European Journal of Clinical Nutrition (1999) 53, 262±267
ß 1999 Stockton Press. All rights reserved 0954±3007/99 $12.00
http://www.stockton-press.co.uk/ejcn
Rye bread decreases postprandial insulin response but does not
alter glucose response in healthy Finnish subjects
K Leinonen,1* K Liukkonen,2 K Poutanen,2 M Uusitupa1 and H MykkaÈnen1
1
Department of Clinical Nutrition, University of Kuopio, P.O.Box 1627, 70211 Kuopio, Finland; and 2VTT Biotechnology and Food
Research, P.O. Box 1500, FIN-02044 VTT, Finland
Objective: To compare if postprandial glucose and insulin responses to wholekernel rye bread are lower than to
wheat bread, and to see if these responses to two types of rye breads are different. To explore starch digestion in
more detail, rate of starch hydrolysis of same breads was measured in vitro.
Design: Subjects were given test breads (43 ± 61 g available carbohydrates by analysis) with standardized
breakfast in a random order after a fast. Eight postprandial blood samples were collected during the following
three hours. Rate of starch hydrolysis was determined by an in vitro enzymatic hydrolysis method.
Subjects: 10 men and 10 women, aged 32 3 and 27 5 y, BMI 24.5 2.2 and 20.3 1.1 kg=m2, respectively,
all had normal glucose tolerance.
Results: Plasma insulin response to wholekernel rye bread was lower than to wheat bread (45 min P ˆ 0.025,
60 min P ˆ 0.002, 90 min P ˆ 0.0004, 120 min P ˆ 0.050, 150 min P ˆ 0.033), but there was no difference in
glucose responses. In comparison of two types of rye breads, glucose response to wholemeal rye bread at 150 and
180 min was higher (P ˆ 0.018 and P ˆ 0.041, respectively) and insulin response at 60 min was lower
(P ˆ 0.025) than those to wholemeal rye crispbread. Total sugar pro®les in vitro were similar for all breads.
When free reducing sugars were subtracted, starch in wholekernel and wholemeal rye breads appeared to be
hydrolysed slower than starch in wholemeal rye crispbread and wheat bread.
Conclusions: Wholekernel rye bread produces lower postprandial insulin response than wheat bread, but there is
no difference in glucose response. The latter is in accordance with in vitro results. Postprandial glucose and
insulin may also be affected by type of rye bread. Characteristics of different types of rye breads must be further
investigated to develop health properties of rye breads.
Sponsorship: Vaasa Bakeries Ltd, P.O. Box 105, 00240 Helsinki, Finland and Fazer Bakeries Ltd, P.O. Box 40,
15101 Lahti, Finland.
Descriptors: rye bread; wheat bread; glucose response; insulin response; starch hydrolysis
Introduction
Wholemeal sour rye breads are an essential part of the
Finnish diet. Rye products comprise approximately 36%
of the total intake of cereals in Finland (Kleemola et al,
1994). The energy and macronutrient contents of rye grain
are similar to those of other cereals. Typical rye products
vary from country to country, variation being caused by
variable ¯our yield and coarseness, the amount of other
ingredients (wheat ¯our, sour dough cultures), and the
baking process. In Finland the traditional and still popular
rye breads are based on wholemeal ¯our, and are thus rich
in dietary ®bre (DF). The DF content of rye ¯our is
15 ± 17%, the main chemical constituents being arabinoxylans (8 ± 10%), beta-glucan (2 ± 3%) and cellulose
Ê man et al, 1995).
(1 ± 3%) (HaÈrkoÈnen et al, 1997; A
Mainly due to its high DF content, wholemeal rye bread
may reduce the health risks associated with coronary heart
disease (Pietinen et al, 1996) and colon, breast and prostate
cancer (Consensus meeting, 1997; Zhang et al, 1997).
Slowly digestible carbohydrates have been suggested to
be nutritionally most desirable, improving metabolic
*Correspondence: K. Leinonen, Department of Clinical Nutrition,
University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland.
Received 30 June 1998; revised 5 November 1998; accepted 16 November
1998
variables not only in diabetes and hyperlipidemia, but also
in healthy subjects (BjoÈrck et al, 1994; Englyst & Hudson,
1997). The glycemic index (GI) concept, although subject to
some critique (Wolever, 1997), is a widely used method for
classi®cation of different foods according to their effect on
postprandial glucose levels. The glucose and insulin
responses of different rye breads and other rye products
have been reported to be variably lower than those of wheat
bread, as reviewed by Foster-Powell & Brand Miller (1995).
The lowest GI-values (66 ± 80) have been reported for
pumpernickel-type breads containing intact kernels (Jenkins
et al, 1985, 1986; Wolever et al, 1987, 1994). There is a
consensus that intact botanical structure protects the encapsulated starch of the kernel against the hydrolysis (Brand et
al, 1990; Granfeldt et al, 1992). The amount of whole
kernels in the bread has been concluded to be more effective
in reducing the glucose and insulin responses than the high
®ber content as such (Jenkins et al, 1985, 1986; Wolever et
al, 1994; Liljeberg et al, 1992).
Heat processing is generally considered to increase the
GI of foods, mainly due to increased enzymatic accessibility of the gelatinized starch. The best known exception to
this rule is pasta manufacture, most pasta products having a
GI-value of 50 ±70 (Foster-Powell & Brand Miller, 1995).
Low temperature and long-time baking may slow the
digestion of bread by increasing the retrogradation of
Rye bread decreases postprandial insulin response
K Leinonen et al
amylose and hence the amount of resistant starch (RS) in
the product (BjoÈrck & Liljeberg, 1997). RS passes the small
intestine without digestion and is available as energy only
after colon fermentation. Traditional Finnish rye bread is
mostly baked on sour dough, which contains organic acids
and their salts. The latter are supposed to lower postprandial glucose and insulin responses (Liljeberg & BjoÈrck,
1994; Liljeberg et al, 1995; Liljeberg & BjoÈrck, 1996)
either by interfering the action of hydrolytic enzymes in the
small intestine or by delaying gastric emptying (BjoÈrck &
Liljeberg, 1997).
The majority of the studies concerning glycemic
responses of rye bread have been conducted in diabetic
patients. In this study we wanted to determine in healthy
subjects whether the postprandial glucose and insulin
responses to rye bread (wholekernel bread) are lower than
those to wheat bread. We also wanted to ®nd out if various
types of rye breads give different glucose and insulin
responses (wholemeal crispbread vs wholemeal bread).
To explore the starch digestion in more detail, the rate of
starch hydrolysis of the same test breads was measured in
vitro.
Methods
Subjects
Twenty healthy Finnish adults (10 men and 10 women,
aged 32 3 and 27 5 y, respectively) with normal glucose tolerance participated in the study. The body mass
index (BMI) of men was 24.5 2.2 kg=m2 and that of
women 20.3 1.1 kg=m2. According to the four day food
records kept before the study, the mean energy intake by
the men was 9668 kJ=d (2302 kcal=d) (range 6145 ±
12243 kJ=d) and by the women 7510 kJ=d (1788 kcal=d)
(range 5998 ±9731 kJ=d). The subjects were asked to maintain their body weight and their energy intake unchanged
during the study.
Test breads and test meals
The test breads were three commercial wholemeal sour rye
breads and a white wheat bread as a reference. The breads
were received from two Finnish bakeries (Fazer Bakeries
Ltd and Vaasa Bakeries Ltd) and they are commonly used
in Finland. One of the rye breads was a dried product,
namely, crispbread. It, as well as the wholemeal rye bread,
were produced from a ®nely milled wholemeal rye ¯our,
whereas the third rye bread contained in addition to wholemeal rye ¯our also coarse grain particles. Each test meal
was planned to contain 50 g of available carbohydrate from
the test bread, 40 g cucumber and 3 dl non-caloric orange
drink (sweetened with sweetening agent). Because the
analysed nutrient compositions of the test breads were not
available as the study started, the portions of the breads
were calculated using data received from the bakeries (rye
breads) or from the Finnish food table (wheat bread)
(Rastas et al, 1993).
Study design
The subjects were fed the test breads in a randomised order
after an overnight fast. All tests were performed during a
two-month period. The subjects were asked to follow their
usual diet during the study. Dietary compliance was monitored by food records kept for one day before each test
day. The subjects were not allowed to drink alcohol during
two days before the tests, and smoking at the test morning
was forbidden. Subjects were also asked to avoid heavy
eating and heavy exercise one day before the tests and on
the test day. A dietitian gave detailed written and oral
instructions on the dietary and study regimen. Dietary
analysis of nutrient
intake was calculated using the
1
Micro-Nutrica software package (Social Insurance Institution, Helsinki, Finland 1993) (Rastas et al, 1993).
In the test morning an intravenous catheter was inserted
in the antecubital vein of the arm. After the fasting blood
sample was drawn, the subject had to eat the test meal
within 15± 20 min. The mean times of eating breads were
8 min for wheat bread, 9 min for wholekernel rye bread,
10 min for wholemeal rye bread and 11 min for wholemeal
rye crispbread. Blood samples were taken through the
catheter at 15, 30, 45, 60, 90, 120, 150 and 180 min after
the start of eating the test meal.
Plasma glucose was analysed by the glucose oxidase
method (Glucose Auto & Stat, Model GA-110, Daiichi,
Kyoto, Japan) and plasma insulin by the RIA-method
(Phadaseph Insulin RIA 100, Pharmacia Diagnostica,
Uppsala, Sweden). Maximal glucose and insulin responses
were calculated by subtracting the highest value of blood
glucose or insulin from the fasting value of blood glucose
or insulin. The areas for glucose and insulin were calculated from initial rise of blood glucose or insulin, respectively, above the baseline (Ha et al, 1992).
Statistical signi®cances of differences in the postprandial glucose and insulin responses between the test bread
(wholekernel rye bread vs wheat bread, wholemeal rye
bread vs wholemeal rye crispbread) were assessed by the
non-parametric Wilcoxon's test.
Approval of the human study was given by the Ethics
Committee at the Kuopio University Hospital.
Chemical composition of the test breads
The moisture content was determined by oven drying at
130 C for 1 h. The protein content was determined by the
Kjeldahl method (nitrogen 6 6.25). The fat was determined
gravimetrically by extraction in diethyl ether and petroleum
ether after hydrolysis with acid (AOAC Of®cial Method
922.06, 1995). The dietary ®ber (DF) content was determined according to Asp et al (1983). Enzymatically available starch contents of test breads were analysed by the
method of McCleary et al (1994) using an assay kit of
Megazyme (Ireland). Free sugars (glucose, fructose, maltose, saccharose) were analysed as follows: The milled
bread sample (1.80 ±3.11 g) was suspended in 30 ml of
0.05 M phosphate buffer, pH 6.9. The suspension was
transferred to the dialysis tubing (cut-off 12-14000) and
incubated at 37 C in a beaker with 800 ml of 0.05 M
phosphate buffer, pH 6.9. Aliquots of the dialysate were
removed after 150 and 180 min incubations for analysis of
free sugar content (glucose, fructose, maltose, saccharose)
by HPLC. The available carbohydrate was de®ned as the
sum of enzymatically available starch and free sugars
(analysed by HPLC). Energy value (kJ) was calculated by
using the formula 17 6 protein (%) ‡ 37 6 fat (%)
‡ 17 6 available carbohydrate (%). The analysed data
on nutrient compositions are shown in Table 1.
In vitro starch hydrolysis
The rate of in vitro starch hydrolysis in test breads was
determined by the enzymatic hydrolysis method according
to Granfeldt et al (1992). An equivalent amount of available starch (1 g based on analysed data) from each test
263
Rye bread decreases postprandial insulin response
K Leinonen et al
264
Table 1 Nutrient composition of the test bread portions
Bread
Wheat bread
Wholekernel rye bread
Wholemeal rye bread
Wholemeal rye
Crispbread
Portion
size
g
121.1
148.4
98.2
79.4
slices
Available
CHO a
g
Dietary
®ber
g
Protein
g
Fat
g
Moisture
g
Energy
content
kJ
5
3.5
4
61 (2.9)
55 (7.4)
43 (2.9)
2.3
13.5
10.1
10.5
9.2
9.3
3.4
2.2
2.3
40.8
61.4
25.4
1341
1173
974
45 (0.9)
12.1
8.7
2.2
2.5
994
14
a
Potentially available starch ‡ free sugars (glucose, fructose, maltose, saccharose; amount of free sugars in parentheses).
bread was chewed by six subjects. In addition, test bread
samples contained different amounts of free sugars which
were mainly mono- and di-saccharides added to the dough
or formed during baking. After chewing and incubation
with pepsin, hydrolysis by pancreatic alpha-amylase was
performed in a dialysis tube. At the same time the same
amounts of milled (not chewed) bread samples were
incubated without enzyme additions in a dialysis tube.
Aliquots of the dialysate were removed for analysis of
reducing sugar content by the 3,5-dinitro salicylic (DNS)
method (Bernfeld, 1955).
Results
Postprandial glucose and insulin response
The test bread portions were calculated to include 50 g
available carbohydrate based on data received from bakeries and from Finnish food table. However, the analysed
data of nutrient composition of the test breads (Table 1),
which was available after the in vivo study had begun,
differed from the data received from the bakeries and the
food table. It was therefore decided to compare two pairs
which had similar carbohydrate content based on analysed
data: wholekernel rye vs wheat bread (two types of cereals)
and wholemeal rye crispbread vs wholemeal rye bread
(different types of rye breads).
Figure 1 Plasma glucose concentrations in healthy subjects after ingestion of the test breads. Comparisons are made between wheat and wholekernel rye bread (left) and wholemeal rye bread and wholemeal rye
crispbread (right). Values are means, n ˆ 20. The values for wholemeal
rye crispbread were signi®cantly lower at 150 and 180 minutes as
compared to wholemeal rye bread, P < 0.05.
Figure 2 Plasma insulin concentrations in healthy subjects after ingestion of the test breads. Comparisons are made between wheat and wholekernel rye bread (left) and wholemeal rye bread and wholemeal rye
crispbread (right). Values are means, n ˆ 20. The values for wholekernel
rye bread were signi®cantly lower at 45, 60, 90, 120 and 150 min as
compared to wheat bread, and those for wholemeal rye bread signi®cantly
lower at 60 min as compared to wholemeal rye crispbread, P < 0.05.
No differences in glucose responses were observed at
any time points between the wholekernel rye bread and
wheat bread (Figure 1). However, insulin values were
signi®cantly smaller at 45 (P ˆ 0.025), 60 (P ˆ 0.002), 90
(P ˆ 0.0004), 120 (P ˆ 0.050) and 150 (P ˆ 0.033) minutes
Figure 3 Plasma glucose and insulin areas in healthy subjects after
ingestion of the test breads. Comparisons are made between wheat and
wholekernel rye bread (left) and wholemeal rye bread and wholemeal rye
crispbread (right). Values are means ‡ s.d., n ˆ 20.* Signi®cantly different,
P ˆ 0.002, from wheat bread.
Rye bread decreases postprandial insulin response
K Leinonen et al
Table 2 Maximal glucose (mmol=L) and insulin (mU=L) responses of
the test breads (n ˆ 20)
Maximal response (mean s.d.)
Bread
Glucose
Insulin
Wheat bread
Wholekernel rye bread
Wholemeal rye bread
Wholemeal rye crispbread
2.0 1.0
1.8 0.6
1.9 0.9
1.8 0.9
42.8 25.3
32.0 13.6a
26.2 14.0
30.3 14.0
a
P ˆ 0.006, different from the wheat bread.
for the wholekernel rye bread than for the wheat bread
(Figure 2). Consequently, insulin area for the wholekernel
rye bread was signi®cantly smaller than for the wheat bread
(P ˆ 0.002), but the respective glucose area was similar for
both breads (Figure 3). Maximal insulin response for the
wholekernel rye bread was also lower than that for the
wheat bread (P ˆ 0.006) (Table 2).
Glucose responses to wholemeal rye bread and wholemeal rye crispbread were statistically different at 150
(P ˆ 0.018) and 180 (P ˆ 0.041) minutes (Figure 1) being
lower for the wholemeal rye crispbread. Insulin response at
60 min (P ˆ 0.025) (Figure 2) was lower for the wholemeal
rye bread than for the wholemeal rye crispbread. In addition, plasma glucose reached the maximal concentration
faster after ingestion of the wholemeal rye bread than after
the wholemeal rye crispbread (34 and 40 min, respectively;
P ˆ 0.012).
In vitro
In in vitro study an amount of test bread containing 1 g of
enzymatically available starch (based on analysed data)
was chewed by the subjects. The sample was 1.80 g for
wholemeal rye crispbread, 2.07 g for wheat bread, 2.45 g
for wholemeal rye bread and 3.11 g for wholekernel rye
bread. The bread samples also contained various amounts
of free sugars (glucose, fructose, maltose, saccharose;
Figure 4 (a) Content of total sugars (sugars from starch hydrolysis ‡ free
sugars in bread) following chewing and incubation of the bread sample
with pepsin and subsequent incubation with pancreatic a-amylase in a
dialysis tube. (b) Content of total sugarsÐfree sugars (determined after
grinding and incubation of the bread sample without enzyme additions).
(wheat bread s, wholekernel rye bread r, wholemeal rye bread m,
wholemeal rye crispbread u).
analysed by HPLC): 20 mg for wholemeal rye crispbread,
50 mg for wheat bread, 74 mg for wholemeal rye bread and
156 mg for wholekernel rye bread. Therefore, the total
contents of available carbohydrates in vitro were 1020 mg
for wholemeal rye crispbread, 1050 mg for wheat bread,
1074 mg for wholemeal rye bread and 1156 mg for wholekernel rye bread.
Total sugar pro®les which were determined as reducing
sugars due to starch hydrolysis and free reducing sugars in
bread (analysed by DNS method) in vitro were similar for
all test breads (Figure 4a). When the free reducing sugars in
the bread samples (analysed by DNS method) were subtracted from the total sugar, the breads showed different
rates of enzymic starch hydrolysis (Figure 4b). Wholemeal
rye crispbread and wheat bread had the fastest and wholekernel rye bread the slowest rate of starch hydrolysis
indicating that starch hydrolysis may be affected by the
type of cereal and bread making process.
Discussion
In comparison of wholekernel rye bread to wheat bread the
main ®nding was that the rye bread gave glucose responses
almost similar to that of the reference wheat bread, but the
rye bread produced signi®cantly lower insulin responses
than the wheat bread. These results are not entirely in
accordance to previous studies which have shown that
breads with whole kernels reduce GI (Granfeldt et al,
1992; Liljeberg et al, 1992; Wolever et al, 1994), and
wholegrain rye bread (80% whole kernels) markedly
reduces both glucose and insulin responses in healthy
subjects compared with wheat bread (Granfeldt et al,
1992; Liljeberg et al, 1992). Our results indicate that rye
kernels in wholekernel rye bread may have been disrupted
during boiling and baking processes, and thereby exposed
to gelatinization and increased enzymatic accessibility of
starch. On the other hand, the present results may have been
in¯uenced by the presence of free sugars in wholekernel
rye bread (7.4 g in the in vivo test bread portion; analysed
by HPLC). When the free sugars were included, the total
sugar curves in vitro (analysed by DNS method) were
similar for wholekernel rye bread and wheat bread, as
were the in vivo postprandial glucose responses to these
breads.
In many previous in vivo studies test portions have been
determined only based on calculated data or data received
from food tables, and those do not necessarily correspond
to the actual nutrient composition of the foodstuff consumed as noted in the present study. Further confusion
in determining the portion size is caused by the poorly
de®ned term `available carbohydrate'. When available
carbohydrate is calculated as a difference of 100-(protein ‡ fat ‡ ash ‡ moisture ‡ DF) there is a risk of overestimation due to the presence of non-digestible short-chain
carbohydrates such as oligosaccharides which are lost in
DF determination (Asp et al, 1983). These oligosaccharides, however, pass the upper gastrointestinal tract and are
fermented in the colon, and as such they act like DF. Such
compounds are for example fructans which are rich in rye
(about 4% of dry matter; unpublished results). In this
present study the available carbohydrate was determined
analytically to consist of available starch and free sugars
(glucose, fructose, maltose, saccharose) because these carbohydrates are absorbed in the small intestine and in¯uence
the postprandial glucose and insulin response. Determining
265
Rye bread decreases postprandial insulin response
K Leinonen et al
266
the portion size on the basis of available carbohydrate can
be criticized, because the absolute portion sizes in grams
may markedly differ between the various breads. Since
people usually would eat the same number of slices of
bread, for comparison of different types of breads it may be
more practical to determine the test portions as grams of
bread rather than based on available carbohydrate.
The discrepancy between glucose and insulin responses
in the comparison of the rye and wheat breads might be
unexpected. However, in healthy subjects insulin secretion
is started immediately after glucose has reached the circulation or as soon as carbohydrate-rich food reaches the
stomach (Wallum et al, 1992). Therefore, it is possible
that in our subjects the blood glucose was effectively
regulated by postprandial secretion of insulin, thereby
producing equal rise in plasma glucose after wholekernel
rye bread and wheat bread. In subjects with impaired
glucose metabolism differences between rye and wheat
breads could have been more pronounced. In fact, the
only earlier study on various types of Finnish rye breads
by Heinonen et al (1985) showed in insulin-dependent
diabetic patients (IDDM) a lower glucose response to
wholemeal rye bread than to mixed wholemeal rye and
wheat ¯our (50:50) bread or wheat bread, and no differences in glucose responses or glucose areas between rye and
wheat breads in non-insulin-dependent diabetic patients
(NIDDM). Wholekernel rye bread (35% whole kernels
and 65% wholemeal rye ¯our) differed from the wholemeal
rye bread neither in NIDDM nor in IDDM patients. Unfortunately Heinonen et al (1985) did not have the same types
of rye breads in their study as we had.
The reason for the lower insulin response observed in
the present study after ingestion of wholekernel rye bread
as compared to wheat bread remains to be explained.
Wolever et al (1994) estimated that 17% of the variability
in GI values of foods is explained by their protein content,
whereas variability in insulin responses is accounted both
by the glycemic response (23%) and the macronutrient
content of the food (10%) (Holt et al, 1997). Both dietary
protein (Nuttall et al, 1984; Gannon et al, 1988) and fat
(Welch et al, 1987) modify glycemic response by either
stimulating insulin secretion (protein) or delaying gastric
emptying (fat). In the present study the variation in the
protein and fat content between the test breads was too
small to in¯uence the results, but the possibility of delayed
gastric emptying from other reason is not excluded.
Hagander et al (1987) found that rye ¯akes produce
signi®cantly lower GIP and glucagon responses, but no
differences in glucose responses as compared to wheat
bread. These ®ndings are in agreement with our results
on lower insulin responses after the rye breads. Besides
dietary factors and ambient glucose values, gastrointestinal
hormones, gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), also mediate messages from
the gut to the pancreatic islets (Morgan, 1992). The enteroinsular axis is composed of neural as well as endocrine
component, and in man hormonal factors are supposed to
predominate in the regulation of insulin secretion after the
oral carbohydrate load.
The second main ®nding in this present study was that
two rye breads (wholemeal rye crispbread and wholemeal
rye) gave different glucose and insulin responses. Although
the plasma glucose peaks or areas under the curve did not
differ among these rye breads, there was a steeper return of
the plasma glucose concentration after the ingestion of
wholemeal rye crispbread (0 min, 5.1 mmol/l; 150 min,
4.8 mmol/l; 180 min, 4.8 mmol/l), while plasma glucose
approached the baseline concentration more slowly after
wholemeal rye bread (5.1, 5.1 and 4.9 mmol/l at respective
time points). This ®nding suggests that wholemeal rye
bread maintains the plasma glucose concentrations in the
non-fasting level longer than wholemeal rye crispbread.
The reason for this ®nding may be the lower insulin
response after ingestion of wholemeal rye bread.
Conclusions
This present study showed that wholekernel rye bread
decreases postprandial insulin response compared to
wheat bread but there was no difference in glucose
response between these breads. In other words, less insulin
is required for regulation of postprandial plasma glucose
concentrations in healthy subjects after rye bread than after
wheat bread. Similarly, Albrink et al (1979) found lower
insulin response in healthy subjects after high-®ber meal
than after low-®ber meal, but no difference in respective
glucose responses. It remains to be shown whether the
higher postprandial insulin concentration after wheat bread
has any health consequence in healthy subjects. High
plasma insulin has been shown to be an independent risk
factor for coronary heart disease (PyoÈraÈlaÈ, 1979; Despres et
al, 1996). The characteristics of the different types of rye
breads must be further investigated, both in vivo and in
vitro, in order to develop new products which could have
more bene®cial health properties regarding glucose and
insulin metabolism.
Contributors
The idea of this study and the hypothesis was conceived by
the senior authors (Hannu MykkaÈnen, Kaisa Poutanen, and
Matti Uusitupa). They were responsible for the protocol
design and planning of the study and writing and editing of
the article. Katri Leinonen was responsible for the practical
coordination of the human study, data collection, statistical
analysis and writing of the ®rst draft of the manuscript.
Kirsi Liukkonen was responsible for the in vitro study, its
collection and analysis, and she also contributed to the
manuscript.
Acknowledgements ÐThis research was carried out as part of the TEKES
national technology programme `Innovation in Foods'. The fruitful discussions with MSC (Eng) Risto Viskari (Fazer Bakeries Ltd) and Dr
Sampsa Haarasilta (Cultor Ltd) are highly appreciated. Fazer Bakeries Ltd
and Vaasa Bakeries Ltd provided the breads and ®nancial support for the
study. Authors also warmly thank the laboratory nurse Erja Kinnunen and
research assistant Siv Matomaa for excellent laboratory work during the
study.
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