Dietary Fibre - ILSI Argentina

4 Concise Monograph Series
ment form. Paradoxically, prospective observational data
show that the intake of non-viscous dietary fibre, e.g. like
that in whole grain cereals, is a better predictor of the risk
of insulin resistance and diabetes (risk being lower at
higher intakes).
Dietary fibre consumption is inversely associated with
body mass index. However, results of intervention
studies on appetite, energy and total food intake are
inconsistent. There are some indications that viscous
fibres such as pectins and guar gum delay gastric
emptying, and that slowly digested starch and resistant
starch increase satiety.
Do isolated or synthetic, so-called functional components
have similar effects when added to foods or taken
separately as supplements, as when they are part of the
intact structure of foods? There is evidence that the
benefits of whole grains, fruits and vegetables outweigh
those of the isolated components of these foods (used
either as supplements or added to foods). Possibly other,
as yet unidentified, substances in such foods can explain
this; perhaps it is the overall combination of the dietary
fibre, nutrients and bioactive substances, acting
synergistically, that is critical to health. However, there
are also isolated types of dietary fibre, such as resistant
starch, non-digestible oligosaccharides and polydextrose,
that help in the prevention and alleviation of bowel
disorders, and decrease risk factors for coronary heart
disease and type 2 diabetes.
such as flatulence. Generally such effects, if occurring at
all, are only seen at high intake levels and may be
transitory. There is also some evidence that high intakes
of certain types of dietary fibre, particularly those
associated with phytate, reduce the absorption in the
small intestine of several minerals: iron, calcium,
magnesium and zinc. On the other hand, dietary fibre
may improve colonic mineral absorption during the
fermentation process. However, the significance of this
latter observation to overall mineral status and to
physiological endpoints such as bone health is uncertain.
The balance of calcium and magnesium is not adversely
affected by large amounts of cereals, vegetables and
fruits. Generally, consumption of foods naturally rich in
fibre is self-limiting due to their bulking character.
However, this applies to a lesser extent to foods enriched
with fibre, and much less to supplements.
Adverse effects
Diets containing large quantities of dietary fibre may be
bulky and of relatively low energy density. This may
make them unsuitable for very young and very old
people. Isolated or synthetic types of dietary fibre, such
as non-digestible oligosaccharides or resistant starch
have been reported to cause gastrointestinal symptoms