Blood glucose response indicators and mixed food meals

[Guest guest]

Hi All, Not just glycemic index, but also values " expressed as rapid

available glucose (RAG), the amount of

rapid carbohydrate/100 g food or meal as eaten, and as the starch digestion

index (SDI), the percentage of rapid carbohydrate digestion rate in relation

to

the total amount of carbohydrate " seems to be important.

What I thought that the full PDF-available at: apater@... paper said well

was that mixing foods in a meal has a profound effect on these parameters.

Cheers, Al.

Araya H, Pak N, Vera G, Alvina M.

Digestion rate of legume carbohydrates and glycemic index of legume-based meals.

Int J Food Sci Nutr. 2003 Mar;54(2):119-26.

PMID: 12701368 [PubMed - in process]

A study was performed to examine the rate of digestion of available

carbohydrate in legumes and its mixtures with cereals, prepared as commonly

eaten. The legumes and cereals studied were lentil (Lens sculenta), pea (Pisum

sativum), bean (Phaseolus vulgaris, var tortola), rice (Oryza sativa) and

spaghetti. Foods were purchased at the city market. Total starch content and

the carbohydrate digestion rates were determined using the enzymatic method

proposed by Englyst et al . Total starch levels ranged from 7.78 g/100 g in

cooked flour bean to 20.6 g/100 g in a bean- spaghetti dish, and dietary fiber

contents ranged from 2.4 g/100 g in a cooked 70:30 lentil / rice mixture to 5.26

g/100 g in a cooked whole bean. The rapid digestion rate carbohydrates showed

values from 4.8 in the bean soup to 8.9 in the bean-spaghetti combination. The

same results show, expressed as rapid available glucose (RAG), the amount of

rapid carbohydrate/100 g food or meal as eaten, and as the starch digestion

index (SDI), the percentage of rapid carbohydrate digestion rate in relation to

the total amount of carbohydrate.The RAG values ranged between 5.0 for

cooked beans and 10 for cooked beans and spaghetti, and the SDI ranged

between 40 for cooked pea flour and 62 for cooked bean flour. Legumes

prepared as soup showed a higher rapid digestion rate than legumes prepared

as whole grain. The bean-spaghetti based-meal and the lentil-based meal

showed glycemic index mean and standard deviation values of 76.8+/- 43.4 and

49.3+/- 29.5, RAG values of 7.0 and 6.0, and SDI values of 57 and 54,

respectively. The knowledge of the importance of the carbohydrate digestion

rates in human health is increasing, and probably will soon be used in the

development of the food pyramid. The foods with a moderate fraction of rapid

digestion rate, such as legumes, should be included in the base of the pyramid.

Introduction

For a long time, dry legumes were considered

to be a basic food, a protein source and an

adequate complement to increase the protein

quality of cereals (Eli´as & Bressani, 1974;

Sgarbieri et al. , 1978; Araya, 1981). Today,

there is a strong effort being made to increase

the legume intake in populations with high

prevalences of diabetes, obesity and cardio-

vascular diseases. In the epidemiological

context, legumes are considered as healthy

foods because of their high dietary fiber and

starch contents (r et al. , 1992). However,

there has been a drastic reduction in legume

consumption as a result of urbanization and

the globalization of the food trade (Lintas &

Cappelloni, 1992).

Complex carbohydrates, essentially starch,

are promoted as beneficial for human health,

especially for sedentary populations at risk of

chronic diseases. Consequently, foods con-sidered

as a good source of this nutrient are

placed at the base of the current pyramid

(Wahlqvist et al. , 1998). However, dietary

carbohydrates are digested and absorbed at

different rates in the human digestive tract.

Foods high in available complex carbohy-drates

such as white bread and potatoes show

high digestion rates and glycemic indexes

(Hermansen et al. , 1986; et al. ,

1988). These physiological responses have

been related to hyperglycemia, hypertrigly-ceridemia

and risk of type II diabetes (Re-aven,

1988).

The different physiological properties of

the food starches make it necessary to

develop a nutritional classification based on

their digestion rate. An in vitro enzymatic

method was developed (Englyst et al. , 1992)

to determine the digestion rate of carbohy-drates,

which were classified as rapid, lente

and resistant starch. While it is important to

study the intrinsic factors of foods and their

relation to the glycemic index, the effect of

the method of food preparation on the

glycemic index also needs to be investigated

(Brand et al. , 1985; Lintas & Cappelloni,

1992). Legumes are customarily prepared in

different forms (e.g. cooked alone, combined

with cooked cereals and blended as soups).

The digestion rate of complex carbohy-drates

depends on several factors, as per

example, the type of ingested food, the

industrial process applied to the foods and

the culinary methods used to prepare the

food before consumption. These factors

influence the food’s physical form, which is

one of the major factors affecting the starch

digestion rate (Wong & O’Deal, 1983;

Wursch et al. , 1986; Bjorck et al. , 1994).

There is evidence that lente digestion carbo-

hydrates are associated with a lower glycemic

index, which in turn related to a lower risk of

non-transmissible chronic diseases (Wolever

& Bolognesi, 1996). Legumes are proposed as

a food that contains large amounts of lente

digestion carbohydrates and a high level of

dietary fiber strongly integrated into the

grain structure (Hoover & Sosulski, 1991).

Furthermore, several studies suggest that

lente digestion carbohydrates may be asso-ciated

with increased ratings of satiety (Ra-ben

et al. , 1996).

The aim of the present work was to study

the in vitro digestion rate of the legume

carbohydrates and how some cooking prac-tices

commonly used in their culinary pre-paration

may affect the in vitro digestion rate

of their carbohydrates, and to provide in-formation

on glycemic index of legume-based

meals in adult young men..

Materials and methods

In vitro study

Dry legumes (lentils, beans, peas) and cereals

(rice and spaghetti) were purchased at the

city market. A sample description and the

preparation methods used, according to

common practices, are described in Table 1......

.. Samples were weighed taking into ac-count

an estimation of carbohydrate content

in order to weigh less than 0.6 g carbohy-drate.

The raw, dried legumes were grounded

and passed through a screen of 200 mesh.

Cooked samples were minced in a food

processor to obtain small particles, less than

1 cm. Wheat starch from Sigma was used as

the reference material.

Table 1. Characteristics of food samples

Sample Prepararion method

Pea flour, cooked Finely ground peas (40 g),

cooked with boiling water (200 ml) for 20 min

Lentil flour, cooked Finely ground lentils (60 g)

cooked with boiling water (300 ml) for 20 min

Lentil, cooked Lentil grains (500 g, 6 mm), soaked in water

(2 l) for 14 h, cooked in the same water for 10 min in a steam

pot and then minced in a food processor

Lentil / rice, cooked Proportion: lentil / rice / 70:30. Lentil

grains (350 g, 6 mm), soaked in water (2 l) for 14 h, cooked in the

same water with rice (150 g) for 10 min in a steam pot and

minced in a food processor

Bean flour, cooked Finely ground beans (40 g), cooked

with boiling water (200 ml) for 20 min

Bean cooked Bean grains (200 g), soaked in water (1.5 l) f

or 14 h, cooked in the same water for 25 min in a steam pot and

minced in a food processor

Bean / spaghetti,cooked Proportion: bean / spaghetti / 70:30.

Beans (140 g), soaked in water (1 l) for 14 h, cooked in the same water

with spaghetti (60 g) for 25 min in a steam pot and minced in a food processor

Bean / spaghetti-based meal Ingredients: bean 57 g; spaghetti 24 g;

squash 30 g; carrot 10 g; onion 10 g; dehydrated vegetables 8 g;

vegetable oil 4 g; orange 80 g. The ingredients of the bean / spaghetti

dish were cooked for 25 min in a steam

pot. Beans were soaked in water (1 l) for 14 h.

Samples were minced in a food processor

Lentil-based meal Ingredients: lentil 88 g; onion 15 g; dehydrated

vegetables 10 g; vegetable oil 5 g; orange 100 g. Lentils were

soaked in water (1 l) for 14 h, cooked for 10 min in a steam pot

and then minced in a food processor, and

then cooked in boiling water for another 10 min

In vivo study

Ten healthy non-smoking men, between the

ages of 21 and 24 years old, were selected

from volunteers at the University of Chile to

participate in the study. According to the

body mass index (BMI) taken for each

subject, their nutritional status was normal.

Their anthropometric measurements are pre-sented

in Table 2. Subjects were in a physio-logical

fasted state, and at 09:00 h consumed

the test meals in the laboratory in a rando-mized

order at 1-2 week intervals. They were

instructed to consume all the food served in a

period of 15 min. Blood samples were

extracted ... at 0 (basal),

15, 30, 60 and 120 min after the end of the

meal. ......The glycemic index was calculated from the 2

h incremental glucose area using wheat bread

as the reference food (glycemic index/ 100).

The incremental area under the blood

glucose-response curve was calculated geo-metrically

by applying the trapezoid rule.

When a blood glucose value falls below the

baseline, only the area above the fasting level

is included. Two legume-based meals were

designed to determine the glycemic index

(Table 1).......

Results

The results of the proximal chemical analysis

in the assayed foods, including the carbohy-drate

percentage obtained by difference, are

presented in Table 3. The carbohydrate

digestion rates of legumes and their combi-nations

with cereals are illustrated in Table 4.

The rapid digestion rate of carbohydrates

showed values from 4.8 g /100 g in the bean

soup to 8.9 g/100 g in the bean-spaghetti

combination. Also shown are the results,

expressed as rapid available glucose (RAG),

the amount of rapid carbohydrate/100 g food

or meal as eaten, and the starch digestion

index (SDI), for the percentage of rapid

digestion of carbohydrate in relation to the

total amount of carbohydrate. The RAG

values ranged between 5.0 for cooked beans

and 10 for cooked beans and spaghetti and

the SDI ranged between 40 for cooked pea

flour and 62 for cooked bean flour.

Table 2. Body weight, height and body mass index of the

young male subjects

Subjects Weight (kg) Height (m) Body mass index (kg/m2)

1 80.2 1.82 24.2

2 64.3 1.62 24.5

3 78.5 1.79 24.5

4 60.5 1.74 20.0

5 69.4 1.76 22.4

6 62.0 1.69 21.7

7 64.4 1.67 23.1

8 75.1 1.72 25.4

9 64.5 1.66 23.4

10 65.6 1.65 24.1

Table 3. Chemical composition of the test foods

Moisture (g/ 100 g) Ash (g/ 100 g) Protein (g/ 100 g) Lipid (g/ 100 g) Total

dietary fiber (g/ 100 g) A v ailable carbohydrate (g/ 100 g)

Pea flour, cooked 75.0 0.81 6.77 0.10 2.93 14.39

Lentil flour, cooked 81.0 0.56 6.36 0.07 3.18 8. 83

Lentil, cooked 79.9 0.50 5.42 1.17 3.41 9. 60

Lentil / rice, cooked 81.0 0.48 4.27 0.73 2.39 11.13

Bean flour, cooked 86.2 0.40 3.40 0.67 2.73 6. 60

Bean, cooked 70.8 0.85 7.19 1.42 5.26 14.48

Bean / spaghetti, cooked 69.0 0.75 6.51 1.02 4.19 18.13

Bean / spaghetti- based meal 81.1 0.34 3.53 1.51 2.72 11.00

Lentil- based meal 80.0 0.53 4,71 1.40 2.61 10.73

The mean values and standard deviations

of the blood glucose levels at different time

intervals designed to determine the glycemic

index of two legume-based meals are pre-sented

in Table 5. The bean-spaghetti-based

meal and the lentil-based meal showed gly-cemic

index mean and standard deviation

values of 76.8=/-43.4 and 49.3=/-29.5, RAG

values of 7.0 and 6.0, and SDI values of 57

and 54, respectively.

Table 5. Blood glucose values* (mmol/l) at different time intervals

Time (min) 0 min 15 min 30 min 60 min 90 min 120 min

Bean / spaghetti-based meal 4.85=/-0.39 6.22=/-0.31 6.60=/-0.85 5.51=/-0.69

4.97=/-0.38 4.90=/-0.39

Lentil-based meal 4.87=/-0.18 5.87=/-0.67 6.20=/-0.61 5.30=/-0.78 4.66=/-0.49

4.53=/-0.34

Discussion

The development of an in vitro enzymatic

method (Englyst et al. , 1992) is an interesting

tool to screen the carbohydrate digestion rate

of foods and meals, one of the more valuable

nutritional properties of carbohydrates. Al-most

all the legumes and their combinations

with cereals assayed showed low values of

rapidly digestible carbohydrates and, conse-quently,

RAG values, explained by the high

water percentages of the test foods. When the

SDI was calculated, an index that does not

consider the water percentage of foods, the

highest values for each legume were observed

in the cooked legume flours, suggesting that

culinary forms of preparation may be im-portant

to define the physiological responses

of starchy foods. These results showed that

legumes finely grounded and prepared as

soups presented higher values of rapid diges-

tion and lesser lente digestion and resistant

starch fractions when compared with their

homologous foods cooked as the whole

grain. These differences may be explained

by the particle size, since small particles of

the grounded grain have a greater contact

superfice, and then the action of digestive

enzymes is more efficient (Heaton et al. ,

1988; Holt & Brand , 1994). This

physical condition makes possible that enzy-matic

hydrolysis and the digestion rate in-crease

and, consequently, the intestinal

absorption of glucose also increase (Cum-mings

& Englyst, 1995).

In the present study, the results differed

than those reported by Englyst et al. (1992).

Our values are higher in the starch fraction

which remains unhydrolyzed after 120 min of

incubation. These unexpected results may be

explained by several factors such as the

different foods assayed, the cooking proce-dures

and the sample treatments applied

before the enzymatic incubations.

The values of the in vitro carbohydrate

digestion rates of the foods and meals

assayed in the present work can be consid-ered

as only moderately beneficial in showing

legumes can be considered as an important

food in lowering the risk of non-transmissible

chronic diseases, based on their high levels of

dietary fiber and lente digestion carbohy-drate

(r et al. , 1992).

It is also remarkable that the addition of

spaghetti to beans produces a less rapid

digestion response, and, consequently an

increment of the slow and very slow frac-tions.

This result may be explained by the

fact that spaghetti is a food that has a great

fraction of lente digestion starch as has been

reported by several authors (Hermansen et

al. , 1986; Bornet et al. , 1990)

The digestion rates of carbohydrates con-dition

the glycemic as well as the insulinemic

index (Englyst et al. , 1996; Holt et al. , 1996;

Wolever & Bolognesi, 1996). Data from

glycemic indexes and the in vitro digestion

rate of two meals based either on bean or

lentil demonstrated that for these prepara-tions

the values of the carbohydrate digestion

rate are related with the glycemic index

determined in young male normal subjects.

Results obtained while studying high carbo-hydrate

meals commonly consumed by the

Chilean population showed that the in vitro

carbohydrate digestion rate was correlated

with the glycemic index in young adult

healthy men (Araya et al. , 2001).

The knowledge of the importance of the

digestion rate of carbohydrates to human

health is increasing and probably soon will be

used in the development of the food pyramid.

The foods with moderate fraction of the

rapid digestion rate, such as legumes, should

be included in the base of the pyramid, and

those with high levels of rapid digestion

starch may be placed in the upper zones of

the pyramid.

References

Araya H (1981): Examining the nutritive value of basic

foods as a tool for the study of diets in poor countries.

Food Nutr. Bull. 3,21-27.

Araya H, Contreras P, Aluin˜ a M, Vera G & Pak N (2002): A

comparison between an in vitro method to determine

carbohydrate digestion rate and the glycemic response in

young men. Eur. J. Clin. Nutr. 56, 735 / 739.

Association of Official Chemists (1980): Official Methods of

Analysis, 13th edn. Washington DC: AOAC.

Bjorck I, Grandfeldt Y, Liljeberg H, r J & Asp N-G

(1994): Food properties affecting the digestion and

absorption of carbohydrates. Am. J. Clin. Nutr. 59(Suppl),

699S / 705S.

Bornet FRJ, Cloaree D, Barry JL, Colonna P, Gouillod S,

Laval JD & Galmiche JP (1990): Pasta cooking time:

influence on starch digestion and plasma glucose and

insulin responses in healthy subjects. Am. J. Clin. Nutr.

51, 421 / 427.

Brand JC, Nicholson PL, Thorburn AW & Truswell AS

(1985): Food processing and the glycemic index. Am. J.

Clin. Nutr. 42, 1192 / 1196.

Cummings JH & Englyst HN (1995): Gastrointestinal

effects of food carbohydrate. Am. J. Clin. Nutr. 61(Suppl),

938S / 945S.

Eli´as LG & Bressani R (1974): Nutritional factors affecting

the consumption of leguminous seeds. Arch. Latinoamer.

Nutr. 24, 365 / 378.

Englyst HN, Kingman SM & Cummings JH (1992):

Classification and measurement of nutritionally impor-tant

starch fractions. Eur. J. Clin. Nutr. 46(Suppl), 33S /

50S.

Englyst HN, Veenstra J & Hudson GJ (1996): Measurement

of rapidly available glucose (RAG) in plant foods: an in

vitro predictor of the glycaemic response. Br.J.Nutr.75,

327 / 337.

Heaton KW, Marcus SN, Emmett PM & Bilton CH (1988):

Particle size of wheat, maize, and oat test meals. Effects

on plasma glucose and insulin responses and on the rate

of starch digestion in vitro. Am. J. Clin. Nutr. 47, 675 /

682.

Hermansen K, Rasmussen O, Arnfred J, Winter E &

Schmitz O (1986): Differential glycaemic effects of potato,

rice and spaghetti in type I (insulin dependent) diabetic

patients at constant insulinaemia. Diabetologia 29, 358 /

361.

Holt SHA & Brand JC (1994): Particle size and

glycemic response. Eur. J. Clin. Nutr. 48, 496 / 502.

Holt SHA, Brand JC & Petocz P (1996): Interrela-tionships

among postprandial satiety, glucose and insulin

responses and changes in subsequent food intake. Eur. J.

Clin. Nutr. 50,788-797.

Hoover R & Sosulski FW (1991): Composition, structure,

functionality and chemical modifications of legume

starches: a review. Can. J. Physiol. Pharmacol. 69,79-92.

DJA, Wolever TMS & AL (1988): Starchy

foods and glycemic index. Diabetes Care 11, 149 / 159.

Lee CL, Prosky L & De Vries JW (1992): Determination of

total, soluble and insoluble dietary fiber in foods */

enzymatic-gravimetric method, MES-TRIS buffer: colla-borative

study. J. AOAC Int. 75, 395 / 416.

Lintas C & Cappelloni M (1992): Effect of processing on

legume resistant starch. Eur. J. Clin. Nutr. 46(Suppl 2),

S103 / S104.

Raben A, Holst JJ, Christensen NJ & Astrup A (1996):

Determinants of postprandial appetite sensation: macro-nutrient

intake and glucose metabolism. Int. J. Obes. 20,

161 / 169.

Reaven GM (1988): Role of insulin resistance in human

disease. Diabetes 37, 1595 / 1607.

Sgarbieri VC, Garuti RS, Morales MAC & Hartman L

(1978): Nutritional and sensory evaluation of mixtures of

soybean (Glycine max L.) and common beans (Phaseolus

vulgaris L.) for direct use as human food. J. Food Sci. 43,

208.

r J, Granfeldt Y & Bjorck I (1992): Effects of processing

on blood glucose and insulin responses to starch in

legumes. J. Agric. Food Chem. 40, 1846 / 1851.

Wahlqvist ML, Kouris-Blazos & Savige G (1998): Food-based

dietary guideline for older adults. Joint WHO/Tufts

University Consultation on Nutrition Guideline for the

Elderly, Boston, MA, USA.26-29 May.

Wolever TMS & Bolognesi C (1996): Source and amount of

carbohydrate affect postprandial glucose and insulin in

normal subjects. J. Nutr. 126, 2798 / 2806.

Wong S & O’Dea K (1983): Importance of physical form

rather than viscosity in determining the rate of starch

hydrolisis in legumes. Am. J. Clin. Nutr. 37,66-70.

Wursch P, Del Vevodo S & Koelrutter B (1986): Cell

structure and starch nature as key determinants of the

digestion rate of starch in legume. Am. J. Clin. Nutr. 43,

25 / 29.