Chemistry Reference
In-Depth Information
infants fed supplemented formula was lower as compared to the standard formula.
40
Supplemental GOS/lcFOS also has the ability to alter fecal microbiota in the wean-
ing period.
41
An alternative approach to influence the colonization of the neonatal gut by GOS/
lcFOS has also been tested.
42
As the maternal microbiota plays an important role in
the first colonization at birth, pregnant woman were supplemented with GOS/lcFOS.
Although the proportions of bifidobacteria were significantly increased in the maternal
gut, no direct effect on the bacterial transfer between mother and child was observed.
Probably, this was due to a masked effect of the HMOs as the infants were breastfed. An
alternative approach could be the targeting of the vaginal microflora prior to delivery.
43
A random controlled trial (RCT) of GOS and the prevention of antibiotic-associated
diarrhea (AAD) showed that, in children who had received amoxicillin for bronchi-
tis (resulting in significantly reduced fecal bifidobacteria concentrations and increased
numbers of
Escherichia coli
), the administration of GOS positively influenced bifi-
dobacteria concentrations.
44
GOS has been shown to have a synergistic effect on the
bifidogenic activity of probiotics.
45
The increase in the amount of bifidobacteria in
school-aged children was significantly greater after the ingestion of GOS combined
with
Lactobacillus rhamnosus
GG (LGG) as compared to the ingestion of LGG alone.
4.5.2.2 Inhibition of Pathogens
Some members of the microbiota are considered potentially harmful (pathogenic)
in view of their involvement in toxin production or activation of carcinogenesis, feed-
ing intolerance, inflammatory responses, mucosal invasion, and infections. As GOS
are able to selectively manipulate the intestinal microbiota in the lumen and at the
mucosal surface, they indirectly result in the displacement of less-desirable members
of the microbiota.
46, 47
In addition, the metabolism of GOS by the specific members of
the microbiota results in the production of antagonistic agents (e.g., diacetyl, hydrogen
peroxide), antimicrobial peptides,
48,49
and SCFAs. The last reduce the luminal pH in
the colon to levels below those at which the pathogens can effectively multiply.
GOS have also been shown to have a more direct inhibitory effect on pathogens
as they competitively prevent bacterial adherence. GOS resemble the receptor sites
coating the intestinal epithelial cells to which pathogens adhere for initiation of the
infection process.
50
As a result, they can act as “molecular receptor decoys” or “anti-
adhesives” that competitively inhibit bacterial adherence by mimicking the host cell
receptors.
50 -52
GOS were shown to impair the adherence of an enteropathogenic
E.
coli
(EPEC) strain on HEp-2 and Caco-2 cells by 65 and 70 percent, respectively, in
a dose-dependent manner.
52
In addition, the average number of bacteria per micro-
colony was significantly reduced (over 70 percent) when GOS were present. GOS
were also shown to strongly inhibit the attachment of another EPEC and
Salmonella
typhimurium
to HT29 adenocarcinoma cells
in vitro
.
51
