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1093
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-
tnients
Introduction
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.
Methods
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
Foundations.
Wellcome Senior Research Fellows in Clinical Sci-
ence.Received March 15, 1982.
Accepted for publication June 1, 1982.
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1094 JENKINS El AL
Two-g carbohydrate portions either of finely crumbed
white bread or of lentils (20 mm, blended, 1 h, and 12 h
TABLE 1
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.
TABLE 2
Composition of H2 test meals*
Meal Cooked Protein
g
Fat
g
Carbohydrate
g
Dietary fiber
g
Energy
kcat
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
activity.
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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LENTILS: PROCESSING AND DIGESTIBILITY 1095
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.
Results
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
lentils.
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
1).
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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60
Time in minutes
1096 JENKINS El AL
0
E
E
0
U
0
0
0
.
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
at2and3h(p<0.Ol)(FigS).
Discussion
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
LENTILS: PROCESSING AND DIGESTIBILITY 1097
0
E
E
0
U
0
-o
0
0
.
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
1098 JENKINS El AL
E
a
a
C
C
0
-D
>1
I
at
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
glycemia.
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
LENTILS: PROCESSING AND DIGESTIBILITY 1099
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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1100 JENKINS El AL
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.
References
1. Anderson JW, Ward K. High-carbohydrate, high-
fiber diets for insulin treated men with diabetes
mellitus. Am J Clin Nutr l979;32:23l2-2l.
2. Simpson HCR, Lousley 5, Geekie M, et al A high
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-
cet 1978;l:1231-3.
6. Jenkins DJA, Taylor R, Nineham R, et al. Combined
use of guar and acarbose in reduction of postprandial
glycaemia. Lancet 1979:2:924-7.
7. Jenkins DJA, Leeds AR, Gassull MA, et al. Unab-
sorbable carbohydrates and diabetes: Decreased
post-prandial hyperglycemia. Lancet l976;2:l72-4.
8. Walton RJ, Noy GA, Alberti KGMM, Sherif IT.
Improved metabolic profiles in insulin-treated dia-
betic patients given an alpha-glucosidehydrolase in-
hibitor. Br Med J 1979:1:220-I.
9. Jenkins DJA, Wolever TMS, Nineham R, et al.
Guar crispbread in the diabetic diet. Br Med J
l978;2: 1744-6.
10. Sachse G, WilIms B. Effect of the a-glucosidase
inhibitor BAYS 5421 on blood glucose control of
sulphonylurea-treated diabetes and insulin treated
diabetes. Diabetologia 1979:17:287-90.
11. Aro A, Uusitupa M, Voulitainen E, Hersio K, Kor-
honen I, Siitonen 0. Improved diabetic control and
hypocholesterolemic effect induced by long-term di-
etary supplimentation with guar gum in type 2 (in-
sulin-independent) diabetes. Diabetologia 1981;
21:29-33.
12. Jenkins, DJA, Wolever TMS, Taylor RH, et al.
Glycemic index of foods: A physiological basis for
carbohydrate exchange. Am J Clin Nutr 1981;
34:362-6.
13. Jenkins DJA, Wolever TMS, Taylor RH, Barker
HM, Fielden H. Exceptionally low blood glucose
response to dried beans: comparison with other car-
bohydrate foods. Br Med J l980;281:578-80.
14. Jenkins DJA, Wolever TMS, Taylor RH, et al. Slow
release dietary carbohydrate improves second meal
tolerance. Am J Clin Nutr 1982;35:1339-46.
15. Paul AA, Southgate DAT. McCance and Widdow-
son’s the composition of foods. 4th ed London:
HMSO, 1978.
16. Clark LC Jr. A polarographic enzyme electrode for
the measurement of oxidase substrates. In: Kessler
M, Bruley DF, Leland CC, Lubbers DW, Silver IA,
Strauss J, eds. Oxygen supply. Munich: Urban &
Schwarzenberg 1973:120-8.
17. Jenkins DJA, Wolever TMS, Taylor RH, Barker
HM, Fielden H, Gassull MA. Lack of effect of
refining on the glycemic response to cereals. Diabetes
Care 1981:4:509-13.
18. Metz G, Gassull MA, Leeds AR, Blendis LM, and
Jenkins DJA. A simple method of measuring breath
hydrogen in carbohydrate malabsorption by end
expiratory sampling. Clin Sci Mol Med 1976:
50:1219-25.
19. Bond JH Jr. Levitt MD. Use of pulmonary hydrogen
(H2) measurements to quantitate carbohydrate ab-
sorption: study of partially gastrectomized patients.
J Clin Invest 1972:51:1219-25.
20. Anderson lH, Levine AS, Levitt MD. Incomplete
absorption of the carbohydrate in all-purpose wheat
flour. N EngI J Med 198 l;l5:891-2.
21. Jenkins DJA, Wolever IMS, Taylor RH, et al. Rate
by guest on July 12, 2011www.ajcn.orgDownloaded from
LENT1LS: PROCESSING AND DiGESTIBILITY 1101
of digestion of foods and post prandial glycemia in
normal and dmabetmc subjects. Br Med J 1980:1:14-
17.
22. Crapo PA, Kolterman OG, Waldeck N, Reaven
GM, Olefsky JM. Postprandial hormonal responses
to different types of carbohydrate in individuals with
impaired glucose tolerance. Am J Clin Nutr
1980;33: 1723-8.
23. Militzer W, Ikeda C, Kreen E. The preparation and
properties of an amylase inhibitor of wheat. Arch
Biochem 1946;9:30.
24. Haber GB, Heaton KW, Murphy D. Depletion and
disruption of dietary fibre. Lancet l977;2:679-82.
25. O’Dea K, Nestel PJ, Antonoff L. Physical factors
influencing post prandial glucose and insulin re-
sponses to starch. Am J Clin Nutr 1980:33:760-5.
by guest on July 12, 2011www.ajcn.orgDownloaded from
