Chemistry Reference
In-Depth Information
3.4.4 Fructans and vitamin Production
As mentioned by Gibson and Roberfroid (1995), bifidobacteria produce vita-
mins, mainly from the B-complex (Gibson and Roberfroid, 1995). In an
in vitro
study, Noda et al. (1994) emphasized the fact that bifidobacteria strains, such as
B.
bifidum,
, produced biotin (vitamin B
8
) extracellularly. Folic acid and vitamin K are
also produced by bifidobacteria. Therefore, it could be thought that consumption of
prebiotics, thanks to their stimulation on bifidobacteria growth, could have benefi-
cial effects for subjects deficient in vitamin K or B. However, quantities of vitamins
produced by bifidobacteria are very limited compared to dietary allowance (RDA),
suggesting that prebiotic stimulation of bifidobacteria is not sufficient to exert sig-
nificant effects on vitamin status.
3.4.5 Fructans and Absorptive-Productive Functions
Although the number of studies on the effect of nondigestible oligosaccharides
on mineral metabolism in humans is limited, so far, positive effects on Ca absorp-
tion seem to occur under conditions of increased Ca requirements (e.g., adolescence
and postmenopause). The extent of the effect seems to be specific for the type of
carbohydrate. Contradictory results on the effect of prebiotics in the literature may
be due to differences in the experimental design. Several experimental conditions
promoted the stimulation of Ca absorption and retention by nondigestible oligosac-
charides, such as high dietary Ca, an optimum dose of prebiotics, sufficient duration
of administration, and the age of subjects (Scholz-Ahrens
et al., 2001).
Despite the belief that Ca absorption is thought to occur in the proximal gut in
humans, a colonic phase may exist. Ellegard et al. (1997) showed that neither inulin
nor FOS when fed to ileostomy subjects had any effect on ileostomy excretion of
Ca, Mg, zinc, or iron. Because prebiotic carbohydrates pass through the small bowel
unchanged, but are fermented in the cecum or colon, a large bowel effect on absorp-
tion is possible (Macfarlane
et al., 2006).
3.4.6 Metabolic Parameters and satiety
Recent research has been reported concerning the effect of fructans on satiety
and control of energy intake. The available data suggest a beneficial effect of inulin
and FOS in modulating energy balance in humans consuming diet
ad libitum
. In
a recent pilot study (Cani
et al., 2006), 10 healthy volunteers were included in two
2-week phases during which they received twice a day either 8 g oligofructose or 8
g placebo (maltodextrin), with each phase separated by a 2-week wash-out period.
It appeared that oligofructose treatment increases satiety following breakfast and
dinner and reduces hunger and prospective food consumption following dinner.
However, total energy intake per day was only 5 percent lower during the oligofruc-
tose than the placebo periods, what should not have a high impact on the body mass
index of subjects.
