Chemistry Reference
In-Depth Information
bifidobacteria is induced by bifidogenic components in breast milk, including
oligosaccharides (Harmsen et al., 2000; Mountzouris et al., 2002). Indeed,
human milk oligosaccharides (HMOs) are the original prebiotics. The concen-
tration of HMOs in breast milk (5-12 g/L) is about 100 times that found in
cow's milk (0.03-0.06 g/L) (Kunz et al., 2000; Boehm and Stahl, 2007), repre-
senting the third largest solid component behind lactose and fat (Bruzzese et al.,
2006). That mothers direct so much energy towards components of breast milk
that are not directly metabolized by the infant, but rather selectively feed and
direct the composition of the microbiota, shows evolutionarily just how impor-
tant the infant gut microbiota is to well-being.
In contrast to breast-fed infants, infants fed traditional cow's milk-
based formulae develop a more mixed intestinal microbiota, with lower
counts of bifidobacteria and higher counts of clostridia and enterococci
(Adlerberth, 1999). Formula-fed infants also have been observed to have
higher faecal ammonia and other potentially harmful bacterial products
(Heavey et al., 2003; Edwards and Parrett, 2002). The bifidogenic effect
of HMOs
can
be
emulated
using
oligosaccharides
such
as
GOSs
or
fructo-oligosaccharides
(FOSs).
In
fact,
most
Japanese
infant
formula
manufacturers
have
been
supplementing
their
products
with
prebiotic
oligosaccharides for many years (Boehm et al., 2005).
GOSs share some structural similarities with the backbone of HMOs,
although HMOs are considerably more complex, with over 200 different
structures identified based on a variable combination of glucose, galactose,
sialic acid, fucose and/or N-acetylglucosamine, with varied sizes and linkages
accounting for the considerable variety (Kunz et al., 2000). In recent years, a
number of studies have investigated the effect of infant formula containing
8 g/L of a mixture of 9:1 GOSs:FOSs on the intestinal microbiota of infants.
The GOSs:FOSs mixture was designed to mimic the molecular size distribu-
tion of HMOs (Knol et al., 2005). Summarized in Figure 5.10, they show that
feeding this formula induced a microbiota similar to that of breast-fed
infants, both in terms of composition of the overall microbiota and the
proportion and species composition of lactobacilli and bifidobacteria
(which tends to be more adult-like in traditional formula-fed infants)
(Rinne et al., 2005; Haarman and Knol, 2005, 2006; Knol et al., 2005). The
oligosaccharide-containing formula also resulted in a reduced faecal pH and
a SCFA profile that mimicked breast milk (dominated by acetate) and was
different from that produced by traditional infant formulae (higher in buty-
rate and propionate) (Boehm et al., 2005; Fanaro et al., 2005; Knol et al.,
2005; Bakker-Zierikzee et al., 2005). Feeding the oligosaccharide formula
also resulted in an improved stool consistency and frequency, similar to
breast-fed infants, while having no adverse impacts on measures of infant
growth or other adverse effects (Boehm et al., 2005; Bruzzese et al., 2006;
