An investigation of the effect of fresh and frozen breast milk on gut microbiota in preterm neonates

This paper prospectively and observationally investigated the effect of fresh and frozen breast milk on gut microbiota in preterm neonates. The sample consisted of 40 preterm neonates with a gestational age of 28-326 weeks monitored at a neonatal intensive care unit (NICU). The sample was equally divided into two: fresh breast milk group (n=20) and frozen breast milk group (n=20). Data were collected using a Descriptive Information Form and a Neonatal Follow-Up Form. According to the inclusion criterias. The first meconium and day-10 stool samples that were obtained from neonates who were selected according to the inclusion criteria were stored at -80 °C until analysis. The type and amount of nutritional solutions (fresh breast milk, frozen breast milk, and formula) were regularly recorded for ten days. A neonate was assigned to either of the three groups depending on which type of nutritional solutions constituted more than 70% of its 10-day feeding. Neonates whose more than 70% of their diets consisted of formula were excluded from the study. The data were analyzed using the Mann-Whitney U test, Chi-square test, and t-test. The stool samples were analyzed sequencing the V3-V4 region of the 16S rRNA gene from the extracted DNA. Streptococcus was more abundant in the frozen breast milk group (69%) than in the fresh breast milk group (16%). Enterobacteriaceae was more abundant in the frozen breast milk group (79%) than in the fresh breast milk group (49%). Streptococcus and Enterobacteriaceae spp. are considered human pathogens and disease agents. Lactobacillus was more abundant in the fresh breast milk group (17%) than in the frozen breast milk group (3%). Bifidobacterium was more abundant in the fresh breast milk group (12%) than in the frozen breast milk group (1%). Lactobacillus and Bifidobacterium are two species of common probiotics with many health benefits. The results showed that fresh breast milk was better than frozen breast milk at maintaining infant gut microbiota and creating a healthier microenvironment. Therefore, it is recommended that nurses be supportive in making sure that all neonates, especially those monitored in NICUs, are fed fresh breast milk.