Pectin supplementation of the diet also influenced
other aspects of the hindgut flora, increasing the rate
of ammonia formation by faecal incubations in vztro
and its concentration in the freshly voided stool.
Ammonia is formed in the large intestinal contents
following microbial degradation of urea or amino
a ~ i d s , ’ , ’ a~n.d~ h~a s been proposed to play a role in
the promotion of disease in the Pectin
ingestion also appeared to be linked to a pronounced
‘carry-over’ effect, since certain faecal parameters
during the subsequent control period (e.g.
bacterial numbers, stool output, ammonia concentration)
returned values lower than the other control
collections. Possibly, three weeks for the following
control diet was not long enough to ensure that
gut function had returned to normal, and may have
lead to an underestimation of the influence of wheat
bran on the faecal parameters measured.In contrast to the bacterial effects recorded during
pectin or wheat bran supplementation of the diet,
increased fat consumption by the six volunteers
gave no significant changes in faecal microbial
enzyme activities. An increase in fat intake is
reported to generally elevate a number of bacterial
biotransformation activities in both rodent and
human gut bacterial populations, with saturated fat
producing the greatest change.26 The absence of
any effect linked to fat intake in this investigation
may reflect the relatively high fat content of the
subjects’ basal diet prior to supplementation; an
experimentally-induced decrease in fat intake
might have produced more interesting changes.
Alternatively, the basal dietary fibre content of the
diets may have been sufficient to interefere with any
fat-related alteration, since Domellof et aL9 in a
study contrasting dietary habit and faecal profile
in Sweden and North America, reported that any
stimulatory effect of a high-fat intake on the flora
may be modulated by a concomitant increase in
fibre consumption. The basal intake of dietary fibre
during the period of increased fat consumption in
the present study may have been therefore sufficient
to ameliorate effects on bacterial metabolic activity.
In conclusion, the results of the present study
demonstrate that the indigestible plant components
Dectin and wheat bran sienificantlv alter certain
human volunteers maintaining an otherwise
normal, mixed dietary intake.