Chemistry Reference
In-Depth Information
Related to the use of prebiotics during infancy the most experience exists for
GOS and FOS. Most of the prebiotic infant formulas currently on the market con-
tain these ingredients either as an individual compound or in various combinations.
Therefore, the following section focuses on these two prebiotic ingredients.
15.3.3.1.1 Digestibility of Galacto-Oligosaccharides
and Fructo-Oligosaccharides
As nondigestibility in the small intestine and selective fermentation by the intes-
tinal microbiota are prerequisites of any prebiotic effect of dietary ingredients,
27,28
human studies have been performed to address this issue.
In a study in fructose-sensitive patients, no side effects of inulin could be
detected demonstrating the low or absent digestibility of lcFOS.
118
In a study in
adult patients with ileostoma focusing on pectin hydrolysates,
119
we could also dem-
onstrate that scGOS are still detectable after passage through the small intestine
(data not yet published). In a group of term infants fed with a prebiotic formula, the
presence of the dietary scGOS and lcFOS could be detected in the feces.
92
The data
clearly indicate that the studied prebiotics can reach the colon. This assumption is
supported by the fact that the fecal pH and the concentrations of short-chain fatty
acids could be significantly influenced by these prebiotics.
91,94,102,114
These findings
are in line with results of fermentation experiments.
120-122
In addition, there is also
evidence from such studies that the metabolic rate decreases with increasing chain
length.
123
15.3.3.1.2 Prebiotic Function of Galacto-Oligosaccharides
and Fructo-Oligosaccharides
The counts of fecal bifidobacteria or the percentage of fecal bifidobacteria of the
total bacteria are generally accepted measurements to detect a prebiotic effect. Using
this marker, GOS and FOS can be classified as prebiotics.
124
As demonstrated in Table 15.1 and Table 15.2, many authors use combinations of
prebiotic oligosaccharides. There are several aspects favoring the use of mixtures of
oligosaccharides instead of individual components. One principal aspect is the diver-
sity and complexity of the HMOS,
39,41- 44
which indicates that several structures and
a wide range of molecule sizes
125
are necessary to provide the full functionality of
HMOS.
In one study with the prebiotic mixture of scGOS/lcFOS, the counts of bifido-
bacteria were measured either with a conventional plating technique (measuring
the living bacteria) or with a molecular biologic technique (measuring all bacte-
ria). With both methods, an increase of bifidobacteria could be recorded. However,
with increasing concentration of the prebiotics, this difference between the different
methods disappeared.
126
This indicates that the counts of bifidobacteria as well as
their metabolic activity have been stimulated by the prebiotics.
As the interaction between dietary components and the intestinal ecosystem is
very complex, the matrix of the food might be important for the effect. Prebiotics
