion resulted in a loss of 0.5 g of fat per 100 mL of Raf inhibitor milk, implying a reduction of approximately 18% of the fat content of the milk, which may cause important clinical and nutritional consequences for preterm infants.1 One way to reduce these losses is by homogenizing milk before offering it to the newborn.15 One question raised in this study was the lower concentrations of fat and total calories in human milk than those reported in other international Hydroxychloroquine studies.8, 9 and 16 Other studies performed in Brazil have also observed lower fat content values, even though different techniques were used.17 and 18 With regard

to protein and lactose, it was observed that their values had an unexpected and significant increase after thawing. This fact may be related to the loss of water during the freezing and thawing process (volatilization), and sublimation, with increased infrared absorbance of protein at wavelength 5.7 μm, which was also observed in other studies and attributed to these properties.10 and 19 Furthermore, thawing of human milk may cause aggregation of the protein micelles, resulting in a variation of the protein content.20 In relation to energy content, there was a significant variation (50.1 Kcal/100 mL) between the studied samples of natural milk, demonstrating the importance of control related to the nutritional content of donated human milk in human milk banks. The energy content of the milk is mainly related to overall fat content, as the energy density of this macronutrient is responsible for most of the calories in human milk.