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Effect of processing on digestibility and the blood glucose response: A study of lentils


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To test the effect of processing on digestibility and the glycemic response to a leguminous seed, a group of eight healthy volunteers took a series of breakfast test meals containing either lentils which had been processed in four different ways or the same amount of carbohydrate as white bread. Lentils, boiled for 20 min, resulted in a flattened blood glucose response by comparison with bread. This was unaltered by blending the lentils to a paste or boiling them for an additional 40 minutes. However the blood glucose response was significantly enhanced by drying the boiled blended lentils for 12 h at 250 degrees F. In vitro digestion with human saliva showed the rate of sugars released from the food related positively to the blood glucose rise. Breath hydrogen studies indicated that carbohydrate malabsorption was too small to account for differences in the blood glucose response. These results emphasize the importance of processing in determining digestibility and hence the glycemic response to a food.
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The American Journal of Clinical Nutritions 36: DECEMBER 1982, pp 1093-110 1. Printed in USA
© 1982 American Society for Clinical Nutrition
Original Research_Communications-general
Effect of processing on digestibility and the
blood glucose response: a study of lentils1’2
David JA Jenkins,3 DM, Mary Jane Thorne, BSc, Kathy Camelon, RPDt, Alexandra Jenkins,
A Venketeshwer Rao, PhD, Rodney H Taylor,4 MRCP, Lilian U Thompson, PhD,
Janet Kalmusky, BA Sc, Rochelle Reichert, RPDI, and Thomas Francis, PhD
ABSTRACT To test the effect of processing on digestibility and the glycemic response to a
leguminous seed, a group of eight healthy volunteers took a series of breakfast test meals containing
either lentils which had been processed in four different ways or the same amount of carbohydrate
as white bread. Lentils, boiled for 20 mm, resulted in a flattened blood glucose response by
comparison with bread. This was unaltered by blending the lentils to a paste or boiling them for an
additional 40 minutes. However the blood glucose response was significantly enhanced by drying
the boiled blended lentils for 12 h at 250#{176}F.In vitro digestion with human saliva showed the rate
of sugars released from the food related positively to the blood glucose rise. Breath hydrogen
studies indicated that carbohydrate malabsorption was too small to account for differences in the
blood glucose response. These results emphasize the importance of processing in determining
digestibility and hence the glycemic response to a food. Am J Clin Nutr 1982;36: 1093-1101.
KEY WORDS Digestibility, blood glucose response, diabetes, legumes, dietary fiber, antinu-
Recently leguminous seeds have been used
successfully as part of the dietary treatment
of diabetics (1-3). These foods are especially
rich sources of both dietary fiber and enzyme
inhibitors. Certain types of dietary fiber and
enzyme inhibitors have been shown to flatten
the postprandial glycemia in normal (4-6)
and diabetic (7, 8) volunteers and also to
improve diabetic control when incorporated
into the diet (9-11). However the factors re-
sponsible for the differences in glycemic re-
sponse noted between beans and other car-
bohydrate foods (12, 13) are unknown.
It was therefore decided to study the lentil
(lens esculenta), as an example of a legumi-
nous seed, to determine in what way process-
ing might alter its digestibility and its effect
on postprandial glycemia.
Volunteer test meals
Eight healthy volunteers (two men, six women, 29 ±
8 y, 94 ±5% desirable weight) took part in a series of
‘From the Department of Nutritional Sciences, Fac-
ulty of Medicine, University of Toronto (DJAJ, MJT,
AJ, AVR, LUT. JK, RR, IF) and Department of Nu-
tritional Sciences (KC), Toronto General Hospital, To-
ronto, Canada and Department of Gastroenterology and
Nutrition (RHT), Central Middlesex Hospital, London
University, England.
2Address reprint requests to: David JA Jenkins, De-
partment of Nutritional Sciences, Faculty of Medicine,
Toronto University, Toronto. Canada M55 lA8.
Recipient of funds from the Canadian Diabetes
Association, The Natural Sciences and Engineering Re-
search Council and the Bickel and Atkinson Charitable
Wellcome Senior Research Fellows in Clinical Sci-
ence.Received March 15, 1982.
Accepted for publication June 1, 1982.
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Two-g carbohydrate portions either of finely crumbed
white bread or of lentils (20 mm, blended, 1 h, and 12 h
Test meals taken by normal volunteers
Constituents Cooked as Protein Fat Carbohydrate Dietary fiber Energy
g g g g g kcat
Whitebread 119 8 1 50 3 235
Red lentils (94g)
20 mm lentils 280 22 1 50 11 283
20 mm blended lentils 280 22 1 50 11 283
1 hlentils 270 22 1 50 11 283
12 h dried lentils* 89 22 1 50 11 283
*250 ml of water added in final preparation.
Composition of H2 test meals*
Meal Cooked Protein
Dietary fiber
Bread and cheese 493 54 16 121 24 813
20 mm lentils 685 54 2 120 26 687
12 h dried lentilst 203 54 2 120 26 687
*In addition all meals were taken with 150 g tomato and tea containing 50 ml 2% butterfat milk.
t500 ml water added in final preparation.
breakfast test meals where 50-g carbohydrate portions,
as calculated from food tables (15), of either white bead
or lentils, processed in one of four different ways, were
eaten in random order on separate mornings after over-
night fasts (Table I). The lentils were either boiled in
small batches for 20 mm in twice their own volume of
water (20 mm lentils); boiled for 20 mm and blended
(blended lentils); boiled for I h (I h lentils); or boiled for
20 mm, blended and dried for 12 h in an oven at 250#{176}F
before grinding to a powder (12 h dried lentils). Meals
were cooked in small batches to allow rapid cooling and
ensure standardization of the cooking procedures.
Batches were pooled and then aliquoted. The 12 h dried
lentils were reconstituted in twice their volume of water
before eating. All meals were taken hot with tea or coffee
containing 50 ml milk, the total beverage volume for
bread and lentils respectively, being either 600 or 450 ml
to equalize the fluid volume of the meal.
Finger prick blood samples were obtained with Au-
tolet lancets (Owen Mumford Ltd, Woodstock, Oxford,
England) at 0, 15, 30, 45, 60, 90, and 120 mm after the
start of the meal. Blood samples were collected into tubes
containing 410 zg sodium fluoride and 250 g potassium
oxalate and stored on crushed ice or frozen at -20#{176}C
before analysis of glucose by a glucose oxidase method
(YSI 23 AM Glucose Analyser, Yellow Springs Instru-
ments, Box 279, Yellow Springs, OH) (16).
To define the glucose tolerance status of the subjects
selected for study at least two standard 50 g glucose
tolerance tests were performed on each subject. Tests
were performed with 600 ml tea or coffee.
Breath hydrogen studies
In addition experiments were performed on five sub-
jects (three male, two female age 28 ±8 yr. 96 ±7%
ideal weight) to assess hydrogen evolution from unab-
sorbed carbohydrate. These individuals took a series of
four test meals containing 2.4 times as much bread and
lentils as in the previous meals (Table 2). The meals
consisted of 20 mm boiled lentils, and 12 h dried lentils
prepared as already described, and 280 g wholemeal
bread and 280 g wholemeal bread with 60 g lactulose
solution (an unabsorbable carbohydrate). Wholemeal
rather than white bread was used to balance the fiber
content in the lentil meals since it has been shown that
the glycemic responses to white and wholemeal bread
are the same (17). The available carbohydrate content
was 120 g in each meal, the protein in the bread meal
was increased to that of the lentils by addition of 213 g
cottage cheese (2.3 fat) and 150 g tomato was included
in all meals to increase palatability. Three hundred and
600 ml tea or coffee containing 50 ml 2% butterfat milk
were taken with lentil and bread meals respectively. The
meals were eaten in random order over a 20 to 30 mm
period in the morning after an overnight fast.
At the start and at hourly intervals for the next 14 h
forced end-expiratory samples of alveolar air were col-
lected with a modified Haldane-Pniestley tube for the
analysis of breath hydrogen (H2) using a Gow-Mac gas
chromatograph (series 552, column molecular seive 5A,
60-80 mesh, at 75#{176}Cwith argon carrier gas at flow rate
of 20 mI/mm, Gow Mac Instrument Co., Shannon,
Ireland) (18). Throughout the day on all three occasions
each subject adhered to the same diet and physical
Hydrogen is produced from the fermentation of un-
absorbed carbohydrate by the colonic bacterial flora. It
diffuses to the blood stream and is exhaled in the breath.
By giving a known amount of unabsorbable carbohy-
drate (Iactulose) an estimate of the amount of carbohy-
drate (starch and fiber) not absorbed in the other two
meals can be calculated (19).
In vitro studies
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dried) were ground to a smooth paste. Each food was
then mixed with 10 ml fresh pooled human saliva. The
volume of all mixtures was made up to 30 ml with
distilled water and the resulting slurries were placed in
dialysis bags made of 13 cm strips of dialysis tubing
(width 4.5 cm, pore diameter 4.8 nm, mw cut-off 12,000,
Fisher Scientific Ltd, Toronto, Canada Cat No 8-667E).
Each bag was suspended in a separate stirred water bath,
containing 800 ml distilled water at 37#{176}C.Five-ml ali-
quots of dialysate were taken at hourly intervals for the
next 3 h for sugar analysis.
Further tests were undertaken with human saliva
inactivated by boiling to make allowance for free sugars
already in the food.
Four replicates of each test were performed. Dialysate
samples 0 to 3 h were analysed for individual sugars
using an HPLC system (Waters HPLC System, WISP
automatic injector, model 600A pump, two Dextropac
columns placed in series inside two radial compression
modules, with water as mobile phase at 0.5 mI/mm and
differential refractometer detector, Waters Associates,
Milford, MA). Glucose, maltose, and maltotniose were
measured against standards of these sugars.
The results are expressed as means ±SEM and the
significance of the difference between treatments was
calculated using “Student’s” ttest for paired data.
The 20 mm lentils had the appearance of
a dahl or paste, containing discrete and rec-
ognizable lentil forms. All recognizable form
had been lost in the blended, I and 12 h dried
Volunteer test meals
In general the meals were well received
and were finished in 10 to 15 mm. No pref-
erence was expressed for a particular form of
processed lentils. The mean fasting blood
glucose concentration for the normal volun-
teers ranged from 4.4 to 4.5 mmol/l for the
six tests. Both the bread and the 12 h dried
lentils produced substantial rises in the blood
glucose which were significantly higher than
the relatively flat curve resulting from 20 mm
lentils (Figs I and 2). The mean peak rise in
blood glucose was 0.87 ±0.11 mmol/l on 20
mm lentils and this was substantially below
the 2.44 ± 0.3 mmol/l for 12 h dried lentils
(p <0.02), 2.94 ±0.26 mmol/l for bread (p
<0.001) and 3.80 ±0.27 mmol/l for the
glucose tolerance test (p <0.001) (Figs 1 and
2). No significant difference was seen between
the 20 mm boiled lentils and the blended or
1 h lentils although the 1 h lentils tended to
give a slightly higher glucose response (Fig
Breath hydrogen studies
The meals were eaten without complaint
over a 20 to 30 mm period although com-
ments were made on the volume of the bread.
The mean breath H2 responses to the three
meals compared with the lactulose containing
breakfast are shown in Figure 3.
The mean elevation of breath hydrogen
level over the 14 h of the test was 20 ±7ppm
for lactulose, 13 ±8 ppm for 20 mm lentils,
9±5 ppm for 12 h dried lentils, and 5 ±I
ppm for wholemeal bread. Only the mean
bread level was significantly less than that for
lactulose (p <0.02). Subtraction of the whole-
meal bread response from the lactulose and
bread response allowed the hydrogen gener-
ated from the 30 g unabsorbable carbohy-
drate as lactulose itself to be derived. On this
basis the estimated carbohydrate malab-
sorbed after wholemeal bread was 7 g, for 20
mm lentils this was 20 g, and for 12 h dried
lentils, 14 g.
In vitro studies
The mean percentage of the three sugars
liberated at 3 h during the digestion of bread
and lentils showed no significant differences
when expressed as a proportion of the total
carbohydrate liberated (Fig 4). For bread the
values were 74 ± 1% for maltose, 17 ± 2% for
maltotriose, and 9 ±1% for glucose. For the
lentils the mean values ranged from: 74-75%
for maltose; 15-18 for maltotriose, and 7-11%
for glucose. In addition the various processed
lentils did not differ from each other in the
mean percentages of maltose and maltotriose
sugars they released. However the percentage
of glucose liberated from the 20 mm,
blended and 1 h lentils (10 to 11%) was
significantly higher than the bread (9%, p <
0.01) which was in turn more than that for 12
h dried lentils (7%, p <0.01). Sugars identi-
fied as fructose, sucrose, raffinose, and stach-
yose were also liberated nonenzymatically
from the lentils irrespective of whether boiled
or unboiled saliva had been used.
The percentage of the original 2-g carbo-
hydrate food portion liberated at 3 h (meas-
ured as the sum of glucose, maltose, and
maltotriose) was: 14 ±1% for 20 mm lentils;
14 ±1% for blended lentils; 16 ±1% for I h
lentils; 24 ±2% for 12 h dried lentils; and 39
±3% for bread.
The rate of digestion was similar for 20
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Time in minutes
FIG. I. Blood glucose response over 2 h after 50 g carbohydrate meals of blended lentils, I h lentils, and 12 h
dried lentils compared with 20 mm lentils.
mm, blended and 1 h lentils as illustrated by
the total carbohydrate released (Fig 5). These
figures were significantly below the values for
12 h dried lentils at 1, 2, and 3, h (p <0.01).
All the lentil values, including the 12 h dried
lentils were significantly below those of bread
The present study confirms the previous
observation that the blood glucose response
was markedly flatter after eating lentils com-
pared with bread (13). This difference was
reduced when the lentils were dried in an
oven for 12 h whereas boiling for 1 h was
without effect. The in vitro digestion studies
show that the 12 h dried lentils liberate car-
bohydrate more rapidly than the 20 min len-
tils. The 20 mm lentils, in turn cannot be
differentiated from the blended or 1 h lentils,
and the results therefore parallel the in vivo
blood glucose responses to these foods.
The present approach may be critisized for
using salivary amylase and a 3-h incubation
period as an in vitro model of digestion.
However, earlier studies with this system us-
ing a digestive juice mixture which contained
75% by volume of human pancreatic juice
gave similar 3 h results. In that situation 27%
of the carbohydrate was digested from bread
and 15% from lentils. This compares with 39
and 14% for bread and lentils seen here using
only saliva. The more rapid salivary digestion
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Time in minutes
FIG. 2. Blood glucose response over 2 h after 50 g carbohydrate meals of bread or glucose compared with 20
mm lentils.
of bread in the current studies may have
related to the use here of laboratory prepared
white bread as opposed to commercially pro-
duced whole-meal bread. Nevertheless the
lentil results were almost identical. We con-
sider that the present in vitro system may be
useful in predicting the rate of starch diges-
tion in vivo although it was not intended as
an attempt to reproduce the actual conditions
of small intestinal digestion.
Major carbohydrate malabsorption as
judged by breath hydrogen studies (18) did
not appear to be responsible for the effects
seen here since the difference in estimated
carbohydrate malabsorbed between 20 mm
and the 12 h dried lentils was only 6 g. Values
of 14 and 20 g carbohydrate malabsorbed do
not even account for the 26 g lentil fiber
present in the original meal. This should have
appeared in the colon as malabsorbed car-
bohydrate and therefore as substrate for bac-
terial fermentation and hydrogen production.
The lower value for hydrogen evolved after
wholemeal bread by comparison with lentils
may reflect, in part, differences in the degree
to which fibers from these two sources are
fermented in the colon. Although 280 g of
whole meal bread may contain 24 g fiber,
much of it is cellulose and lignin and is
therefore less readily degradable. On the
other hand, lentils are good sources of hemi-
cellulosic fiber which is more completely me-
tabolized by colonic bacteria.
Studies of white bread and pasta have
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0 5 10
Time in hours
FIG. 3. Change in breath hydrogen concentration in
five subjects over 14 h after eating 120 g carbohydrate as
20 mm lentils, 12 hdried lentils, wholemeal bread, or
bread and lactulose (60 g lactulose solution).
given similar results and it has been suggested
that 10 to 20% of the wheat flour is malab-
sorbed to account for the hydrogen evolution
seen (20).
The effect of lentils on blood glucose may
be due to the presence of many factors in the
food including the dietary fiber of legumi-
nous seeds which has attracted much atten-
tion recently because of possible therapeutic
benefit in the treatment of insulin dependent
and independent diabetics (1-5, 7, 9, 11-13,
21). It is possible that prolonged dry heat here
may have altered the relationship between
starch and fiber making the starch more read-
ily available and so abolishing the effect on
Differences in the nature of the starch have
a strong claim as possible factors that may
influence the rate of digestion and hence the
glycemic response (22). However, an in-
creased percentage of maltose in the lentil
dialysate which would have been compatible
with a higher proportion of amylose in lentils
as opposed to bread was not seen here. In
addition the ratio of maltose to maltotriose in
lentils was not influenced by processing and
therefore did not explain the higher blood
glucose response to the 12 h dried lentils.
Only the glucose results suggested differ-
ences in the nature of the starch, the lower
levels for the bread dialysate being compati-
ble with a higher amylopectin content. The
reason for a reduced glucose level with 12 h
lentils is less clear and may indicate an alter-
ation in the starch and perhaps relate to the
higher glycemic response produced.
Leguminous seeds are amongst the richest
natural sources of the so called antinutrients:
enzyme inhibitors (eg, anti a-amylase); lec-
tins; saponins; antigenic proteins; phytates;
tannins, etc. Some of these have been shown
to reduce the rate of carbohydrate digestion
and absorption. Many of these are heat labile,
and although the a-amylase inhibitor of
wheat may withstand cooking in bread (23),
the inhibitors in lentils may have been de-
stroyed by 12 h of dry heat. Enzyme inhibi-
tors such as these have already been devel-
oped by the pharmaceutical industry for ther-
apeutic trials. One inhibitor that retards su-
crose and starch absorption is currently being
used to treat diabetics (6, 8). We are, there-
fore, now actively investigating the antinu-
trient contents of processed and unprocessed
legumes and it is possible that more useful
therapeutic agents will emerge from such
studies of foods.
The effect of protein acting through in-
creased insulin release seems less likely to
explain the effects seen here even though
lentils and other leguminous seeds are richer
sources of protein than bread and cereal
products. Previous studies have shown that a
flatter blood glucose profile is seen after eat-
ing lentils even in insulin dependent diabetics
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01 2 3
Time in hours
Percent Sugars in Dialysate
20mm Lentils Blended Lentils lb Lentils l2hDried Lentils White Bread
FIG. 4. The proportion of glucose maltose and maltotriose liberated at 3 h during the in vitro digestion of lentils
and bread expressed as a percentage of the total carbohydrate liberated.
FIG. 5. The total carbohydrate, glucose, maltose,
and maltotriose liberated into the dialysate over the 3 h
of in vitro digestion of 20 mm lentils, blended lentils. 1
h lentils, 12 h dried lentils, and white bread.
(13). The effect, in these and in other studies
of the 20 mm lentils, was seen even when
compared with a bread meal balanced in
protein by inclusion of cottage cheese. In
addition where both insulin and gastric inhib-
itory polypeptide levels were measured they
were found to be significantly reduced after
lentils by comparison with bread (14).
It is quite possible that the nature of the
protein and its interaction with other food
components is important. Thus, for example
heat treatment may have altered the protein-
starch relationship in the 12 h dried lentils.
Studies on the effect of removal of wheat
protein from bread and pasta suggested that
this increased the digestibility of the new
formulations compared to the original prod-
uct (20). Once removed, simple addition of
wheat protein to gluten-free bread failed to
restore its former property. It was suggested
that the starch-protein interaction in the orig-
inal product was the determining factor. The
same effects may be important here despite
the fact that the starch and protein were not
physically separated in the production of the
12 h dried lentils.
Alternatively the heat treatment may have
been responsible for fracturing the starch
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granules, thereby increasing their surface area
and allowing more rapid digestion. In another
context it has been suggested that this may
be achieved by mechanical means. Pur#{233}ed
apples have been shown to raise the blood
glucose more than whole apples (23) and
ground rice more than wholecooked rice
grains (24). In our study a lack of effect of
blending on the 20 mm lentil response argues
against this being of importance here.
Other factors such as the effect of fat or
free sugar content do not seem relevant to
this study in that in both lentils and bread
these are very minor components.
Nevertheless despite a lack of precise
knowledge of the factors determining their
mechanism of action recent work has shown
that leguminous seed-rich diets may be of
benefit to the diabetic (1-3). It has also been
shown that meals of leguminous seeds raise
the blood glucose less than meals of the same
carbohydrate content from other sources (12,
13, 21) and the present study adds support to
these findings.
We conclude that the acute effects of leg-
umes in the content of mixed meals require
further study in what may be a more physi-
ological situation. In this way it may be pos-
sible to determine whether they induce alter-
ations in absorption of major nutrients de-
rived from the other foods. However, the
present observations indicate that the “slow
release” property of legumes is heat labile
and that loss of this property is independent
of alterations in fiber or macronutrient con-
tent of the food such as might result from
milling or refining. Therefore, if the most use
is to be made of legumes and similar foods in
the diets of diabetics (as in the use of legum-
inous seed flours in breads) much attention
must be paid to the amount of heat, especially
dry heat, used in their preparation.
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fiber diets for insulin treated men with diabetes
mellitus. Am J Clin Nutr l979;32:23l2-2l.
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carbohydrate leguminous fibre diet improves all as-
pect of diabetic control. Lancet 1981:1:1-5.
3. Rivellese A, Giacco A, Genovese 5, et al. Effect of
dietary fibre on glucose control and serum lipopro-
teins in diabetic patients. Lancet 1980:1:447-9.
4. Jenkins DJA, Leeds AR, Gassull MA, Cochet B,
Alberti KGMM. Decrease in postprandial insulin
and glucose concentrations by guar and pectin. Ann
Intern Med 1977:86:20-3.
5. Caspari WF. Sucrose malabsorption in man after
ingestion of an a-glucosidehydrolase inhibitor. Lan-
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use of guar and acarbose in reduction of postprandial
glycaemia. Lancet 1979:2:924-7.
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HM, Fielden H. Exceptionally low blood glucose
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HM, Fielden H, Gassull MA. Lack of effect of
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absorption of the carbohydrate in all-purpose wheat
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GM, Olefsky JM. Postprandial hormonal responses
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properties of an amylase inhibitor of wheat. Arch
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... Resistant to enzymatic breakdown, RS does not appear to contribute to acute blood glucose spikes. Notably, the carbohydrate fraction in pulses is particularly rich in SDS and contains significant amounts of RS, a profile superior to cereals, tubers, and unripe fruits, irrespective of their processing [50][51][52]. Such a composition ensures slower starch digestion, thereby modulating postprandial glycaemic responses [51,52]. ...
... Notably, the carbohydrate fraction in pulses is particularly rich in SDS and contains significant amounts of RS, a profile superior to cereals, tubers, and unripe fruits, irrespective of their processing [50][51][52]. Such a composition ensures slower starch digestion, thereby modulating postprandial glycaemic responses [51,52]. Additionally, RS may also confer an independent hypoglycaemic effect [52,53]. ...
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Management of type 2 diabetes mellitus (T2DM) is a pressing global healthcare challenge. Innovative strategies that integrate superior medical and nutritional practices are essential for holistic care. As such, pulse consumption is encouraged for its potential benefit in reducing hypercholestero-laemia, dyslipidaemia, and triglyceride levels, as well as enhancing glycaemic control. This scoping review aims to assess the depth of evidence supporting the recommendation for pulse consumption in T2DM management and to identify gaps in the existing literature. We conducted a comprehensive search across the databases MEDLINE, Global Health, EMBASE, CINAHL, Web of Science, and the Cochrane Library (up to July 2023). We included population-based studies of any design, and excluded review-style articles. Articles published in languages other than English were also excluded. From the 2449 studies initially identified, 28 met our inclusion criteria. Acute postprandial trials demonstrated improved glucose responses and enhanced insulin responses to pulse-based intervention. Meanwhile, long-term trials reported meaningful improvements in T2DM indicators such as haemoglobin A1C (HbA1c), fasting glucose, fasting insulin, C-peptide, and markers of insulin resistance like homeostatic model assessment (HOMA). Integrating more pulses into the diets of diabetic individuals might offer an efficient and cost-effective strategy in the global initiative to combat T2DM.
... A number of randomized controlled trials have assessed the effect of pulse intake on acute post-prandial and longterm glucose response [14][15][16][17][18][19][20][21][22][23]. The studies differed in the type of pulses used, processing, doses and control group, and in different volunteer profiles [6,[24][25][26][27][28][29][30][31][32][33]. The study outcomes vary considerably with low quality of evidence and, therefore, the true effect size of pulse intake on measures of glycemic handling remains unclear [34]. ...
... In alignment with blood glucose, pulse intake favorably affected post-prandial insulin levels with a larger effect in T2D population where reduction in PPGR was greater. There were large variations between RCTs with regards to characteristics of participants such as mean age (22-66 y) and BMI (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31), that might influence insulin secretion and sensitivity. ...
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Purpose Findings from randomized controlled trials (RCTs) evaluating the effect of pulse intake on glycemic control are inconsistent and conclusive evidence is lacking. The aim of this study was to systematically review the impact of pulse consumption on post-prandial and long-term glycemic control in adults with and without type 2 diabetes (T2D). Methods Databases were searched for RCTs, reporting outcomes of post-prandial and long-term interventions with different pulse types on parameters of glycemic control in normoglycemic and T2D adults. Effect size (ES) was calculated using random effect model and meta-regression was conducted to assess the impact of various moderator variables such as pulse type, form, dose, and study duration on ES. Results From 3334 RCTs identified, 65 studies were eligible for inclusion involving 2102 individuals. In acute RCTs, pulse intake significantly reduced peak post-prandial glucose concentration in participants with T2D (ES – 2.90; 95%CI – 4.60, – 1.21; p ≤ 0.001; I ² = 93%) and without T2D (ES – 1.38; 95%CI – 1.78, – 0.99; p ≤ 0.001; I ² = 86%). Incorporating pulse consumption into long-term eating patterns significantly attenuated fasting glucose in normoglycemic adults (ES – 0.06; 95%CI – 0.12, 0.00; p ≤ 0.05; I ² = 30%). Whereas, in T2D participants, pulse intake significantly lowered fasting glucose (ES – 0.54; 95%CI – 0.83, – 0.24; p ≤ 0.001; I ² = 78%), glycated hemoglobin A1c (HbA 1c ) (ES – 0.17; 95%CI – 0.33, 0.00; p ≤ 0.05; I ² = 78) and homeostatic model assessment of insulin resistance (HOMA-IR) (ES – 0.47; 95%CI – 1.25, – 0.31; p ≤ 0.05; I ² = 79%). Conclusion Pulse consumption significantly reduced acute post-prandial glucose concentration > 1 mmol/L in normoglycemic adults and > 2.5 mmol/L in those with T2D, and improved a range of long-term glycemic control parameters in adults with and without T2D. PROSPERO registry number (CRD42019162322).
... Recently, second meal effect, which is defined as the influence of food intake in one meal on the postprandial glucose level after the second meal, has become a popular strategy for controlling the postprandial glucose level [5]. Glycemic index (GI) is usually used to describe the rate at which glucose level increases after eating a kind of food. ...
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This study aimed to examine the effect of high protein breakfast diet with or without lunch on the postprandial glucose level during the day. A randomized, crossover design that recruited 12 healthy young participants (three men and nine women) was performed and four trials (normal breakfast + skipped lunch, high protein breakfast + skipped lunch, normal breakfast + lunch, and high protein breakfast + lunch) were conducted in two weeks. During each trial, breakfast, lunch, and dinner on the trial day, and dinner before the trial day, were provided as test meals, and the meal timing was fixed. Continuous glucose monitoring (CGM) was used to assess the blood glucose level during the whole experiment. Incremental area under the curve (iAUC) of the postprandial glucose level was calculated. The results suggested that compared with normal breakfast, high protein breakfast suppressed the 3 h iAUC of postprandial glucose level after breakfast (p < 0.05 or p < 0.0001) and 1.5 h iAUC after lunch (p < 0.01). During lunch, high protein breakfast diet suppressed the dinner and overall day postprandial glucose level (p < 0.05 vs. normal breakfast), but no significant difference was observed when skipping lunch. Our findings indicate that high protein breakfast could suppress the breakfast postprandial glucose level, as well as following lunch and dinner, but this effect on dinner was attenuated when skipping lunch.
... Thus, the impact of diet on SCFA production can be prolonged, and regular consumption of a high-fiber diet results in continuous stimulation of the colonic microbiota to produce and absorb SCFAs (59). For example, high-fiber diets have been shown to result in higher FA serum acetic acid concentrations compared with a diet poor in fiber (30,60). The dietary patterns examined in this study incorporated a healthy diet based on WHO recommendations (19), in which diverse types of NDCs were consumed (57), compared with a typical Western diet with high fat and sugar content with low fiber. ...
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Background Production of SCFAs from food is a complex and dynamic saccharolytic fermentation process mediated by both human and gut microbial factors. Knowledge of SCFA production and of the relation between SCFA profiles and dietary patterns is lacking. Objectives Temporal changes in SCFA concentrations in response to 2 contrasting diets were investigated using a novel GC-MS method. Methods Samples were obtained from a randomized, controlled, crossover trial designed to characterize the metabolic response to 4 diets. Participants (n = 19) undertook these diets during an inpatient stay (of 72 h). Serum samples were collected 2 h after breakfast (AB), after lunch (AL), and after dinner (AD) on day 3, and a fasting sample (FA) was obtained on day 4. The 24-h urine samples were collected on day 3. In this substudy, samples from the 2 extreme diets representing a diet with high adherence to WHO healthy eating recommendations and a typical Western diet were analyzed using a bespoke GC-MS method developed to detect and quantify 10 SCFAs and precursors in serum and urine samples. Results Considerable interindividual variation in serum SCFA concentrations was observed across all time points, and temporal fluctuations were observed for both diets. Although the sample collection timing exerted a greater magnitude of effect on circulating SCFA concentrations, the unhealthy diet was associated with a lower concentration of acetic acid (FA: coefficient: –17.0; SE: 5.8; P-trend = 0.00615), 2-methylbutyric acid (AL: coefficient: –0.1; SE: 0.028; P-trend = 4.13 × 10–4 and AD: coefficient: –0.1; SE: 0.028; P-trend = 2.28 × 10–3), and 2-hydroxybutyric acid (FA: coefficient: –15.8; SE: 5.11; P-trend: 4.09 × 10–3). In contrast, lactic acid was significantly higher in the unhealthy diet (AL: coefficient: 750.2; SE: 315.2; P-trend = 0.024 and AD: coefficient: 1219.3; SE: 322.6; P-trend: 8.28 × 10–4). Conclusions The GC-MS method allowed robust mapping of diurnal patterns in SCFA concentrations, which were affected by diet, and highlighted the importance of standardizing the timing of SCFA measurements in dietary studies. This trial was registered on the NIHR UK clinical trial gateway and with ISRCTN as ISRCTN43087333.
... Glycemic responses • processing apples into puree or juice affects glycemic responses negatively (Haber et al., 1977) • processing affects glycemic responses of lentils (Jenkins et al., 1983) • glycemic responses of bread strongly dependent on food matrix Post-prandial aminoacidemia • faster postprandial rise in blood amino acid levels after consumption of minced beef compared to steak (Pennings et al., 2013) • faster postprandial rise in blood amino acid levels after consumption of yoghurt than milk and slower again for cheese (Horstman et al., 2021) Another important consideration in relation to food, nutrition and health is that in many cases food items are not consumed on their own but as part of a meal. In that case, synergistic or antagonistic effects between food items can occur. ...
... Glycemic responses • processing apples into puree or juice affects glycemic responses negatively (Haber et al., 1977) • processing affects glycemic responses of lentils (Jenkins et al., 1983) • glycemic responses of bread strongly dependent on food matrix Post-prandial aminoacidemia • faster postprandial rise in blood amino acid levels after consumption of minced beef compared to steak (Pennings et al., 2013) • faster postprandial rise in blood amino acid levels after consumption of yoghurt than milk and slower again for cheese (Horstman et al., 2021) Another important consideration in relation to food, nutrition and health is that in many cases food items are not consumed on their own but as part of a meal. In that case, synergistic or antagonistic effects between food items can occur. ...
Technical Report
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The Food and Agriculture Organization of the United Nations (FAO) initiated a project to identify opportunities for further developing environmental and nutritional LCA methodology and building consensus about best practice, and to propose future research needs. The project involved 30 environmental and nutritional LCA researchers from 18 countries and ran between May and November 2021. The project focused on assessing food items as opposed to raw materials, meals and/or diets, and it is a step towards more comprehensive meal and dietary LCA studies.
... Our outcomes are in contrast with some previous findings showing that ingestion of pulse flour based meals led to significantly higher postprandial glycaemic responses compared with whole pulses. [33][34][35] This discrepancy is likely to be due to divergent test meals, specifically the use of pulse flour based pasta in the present study as opposed to other test meals made from pulse flour such as bread. White pasta is generally considered to elicit a lower glycaemic response compared to white bread, despite both being produced from refined wheat flour. ...
Chickpeas are among the lowest glycaemic index carbohydrate foods eliciting protracted digestion and enhanced satiety responses. In vitro studies suggest that mechanical processing of chickpeas significantly increases starch digestion. However, there is little evidence regarding the impact of processing on postprandial glycaemic response in response to chickpea intake in vivo. Therefore, the aim of this study was to determine the effect of mechanical processing on postprandial interstitial glycaemic and satiety responses in humans. In a randomised crossover design, thirteen normoglycaemic adults attended 4 separate laboratory visits following an overnight fast. On each occasion, one of four test meals, matched for available carbohydrate content and consisting of different physical forms of chickpeas (whole, puree, and pasta) or control (mashed potato), was administered followed by a subsequent standardised lunch meal. Continuous glucose monitoring captured interstitial glucose responses, accompanied by periodic venous blood samples for retrospective analysis of C-peptide, glucagon like peptide-1 (GLP-1), ghrelin, leptin, resistin, and cortisol. Subjective appetite responses were measured by Visual Analogue Scale (VAS). Postprandial glycaemic responses were comparable between chickpea treatments albeit significantly lower than the control (p < 0.001). Similarly, all chickpea treatments elicited significantly lower C-peptide and GLP-1 responses compared to the control (p < 0.05), accompanied by enhanced subjective satiety responses (p < 0.05), whilst no significant differences in satiety hormones were detected among different intervention groups (p > 0.05). Chickpea consumption elicits low postprandial glycaemic responses and enhanced subjective satiety responses irrespective of processing methods.
Глютенсіз макарон бидай өнімдеріне пайдалы және дәмді балама болып табылады. Соңғы бірнеше онжылдықта глютенсіз макаронның бұл тобы целиак ауруының өсіп келе жатқан санымен ғана емес, сонымен қатар денсаулығына байланысты глютен негізіндегі өнімдерді диетадан шығарғысы келетін басқа адамдармен де тұтынылады. Алайда, глютенсіз макарон дайындау қиын, өйткені глютен пісіру кезінде макаронның еруіне жол бермейтін күшті ақуыз желісінің пайда болуына ықпал етеді. Қазіргі уақытта нарықта глютенсіз көптеген өнімдердің сапасы төмен болып келеді. Балама материалдардан сапалы макарон алу үшін дәстүрлі өндіріс процесін жиі өзгерту қажетігі туады. Бұл мақалада таңдалған отандық ұн үлгілерінің су сіңіру қабілеті көрсетілген. Су - глютенсіз қамырдың реологиялық қасиеттеріне, оның икемділігі мен деформацияға төзімділігіне, газды сақтау қабілетіне айтарлықтай әсер етеді. Сонымен қатар, қамырдың суды сақтау қабілеті нанның сапасына, атап айтқанда оның құрылымына, сыртқы түріне, дәміне, сақтау мерзіміне әсер етеді. Бұл шикізаттағы негізгі құрылымдық компоненттердің физика-химиялық қасиеттерін зерттеу мүмкіндігін анықтайды.
In tropical and subtropical areas, tuber and root crops are staple foods and a key source of energy. Sweet potato (SP) is currently regarded as one of the world's top ten foods because of its diverse sizes, shapes, color, and health benefits. The resistant starch (RS) content of SP is substantial. It is predicted to become the cheapest item in the food industry due to its extensive variety, food stability, emulsifier and fat substitution capabilities, and as filler. As a result, interest in SP-sourced RS has recently increased. Due to their unique nutritional and functional qualities, novelty has become a popular research focus in recent years. This review will summarize the current understanding of SP starch components and their impact on the technological and physicochemical properties of produced starch for commercial viability. The importance of sweet potato RS in addressing future RS demand sustainability is emphasized. SPs are a viable alternative to tubers as a sustainable raw material for RS production. It has an advantage over tubers because of its intrinsic nutritional value and climatic endurance. Thermal, chemical, and enzymatic treatments are effective RS manufacturing procedures. The adaptability of sweet potato RS allows for a wide range of food applications.
Dry beans are the world's second most important legume class after soybeans. Nutritionally, dry beans and other pulses have special importance in countries where protein energy malnutrition is widely prevalent. In developed countries, these grain legumes are becoming increasingly popular as due to their importance as meat alternative. Legumes are high in protein, non-digestible starches, fiber, bioactive components, and they possess bio-functional and techno-functional properties, which are of interest to consumers and food processors. However, raw seeds of dry beans contain several undesirable antinutritional factors that can adversely affect human health and, therefore, it is advisable to eliminate or reduce those components prior to consumption. A wide range of processing techniques has been employed to improve the nutritional value of beans, including dehulling, soaking, size reduction, fermentation, germination, cooking, extrusion cooking, and high-pressure processing. This chapter covers composition and nutritional profile of raw and processed dry beans.
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An alpha-glucosidehydrolase inhibitor (acarbose; BAY g 5421) taken with food was compared with dummy tablets in seven insulin-treated diabetic patients over eight-hour periods that included breakfast, lunch, and two snacks. Acarbose diminished the postprandial increases in blood glucose, lactate, and pyruvate concentrations and may therefore be of value in the management of insulin-dependent diabetes.
The British tables of Paul and Southgate provide by far the most extensive introductory and explanatory material with the tables. As it is a resource which is often utilized, we thought it important to mention here. Since, however, the introduction is 52 pages long and is already in the English language we refer you to the original. A sample page is presented (see Table 1).
Two test meals were taken in random order on separate days by 8 non-insulin-requiring diabetic volunteers after 14-hour overnight fasts. Addition of 16 g guar and 10 g pectin to the control meal containing 106 g carbohydrate decreased markedly and significantly the rise in blood-glucose between 30 and 90 minutes and also resulted in significantly lower insulin levels between 30 and 120 minutes. When these meals were fed to 3 insulin-dependent diabetic subjects, a similar flattening of the post-prandial glucose rise ensued. This addition of certain forms of dietary fibre to the diet of diabetics significantly decreases post-prandial hyperglycaemia and would be expected to improve the control of blood-glucose concentration.
The effect of an alpha-glucosidehydrolase inhibitor (alpha-G.H.I.) on intestinal absorption of sucrose was assessed by measuring rises in blood-glucose and intestinal hydrogen production after ingestion of 100 g sucrose. 200 mg alpha-G.H.I. given with the sucrose completely inhibited early postprandial blood-glucose rises, prevented late postprandial dips in blood-glucose, and considerably increased breath-hydrogen levels, which indicates sucrose malabsorption. Thus the inhibitor can be used to study carbohydrate malabsorption and may be useful as a method for retarding carbohydrate absorption.
Symptoms associated with carbohydrate malabsorption limit the usefulness to diabetics of a powerful glycoside-hydrolase inhibitor (acarbose) which reduces postprandial glycaemia. Addition of a low dose (50 mg) of a acarbose together with 14.5 g guar gum to a breakfast test meal taken by 8 healthy volunteers reduced the mean peak rise in blood-glucose at 30 min by 70%. Areas under the insulin and gastrointestinal-polypeptide response curves were also greatly reduced. No evidence of carbohydrate malabsorption, as assessed by measurement of breath hydrogen, was found during any of the test periods. When acarbose was taken alone, 3 of the 8 subjects had troublesome symptoms and the 30 min rise in blood-glucose was reduced by only 28%. Thus, combination of these two agents effectively reduces the rate of carbohydrate absorption without increasing side-effects and may make combined acarbose and guar acceptable in the management of some diabetics.
Summary BAY-g-5421 is an -glucosidase-inhibitor which inhibits intestinal absorption of carbohydrates. In a double-blind cross over study 12 diabetics taking sulphonylureas and 12 insulin-treated diabetics were treated additionally with BAY-g-5421 or a placebo for two seven day periods. In the pretreatment period and on the 7th and 14th day of the treatment periods serial blood glucose profiles were measured. In comparison to placebo BAY-g-5421 significantly lowered the mean (140 versus 157 mg/dl) and the maximal (192 versus 230 mg/dl) blood glucose values and the integrated blood glucose response (3112 versus 3421 mg/dl · 24 h) in the sulphonylurea-treated group as well as in the insulin-treated group (mean blood glucose 161 versus 192 mg/dl, maximal blood glucose 238 versus 283 mg/dl, integrated blood glucose response 3109 versus 3857 mg/dl · 24 h). The amplitude of glycaemic excursions was significantly decreased only in the sulphonylurea-treated group (96 versus 129 mg/dl), but not in the insulin-treated diabetics. No influence on routine liver function, renal function or haematological tests was observed. Side effects included hypoglycaemia in 3 patients of the insulin-treated group and meteorism in both groups. BAY-g-5421 could be a useful additional treatment for diabetic patients.
The effects of high-carbohydrate, high plant fiber (HCF) diets on glucose and lipid metabolism of 20 lean men receiving insulin therapy for diabetes mellitus were evaluated on a metabolic ward. All men received control diets for an average of 7 days followed by HCF diets for an average of 16 days. Diets were designed to be weight-maintaining and there were no significant alterations in body weight. The daily dose of insulin was lower for each patient on the HCF diet than on the control diet. The average insulin dose was reduced from 26 +/- 3 units/day (mean +/- SEM) on the control diets to 11 +/- 3 (P less than 0.001) on the HCF diets. On the HCF diets, insulin therapy could be discontinued in nine patients receiving 15 to 20 units/day and in two patients receiving 32 units/day. Fasting and 3-hr postprandial plasma glucose values were lower in most patients on the HCF diets than on the control diets despite lower insulin doses. Serum cholesterol values dropped from 206 +/- 10 mg/dl on the control diets to 147 +/- 5 (P less than 0.001) on the HCF diet; average fasting serum triglyceride values were not significantly altered on the HCF diets. These studies suggest that HCF diets may be the dietary therapy of choice for certain patients with the maturity-onset type of diabetes.
Nine diabetic patients who were receiving various treatments supplemented their normal home diets (two patients) or metabolic ward diets (seven patients) with guar crispbread for five days. Their mean urinary glucose excretion fell significantly by 38% during the last two days. A significant fall in fasting blood glucose concentration of 1.1 +/- 0.4 mmol/1 (19.8 +/- 7.2 mg/100 ml) was seen only in those who took guar after the control period. Over eight weeks' treatment insulin dosage was reduced by 21% in five patients, and home testing showed that glycosuria was reduced by 68% in six patients. Guar crispbread is likely to be a useful adjunct to diabetic treatment irrespective of the type of treatment or insulin dosage used.
Postprandila glycaemia and rise in serum insulin after carbohydrate-containing meals were reduced by the addition of guar flour or pectin, or both. After a liquid test meal (four subjects) the 30-min blood glucose was reduced from 6.33 +/- 0.19 mmol/litre (114 +/- mg/dl), mean +/- SEM, in the control subjects of 4.77 +/- 0.17 mmol/litre (86 +/- 3 mg/dl) by addition of guar gum (P less than 0.05). The mean insulin level was also significantly lower at 15 min. A breakfast test meal (bread, butter, marmalade, and tea) resulted in a mean 15-min blood glucose of 6.18 +/- 0.21 mmol/litre (111 +/- 4 mg/dl) in eight subjects; 10 g of pectin added to the marmalade reduced this level to 5.64 +/- 0.17 mmol/litre (102 +/- 3 mg/dl) (P less than 0.01). The insulin levels were significantly lower at 15, 30, and 45 min. A similar meal in which guar was added to the bread and pectin to the marmalade resulted in significant reductions of blood glucose at 15 min (P less than 0.002) and 30 min (P less than 0.01). The insulin values were also significantly lower throughout the first 90 min of the test. This action of unavailable carbohydrate may prove useful in the dietary control of diabetes.