Dietary Fibre - ILSI Argentina

Dietary Fibre 33
to some foods, including breakfast cereals, biscuits and
other baked goods, pasta and breads. Other commonly
reported effects in healthy individuals are bloating and
mild laxative effects, which have been described at levels
above 30 g resistant starch per day. However, resistant
starch was given together with other types of dietary
fibre in some studies, which limits the interpretability of
their results. Perhaps resistant starch is well tolerated
because of the very low gas production resulting from its
fermentation.
meals can significantly reduce the absorption of iron.
Reduced bioavailability of minerals may in practice be –
partly – compensated by the fact that fibre-rich foods
tend to be rich in minerals as well.
The gastrointestinal tolerance to polydextrose is relatively
good. It does not appear to cause gastrointestinal
discomfort at lower levels of intake (12-15 g/day). Even a
single dose of up to 50 grams and a daily intake up to
90 grams are tolerated without adverse effects.
Decreased mineral bioavailability
The fermentation of fibres in the colon is associated with
the release and solubilisation of minerals, which
facilitates colonic absorption. In contrast with this, diets
rich in certain other types of dietary fibre, particularly
those associated with phytate, seem to decrease the
absorption in the small intestine of several minerals,
notably iron, calcium, magnesium and zinc. This has
been seen in both animal and human studies. Phytate
binds with these minerals thereby potentially reducing
their availability for absorption from the small intestine.
The overall results of studies on these effects suggest:
dietary fibre intake does not decrease absorption or
balance of magnesium or calcium; the consumption of
large amounts of cereals, vegetable and fruit fibres have
no effect on calcium absorption and balance; soluble
fibres such as inulin have no effect on the absorption in
the small intestine of iron or zinc; and resistant starch
derived from high-amylose maize (30 g/day) does not
reduce calcium absorption in the small intestine.
However, the addition of unprocessed wheat bran to