Tmcm. Dekok et al., INVITRO STUDY ON THE EFFECTS OF FECAL COMPOSITION ON FECAPENTAENE KINETICS IN THE LARGE-BOWEL, MUTATION RESEARCH, 302(2), 1993, pp. 103-108
Dietary factors have been shown to affect excretion of fecapentaenes,
potent mutagens present in human feces. Apart from effects of the diet
on the bacterial synthesis of fecapentaenes in the bowel, fecapentaen
e excretion is likely to be indirectly influenced by the composition o
f the bowel contents, in particular fecapentaene-binding or -solubiliz
ing factors. In the present study, interactions between dietary fiber
and fecapentaene-12 (FP-12), as well as the effects of bile acids and
calcium on the solubility of FP-12 in aqueous solutions, have been inv
estigated in vitro. The results demonstrated that FP-12 may strongly a
dsorb to fiber, as indicated by reduced concentrations in the aqueous
PBS phase when increasing amounts of fiber are added. This fecapentaen
e-binding capacity of fiber may explain the positive correlations that
have previously been found between excreted fecapentaene concentratio
ns and fiber consumption in human population studies. Further, it was
found that at concentrations physiologically occurring in feces, both
cholic and deoxycholic acid as well as mixtures of bile acids may incr
ease the aqueous solubility of FP-12. This solubilizing effect of bile
acids can be reduced by adding calcium at physiological concentration
s of 2.5 mg/ml. It is hypothesized that high dietary fiber intake may
increase fecapentaene excretion as a result of this fecapentaene fiber
adsorption, which in turn may result in diminished exposure of the hu
man bowel epithelium to these putative initiators of colorectal cancer
. In contrast, high concentrations of fecal bile acids may act as feca
pentaene-solubilizing factors which increase fecapentaene bioavailabil
ity, thereby possibly resulting in increased risk for colorectal cance
r.