Chemistry Reference
In-Depth Information
have also been successfully added to infant formula of different protein quality and
quantity as well as to solid weaning food or cereals (recently reviewed by Boehm and
Moro
53
). Prebiotic effects have also been seen with these compounds in adults when
used as a supplement to a typical western diet.
127
Thus, there is evidence that the prebi-
otic effect can be independent of the type of food used as the basis for the nutrition.
The bifidogenic effect is often associated with a reduction of the stool pH and
changes in the short-chain fatty acid pattern. Short-chain fatty acids are the fer-
mentation products of bacteria in the colon. They are, therefore, an important char-
acteristic feature of the intestinal microbiota.
128
As already mentioned, the profile
of short-chain fatty acids depends considerably on the composition of the diet.
Supplementing an infant formula with a mixture of scGOS/lcFOS resulted in a pat-
tern of short-chain fatty acids in the feces that corresponded to the pattern found in
the feces of breastfed infants.
94
Since the bifidobacteria produce only acetate and
lactate, the short-chain fatty acid pattern reflects the metabolic activity of the entire
microbiota and not only the activity of bifidobacteria. Thus, it can be assumed that
short-chain fatty acid profiles similar to the profiles found in breastfed infants reflect
similarities of the entire microbiota between breastfed infants and infants fed with a
formula supplemented with the studied mixture.
There are several results available indicating that the short-chain fatty acid pro-
file and pH influence the physiological role of intestinal cells. In particular, effects
on mucin-2 synthesis and barrier integrity are described.
130
In addition, there was
also an effect of the short-chain fatty acids pattern and pH on the growth of several
pathogens.
131
This effect has a particular clinical relevance during infancy. In fact,
the reduction of fecal pathogens could be demonstrated in a study in preterm
115
as
well as term infants.
94
There is evidence that early colonization with specific microbiota might be asso-
ciated with the development of allergic symptoms later in life. Bjorksten et al.
132
found that allergic infants were less often colonized by lactobacilli and bifidobac-
teria than nonallergic infants. Additionally, it was found that allergic infants had
more adultlike species in their fecal flora, including
B. adolescentis
, compared with
healthy infants. In the latter,
B. bifidum, B. infantis,
and
B. breve
predominated.
133
Also in Japanese infants suffering from atopic dermatitis, similar findings have been
reported.
134
This suggests that different bacterial species may have different func-
tional effects on the immunological reaction of the host. In two studies using a mix-
ture of scGOS/lcFOS as the prebiotic ingredient, it could be demonstrated that the
prebiotic mixture promoted
B. infantis
and depressed
B. adolescentis.
95,109
In summary, the experimental data as well as the results of clinical trials prove
that substances with a structure different from the structure of HMOS are able to
influence the intestinal microbiota comparable to those found in breastfed infants.
15.3.3.2 Influence on Postnatal Development of the Immune System
There is accumulating evidence that the interaction between the intestinal micro-
biota and the gut plays an important role for the postnatal development of the immune
system. However, the interactions between the intestinal epithelial and immune cells
