Home > Supplementation of a bovine milk formula with an oligosaccharide (OS) mixture increases counts of faecal bifidobacteria in preterm infants

Supplementation of a bovine milk formula with an oligosaccharide (OS) mixture increases counts of faecal bifidobacteria in preterm infants


Preterm infants are particularly vulnerable to intestinal infections; therefore, the establishment of a balanced microflora that may protect against infection is desirable in such infants. One external factor that is important for the quality of intestinal colonisation is the diet.


The aim of this study was to investigate the effect of a preterm formula milk supplemented with a mixture of oligosaccharides (a mixture of 90% Galacto-oligosaccharides and 10% Fructo-oligosaccharides in a concentration of 1g/100ml) on the stool flora (with particular respect to bifidobacteria concentration) and stool characteristics of preterm infants.

Study design

30 preterm infants (maximum gestational age 32 weeks) were randomised to receive a non-prebiotic-containing preterm formula (control) or preterm formula containing prebiotic OS (1g/100ml) for 28 days. Twelve breastfed infants were also studied. On day 1, 7, 14 and 28, faecal flora, stool characteristics, any side effects and body weight were recorded. The crown heel length was measured at the start and end of each feeding period.

All infants started feeding with pasteurised breast milk. When the neonatologist decided to start formula feeding, the infants were randomised to one of the two intervention groups.


Effects on stool flora

  • At the initiation of treatment, the numbers of bifidobacteria present did not differ between intervention groups.
  • The number of bifidobacteria was significantly higher on day 28 in infants receiving the prebiotic OS-supplemented formula milk compared to the control  group (p=0.0008).
  • At day 28 the number of bifidobacteria in the prebiotic OS group was in the upper range of the reference breastfed group.

Effects on stool consistency and frequency

  • The stool consistency of infants receiving the prebiotic OS formula milk was similar to that of the infants receiving breast milk.
  • Infants in the control group developed significantly harder stools than the prebiotic OS group (p=0.0102) and the breast milk group (p=0.0003).
  • The stool frequency in the prebiotic OS formula group and breastfed group were similar. The stool frequency after 28 days was significantly higher in the reference breastfed group than in the control group (p<0.0001).

Weight and length

  • Weight and length gain did not differ between intervention groups.
  • There was no effect of the oligosaccharides (prebiotics) on the incidence of side effects (crying, regurgitation or vomiting).


Supplementation of a preterm formula with a mixture of Galacto- and Fructo-oligosaccharides (prebiotics) stimulates growth of bifidobacteria and results in a stool frequency and consistency similar to those found in preterm infants fed breast milk. Thus prebiotic mixtures such as those studied here may help to improve intestinal tolerance to enteral feeding.