Glycative Stress Research
Online edition : ISSN 2188-3610
Print edition : ISSN 2188-3602
Received : July 9, 20 16
Accepted : November 11, 2016
Published online : December 31, 2016

Original article

Influence of beef bowl (gyudon) materials on postprandial blood glucose.

Mari Ogura, Risako Kubo, Tomoko Kobayashi, Wakako Takabe, Masayuki Yagi, Yoshikazu Yonei
Anti-Aging Medical Research Center and Glycative Stress Research Center,
Graduate School of Life and Medical Sciences, Doshisha University, Kyoto, Japan

Abstract

Objectives: This study was designed to examine the inhibition of postprandial blood glucose (PBG) levels in four materialsof gyudon, a bowl of rice topped with beef. A previous report has already shown that beef-on-rice bowls, a fast food, areeffective to alleviate hyperglycemia of PBG levels and to reduce glycative stress, compared with the cases of intaking
steamed white rice alone. Based on the previous study, this study was intended to clarify how each material contributes tothe reduction of PBG levels: 1. Raw sauce, nama-tare; 2. Cooked sauce, ni-tare; 3. Meat; 4. Onion. Moreover, analysis wasadded about the relation between PBG levels and physical information.
Methods: A total of 19 healthy subjects (9 men and 10 women, mean age of 23.7 ± 5.1 years) were asked by written consent
for participation in the experiment and were given anti-aging medical examinations. Fasting BS levels of subjects were evaluatedon the day of the examination. Test food intake was lasted 10 minutes. 30, 45, 60, 90 and 120 minutes after starting to eat,
BS levels and the area under the curve (AUC) were measured by OneTouch Ultra View: Jonson & Jonson. 10 subjects, consistingof 9 subjects from the 19 subjects and one more newly added subject, (4 men and 6 women) ingested the following types oftest food: Steamed white rice + (One type of the test food material for one experiment) 1, 2, 3, 4 and 5 gyudon, a beef bowl.
The results of these test foods were compared to steamed rice alone.
Results: The case of one, nama-tare, raw sauce, showed no significant difference in PBG levels or AUC, compared with thecase of steamed white rice alone. The PBG levels and AUC were significantly lowered in the following cases, compared withthe case of steamed rice alone. 2. The PBG after 45 minutes in the cooked sauce, ni-tare, cases. 3. The PBG levels and AUC
after 45 and 60 minutes in the meat cases. 4. The PBG after 45 minutes in the onion cases. 5. The PBG levels and AUC after
45 and 60 minutes in the beef bowl, gyudon, cases. Four material items were placed in descending order of strength for
inhibitory effects on the elevation of glycemia; 3. meat > 2. ni-tare, cooked sauce = onion > nama-tare, raw sauce. Correlation
between the PBG and physical information was recognized between BMI and AUC by using secondary regression expression;r = 0.400, p = 0.009. AUC was minimized in BMI 23.3 kg/m 2. Physical functions of age showed no significant correlation,
mainly because the range of subject’s age was narrow in this study.
Conclusion: The component of beef had a great contribution, among ingredients of the beef bowl, to inhibit the PBG
levels and to reduce glycative stress. Moreover, further increasing the amount of onion and using more kinds of vegetables
would expand the potential of contribution to reduce glycative stress. This study also proved that the PBG levels were more
effectively inhibited as the BMI was closer to 23.

KEY WORDS: glycative stress, postprandial blood glucose, lipids, protein, body mass index (BMI)

Contact Address: Professor Yoshikazu Yonei, MD, PhD
Anti-Aging Medical Research Center / Glycative Stress Research Center,
Graduate School of Life and Medical Sciences, Doshisha University
1-3, Tataramiyakodani, Kyotanabe-shi, Kyoto, 610-0394 Japan
Phone/Fax: +81-774-65-6394 Email: yyonei@mail.doshisha.ac.jp
Co-authors; Ogura M, m-ogura@po.kbu.ac.jp ;Kubo R, kubontaname1840@gmail.com ; Kobayashi T, linari0823@gmail.com ;Takabe W, wtakabe@mail.doshisha.ac.jp ; Yagi M, myagi@doshisha.ac.jp_ 210 _

Glycative Stress Research 2016; 3 (4): 210- 221(c) Society for Glycative Stress ResearchGlycative Stress Research

Introduction

Glycation is a reaction where reducing sugar, such as
glucose, is nonenzymatically bound with protein and turns
into glycoprotein. Stress to organisms by reducing sugar andaldehyde load is designated as glycative stress 1, 2). Glycative
stress is a risk factor for age-related deterioration and could
be a progress factor in acceleration of skin aging and diabetic
complications. Treatment methods for reducing glycative
stress are categorized as follows: reduction of postprandial
hyperglycemia, inhibition of advanced glycation end product(AGE) formation, and enhancement of AGE degeneration andexcretion palpation. One of the methods for the inhibition of
postprandial hyperglycemia is the dietary method, which is
the method of choice. The diet of eating vegetable first has
been commended because dietary fibers should be ingested
before carbohydrates.
The previous research showed three groups that werecompared in the examination of postprandial blood glucose(PBG). The groups were gyudon with ginger, gyudon without
ginger and steamed rice. As a result, there was no significant
difference in the area under curve (AUC). However, thechanges in blood glucose values had a significant differencecompared with steamed rice. They were measured 15
minutes and 60 minutes after the intake of gyudon withginger, and the PBG levels were significantly low. Measured
60 minutes after the intake of gyudon without ginger, thePBG levels were significantly low 3). The findings of theprevious research suggested that gyudon is an effective
diet to inhibit postprandial hyperglycemia. Following theseprevious findings, this study was designed to examine thefood items contained in gyudon to elucidate how each item
could function to inhibit postprandial hyperglycemia.

Methods
Subjects

Subjects were recruited from among persons with
relevance to the Department of Anti-Aging Medicine,
Doshisha University Faculty of Life and Medical Sciences as
the previous experiment had been performed 3-5). The subjects
were comprised of healthy people ages 20 years or older
who did not meet any of the following exclusion criteria:
people with food or drug allergies, pregnant or lactating
women, people under treatment with medication or followup, people who were diagnosed with diabetes mellitus,
people with obvious cardiopulmonary functional disorder,
people on therapeutic medication for hypertension, people
with a past history of gastrointestinal surgery, or people withsuspicion of infectious diseases. Other subjects judged by theinvestigators as being inappropriate for inclusion in the study
were also excluded from the study.
A total of 19 healthy subjects (9 men and 10 women,mean age of 23.7 ± 5.1 years, height of 164.0 ± 6.4 cm,
weight of 55.2 ± 7.7 kg, body mass index [BMI] of 20.4 ±2.2 kg/m 2 ) were given anti-aging medical checkups 6 - 8) andexaminations of blood glucose levels by the way of intaking
the standard food of steamed rice. 10 subjects, consisting ofnine subjects from the nineteen subjects and one more newly
added subject, were given sufficient explanations of the study
and agreed to it with prior written consent. Blood glucose
tests were performed for each food item contained in gyudon.

Protocol for the blood glucose test

A blood glucose test was performed, as previously
reported 3 -5), according to the unified protocol establishedby the Japanese Association for the Study of Glycemic
Index (JASGI) 9, 10). On the day before the test the following
was prohibited: strenuous exercise, taking meals after 8:00
p.m, surfeit, overdrinking, and staying up late at night. If
the subject felt ill on the day before the test, or prior to or
during the test, the test was postponed or terminated. On the
day of the test, the reference diet and test food were takenover a period of 5 to 10 minutes with about 30 chews permouthful required. Blood glucose was measured at 15 (thesecond time), 30 (the third time), 45 (the fourth time), 60 (thefifth time), 90 (the sixth time), and 120 minutes (the seventhtime) after the start of taking each test food. AUC was
calculated, using a PBG variation diagram. A glucose meterfor self-monitoring (OneTouch Ultra View: Jonson & Jonson,
Chiyoda-Ku, Tokyo, Japan) was used as test equipment.

Test foods

The test foods in this study were steamed white rice(200 g), raw sauce, nama-tare, of gyudon (35 g), cookedsauce, ne-tare of gyudon (35 g), beef of gyudon (65 g), onionof gyudon (25 g) and gyudon (325 g, the whole quantity).
Nama-tare had the same ingredients and the same compound
ratio of ne-tare, but was not heated. Raw sauce of gyudon,
cooked sauce of gyudon, beef of gyudon, onion of gyudon
and gyudon were provided by Yoshinoya Holdings Co., Ltd.
(Nakano-ku, Tokyo, Japan). Steamed rice, as the standard
food, were provided by Sato No Gohan (Sato Foods Co., Ltd.
Niigata, Japan).

Anti-aging checkup

The anti-aging medical checkups provided the evaluationsof the functional age including muscle age, bone age, hormone
age, neurological age and blood vessel age. At the same time,height, weight, BMI and blood pressure were measured. To
calculate the functional age of subjects, Age Management
Check was used as previous article 6-8) (Ginga Kobo; Nagoya,Japan). Muscle age: Muscle mass and body tissue were
evaluated with the bioelectric impedance method (a highaccuracy body composition meter, Physion MD, Nippon
Shooter, Chiyoda-ku, Tokyo, Japan). Bone age: The stiffnessof bones was evaluated with a supersonic method (A-1000:
GE Yokokawa Medical System, Hino, Tokyo, Japan). Hormone
age: Biochemical examination of blood was conducted.
Fasting plasma glucose, low-density lipoprotein (LDL)cholesterol, high-density lipoprotein (HDL)-cholesterol,hemoglobin A1c, immunoreactive insulin, insulin-like growth
factor-I (IGF-I), dehydroepiandrosterone-sulfate (DHEA-s),
cortisol, and triglyceride concentration levels in serum were
measured. Neurological age: Executive brain function was
evaluated with the Wisconsin Card Sorting Test (WCST).
Blood vessel age: Estimated vascular age was evaluated byusing Dyna Pulse SDP-100 Fukuda Denshi (Bunkyo-ku,
Tokyo, Japan). The fingertip acceleration pulse wave wasdetermined using the plethysmometer.

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Postprandial Blood Glucose after Beef Bowl (Gyudon) Material Intake

Statistical analysis

The amount of change, Δ of blood glucose value, wasobtained by subtracting the zero-minute values from theblood glucose values, which were measured over time after
starting to eat items of test food. AUC was evaluated fromzero minutes to 120 minutes. Statistical analysis for comparison
was based on one-way analysis of variance: unpaired Tukey
Test, paired LSD Test (least significant difference), paired
Holm Test, and paired t-test (IBM SPSS Statics23, IBM
Japan, Minato ward, Tokyo, Japan).

Ethical Considerations

The examinations of this study were conducted incompliance with the ethical principles of the Declaration of
Helsinki (Note of Clarification added at the 2004 World
Medical Association General Assembly in Tokyo), Japan’s
Act on the Protection of Personal Information, with reference
to the 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, Labor and Welfare, and Ministry of Education,
Culture, Sports, Science and Technology. Further, theDoshisha University Ethics Review Committee on Researchwith Human Subjects was held to deliberate the ethics andvalidity of this study. Under their approval, this clinicaltest was conducted with advanced registration (Application
number: 15014, UMIN# 000018458).

Results

Comparison between five materials of gyudon andsteamed rice were made. Fig. 1- 6 shows the transition in
the blood glucose level from zero to 120 minutes. Table 1-2
shows the comparison of each AUC and the comparisonof PBG at 45 minutes. AUC comparison based on one-way
analysis of variance recognized the significant differences (p= 0.009). Multiple comparisons by the LSD Test and Holm
Test (three-pair comparison) presented the followings.
Significant differences were shown in the comparison
between ③ meat + steamed rice and ⑥ steamed rice, andalso the comparison between ⑤ gyudon and ⑥ steamed
rice (p < 0.05). In the comparison, 45 minutes after eating,significant differences were also noted in the comparison
between ③ meat + steamed rice and ⑥ steamed rice, andalso in the comparison between ⑤ gyudon and ⑥ steamed
rice (p < 0.05). P value in result reports showed the result of
the paired t-test.
① nama-tare + steamed rice and ⑥ steamed rice, incomparison, showed no significant differences in each timeon blood glucose transition and also no significant differencesin AUC (Fig. 1 ).
② Ni-tare case: The PBG at 4 5 minutes in the case of ②
ni-tare + steamed rice showed 67.4 ± 7.4 mg/dL and ⑥
steamed rice showed 75.3 ± 5.3 mg/dL; the former was
significantly lower than the latter (p = 0.048). There were no
significant differences in AUC in either two cases (Fig. 2).
③ Meat case: In the level of 45 minutes, ③ meat + steamed
rice group showed (43.4 ± 3.4 mg/dL) and ⑥ steamed
rice group showed (75.3 ± 5.3 mg/dL); the former was

significantly lower than the latter (p = 0.001, Fig. 3 ). In
the level of 6 0 minutes, the former (41.1 ± 1.1 mg/dL) was
significantly lower than the latter (63.4 ± 3.4 mg/dL, p =0.008). In AUC, the former (3,793 ± 793 mg・min/dL) was
significantly lower than the latter (5,333 ± 333 mg・min/dL,
p = 0.001).
④ Onion case: The comparison between ④ onion + steamed
rice and ⑥ steamed rice showed that the former (64.3 ±4.0 mg/dL) was significantly lower than the latter (75.3± 5.3 mg/dL, p = 0.044, Fig. 4 ). There was no significant
difference in AUC between these two cases.
⑤ Gyudon case: The comparison between ⑤ gyudon and⑥ steamed rice showed that the former (44.6 ± 4.6 mg/dL)
was significantly lower than the latter (75.3 ± 5.3 mg/dL)
in the evaluations 4 5 minutes after eating (p = 0.001, Fig.
5 ). Also, in the comparison of 60 minutes after eating, the⑤ gyudon case (33.6 ± 3.6 mg/dL) was significantly lower
than the ⑥ steamed rice case (63.4 ± 3.4 mg/dL, p = 0.008).
In comparison of AUC, the former (3,996 ± 996 mg・min/dL) was significantly lower than the latter (5,333 ± 333 mg・
min/dL, p = 0.011).
These results, as described above, pointed out that meat
greatly influenced blood glucose levels. Therefore theexamination was conducted to examine the comparison
between ③ meat + steamed rice and ⑤ gyudon to find whichcase inhibited the elevation of blood glucose levels more
(Fig. 6 ). As a result, the former (39.8 ± 9.8 mg/dL) was
significantly lower than the latter (60.8 ± 0.8 mg/dL) in theevaluation of 30 minutes (p = 0.034). There was no significant
difference in the evaluation of AUC.
The evaluation data, which were obtained in the antiaging medical checkups, were compared with the evaluationof AUC to examine the correlation. The functional age,
including muscle age, bone age, hormone age, neurologicalage and blood vessel age, showed no significant correlation.
However, there was a weak correlation recognized between
AUC (y) and BMI (x) by the secondary regression expression(r = 0.400, p = 0.009, Fig. 7 ) among the examinations whichwere conducted of physical information (height, weight,
BMI, body composition, maximal blood pressure, diastolicpressure and fasting plasma glucose). The regression formula
was y = 63.804 x 2 - 2,977.1x + 39,434 and the regression
line indicated that AUC showed the minimum value at BMI
23.3 kg/m 2 .

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90

ΔBlood Glucose (mg/dL)

80
70⑥ Steamed rice60

① Nama -Tare +Steamed rice

50
40
30
20
10
0
0

20

40

60

80

100

120

140

Time (min)Fig. 1. ΔBlood glucose in ① nama-tare + steamed rice and ⑥ steamed rice. Results are expressed as mean ± standard
error mean, n = 10. Nama-tare is a raw source without heating.

100

ΔBlood Glucose (mg/dL)

90
80⑥ Steamed rice

70
60

② Ni - Tare +Steamed rice

＊

50
40
30
20
10
0
0

20

40

60

80

100

120

Time (min)Fig. 2. ΔBlood glucose in ② ni-tare + steamed rice and ⑥ steamed rice. Results are expressed as mean ± standard

error mean, * p<0.05 by paired t tests, n = 10. Ni-tare is made by boiling down both nama-tare (a raw source)and shaved pieces of dried bonito or other staffs together.

_ 213 _

Postprandial Blood Glucose after Beef Bowl (Gyudon) Material Intake

90

ΔBlood Glucose (mg/dL)

80
70⑥ Steamed rice

60
＊＊

50

③ Meat +Steamed rice

＊＊

40
30
20
10
0
0

20

40

60

80

100

120

Time (min)Fig. 3. ΔBlood glucose in ③ meat + steamed rice and ⑥ steamed rice. Results are expressed as mean ± standard error

mean, ** p<0.01 by paired t tests, n = 10. AUC is significantly lower in ③ meat + steamed rice than that in ⑥
steamed rice (p<0.05). AUC, area under curve.

90

ΔBlood Glucose (mg/dL)

80
70⑥ Steamed rice

60
＊

50

④ Onion +Steamed rice

40
30
20
10
0
0

20

40

60

80

100

120

140

Time (min)Fig. 4. ΔBlood glucose in ④ onion + steamed rice and ⑥ steamed rice. Results are expressed as mean ± standard error
mean, * p<0.05 by paired t tests, n = 10.

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100

ΔBlood Glucose (mg/dL)

90
80⑥ Steamed rice

70
60

⑤ Beef bowl

＊＊

50

＊＊

40
30
20
10
0
0

40

20

60

80

100

120

Time (min)Fig. 5. ΔBlood glucose in ⑤ beef bowl (gyudon) and ⑥ steamed rice. Results are expressed as mean ± standard error

mean, ** p<0.01 by paired t tests, n = 10. AUC is significantly lower in ⑤ beef bowl than that in ⑥ steamed rice(p<0.05). Beef bowl (gyudon) consists of steamed rice, meat, onion and ni-tare; AUC, area under curve.

80

ΔBlood Glucose (mg/dL)

70

＊

60

③ Meat +Steamed rice50

⑤ Beef bowl

40
30
20
10
0
0

20

40

60

80

100

120

140

Time (min)Fig. 6. ΔBlood glucose in ③ meat + steamed rice and ⑤ beef bowl (gyudon). Results are expressed as mean ± standard
error mean, * p<0.05 by paired t tests, n = 10. Beef bowl (gyudon) consists of steamed rice, meat, onion and Nitare.

_ 215 _

Postprandial Blood Glucose after Beef Bowl (Gyudon) Material Intake
Table 1. Comparison of each AUC

p value vs. ⑥ steamed rice

AUC
(mg・min/dL)

Tukey

LSD *

Holm **① Nama-tare + steamed riced

5097 ± 632

1.000

0.660

> 0.05② Ni-tare + steamed rice4979 ± 680

0.998

0.291

> 0.05③ Meat + steamed rice3793 ± 482

0.374

0.024

0.024

④ Onion + steamed rice5226 ± 685

1.000

0.786

> 0.05⑤ Beef bowl (gyudon)

3996 ± 444

0.533

0.011

0.033

⑥ Steamed rice5333 ± 533

Results are expressed as mean ± standard error mean, n = 10.* There is a significant difference in AUC in 6 groups with p = 0.009 by one-way
ANOVA. ** Holm analysis is conducted in 3 pair cases, no significant difference when the number of cases is more than 3. AUC, area under curve;
ANOVA, one way analysis of variance; LSD, least significant difference: Nama-tare, the raw source without heating; Ni-tare is made by boiling
down both nama-tare and shaved pieces of dried bonito or other staffs together.

Table 2. Comparison of Δblood glucose at 45 minutes.

p value vs. ⑥ steamed rice

ΔBlood glucose(mg /dL)

Tukey

LSD *

Holm **① Nama-tare + steamed riced

67.8 ± 8.8

0.974

0.399

> 0.05② Ni-tare + steamed rice

67.4 ± 5.5

0.968

0.048

> 0.05③ Meat + steamed rice

4 3.4 ± 5.5

0.028

0.002

0.018

④ Onion + steamed rice

6 4. 3 ± 8.6

0.878

0.044

> 0.05⑤ Beef bowl (gyudon)

4 4.6 ± 6.8

0.037

0.001

0.009

⑥ Steamed rice

75. 3 ± 7.3

Results are expressed as mean ± standard error mean, n = 10. * There is a significant difference in 45-minute Δblood glucose in 6 groups with p <0.001 by one-way ANOVA. ** Holm analysis is conducted in 10 pair cases. ANOVA, one way analysis of variance; LSD, least significant
difference: Nama-tare, the raw source without heating; Ni-tare is made by boiling down both nama-tare and shaved pieces of dried bonito or otherstaffs together.

_ 216 _Glycative Stress Research

9000
8000

AUC (mg・min/dL)

7000
6000
5000
4000
3000
2000
1000
0
15

17

19

21

23

25

27

BMI (kg/m2 )Fig. 7. Correlationbetween BMI and AUC of postprandial blood glucose.

y = 63.804x 2 - 2976.1x + 39434, p = 0.009, r = 0.400, n = 19. BMI, body mass index; AUC, area undercurve in ⑥ Steamed rice.

Discussion

This study examined how the materials of gyudon
influenced PBG levels. Gyudon is a rice bowl topped withbeef. Moreover, analysis covered the influences caused bypersonal differences. This study clarified the PBG levels in
the experiments where staple food and each food item wereingested at the same time. Although the order of eating fooditems was an important factor 11, 12), this study was rather
focused on the individual evaluation for the inhibition of
the elevation of PBG levels after simultaneously ingesting
staple food (carbohydrate) and subsidiary food items,
onion (dietary fiber), meat (protein and lipid), tare, andsauce (carbohydrates and amino acid). The results of thisexamination proved that meat most effectively functioned
to inhibit the elevation of glycemia among materials
comprising gyudon. Onion (dietary fiber) followed meat.
Main nutrients are written in parentheses after the name ofmaterial. Concerning physical information, BMI had thegreatest influence on change of blood glucose levels.
The results proved that the case of ③ meat + steamed
rice and the case of ⑤ gyudon, both of which contained
meat, remarkably inhibited the elevation of glycemia whensamples one to five were compared with ⑥ steamed rice.
⑤ gyudon more effectively inhibited PBG levels than ⑥
steamed rice, while ⑤ gyudon had more nutrients than
⑥ steamed rice. The former had five grams more ofcarbohydrates, 13 g more of protein and 21 g more of lipids
than the latter. The case of ③ meat + steamed rice had lessamount of carbohydrate by only two to three grams than thecase of ⑥ steamed rice. Considering these results, it could
be proved that protein and lipids could function to inhibit theelevation of glycemia.
The statistical analyses of this study employed one-way
analysis of variance. Unpaired Tukey Test, paired LSD Test(least significant difference), and a paired Holm Test were
performed. Type Ⅰ error (Even when there is no difference,
it is misjudged and “there is difference” is shown) and typeⅡ error (Even when there is a difference, it is misjudged and“there is no difference” is shown) must be comprehensively
reviewed 13). Tukey Test showed that there was no significant
difference in multiple comparison of AUC. LSD Test showedthat there was significant difference in the comparisons
between ③ and ⑥ and between ⑤ and ⑥ . The Tukey Test
tends to be too strict in multiple comparisons like paired
cases in this examination. There were possibilities of typeⅡ error. However, a paired t-test was performed in a mannerof diversified combinations, and the t-test showed almost thesame p value which was obtained by the LSD Test. The resultof the statistical analysis tends to be lenient and Type Ⅰ error
must be considered. For AUC of the Holm Test there was asignificant difference when three pairs were selected fromten pairs. However, the significant difference disappeared
when four pairs were selected.
In the results of the analysis for the 45 minute evaluation,
the Tukey Test, LSD Test and Holms Test all showed that
there were significant differences in the comparisons between③ and ⑥ and between ⑤ and ⑥. The Holm Test recognizeda significant difference when ten pairs were selected. The_ 217 _

Postprandial Blood Glucose after Beef Bowl (Gyudon) Material Intake
results of the Holm Test could be found interesting as astatistical description to make a comprehensive judgment ofType Ⅰ and Type Ⅱ error.
There have been several studies which examined
how the proteins intaken by eating meals influence thecarbohydrate metabolism and insulin secretion. However,examinations of influences on the PBG levels were limited
in number. Generally, proteins secrete a glucose-dependent
insulinotropic polypeptide, which accelerates insulin
secretion 14). Lipids influence smooth movements through thegastro-entero-pancreatic and nervus vagus systems and alsofunction to lower the gastric emptying rate 15). Intaking protein
plays a notable role in the secretion process of insulin andglucagon through incretin secretion 16). Incretin and pancreatichormones were examined over five hours after intaking
lipids (oleic acid) and proteins (milk, egg proteins). It waspointed out that the secretion of GIP (glucose-dependent
insulinotropic peptide) played a notable role in secreting
pancreatic hormones in the initial stage of intaking protein,while lipids and proteins accelerated the secretion ofincretin and pancreatic hormones 16). Furthermore, someprevious studies reported that intaking proteins could
inhibit the elevation of blood glucose two to three times
more effectively as a lipid and that there was no multipliereffect between them 17). The reports also stated that the PBG
levels were evaluated in comparison among standard food,
food containing excessive carbohydrates, food containing
excessive lipids, and food containing excessive proteins.
The results of previous examinations proved that foodcontaining excessive proteins slowed the elevation of blood
glucose level the most drastically. The second best was foodcontaining excessive lipids, the third was standard food, andfood containing excessive carbohydrates had a remarkably
high value of elevation of blood glucose 18). Similarly, theexperiments of this study showed that among the nutrientsof beef, protein was the most likely to contribute to inhibit
the elevation of blood glucose level.
④ Onion followed ③ meat in the inhibition of the blood
glucose elevation. When the amount of onion nutrient wascalculated, assuming that the onions used in this experiment
had as much nutrient as ordinary onions, the onions of Test
Food 3 contained more dietary fiber by 0.4 g/cooked onion
25 g than the Test Food ⑥ steamed rice alone.
Dietary fiber has the diversified mechanisms ofgastrointestinal tract functions to influence the change inblood glucose levels 19 -32). Previous studies stated that
gastrointestinal tract contents formed gel in the uppergastrointestinal tract, which boosted viscosity, lowered themoving speed in the gastrointestinal tract and the digestion
absorption speed, and slowed carbohydrate absorption.
Furthermore, mechanical stimulus promoted the secretion of
glucagon peptide-1, which accelerated insulin secretion 33).
These two functions inhibited the elevation of PBG levels. It
was recommended that the amount of dietary crude fiber a
day should be one gram per 100 kcal intaken in a day 19).
Breakfast containing sufficient dietary fiber is, inparticular, recommended. This reduces ghrelin (the hormone
causing the feeling of hunger) from stomach, and promotes
intestinum tenue, GIP (glucose dependent insulinotropic
polypeptide), cholecystokinin and peptide YY (hormones
causing the feeling of fullness) 34). This also contributes
to weight control. Dietary fiber inhibits the secretion ofghrelin 35).
This examination proved that the most effective food
item of all the items was meat (protein and lipid). Onions(dietary fiber) followed meat. Lipids, as nutrition, could
influence PBG levels. A previous report referred to theeffects on the elevation of the PBG level by simultaneously
intaking steamed rice (carbohydrate 50 g), as a staple food,and dietary fiber, vinegar, soybean curd, milk and cheese as
the secondary foods. The report stated that AUC was reduced
when steamed rice was intaken with 200 g of soybean curd
and milk and cheese, which contained a great deal of lipids
and proteins 22). It was assumed that a certain amount oflipids and protein were required to reduce the elevation of
the PBG level.
Free fatty acids plays a notable role of enhancing thesecretion of insulin from pancreatic β cells, which could
make a contribution to reducing the elevation of the PBG
level 36). However, high fat diets should not be necessarily
encouraged, because high fat diets have high calorie
counts and, what is worse, they harm the intestinal bacteria
flora 37-41). Linseed bread contains a great amount of lignin
and α-linolenic acid and inhibits the elevation of the PBG
level 42). Active intake of α-linolenic is regarded as desirable.
The experiments of this study also suggested that thecomparison between nama-tare, raw sauce, and ni-tare,cooked sauce, showed differences in the PBG curve. In thecomparison between ① nama-tare + steamed rice and ②
ni-tare + steamed rice, the case of ① nama-tare + steamed
rice showed no significant difference in any evaluation,
but the case of ② ni-tare + steamed rice was significantly
lower in blood glucose levels than the case of ⑥ steamed
rice at the evaluation of 45 minutes after intaking. It could
be explained that proteins and lipids of meat could eluteinto ni-tare, and these components could function to inhibit
the elevation of the PBG level. However, in this experiment,
eluted substances were not detected.
② ni-tare, ③ meat and ④ onion, excluding ① namatare, showed the inhibition of blood sugar elevation.
Therefore, it was expected that ⑤ gyudon was supposed
to function the most effectively because of the fact thatgyudon contains all the effective food items, ②, ③ and ④.
However, the test results oppositely showed that ⑤ gyudon
had higher blood sugar levels than ③ meat + steamed riceat the evaluation of 45 minutes after eating. The possible
reason that ⑤ gyudon, which contained all the food items,
was not the strongest inhibitor was that ② ni-tare containedcarbohydrates, including sugar, as seasoning. However,
judging from the experiments where ① nama-tare did notshow high glucose levels, ① nama-tare + steamed rice and② ni-tare + steamed rice did not show high levels comparedwith ⑥ steamed rice. The amount of carbohydrates whichwere contained in tare, sauce, were not regarded as a big
factor influencing the fluctuation of blood glucose levels.
Considering these results above, it was clearly suggested
that gyudon made a great contribution to the inhibition of
the elevation in PBG levels, not thanks to dietary fiber, but
thanks to protein (meat). Among the subject food items ofthis experiment, meat was larger in quantity by 40 g thanonion. The effectiveness of the inhibition of it seemed to beremarkable.
This study reconfirmed that the intake of gyudon could
inhibit the blood sugar elevation and reduce the glycative
stress compared with the intake of steamed rice alone.

_ 218 _Glycative Stress Research

The further goal is to arrange the nutrition balance byanalyzing the nutritional components among proteins, lipids,
and carbohydrates (sugars, dietary fiber), although finetuning and replacement experiments of food items were not
performed in this study. New menus would be created toenhance the effects on the inhibition of blood glucose levels
compared with steamed rice alone. The misunderstandingthat gyudon “fast foods could be undesirable for health”
would be swept away and gyudon would be fairly evaluatedas reducing glycative stress and a nutritionally well balanced
diet.
This study examined the correlation between the
results of physical measurements and the changes in PBG
levels. Significant differences were recognized only inthe evaluation of BMI. However, it was elucidated that the
reduction of blood glucose levels was recognized when BMI
was closer to 23, which is the standard value of BMI. It has
been reported that the condition of a BMI of 23 enables
life support and prevention of diseases, including diabetes,
to be easily reached. This study confirmed the correlation
between BMI and PBG levels. It was also suggested thatpeople who have BMI values closer to the standard valueof 22 have a tendency to have higher muscle mass thanpeople with BMI values not close to 23. It is considered that,
because glucose is consumed by the muscle, muscle mass
could affect the inhibition of the blood glucose elevation.
However, the results of this research require considerationof the ratio of subjects. The number of subjects with BMI
values lower than 23 was greater than that of subjects with
BMI values higher than 23. Moreover, it must be consideredthat the influences by the cases of low AUC could besizable. These problems will require further examination.
It was assumed that there was no significant differencein any category, except for BMI, partly because there wereno major differences recognized in any categories of antiaging checkup where the subjects of the examination wereyoung, age 25.2 on average. Furthermore, examination ofsubjects in a wider range of ages would have the possibility
that categories other than BMI could have a relation with thefluctuation in PBG levels.

of glucose and the amplifiers, including free fatty acids 36).
The examinations of this study did not completely cover
all the factors. As all the studies have research limitations,the information which was obtained from the reactions ofspecific nutrients in the experiments could not explain all
the phenomena in real life. Foods in daily life are usuallyintaken in a manner of a mixed diet.

Conclusion

This study concluded that meat, a food item of gyudon,
had the greatest effect on the inhibition of glycative stressin these examinations. Increasing the amount of onion andusing more kinds of vegetables would expand the potential
to reduce glycative stress. This study also proved that BMI
was determined as a physical finding which could affect the
PBG level, which tended to be more effectively inhibited as
the BIM was closer to 23.

Conflict of Interest Statement

The present study was partly supported by Yoshinoya
Holdings.

Acknowledgments

This study was presented at “the 16th Meeting of theJapanese Society for Anti-Aging Medicine” on June 1012, 2016, at Yokohama, Japan. A part of this study was
supported by the Japanese Council for Science, Technology
and Innovation, SIP (Project ID 14533567), “Technologies
for creating next-generation agriculture, forestry andfisheries” (funding agency: Bio-oriented Technology
Research Advancement Institution, NARO).We wereindebted to Mr. Takahiro Honbu for the statistical analysis.

Research Limitations

Various factors are the cause for the fluctuation in
the PBG levels of humans, such as calories of food, eatingorder 11, 12), nutrition balance among glucose, protein, lipids,
dietary fiber, eating speed, the number of chewing times,
gastrointestinal function, pancreas exocrine functions 43)
and several others. Interdigestive migrating contractions(IMC), a strong contraction, occurred every two hours
in digestive organs at the time of hunger 44). When foodis intaken, the movement drastically turns into a weakcontraction compared with IMC. This movement occurs andis sustained which moves food through the gastrointestinal
tracts. The movements of digestive organs concerning
food intake are classified into three phases: preingestion
phase, ingestion phase, and postingestion phase 44). Manykinds of peptic juices are secreted and contribute to thedigestion and the absorption of food. The secretion of
insulin from the pancreas β cell is adjusted in a complicatedmechanism by the stimulators, which are mainly composed_ 219 _

Postprandial Blood Glucose after Beef Bowl (Gyudon) Material Intake

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