The effects of dietary nucleotides on intestinal blood flow in preterm infants

Nucleotides (NT) are reported to affect development of the immune and gastrointestinal systems, and they are currently added to most term infant formulas. In the present study, dietary NT effects on superior mesenteric artery blood flow were investigated. Formula-fed preterm infants were studied once with a 20 kcal/oz. term infant formula containing 80.6 mg/L of NT (NT+), and once with the same formula with no added NT (NT-) (n = 20, gestational age 28.0 +/- 2.2 wk). A reference group of preterm infants fed human milk was also studied (n = 20, gestational age 29.0 +/- 1.6 wk). Superior mesenteric artery blood flow velocities (BFV) were measured by Doppler ultrasound 15 min before and 30, 60, and 90 min after the start of the feed. BFV rose in all infants from baseline to 30 min after feed initiation, and progressively declined thereafter in infants fed NT- or human milk. However, NT+ feedings were associated with a minimal change in BFV between 60 and 90 min. As a result, the difference in blood flow velocities between baseline and 90 min was significantly greater with the NT+ versus the NT- feedings for the mean, peak systolic, and end diastolic velocities (p = 0.03, 0.05, and 0.03, respectively). BFV after the NT- and human milk feedings were similar. These data suggest that orally administered NT are associated with effects on the intestinal vasculature.