Original Article

診療と新薬 2018; 55: 217‑224

Eﬃcacy of Jerusalem Artichoke in Healthy Japanesewith Postprandial Plasma Glucose Level:

診療と新薬 WebA Randomized, Double-blind, Placebo-controlled Study

Masatomo NAJIMA1) ／ Taro SHIRAKAWA2) ／ Otoha UEKI3)● Abstract
Objective: The objective of this study is to examine how the ingestion of Jerusalem artichoke containing inulin
contributes to inhibiting the increase of postprandial plasma glucose level.
Methods: A randomized, placebo-controlled, double-blind study was conducted to elucidate how the ingestionof a supplement made from the Jerusalem artichoke containing inulin lowers blood glucose level. In this study
we measured the postprandial plasma glucose level after OGTT as the primary outcome. Furthermore,
adverse events were collected by means of a written questionnaire during the study.
Results: From all of 61 applicants, 13 were eliminated due to not-meeting inclusion criteria. The 48 subjects
were randomly assigned to an intervention group and made a start with ingestion. 21 were withdrawn due tofever or business, and the remaining 27 subjects completed the study. Thus, data obtained with 27 subjects(KK: 14〈M; 5, F; 9〉, Placebo: 13〈M; 3, F; 10〉) was used for the analysis of eﬃcacy. At Visit 1 (0-week) and
Visit 3 (12-week), a signiﬁcant diﬀerence was observed between two groups; the changes from FPG to 0.5
h-OGTT. At 0-week, KK did not present a signiﬁcant diﬀerence in 2 h-OGTT, meanwhile Placebo yielded asigniﬁcant increase. Also, at 12-week, KK decreased compared to FPG in 2 h-OGTT, while no decrease wasobserved in Placebo. No adverse eﬀects were observed after the ingestion of the test product.
Conclusion: We found out that the ingestion of the supplement made from Jerusalem artichoke containing
inulin contributed to inhibiting the increase of postprandial plasma glucose level. In addition, no safety-related
matter occurred during the test period.
Key Words : Jerusalem artichoke, inulin, plasma glucose level

1. INTRODUCTION
According to National Health and Nutrition Survey
conducted by the Ministry of Health, Labor and Welfare( MHLW ) in 2016 1), the estimated numbers of both theprevalence of diabetes and the risk of developing diabetes
are about 10 million people in Japan. Diabetes, along withhypertension or dyslipidemia, are often called Lifestylerelated diseases , and it is said that one of the major
causes for these diseases is obesity triggered by dietary
habits and/or the lifestyle habits of modern people 2). As
the basic direction for comprehensive implementation ofnational health promotion, the MHLW implemented the
movement called Health Japan 21 3). Since the control ofblood glucose level is important to prevent the diabetes,
Glycemic index (GI) 4), the index determining the eﬀect of
diﬀerent foods on blood glucose, came to public attention.
The active consumption of foods with low GI cancontribute to preventing a rapid increase in blood glucose
1) JACTA (Japan Clinical Trial Association)2) AKASAKA FREUDE CLINIC
3) GRANDE CO., LTD.

level.
Potatoes are regarded as a popular source of dietarycarbohydrate worldwide, and are generally considered to
be a high glycemic index (GI) food 5). Jerusalem artichoke,on the other hand, contain little starch, and are delicious
tubers that act quite similarly to potatoes when cooked.
The main ingredient of Jerusalem artichoke is the soluble
ﬁber called Inulin 6), and therefore they are considered asa low GI food 7). The consumption of Jerusalem artichoke
can contribute to inhibiting the elevation of the
postprandial glucose levels and is also expected to fend of
diabetes.
However, in Japan the cultivation area of Jerusalem
artichoke is limited, and this fact hinders easy ingestionin our daily life. If there is a supplement-type ofJerusalem artichoke which is dried and powdered, it will
promote distribution and enable us to intake them moreeasily in our daily life.
In this study, we conducted a randomized, placebocontrolled, double-blind study to verify the eﬃcacy of the
supplement containing Jerusalem artichoke forpostprandial plasma glucose level, by using healthy
Japanese adults as test subject. At the same time, we also

34 （218）

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第 3 号（2018 年 3 月）

examined the safeness of ingesting the supplement.

Table 1 Ingredient (ratio)

2. METHODS

Item

KK

Placebo

Jerusalem artichoke roasted powder

59.4%

−

Jerusalem artichoke powder
Calcium stearate
LactoseIndigestible dextrin
Crystalline cellulose
Magnesium stearate

39.6%
1%
−
−
−
−

−
−
84%
10%
5%
1%

Total

100%

100%

2.1. Trial design
A randomized, placebo-controlled, double-blind study was
conducted with the aid of a fund GRANDE CO., LTD.
(Fukuoka) at Japan Clinical Trial Association ( JACTA,Tokyo). The baseline examination was performed for theapplicants between May and June, 2017. Based upon thisexamination, the screening and the assignment was
carried out. Then, the intervention started on June 24th
until September 16th, 2017 (12 weeks). This study was
conducted in accordance with the ethical principles of thedeclaration of Helsinki. The study protocol was approvedby the Institutional Review Board of Pharmaceutical Law
Wisdoms (Tokyo). Written informed consent was
obtained from all Subjects. This trial was registered at
UMIN Clinical Trial Registry (Trial ID:
UMIN000027027).
The allocation of the test product to the subjects was
carried out by the person in charge of allocation. The
allocation list was sealed and strictly controlled in a safe
deposit box of JACTA until the end of the study.
2.2. Subject
Healthy subjects participated in the present study. All of
the subjects in this study were public volunteers who had
enrolled in the monitor bank of TRIBELATECORPORATION (Tokyo), recruited from April throughJune, 2017.
2.2.1. Inclusion criteria(1) Healthy Japanese males and females aged between 20
and 59 years;(2) Individuals fasting plasma glucose (FPG) level lessthan 126 mg/dL;(3) Individuals postprandial plasma glucose (PPG) level 2hours after oral glucose tolerance test, 2 h-OGTT lessthan 200 mg/dL.
2.2.2. Exclusion criteria(1) Subjects with food allergies;(2) Subjects who are pregnant or lactating;(3) Subjects who consume medicinal product which may
inﬂuence the outcome of the study;(4) Subjects who consume food which may inﬂuence theoutcome of the study;(5) Subjects who are judged as unsuitable for the study by
the principle investigator.
2.3. Randomization
From all 61 applicants, 13 were eliminated according to
the exclusion criteria. The inclusion /exclusion criteria
was judged by the principle investigator. All subjects
were sequentially allocated to Group A (n ＝ 23, M; 9, F;
14) and Group B (n ＝ 25, M; 11, F; 14) using a random
number table. In the process of subject assignment,
background factors such as gender, age, and FPG weretaken into consideration to avoid biased distribution.
Subjects in Group A ingested placebo and subjects inGroup B ingested the test sample for 12 weeks.
2.4. Description of test foods and blinding
The test product was Kin-no-KIKUIMO ( KK )containing inulin prepared by GRANDE CO., LTD. The
amount of daily intake was 7 tablets (1 tablet weighs 250
mg, therefore 7 tablets weigh 1,750 mg), which include
inulin 750 mg per day. The Placebo does not include
Jerusalem artichoke or inulin. Both tablets wereindistinguishable in shape, color, or taste, and weremanaged by an identification symbol. All involved wereblinded. Table 1 shows ingredient of the samples.
2.5. Experimental procedures
2.5.1. Experimental protocol
Subjects consumed 7 tablets of the supplement with hotor cold water per day before dinner for 12 weeks. Clinicalvisits were scheduled every 6 weeks at Higashikoganei
Sakura Clinic, Tokyo. They consumed the tablets justbefore consuming loading food on the visit of 6w and 12
w. Subjects were instructed as follows: to take theassigned supplement as indicated; to maintain their usual
lifestyles and habits; to avoid excessive amounts of food,drink, and alcohol; to maintain a daily record of every
meal eaten and to use a pedometer during the test period;
and to send the diary to the study coordinator.
2.5.2. Outcome
The objective of this study is to elucidate the effect onlowering blood glucose level by consuming the Jerusalem
artichoke containing inulin. To evaluate this objective,
the postprandial plasma glucose level after OGTT (Oralglucose tolerance test) was measured as the primary
outcome. Furthermore, other blood biochemicalparameters were recorded to evaluate the safety of KK,
and adverse events were collected by means of a written
questionnaire during the study. According to theschedule shown in Table 2, we measured parameters on
eﬃcacy and safety.
During every clinical visit, the subjects would have theirblood taken four times to check plasma glucose levels. 12hours prior to the visit, the subjects were not allowed toeat or drink (except water). The subjects took a 10
minute rest before proceeding with the first blood
extraction to check blood biochemical parameters andglucose levels. Then, the subjects would eat 2 rice balls

診療と新薬・第 55 巻

Table 2Term
Item
Informed consent
Selection and/or allocation
Blood extraction (4 times)
OGTT
Biochemical parameters
Ingestion of test foods

第 3 号（2018 年 3 月）

35 （219）

Schedule for the study

Pretrial test

Screening

●
●
●
●
●

●
●
●
●
●

Test period
6w

12 w

●
●
●

●
●
●

Log

● :Implementation↔ :Daily practice during the test period(equal to 75 g dextrose grape sugar) and the second blood
test was taken 30 minutes after eating. Two more tests
followed an hour and 2 hours after eating to checkglucose levels. The trial procedure of the test day isshown in Figure 1.
2.6. Data analysis
A full analysis set (FAS) was adopted in the study and nosample size design was used. All statistics wereexpressed as mean ± standard deviation (SD). For the
blood plasma level and blood biochemical parameters,
Student s t-test was used for intergroup comparisons ofchanges from the baseline. Changes from the baseline in
the same group were assessed using paired t-test. A chisquare test and Student s t-test were used to compare
subject backgrounds between groups.
Multiplicity according to the occasions was not adjusted.
Any subjects with missing values were eliminated fromthe analysis. Statistical analyses were performed using
Statcel 4 (Yanai, 2015) and Excel Tokei 2015 (SSRI). The
results were considered signiﬁcant at a ＜ 5% level in the
two-sided test.

3. RESULTS
3.1. Participant demographics
The 48 subjects were randomly assigned to anintervention group and made a start with ingestion. 21
subjects were withdrawn due to business or fever, andthe remaining 27 subjects completed the study. Thus,
data obtained with 27 subjects (KK: 14〈M; 5, F; 9〉,Placebo: 13〈M; 3, F; 10〉) was used for the analysis ofeﬃcacy (Figure 2). There was no signiﬁcant diﬀerence ingender, age, or FPG (0 w) between groups (Table 3).
3.2. Postprandial plasma glucose
Table 4 shows the results of OGTT. At Visit 1 (0-week)
and Visit 3 (12-week), a significant difference wasobserved between two groups from FPG to 0.5 h-OGTT.
As for Visit 2 (6-week) of intergroup analysis, KK
suppressed OGTT more than Placebo, but a significant
difference was not found. At 0-week, KK did not
represent a significant difference in 2 h-OGTT,〈Visit 1（0 w）, Visit 2（6 w）, Visit 3（12 w）〉
Keep quiet for 10 minutes＊
Blood extraction ①（fasting）

Ingestion of the test sample（7 tablets）＊＊
Ingestion of 2 riceballs（glucose tolerance）
Keep quiet
Blood extraction ②（0.5 h-OGTT）
Blood extraction ③（1 h-OGTT）
Blood extraction ④（2 h-OGTT）＊：tested for biochemical parameters：at Visit 2 and Visit 3＊＊

Figure 1 Trial procedure of the test day

meanwhile Placebo yielded a signiﬁcant increase. Also, atweek 12, KK decreased compared to FPG in 2 h-OGTT.
On the other hand, there was no decrease in Placebo.
3.3. Biochemical blood test
Table 5 shows the blood biochemical parameters (⊿ 0-12w). In the blood biochemical parameters data, one
subject s level of CK (CPK) was recorded too high as adata collection mistake. Therefore this data was not usedin the results of this study, so therefore 26 subject s (KK:
14〈M; 5, F; 9〉, Placebo: 12〈M; 2, F; 10〉) data wasevaluated. With respect to the blood biochemical test, nosigniﬁcant diﬀerence was observed in KK after 12 weeks
of ingestion. In Placebo, Total bilirubin, AST (GOT),
ALT (GPT), and Calcium showed a signiﬁcant diﬀerence.
γ-GT (γGTP) (males and females), Total cholesterol,and Neutral fat (TG) of placebo at week-0 as well as ALT

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第 3 号（2018 年 3 月）

Assessed for eligibility (n ＝ 61)〔M:25, F:36〕

Enrollment

Excluded (n ＝ 13)〔M:5, F:8〕
¨ Did not meet inclusion criteria (n ＝ 13)¨ ¨ FPG 侒 126 mg/dL (n ＝ 13)¨ Declined to participate (n ＝ 0)

Randomized (n ＝ 48)〔M:20, F:28〕

Group AGroup B

Allocation
Allocated to Placebo (n ＝ 23)〔M:9, F:14〕

Allocated to KK (n ＝ 25)〔M:11, F:14〕¨ Received allocated intervention (n ＝ 25)¨ Did not receive allocated intervention (n ＝ 0)

¨ Received allocated intervention (n ＝ 23)¨ Did not receive allocated intervention (n ＝ 0)

Follow-Up
Lost to follow-up (n ＝ 0)
Discontinued intervention (n ＝ 10)〔M:6, F:4〕
¨ Unexpected business (n ＝ 8)〔M:5, F:3〕
¨ Fever (n ＝ 2)〔M:1, F:1〕

Lost to follow-up (n=0)
Discontinued intervention (n ＝ 11)〔M:6, F:5〕
¨ Unexpected business (n ＝ 9)〔M:6, F:3〕
¨ Fever (n ＝ 2)〔M:0, F:2〕

AnalysisAnalysed (n ＝ 13)〔M:3, F:10〕¨ Excluded from analysis (n ＝ 0)※n ＝ 12 〔M:2, F:10〕for blood biochemical test
due to a data collection mistake of CK (CPK)

Analysed (n ＝ 14)〔M:5, F:9〕
¨ Excluded from analysis (n ＝ 0)

Figure 2 Flow diagram of subject disposition

Table 3 Subject demographics
Item

Unit

KK

Placebo

Subjects
Male: Female ＊numbers
numbers

14
5:9

13
3:10

Age ＊

years
mg/dL

40.3 ± 11.3
94.0 ± 13.8

47.1 ± 8.3
93.7 ± 11.0

FPG (0 w) ＊mean ± SD＊

No signiﬁcant diﬀerence(GPT) of placebo at week-12 were not found to remain
within the normal range (data not shown). However, theprinciple investigator judged it as the range ofphysiological variation (or clinically safe).
3.4. Safety
No adverse eﬀects associated with the test product wereobserved in the course of the reporting.

4. DISCUSSION
We conducted a randomized, placebo-controlled, doubleblind study for examining the eﬃcacy of the supplementof Jerusalem artichoke containing inulin, for the loweringof postprandial plasma glucose level.
As the primary outcome, after 12-weeks of ingestion of
the test product, while the postprandial plasma glucose

診療と新薬・第 55 巻

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37 （221）

Table 4 Postprandial blood glucose
Values1)

Item(Time points)

0-week

6-week12-week

KK (n ＝ 14)

Placebo (n ＝ 13)

P-value 2)FPG
0.5 h-OGTT⊿ FPG-0.5 h

94.0 ± 13.8

93.7 ± 11.0

129.9 ± 28.0 ＊＊35.9 ± 23.3

148.8 ± 28.3 ＊＊55.2 ± 22.4

1 h-OGTT⊿ FPG-1 h

121.9 ± 27.9 ＊＊27.9 ± 22.8

136.3 ± 35.9 ＊＊42.6 ± 31.6

0.176

2 h-OGTT⊿ FPG-2 h98.5 ± 20.6
4.5 ± 15.2

105.8 ± 19.8 ＊＊12.1 ± 13.9

0.190

FPG
0.5 h-OGTT⊿ FPG-0.5 h

92.9 ± 16.2
132.9 ± 37.0 ＊＊40.1 ± 26.9

90.8 ± 11.4
145.2 ± 29.2 ＊＊54.4 ± 26.5

0.177

1 h-OGTT⊿ FPG-1 h

120.1 ± 35.6 ＊＊27.3 ± 24.4

130.2 ± 29.7 ＊＊39.3 ± 24.6

0.214

2 h-OGTT⊿ FPG-2 h95.4 ± 23.0
2.5 ± 14.4

97.5 ± 21.7
6.6 ± 14.5

0.466

FPG
0.5 h-OGTT⊿ FPG-0.5 h

94.1 ± 29.6
121.2 ± 35.5 ＊27.1 ± 35.4

92.9 ± 12.1
147.5 ± 30.4 ＊＊54.6 ± 22.1

0.024 ＃

1 h-OGTT⊿ FPG-1 h

112.6 ± 30.3 ＊18.5 ± 30.8

129.2 ± 36.9 ＊＊36.3 ± 30.2

0.142

2 h-OGTT⊿ FPG-2 h

92.1 ± 15.4
− 2.0 ± 24.5

95.0 ± 24.0
2.1 ± 13.9

0.603

0.038 ＃

Values are expressed as the mean ± SD.
1) ＊ p ＜ 0.05, ＊＊ p ＜ 0.01 against FPG
2) ＃ p ＜ 0.05 between-group diﬀerence in change from FPG

level after OGTT among Placebo showed an abrupt
increase in blood glucose level, the increasing level of KK
was signiﬁcantly inhibited.
In addition, as the secondary outcome, no adverse
eﬀects associated with the test product were observed in
the course of the reporting, and the safety of ingesting
the test product was suggested by the results of bloodbiochemical analysis and inquiries.
Main Findings
This study examined the effectiveness of ingesting the
supplement made from Jerusalem artichoke whichcontains inulin as its main ingredient, for the lowering of
postprandial plasma glucose level. At Visit 1 (0-week) and
Visit 3 (12-week), significant difference was observed
between two groups of the changes from FPG to 0.5
h-OGTT. At 0-week, KK did not represent a signiﬁcantdifference in 2 h-OGTT, meanwhile Placebo yielded asignificant increase. Also, at week 12, KK decreased
compared to FPG in 2 h-OGTT, while no decrease wasobserved in Placebo.
The increase in postprandial plasma glucose level iscaused when the digested starch changes into glucose,then it is absorbed from the small intestine and is mixed
into the blood circulation. For healthy people, insulin issecreted immediately after the mixture, and it turns the
glucose in the blood into the glycogen. Then the glycogenis stored in various organs. Therefore, the glucose levelin the blood returns to a normal level two hours after the
meal. On the other hand, if the secretion of insulin is
insuﬃcient, the performance of insulin is not appropriate,or the excessive amount of glucose is ingested after themeal, it becomes hard for the blood glucose level todecrease 8) 9). The long-term continuance of the status ofhigh blood glucose level can cause diseases such as
diabetes.
In this study the result among Placebo showed that fromweek 0 through week 12, just 0.5 h after glucose
tolerance the blood glucose level suddenly increases, andreturns to the normal level after 2 h. Although KK
showed a similar tendency, the increasing rates of blood
glucose level 0.5 h after the glucose tolerance are
signiﬁcantly lower than those of Placebo. In addition, as
for the blood glucose level after 2 h, while the level ofPlacebo increased compared to the level before the38 （222）

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Table 5

第 3 号（2018 年 3 月）

Changes in biochemical blood testTime

KK (n ＝ 14)

Placebo (n ＝ 12)

points〔M:5, F:9〕

〔M:2, F:10〕

M/F
M/F
M/F
M/F
M/F
M/F
M/F

⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w− 0.07 ± 0.15
− 0.1 ± 0.3− 0.1 ± 0.2− 0.1 ± 1.7− 0.8 ± 4.8
0.8 ± 16.5
4.4 ± 18.3

0.13 ± 0.17 a,c
0.1 ± 0.3
0.0 ± 0.2
5.2 ± 7.4 a,b
7.2 ± 8.6 a,c
2.8 ± 26.5
5.8 ± 17.6

U/L

M
F

⊿ 0-12 w⊿ 0-12 w− 1.0 ± 6.2
0.8 ± 6.6

19.5 ± 9.2 b− 11.2 ± 46.8

CK (CPK)

mg/dL

M
F

⊿ 0-12 w⊿ 0-12 w

16.8 ± 18.8
4.6 ± 27.7

− 1.0 ± 9.9− 5.6 ± 9.4

Total cholesterol
Neutral fat (TG)
SodiumChloride
Potassium
Calcium
Inorganic phosphorus
Urea nitrogen

mg/dL
mg/dL
mEq/L
mEq/L
mEq/L
mg/dL
mg/dL
mg/dL

M/F
M/F
M/F
M/F
M/F
M/F
M/F
M/F

⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w⊿ 0-12 w− 1.5 ± 18.4
4.6 ± 25.8
− 0.1 ± 1.1
0.0 ± 1.8
− 0.1 ± 0.3
0.0 ± 0.3
0.1 ± 0.5
− 0.5 ± 3.9

4.1 ± 16.9
− 41.4 ± 185.1
0.3 ± 2.3
0.4 ± 1.8
− 0.1 ± 0.3
0.2 ± 0.2 aCreatinine

mg/dL

M
F

⊿ 0-12 w⊿ 0-12 w− 0.02 ± 0.07
0.02 ± 0.03

0.03 ± 0.01
0.02 ± 0.06

Item

Unit

GenderTotal bilirubin
Total protein
AlbumenAST (GOT)
ALT (GPT)ALP
LD (LDH)

mg/dL
g/dL
g/dL
U/L
U/L
U/L
U/L

γ-GT (γ GTP)

0.1 ± 0.4
0.5 ± 1.8

Values are expressed as the mean ± SD.
ap ＜ 0.05 against 0-week.

b

p ＜ 0.05, cp ＜ 0.01 between-group diﬀerences in change from 0-week.

glucose tolerance, the data of KK showed the decreased
level compared to before the glucose tolerance after 12
weeks of ingestion. Therefore, it is speculated that theingestion of KK contributed to the inhibition of theincrease rate of the blood glucose level after 0.5 h, andthe continuous ingestion of KK enhances the decreasingrate of the blood glucose level after 2 hours.
This test product is the supplement consisting of thedried powder of Jerusalem artichoke. The tubers ofJerusalem artichoke are rich in inulin, which makes theplant one of the primary inulin resources10) 11). It is wellknown that inulin can impart certain nutritional andtherapeutic benefits which can improve our healthconditions and reduce the risk of many lifestyle relateddiseases, and there are many study reports that supports
these functionalities12).
Inulin is categorized as a water soluble dietary ﬁber innutriology. Inulin is a batch of fructan of polysaccharide,and this polysaccharide is a polymer of fructose 13). It
cannot be decomposed in human digestive organs,however it is metabolized in the microﬂora of a human slarge bowel. Since it is equipped with the high waterretention capacity, swelling capacity and oil-holding
capacity14), it turns into a gel once dissolved in water andeases the movements of foods from the stomach to thesmall intestines. At that time, it wraps around thecarbohydrates or fats which are ingested at the sametime and moves them to the small intestines while
avoiding digestion. Eventually, this function slows down
the speed of absorbing carbohydrates and inhibits thesudden increase of postprandial plasma glucose level 15).
Based upon the discussion above, we can speculate thatthe function of inulin contained in the test productcontributed to the inhibition of the increase level of
postprandial plasma glucose level.
Secondary Findings
In this study, we conducted the blood biochemical
analysis and inquiries as a secondary endpoint, and theresults revealed that no abnormal change caused by thetest product was observed during the ingestion period.
As for the blood test, Total bilirubin, AST (GOT), ALT(GPT), and Calcium showed significant difference
between two groups, and ALT (GPT), γ-GT (γ GTP),
Total cholesterol and Neutral fat (TG) of Placebo
exceeded the normal range. On the other hand, no
signiﬁcant diﬀerence was observed in KK after 12 weeks
of ingestion. The investigator judged it as the range ofphysiological variation (or clinically safe).

診療と新薬・第 55 巻

During the test period 21 subjects discontinued the test.
17 of them discontinued the test due to an unexpectedbusiness matter, whereas the other 4 stopped the test
because of illness (cold). However, both have nothing to
do with the ingestion of the test product. In addition, thediary of the subject did not show any adverse events.
Therefore, the results of the medical interview, blood
test, and determination of adverse events all suggested
there was no adverse inﬂuence associated with the test
product. These results indicated the safety of theingestion of the test product for the 12-week test period.
General Information
Normally, the blood glucose level increases when we
i n g e s t f o od s . O n t h e o t h e r h a n d , h o w e ve r, t h eabnormally-high level of postprandial plasma glucose level
can not only increase the risk of developing diabetes, butalso expose the blood vessel to oxidant stress as a resultof the production of active oxygen and eventually cause
the risk of arteriosclerosis. Arteriosclerosis often causes
high blood pressure, which can eventually trigger
Myocardial infarction and/or stroke16) 17). In addition, theresidual glucose in the blood which is not consumed as anenergy is transported to the fat tissues and stored as fat;this can be one of the major causes of obesity 18) .
Furthermore, the condition of postprandial hyperglycemia
is reported to increase the risk of dementia19). Therefore,
the increase in the postprandial plasma glucose level cantrigger the risks of various diseases even among healthypeople.
To combat the above problems, previous studies
reported a wide variety of possible preventative measuresin our daily life, such as ingesting foods with low GI,
applying the second-meal 20) , and/or changing of thepattern of ingestion (such as Vege-first ). If healthypeople, along with the above-explained measures, use theeasily-prepared supplement in daily life and inhibit theincrease rate of postprandial plasma glucose level, they
can reduce the risk of diseases and extend healthy life
expectancy.
In addition, inulin contained in the test product has
functions of normalizing the condition of the microflora
and maintaining the intestinal environment21). In addition,
it is also reported that the ingestion of inulin can decrease
the amount of serum cholesterol and neutral lipid,
and this supports that inulin can control the lipid
metabolism 22) 23). Therefore, the ingestion of the test
product can contribute to the prevention of obesity
thanks to not only the eﬀect of inhibiting the increase of
postprandial plasma glucose level but also improving theintestinal environment or the lipid metabolism. In sum, it
is highly speculated that the above-discussed functions
eventually lower the risk of previous mentioned diseases.
Limitations
In this study we examined the effect of inhibiting theincrease of postprandial plasma glucose level by OGTT
testing. The increase rate of postprandial plasma glucose

第 3 号（2018 年 3 月）

39 （223）level diﬀers substantially between individuals. Since thisstudy focused on the inhibiting eﬀect against the increaseof the blood glucose level, it only discussed thedifferences between prior-glucose tolerance and postglucose tolerance in OGTT. However, in order to discuss
the individual differences between testing subjects, thedifference of fasting blood glucose level should be also
considered. Therefore, it is necessary for the further
study to increase the number of subjects and conduct thetest study that includes the comparison of the glucose
tolerance level performed by the tests such as stratiﬁed
analysis of fasting blood glucose level. In addition, thefunctional mechanism of the ingredients other than inulin
in Jerusalem artichoke is unknown, and this point isdesirably considered for further scrutiny.

5. CONCLUSION
In conclusion, we found out that the ingestion of the
supplement made from Jerusalem artichoke whichcontains inulin as its main ingredient for 12 weeks
contributed to inhibiting the increase of postprandial
plasma glucose level. In addition, no safety-related
matter occurred during the test period.
CONFLICT OF INTEREST
All parts of this study were funded by GRANDE CO.,LTD. Otoha Ueki isan employee. All authors state that the study was conducted in theabsence of any other relationships that could be interpreted as a conﬂict ofinterest.

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（Table 1 was corrected in July 2018.）