In vivo methods
Different methods are used to analyze RS in vivo.
One of the ways to assay RS physiologically is to determine
starch in the undigested ileal content. Terminal ileal samples can
be recovered by intubation or from ileostomy bags. The classic
way to substantiate starch digestion is by measuring the glycemic
index as described by Jenkins and others (1981). This implies
measuring the area under the curve (AUC) of the serum glucose
concentration over the first 2 h after administering a starch and dividing
this by the serum glucose response after consumption of
an equal amount of glucose.
Determination of breath hydrogen (breath tests) can also be
used as a semiquantitative measurement for RS. In a study on effect
of RS on human colon, increased fermentation was verified
by elevated breath hydrogen excretion (Hylla and others 1998).
From the different animal models, the antibiotic-treated rat model
is the one commonly used (Gudmand-Hoyer 1991).