The effect of neutral and acidic oligosaccharides on stool viscosity, stool frequency and stool pH in preterm infants

Aim: To determine the effect of neutral oligosaccharides [small-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides (scGOS/lcFOS)] in combination with acidic oligosaccharides (pAOS) on stool viscosity, stool frequency and stool pH in preterm infants. Methods: In this explorative RCT, preterm infants with gestational age <32 weeks and/or birth weight <1500 g received enteral supplementation with scGOS/lcFOS/pAOS or placebo (maltodextrin) between days 3 and 30 of life. Stool samples were collected at day 30 after birth. Results: In total, 113 infants were included. Baseline and nutritional characteristics were not different between both groups. Stool viscosity at day 30 was lower in the prebiotics group (16.8N) (3.9-67.8) compared with the placebo group (26.3N) (1.3-148.0) (p = 0.03; 95% CI -0.80 to 0.03). There was a trend towards higher stool frequency in the prebiotics group (3.1 +/- 0.8) compared with the placebo group (2.8 +/- 0.7) (p = 0.15; 95% CI -0.08 to 0.52). Stool pH at day 30 was lower in the in the prebiotics group (5.9 +/- 0.6) compared with the placebo group (6.2 +/- 0.3) (p = 0.009; 95% CI 0.08 to 0.53). Conclusions: Enteral supplementation of a prebiotic mixture consisting of neutral (scGOS/lcFOS) and acidic oligosaccharides (pAOS) decreases stool viscosity and stool pH with a trend towards increased stool frequency in preterm infants. The inclusion of pAOS in a formula containing a mixture of scGOS/lcFOS does not add specific advantages to the formula in terms of stool viscosity, frequency, pH as well as feeding tolerance.