Very preterm infants (< 32 weeks gestation) have a relatively high nutrient requirement for growth and development. The composition of human milk is often inadequate to ensure optimal growth so it is common to fortify human milk for very preterm infants with nutrient fortifiers based on bovine milk. However, there are concerns that bovine milk-based fortifiers may increase the risk of feeding intolerance, necrotizing enterocolitis and late-onset sepsis. We hypothesize that a bovine colostrum-based product is a suitable alternative to bovine milk-based products when used as a fortifier to human milk in very preterm infants. In an open-label multicentre randomised controlled pilot trial, 200 very preterm infants (26 + 0 to 30 + 6 weeks gestation at birth) will be randomly allocated to a bovine colostrum-based or a bovine milk-based fortifier added to mother’s own milk and/or human donor milk. Outcomes are growth rate, incidence of necrotizing enterocolitis and late-onset sepsis, a series of paraclinical endpoints, and practical feasibility of using the novel fortifier for very preterm infants. The optimal enteral diet and feeding regimen for very preterm infants remain debated; this clinical trial will document the feasibility, safety and preliminary efficacy of using bovine colostrum, rich in nutrients and bioactive factors, as a novel fortifier for human milk to very preterm infants. Data on infant growth, metabolism, gut function and immunity will be assessed from clinical data as well as blood and stool samples. Registered retrospectively 25 May 2018 at ClinicalTrials.gov: NCT03537365 .

Background: Human milk does not meet the nutritional needs to support optimal growth of very preterm infants during the first weeks of life. Nutrient fortifiers are therefore added to human milk, though these products are suspected to increase gut dysmotility. The objective was to evaluate whether fortification with bovine colostrum (BC) improves bowel habits compared to a conventional fortifier (CF) in very preterm infants. Methods: In an unblinded, randomized study, 242 preterm infants (26–31 weeks of gestation) were randomized to receive BC (BC, Biofiber Damino, Gesten, Denmark) or CF (FM85 PreNAN, Nestlé, Vevey, Switzerland) as a fortifier. Stools (Amsterdam Stool Scale), bowel gas restlessness, stomach appearance score, volume, and frequency of gastric residuals were recorded before each meal until 35 weeks post-menstrual age. Results: As intake of fortifiers increased, stools became harder in both groups (p < 0.01) though less in BC infants (p < 0.05). The incidence of bowel gas restlessness increased with laxative treatments and days of fortification in both groups (p < 0.01), but laxatives were prescribed later in BC infants (p < 0.01). With advancing age, stomach appearance scores improved, but more so in BC infants (p < 0.01). Conclusions: Although there are limitations, a minimally processed, bioactive milk product such as BC induced similar or slightly improved bowel habits in preterm infants.

Fecal filtrate transfer (FFT) is emerging as a safer alternative to traditional fecal microbiota transplantation (FMT) - particularly in the context of necrotizing enterocolitis (NEC), a severe gastrointestinal condition affecting preterm infants. Using a preterm piglet model, FFT has demonstrated superiority over FMT in safety and NEC prevention. Since FFT is virtually devoid of bacteria, prokaryotic viruses (bacteriophages) are assumed to mediate the beneficial effects. However, this assumption remains unproven. To address this gap, we separated virus-like particles (30 kDa to 0.45 µm) of donor feces from the residual postbiotic fluid. We then compared clinical and gut microbiota responses to these fractions with the parent FFT solution after transferring them to NEC-susceptible preterm piglets. Virome transfer was equally effective as FFT in reducing the severity of NEC-like pathology. The bacterial compositional data corroborated clinical findings as virome transfer reduced the relative abundance of several NEC-associated pathogens e.g. Klebsiella pneumoniae and Clostridium perfringens. Virome transfer diversified gut viral communities with concomitant constraining effects on the bacterial composition. Unexpectedly, virome transfer, but not residual postbiotic fluid, led to earlier diarrhea. While diarrhea may be a minor concern in human infants, future work should identify ways of eliminating this side effect without losing treatment efficacy.

Human milk is the optimal diet for infant development, but infant milk formula (IMF) must be available as an alternative. To develop high-quality IMF, bovine milk processing is required to ensure microbial safety and to obtain a protein composition that mimics human milk. However, processing can impact the quality of milk proteins, which can influence gastro-intestinal (GI) tolerance by changing digestion, transit time and/or absorption. The aim of this study was to evaluate the impact of structural changes of proteins due to thermal processing on gastro-intestinal tolerance in the immature GI tract. Preterm and near-term piglets received enteral nutrition based on whey protein concentrate (WPC) either mildly pasteurized (MP-WPC) or extensively heated (EH-WPC). Clinical symptoms, transit time and gastric residuals were evaluated. In addition, protein coagulation and protein composition of coagulates formed during in vitro digestion were analyzed in more detail. Characterization of MP-WPC and EH-WPC revealed that mild pasteurization maintained protein nativity and reduced aggregation of β-lactoglobulin and α-lactalbumin, relative to EH-WPC. Mild pasteurization reduced the formation of coagulates during digestion, resulting in reduced gastric residual volume and increased intestinal tract content. In addition, preterm piglets receiving MP-WPC showed reduced mucosal bacterial adherence in the proximal small intestine. Finally, in vitro digestion studies revealed less protein coagulation and lower levels of β-lactoglobulin and α-lactalbumin in the coagulates of MP-WPC compared with EH-WPC. In conclusion, minimal heat treatment of WPC compared with extensive heating promoted GI tolerance in immature piglets, implying that minimal heated WPC could improve the GI tolerance of milk formulas in infants.