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were also observed following chewing of the two breads due to difference in
this food structure, which made the starch accessibility different in the two
breads.
The difference in response to insulin rather than glucose has also been
highlighted in a study comparing rye products with other cereal grain prod-
ucts from wheat and oats. Juntunen et al. (2002) tested whole kernel rye
bread, whole meal rye bread with oat b -glucan concentrate, dark durum
wheat pasta, and white wheat bread in healthy subjects. The rye kernel bread
had 60% rye kernels and the whole meal bread had 20% oat b -glucan con-
centrate. The whole kernel rye bread had significantly lower insulin
response compared to the other test breads thus emphasizing the role of
structure of food on physiological responses. The response was similar to that
of the pasta with less fiber but a compact structure compared to the other two
test breads. A long-term study using rye bread against white bread for
8 weeks in postmenopausal women also showed increased insulin secretion,
which was attributed to the slow-digesting properties of the rye carbohy-
drates and also to the polyphenol compounds in rye that may serve as insulin
stimulants ( Juntunen, Laaksonen, Autio, et al., 2003; Juntunen, Laaksonen,
Poutanen, et al., 2003 ) . In women with impaired glucose tolerance and with
history of gestational diabetes, low-GI breads were supplied for 3 weeks to
see the effect on glucose and insulin response ( Ostman, Frid, Groop, &
Bjorck, 2006 ). There was a light and dark version of the test breads, the
light containing sour dough, rye kernels, and oat bran concentrate with
oat b -glucan. The dark bread also contained rye kernel and sourdough
but no b -glucan from oats. Both the breads lowered the insulin response
to a glucose tolerance test in the women after 3 weeks. However, there
was no difference in the fasting plasma glucose or insulin.
Foods that modulate blood glucose response can improve insulin sensi-
tivity and reduce the incidence of metabolic syndrome. However, there are
a number of reports that discuss the methodologies used for determination of
the glucose response to a particular food. Hatonen et al. (2006) compared the
use of capillary and venous blood sampling methods for determination of
glycemic response to rye bread, oat meal porridge, and instant mashed pota-
toes. They found that the GIs calculated based on capillary blood glucose
AUC were lower than that calculated using venous blood glucose measure-
ments. However, another disadvantage with venous blood samples was the
high individual variation compared to the capillary blood samples. Like
many other studies, this trial also highlighted the need to use glucose as
the reference food rather than white bread. Rye bread showed a high GI
in this study and showed a lower insulin response. Contrary to many studies
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