Chemistry Reference
In-Depth Information
prebiotic alone. Specifically, a more potent inhibition of azoxymethane (AOM)-
induced aberrant crypt foci (ACF) was found in rats administrated both inulin (pre-
biotic) and
Bifidobacterium longum
(probiotic) than in rats administered either inulin
or
B. longum
separately (Rowland et al., 1998). Probiotic bacteria may use prebiotic
substrates as an energy source in the colon, which facilitates the growth of the probi-
otic bacteria while reducing pathogenic bacteria in the large intestine.
It has been reported that HACS acted as a prebiotic and a synbiotic in promoting
the fecal excretion of probiotic organisms in pigs (Brown et al., 1997). High counts
of bifidobacteria were found when pigs were fed the experimental HACS
diet with
the bacterial supplementation (Brown et al., 1997). No bifidobacteria were
detected
in the absence of the supplement (at a detection limit
of 4 cfu/g). The high HACS
diet resulted in significantly higher counts than did the low HACS diet. The high
HACS diet increased average
fecal concentrations and total fecal excretion by 0.79
log
10
cfu/g wet wt and 0.97 log
10
cfu/day higher, respectively (Table 6.3). Several
mechanisms have been proposed for HACS action on increased fecal probiotic num-
bers (Brown et al., 1997): (1) RS may protect the bacteria from bactericidal materi-
als, such as bile acids,
free fatty acids, and other products, by acting as a diluent in
the upper gut; (2) the bacteria may have been protected in the gastrointestinal tract
by adhesion
to undigested starch or through entry into the pits formed in
the starch
granules; and (3) the HACS could serve as a substrate for the
bifidobacteria, although
bifidobacteria do not metabolize starches efficiently. This is supported by the lack
of difference
in fecal starch excretion between pigs fed RS alone and those
fed RS
with probiotic.
Synbiotic effects of RS (20 or 30 g HACS/100 g diet) and two strains of
B. lac-
tis,
which facilitated the apoptotic response to a genotoxic carcinogen (AARGC)
in the colon have been reported in studies using rats (Le Leu et al., 2005) and mice
(Wang et al., 2002). A dosage used in this study was based on the study of Le Leu
et al. (2003), which reported that higher amounts (i.e., 20 or 30 g HACS/100 g diet)
do have an effect and that the moderate amount of RS did not affect the AARGC.
The synbiotic combination of RS with
B. lactis
enhanced the apoptotic response by
33 percent (Le Leu et al., 2005). This change may have biological significance since
only a small change (approximately 2 percent) in the proportion of apoptotic cells in
the crypt column may be enough to influence colorectal tumor development (Chang
Table 6.3 Fecal Concentrations and Daily Excretion of bifidobacteria of Pigs Fed
Either A low Amylose or high Amylose (Amylomaize) Cornstarch
with
live
Biidobacter
i
um Longum
Fecal Concentration, log
10
cfu/g Wet wt
Fecal Excretion, log
10
cfu/d
starch Type in the Diet
Low amylase
8.12
10.76
HaCs
8.91
11.73
difference
0.79
0.97
statistical analysis,
P
value
P
< 0.01
P
< 0.01
Source:
adapted from brown et al., 1997.
