Role Of Prebiotics On Stool Characteristics banner

Role Of Prebiotics On Stool Characteristics

Prebiotics are non-digestible food ingredients that selectively trigger the growth and activity of microbes in the gut that are linked with the good health of the host.1 Evidence suggests that they are effective in the management of various conditions such as constipation and weight gain in infants. They are also seen to improve stool characteristics in infants,1,2which is discussed in this article.

Oligosaccharides are a part of the functional ingredients of breast milk that perform a variety of biological functions other than acting as a source of energy for infants .3,4Among them, the prebiotic effect of these oligosaccharides is well-known and most referenced.3,4 These oligosaccharides selectively promote the growth of beneficial species in the gut of the infants.3,4 Intestinal microbiota produces short-chain fatty acids (SCFAs) and lactate via fermentation of these prebiotic oligosaccharides. SCFAs not only provide energy to the gut epithelial cells but also play a role in metabolite and water absorption, appetite control, gut motility, and barrier functions, regulation of the immune system, etc. Owing to these actions, SCFAs prevent constipation, diarrhea and other clinical conditions in infants.1

Stool characteristics in healthy breast-fed infants

In breast-fed infants, prebiotic oligosaccharides found in breastfeeds influences stool characteristics of infants via the following mechanisms:5

  1. They increase the water content of the fecal mass via promoting the selective growth of beneficial organisms such as Bifidobacteria and Lactobacillus species, and the subsequent production of SCFA. The SCFA produced helps with gut motility and water retention which helps promote softer stool consistency in infants.
  2. Oligosaccharides may also enhance fecal water content by binding to water as they act as specific types of dietary fiber.

Evidence suggests that breast-fed infants have a higher stool frequency and softer stool consistency than the infants exclusively on infant-feeding.6

Impact of prebiotics containing infant feed on stool characteristics 

Considering the benefits, food-grade prebiotic ingredients have been added to the infant feed to mimic the functions of oligosaccharides found in human milk .2,5Evidence suggests that the introduction of prebiotics in infant feed helps modulate the gut microbiota to a pattern similar to that of breast-fed infants.7In the last >10 years, various oligosaccharides including polydextrose (PDX), galactooligosaccharides (GOS), inulin, lactulose (LOS), pectin hydrolysate, fructooligosaccharides (FOS) and their combinations have been used as prebiotics in infant feed.5

A multi-center, randomized, double-blind, placebo-controlled trial conducted on 1130 infants demonstrated that infant in prebiotic group had softer stool consistency (P < 0.001) than those in group without prebiotic when assessed at 8, 16, and 24 weeks post birthIt was also found that both the breastfed group and the infant feed group with prebiotics had similar stool consistencies.A number of studies are available particularly studying the prebiotic oligosaccharide mix of short-chain GOS(scGOS)/long-chain FOS(lcFOS) in 9:1 ratio in infants. Clinical studies conducted on term infants to evaluate the effect of infant feed supplemented with GOS:FOS (9:1) on stool characteristics indicated that scGOS:/lcFOS group had significantly lower stool consistency (softer stools) and higher stool frequency than the control group (infant feed without GOS:FOS).5 Evidence suggests that beneficial effects of this mixture resembles the oligosaccharides found in human milk due to their ability to increase the concentration of beneficial microbes such as bifidobacteria and lactobacilli in the colon.2

These findings were in line with the results of a study conducted to evaluate the bifidogenic effect of GOS:FOS (9:1). In this study, term infants (n=90) received an infant feed with 0.4 g/100 mL or 0.8 g/100 mL scGOS/lcFOS (9:1) or a control feed without scGOS/lcFOS (9:1) for 28 days. The fecal species and colony-forming units (CFU) were measured at day 1 and 28. It was found that the number of bifidobacteria was significantly higher for groups receiving GOS/FOS supplemented feed (0.4 g/dL group: 9.3 CFU/g; 0.8 g/dL group: 9.7 [0.8]CFU/g) as compared to the control group (7.2 CFU/g, P < 0.001).The number of Lactobacilli was also higher in supplemented groups compared to placebo (P < 0.001).9

Benefits of prebiotics infant feed in preterm infants

In preterm infants, enteral feeding may be linked with the disturbed intestinal passage, hence, consideration of gut tolerance to infant feed is a prerequisite.5 A placebo-controlled, double-blind trial was conducted on 20 preterm infants to evaluate the impact of prebiotic oligosaccharides (GOS:FOS 9:1) on feeding tolerance, stool viscosity, and stool characteristics. The results indicated that median stool viscosity (measured as extrusion force) and gastrointestinal transient time was significantly reduced in the GOS:FOS group (32 N; 12 h) as compared to the control group (158 N; 26 h). Thus, infant feed supplemented with GOS:FOS enhances the gastrointestinal motility which in turn may increase the tolerance to enteral feeding in preterm infants.10

It was found that the stool consistency of GOS:FOS supplemented group was softer than those in the control group. This group also showed higher stool frequency (3.6 stools/day) than those in the control group (2.6 stools/day; P=0.059). Stool frequency observed for GOS/FOS group was similar to those reported for breast-fed preterm infants.10


  1. Prebiotic oligosaccharides in human milk trigger the growth of beneficial gut microbial population which in turn helps in improving immune functions and stooling patterns in infants.
  2. Sizeable evidence has established the beneficial effects of introducing prebiotics in infant feed on the intestinal flora, stool consistency, and frequency.
  3. Thus, the addition of prebiotic oligosaccharides mixture may help bring infant feed into closer alignment with breast milk.


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  9. Moro G, Minoli I, Mosca M, Fanaro S, Jelinek J, Stahl B, Boehm G. Dosage-related bifidogenic effects of galacto-and fructooligosaccharides in formula-fed term infants. Journal of pediatric gastroenterology and nutrition. 2002 Mar 1;34(3):291-5.
  10. Mihatsch WA, Hoegel J, Pohlandt F. Prebiotic oligosaccharides reduce stool viscosity and accelerate gastrointestinal transport in preterm infants. Acta Paediatrica. 2006 Jul;95(7):843-8.