Glycative Stress Research
Online edition : ISSN 2188-3610
Print edition : ISSN 2188-3602
Received : February 27, 2015
Accepted : March 29, 2015
Published online : June 30, 2015

Original ar ticle

Postprandial blood glucose level after intake of a bowl of rice topped with beef
Arisa Kawabata, Masayuki Yagi, Mari Ogura, Yoshikazu Yonei
Anti-Aging Medical Research Center and Anti-Glycation Research Center, Graduate School of Life and Medical Sciences,
Doshisha University

Abstract

Objectives: The combination of a staple food and a side dish has been reported to prevent postprandial glucose elevation,
contributing to glycative stress reduction. In this study, we evaluated the effect of a rice bowl topped with beef, “gyudon,” withan additive of red ginger on blood glucose.
Methods: Subjects were 12 healthy volunteers (26.9 ± 5.9 years) from whom informed consent was obtained. On the test day,fasting blood glucose was measured followed by test food ingestion for 10 min, then glucose levels were checked by a glucose
meter for self monitoring at 15, 30, 45, 60, 90, and 120 min. Postprandial blood glucose and the area under the curve (AUC)
were analyzed and compared between 3 test foods: steamed rice (230 g), “gyudon” with or without ginger (15 g).
Results: Analysis was conducted in the 11 subjects with steamed rice AUC of more than 5,000. There was no significant
difference in AUC among the 3 test foods; steamed rice, “gyudon” with or without ginger. Blood glucose at 15 min was
significantly higher in “gyudon” with ginger than in steamed rice ( p = 0.006). Blood glucose at 60 min was significantly lower
in “gyudon” without ginger than in steamed rice ( p = 0.040).
Conclusion: Although “gyudon” is a fast food, it can reduce postprandial glucose elevation by combining a staple food and aside dish, thus potentially contributing to glycative stress control.

KEY WORDS: postprandial blood glucose, glycative stress, beef, protein, lipids

Introduction

When simple sugar molecules, like glucose and fructose,
react non-enzymatically with proteins advanced glycation
endoproducts (AGEs) are formed; this reaction is called“glycation”. When excess amounts of reducing glucose or
aldehydes are loaded in the body, it causes physical stress,
which is called “glycative stress” 1, 2 ). The glycative stressplays a role as a risk factor for age-related deterioration
including skin aging and diabetic complications. Treatment
methods for reducing glycative stress are categorized into as
follows: reduction of postprandial hyperglycemia by foodintake, inhibition of AGE formation and enhancement of AGE
degeneration and excretion.
In our laboratory, the research has been focused on theelucidation of the influence of food combinations and added
dietary fibers on the postprandial glucose values. We haveconfirmed that grapefruit intake before a meal 3) and additive
dietary fibers 4) can reduce postprandial hyperglycemia. Also
we reported that the area under the curve of postprandial
blood glucose values can be further reduced by combining
staple food with eggs, vegetables or braised meat and eggplantContact Address: Professor Yoshikazu Yonei
Anti-Aging Medical Research Center,
Graduate School of Life and Medical Sciences, Doshisha University
1-3, Tataramiyakodani, Kyotanabe-shi, Kyoto, 610-0321 Japan
Phone/Fax: + 81-774 - 65-6394 Email: yyonei@mail.doshisha.ac.jp
Co-authors: Kawabata A, bml2025@mail4.doshisha.ac.jp,
Yagi M, myagi@doshisha.ac.jp, Ogura M, mogura@dwc.doshisha.ac.jp“mabonasu” compared to only staple food, such as udon
noodle or rice 5).
In the present study, the postprandial blood glucose level
was measured after the intake a bowl of rice topped with
beef, with or without red ginger, and compared with the level
after rice intake alone. Thus we explored other measures
which can reduce glycative stress from the viewpoint of
dietary education, “Shokuiku”.

Methods
Subjects

Subjects were recruited from among those with relevanceto the Department of Anti-Aging Medicine, Doshisha
University Faculty of Life and Medical Sciences as previously
reported 4, 5). The subjects comprised healthy persons aged 20
years or older who did not meet any of the following exclusion
criteria: food or drug allergy, pregnant or lactating women,_ 67 _

Glycative Stress Research 2015; 2 (2): 67- 71(c) Society for Glycation Stress ResearchBeef-topped Rice Bowls and Post-prandial Blood Glucose
under treatment with medication or follow-up, diagnosis of
diabetes mellitus, pronounced cardiopulmonary functional
disorder, on therapeutic medication for hypertension, a pasthistory of gastrointestinal surgery, and suspicion of infectious
disease. Other subjects judged by the investigator as being
inappropriate for inclusion in the study were also excluded
from the study.
The study population comprised 12 subjects ( 5 males
and 7 females, age 26.9 ± 5.9 years, body mass index [BMI]
20.6 ± 3.5 ). These subjects provided written consent toparticipate in the study after being given a full explanation of
the study.

Protocol for blood glucose test

A blood glucose test was performed as previously
reported 4, 5) according to the unified protocol established by
the Japanese Association for the Study of Glycemic Index(JASGI) 6 , 7). On the day before the test the following wereprohibited: strenuous exercise, taking meals after 8:00 p.m,surfeit, overdrinking, and staying up late at night. If thesubject felt ill on the day before the test, or prior to or during
the test, the test was to be postponed or terminated.
On the day of the test, the reference diet and test foodwere taken over a period of 5 -10 minutes, with about 30
chews per mouthful required. Blood glucose was measured at
15 (2nd time), 30 (3rd time), 45 (4th time), 60 (5th time), 90(6th time), and 120 minutes (7th time) after the start of taking
each test food. In the present study, a glucose meter for selfmonitoring (Glucocard MyDia; Arkray, Inc., Nakagyo-ku,
Kyoto, Japan) was used as test equipment.

(steamed rice 230 g + “Gyudon” pack)A bowl of rice topped with beef, “gyudon,” with ginger(steamed rice 230 g + “Gyudon” pack + red ginger“ benishoga” 15 g)

Frozen-packed “Gyudon” packs, provided by Yoshinoya
Holdings, were used for beef topping which were preparedin the same manner as the commercial products, so that we
can compare the test products with the menu products in therestaurants.
The amount of carbohydrates other than dietary fiber ineach test food was set at 75 g ± 5 g , as previously reported 4, 5),in order to correspond to the 75 g amount of carbohydrates
other than dietary fiber for the 75 g oral glucose tolerance test
(OGTT) in common use for diagnosing diabetes mellitus.

Statistical analyses

The 0-minute value was subtracted from the blood
glucose level measured over time after eating each test foodto obtain Δ blood glucose level; the largest change in thelevel observed up to 120 minutes after the start of ingestion
was considered as the maximum blood glucose level change.
Using these parameters, the area under the blood glucose
elevation curve (AUC) was calculated. Data obtained were
statistically analyzed by the Tukey’s multiple comparison
test among the 3 groups, using the SPSS Statics 22 statisticalanalysis software (IBM Japan, Chuo-ku, Tokyo, Japan). A
two-sided p-value of less than 5% was considered to indicate
a significant difference.

Ethical Considerations

Test foods

The test foods used in this study are shown below( Table 1 ). Nutrient contents in these foods were provided
from Yoshinoya Holdings Co., Ltd., ( Kita-ku, Tokyo,
Japan) and calculated using the Standard Tables of Food
Composition in Japan 2010 8) .
A bowl of rice topped with beef “gyudon” is comprisedof steamed rice, “gyudon” topping and ginger. “Gyudon”
topping and ginger were provided by Yoshinoya Holdings.
Packed steamed rice (Sato No Gohan [Sato Foods Co., Ltd.,
Niigata, Japan], 100% consisting of Koshihikari, produced in
Niigata Prefecture) was to be twice tested.

..

.

Steamed rice 230 g
A bowl of rice topped with beef, “gyudon,” without ginger

The present study was conducted in compliance withthe ethical principles of the Declaration of Helsinki (Note ofClarification added at the 2004 World Medical Association
General Assembly in Tokyo) and Japan’s Act on theProtection of Personal Information, and with reference tothe Ministerial Ordinance on Good Clinical Practice (GCP)
for Drug (Ordinance of Ministry of Health and Welfare
No.28 of March 27, 1997) and the Ethical Guidelines for
Epidemiological Research established by Japan’s Ministryof Health, Labour and Welfare, and Ministry of Education,
Culture, Sports, Science and Technology. The present
study was conducted after examination and approval for the
ethics and appropriateness of the study at a meeting of theDoshisha University Ethics Committee for Scientific Research
Involving Human Subjects (Approval number #1228-2).

Table 1. Food consumption and nutrients in test food items.
Food items

Consumption(g)Energy( kcaL )Protein(g)

Lipids( g)Carbohydrates(g)

Steamed rice

230.0

338.1

4.8

0.0

78.0

“Gyudon” pack *

135.0

263.3

13.6

20.9

4.9

Red ginger *

15.0

2.6

0.045

0.060

0.59

Numerical figures for food items were calculated based on the provided nutrient information from Yoshinoya Holdings using the Standard Tables of Food
Composition in Japan 2010 8). “Gyudon,” a rice bowl topped with beef. * Data from the distribution products at October 2014 were provided by Yoshinoya
Holdings.

_ 68 _Glycative Stress Research

Results
The results of postprandial blood glucose level arepresented in Fig.1 and AUC in Fig. 2. The subjects for whom
the steamed rice AUC was less than 5,000 were excluded fromthe analysis; steamed rice, 11 subjects; “gyudon,” 11 subjects,“gyudon” + ginger, 10 subjects, since if not excluded, no

significant difference was noted in the study.
There was no significant difference in AUC among the
3 tests of steamed rice and a rice bowl topped beef “gyudon”
with or without ginger. Blood glucose change at 15 min was
significantly higher in “gyudon” with ginger than in steamed
rice (p = 0.006). The glucose level was significantly lower in“gyudon” without ginger than in steamed rice ( p = 0.040).

90

Blood glucose (mg/dL)

80
70
60
50
Steamed rice

40

Gyudon30

Gyudon ＋ ginger

20
10
0
0

15

30

45

60

75

90

105

120

135

Time (min)Fig 1. Postprandial blood glucose changes.

Blood glucose levels were compared among the following 3 tests after taking each meal of steamed rice 230 g (n = 11), “Gyudon” without ginger (n =11), and “Gyudon” with ginger (n=10).
For changes in blood glucose level at 15 min: p < 0.05; “Gyudon” with ginger vs. steamed rice; at 60 min, “Gyudon” without ginger, p < 0.05; Tukey’s
multiple comparison test. “Gyudon”; a rice bowl topped with beef. Data are expressed as mean ± standard error.

7,000
6,000

AUC

5,000
4,000
Steamed rice

3,000

Gyudon2,000
Gyudon ＋ g inger
1,000
0

Fig 2. Comparison of AUC.

AUC of the blood glucose curve were compared among the following 3 tests after taking each meal of steamed rice 230 g (n = 11), “Gyudon” without
ginger (n = 11), and “Gyudon” with ginger (n=10).
No significant difference was noted among the 3 groups; Tukey’s multiple comparison test. “Gyudon”; a rice bowl topped with beef. Data are expressed
as mean ± standard error.

_ 69 _

Beef-topped Rice Bowls and Post-prandial Blood Glucose

Discussion

Data interpretation“Gyudon” is a rice bowl topped with beef and one of
popular fast foods in Japan. In the present study, there was no
significant difference in AUC of blood glucose among the 3groups after taking each of steamed rice, “gyudon” without
ginger and “gyudon” with ginger. Postprandial glucose level
was significantly lower at 15 min in steamed rice than in“gyudon” with ginger and at 60 min in “gyudon” without
ginger than in steamed rice.
It has been thought that postprandial glucose levels
are primarily influenced by carbohydrates, especiallysugars contained in ingested foods. In this study, althoughcarbohydrate amounts were higher in “gyudon” than insteamed rice, AUC was not higher in “gyudon” than insteamed rice ( p = 0.300). When comparing food nutrients,
protein amounts were approximately 9 g higher in “gyudon”
than in steamed rice. Proteins once ingested stimulate
glucose-dependent insulinotropic polypeptide (GIP) which
enhances insulin secretion and results in the elevation of
insulin secretion 9). Also, lipid amounts were approximately
21 g higher in “gyudon” than in steamed rice. Lipids influencegastric smooth muscles mediated by gastrointestinal hormonesand vagus nerves and results in the prolongation of the gastric
emptying time 10). These findings indicate that proteins andlipids contained in “gyudon” may reduce the postprandial
glucose levels.
On the other hand, the blood glucose levels at 15 min
was significantly higher in “gyudon” with ginger. The reason
for this result may be due to the sugar contained in sauce for“gyudon”.

Gastric emptying function

Discussion on the gastric emptying function has not been
active although it is very influential on postprandial glucose
levels. When gastric emptying function becomes low and thegastric emptying time is prolonged, the postprandial glucose
levels do not tend to be high, while postprandial glucose
levels do tend to be high if the gastric emptying time becomesshorter. However, an extreme decrease in gastric emptying
function causes a disease called “functional dyspepsia (FD)”.
Factors which affect gastric emptying time include
aging 11), gastrointestinal diseases like FD and peptic ulcers 12),diabetic state and diabetic disturbance in gastrointestinal
movement 13, 14), ingested food contents 15-17), ingested foodtemperature 15, 18).
Regarding food contents, a comparison study between
carbohydrates, lipids and proteins in healthy subjects showedthat gastric emptying function was the highest by highcarbohydrate food, then high-lipid food, and lowest by highprotein food 15).
The gastric emptying time was compared by the
combination of foods and beverages in the report whichshowed the time was elongated over 2 hours in “fried chicken
and tea”, “boiled barley and rice and tea” and “soybean curd
(tofu) and tea”, then “bread and tea” less than 2 hours, andfastest in “sole tea” less than 1 hour 17). Fried chicken intake
influences the gastric emptying function and may reduce thepostprandial hyperglycemia.
In another study, the gastric emptying time, measured in
10 healthy subjects (average age of 34 years) who received

various kinds of fluid-type foods, showed that lipid content
did not influence gastric emptying, however, it tended to be
slower with high calorie food 16).
In another study, the influence of 3 types of soup intake
was studied in a young group ( 23.0 ± 0.6 years) and an oldgroup ( 73.3 ± 1.6 years); soup without lipids, soup with lipids( 24.6 g triglycerides) and soup with lipid and lipase. The
results of gastric emptying time were longer in the old groupthan in the young group, and longer with soup with lipids thanwith soup without lipids, and additive lipase shortened thegastric emptying time 11).
When considering the influence of “gyudon” intake fromthe viewpoint of gastric emptying time, “gyudon” contains a
relatively high concentration of protein and is highly caloric,
thus its intake may cause a reduction of gastric emptying
function and an prolongation of gastric emptying time. As aresult, it may reduce the postprandial glucose elevation.

Nutrition balance

There is a possibility of mortality risk for an excessive
glucide restriction food 19). Thus, in order to make a plan
to improve eating habits, the reduction of postprandial
hyperglucosemia may be considerably good without excessive
carbohydrate restriction. The protein-fat-carbohydrate (PFC)balance is an index for ingested food which consists ofprotein, fats and carbohydrates which are 3 major nutrients.
PFC balance is considered to be ideally good if the ingested
food energy ratio is P (protein): 20%, F (fats): less than
25%, C (carbohydrates): 50%-60% as recommended by theGovernment 20-23).
When the PFC balance becomes adequate, thepostprandial glucose elevation may be reduced, furthermore,necessary amount of insulin decreases. Thus the load on
the pancreas becomes lighter, and thereby facilitating therecovery of pancreatic function, if exhausted. Recovering
insulin secretion may enhance glucose intake to muscle tissue
and adipose tissue, and consequently blood glucose levels canbe improved 24). In this study, the PFC balance of “gyudon”
without ginger was P = 12.45%, F = 31.74% and C = 55.83%.
Dietary fibers are also considered to be prevent
postprandial hyperglycemia 4). If, for example, a vegetablesalad were to be added to “gyudon”, this effect by
dietary fibers may be augmented as the fiber amountincreases in addition to onion-derived fibers in “gyudon”.
Generally, fast foods contain high lipids, high protein
and high calories, giving the impression that they tend toelevate the incidence prevalence of obesity or diabetes.
However, the previous study indicated that “gyudon”, acombination food with a staple food and a side dish, may beeffective to reduce glycative stress.
Also, by adding high protein and high fat materials to
steamed rice to the meal, the gastric emptying time may
be prolonged more than by only steamed rice; it may bepossible to reduce postprandial glucose elevation by anothermechanism. In this study, because the effectiveness was
judged based on the standard of glycative stress, as a result
the high fat and high protein foods were judged as favorable
to prevent postprandial glucose elevation. However, excessive
ingestion of lipids can cause lipid metabolism disturbance, it
is critical to pay attention to the means and amount of lipid
intake.

_ 70 _Glycative Stress Research

Conclusion

The present study indicates that, if a stable food and aside dish are combined in appropriate amounts, postprandial
glucose elevation can be reduced, and if an adequate fast foodis selected, it will give more favorable effects than the intake
of steamed rice alone.

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Statement of conflict of interest

A part of this study was supported by Yoshinoya Holdings
Co., Ltd.

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