Biology Reference
In-Depth Information
blood glucose. While one study using 27 g fiber did not find any effect on
glycemic response, another study using a soluble fiber, guar gum, showed
favorable effects on lowering blood glucose. Very high doses of about
50 g fiber have also shown considerable improvement in glycemic response
et al., 1976
)
. Another polysaccharide called glucomannan in Konjac has also
been known to lower fasting plasma glucose in type 2 diabetic subjects.
A daily dose of 3.6 g for 28 days reduced the fasting plasma glucose by
12.3% and postprandial blood glucose by 12.2 % due to its unique rheological
properties that reduce carbohydrate digestion and absorption (
Hsiao-Ling,
There is an abundance of evidence stating the effect of soluble dietary
fiber sources in modulating glycaemia, the mechanism by which it causes
the effect is sometimes controversial and highly debated. Food characteristics
such as viscosity and fiber content along with the physical structure of food
can all influence glycemic response dependent on their effects on starch
accessibility (
Riccardi et al., 2008
)
. Bjorck and colleagues stated that dietary
fiber lowers glycemic response due to its ability to increase gastrointestinal
viscosity hampering postprandial glucose absorption rate and gastric empty-
ing (
Bjorck et al., 1994
), thus leading to greater glycemic control (
Chandalia
et al., 2000
)
and improved insulin sensitivity (
Ha & Lean, 1998
).
Chandalia
et al. (2000)
also showed that a high-fiber bolus can reduce gastrointestinal
absorption of cholesterol by 10% and can lead to fat malabsorption. Ou and
coworkers studied the soluble dietary fibers wheat bran, carboxymethyl cel-
lulose, guar gum, and xanthan gum
in vitro
and highlighted increased gastro-
intestinal viscosity as one of the three mechanisms that could lower
postprandial serum glucose levels, along with the binding of fiber to glucose
and decreasing the glucose concentration available for uptake and the inhi-
bition of
a
-amylase action by fiber through encapsulation of starch and
emptying rate increases satiety, which can lower overall energy intake,
which can be indirectly linked to reducing obesity prevalence (
Brown,
Rosner, Willett, & Sacks, 1999
). The viscosity properties of soluble dietary
fiber are therefore most likely to be therapeutically useful in modifying post-
prandial hyperglycemia (
Jenkins et al., 1978
).
There are a number of research studies showing the use of various natural
soluble dietary fiber sources to modulate glycemia. Some of the popularly
used soluble fibers in the food industry include guar gum, locust bean
