82

Japanese Journal of Comprehensive Rehabilitation Science (2017)

Original Article

Efficacy of a novel training food based on the process model offeeding for mastication and swallowing: A study among dysphagia
patients
Seiko Shibata, MD, DMSc,1 Hitoshi Kagaya, MD, DMSc,1 Shinichiro Tanaka, MD,1
Wataru Fujii, DDS, PhD,2 Kazuharu Nakagawa, DDS, PhD,3 Koichiro Matsuo, DDS, PhD,3
Kazumi Abe, MPHARM,4 Naoto Ishibashi, MPHARM,4 Yoko Inamoto, SLHT, DMSc,5Eiichi Saitoh, MD, DMSc1
Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Aichi, Japan
Department of Dentistry, Fujita Health University Nanakuri Memorial Hospital, Mie, Japan3
Department of Dentistry, School of Medicine, Fujita Health University, Aichi, Japan4
Product Design Laboratory, Medical Foods Research Institute, OS-1 Division, Otsuka Pharmaceutical Factory,
Inc., Tokushima, Japan
5
Fuculty of Rehabilitation, School of Health Science, Fujita Health University, Aichi, Japan1
2

ABSTRACT
Shibata S, Kagaya H, Tanaka S, Fujii W, Nakagawa K,
Matsuo K, Abe K, Ishibashi N, Inamoto Y, Saitoh E.
Efficacy of a novel training food based on the processmodel of feeding for mastication and swallowing: A
study among dysphagia patients. Jpn J Compr Rehabil
Sci 2017; 8: 82-87.
Objective: Our goal was to verify the validity andsafety of chew-swallow managing food (CSM) for
dysphagia patients.
Methods: We conducted a study on 14 inpatientsdiagnosed with dysphagia and judged to be capable ofingesting pureed foods. We instructed each participant
to ingest and freely swallow 4-g samples of CSM andpureed food. For each sample, we measured thenumber of chewing cycles, number of swallows,
position of the leading edge of the bolus at the time ofswallowing initiation, amount of residue in the oralcavity and pharynx, and occurrence of laryngeal
penetration or aspiration.
Results: The number of chewing cycles was significantly
higher for the CSM. The position of the leading edge ofthe bolus at the time of swallowing initiation was
Correspondence: Seiko Shibata, MD, DMSc
Department of Rehabilitation Medicine I, School of
Medicine, Fujita Health University, 1-98 Dengakugakubo,
Kutsukake, Toyoake, Aichi 470-1192, Japan.
E-mail: sshibata@fujita-hu.ac.jp
Accepted: June 9, 2017.
COI: This study was supported by a research grant from
Otsuka Pharmaceutical Factory, Inc.
©Kaifukuki Rehabilitation Ward Association 2017
doi.org/10.11336/jjcrs.8.82

primarily in the valleculae for both the CSM and pureed
food, and the rate of laryngeal penetration did not
significantly differ between the two test foods. There wasa high rate of residue on the dorsum of tongue with the
CSM and in the valleculae with the pureed food.
Conclusion: The CSM induced chewing in dysphagia
patients, and the prevalence of penetration did not
differ from the pureed food. Therefore, we concluded
that the CSM could be used in chewing exercises withthe same level of safety as the pureed food.
Key words: process model, chewing, swallowing,
swallowing disorders, direct training
Introduction
Two types of approaches are widely used for treating
dysphagia: direct swallowing training, in which theperson ingests food to practice chewing and swallowing,
and indirect swallowing therapy, which does not use
food [1]. Indirect training avoids the risk of aspiration,and has proven to be effective for improving theswallowing motion by strengthening tongue squeezing
and pharyngeal constriction. However, it does have a
direct effect on the bolus condition during the actual
swallowing motion. Direct training, on the other hand,
can be more easily generalized to the swallowing
motion. Therefore, to improve the swallowing function
more efficiently, it is important to employ direct training
in combination with indirect training in a safe manner.
Direct training usually begins with foods of a uniform
consistency, such as pureed or jellied food. Since thesefoods do not require chewing, aspiration and foodresidue are minimized during the direct training.
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Shibata S et al.: Efficacy of a novel training food for mastication and swallowing among dysphagia patients
83

Typically, the person is instructed to hold the bolus in
the mouth until the swallowing reflex is initiated. Thenthe person is expected to swallow the bolus all at onceby propelling it into the pharynx. This swallowing
process is described in a four-stage model, which isbased on the action of discrete swallowing [2].
However, in the course of stepwise therapy, it isessential to shift from foods of a single consistency tofoods that require chewing. Therefore, it is necessary
to consider shifting from the four-stage swallowing
model to the process model. The process model has
been proposed to describe chewing and swallowing[3, 4]. The characteristic of this model is progressprocessing and stage II transport concurrently. In theprocessing stage, food inserted in the oral cavity isbroken down by chewing and mixed with saliva,
making it swallowable. In the oral propulsive stage, aswallowable portion of the ingested food is transported
to the pharynx during chewing through the squeezeback action of the tongue (stage II transport). Bolus
formation in the chewing and swallowing process isperformed in the valleculae during stage II transport[5, 6]. Furthermore, it is reported that the position of
the bolus at the initiation of swallowing under stage IItransport varies depending on the properties of theingested food [7-9]. When the person is chewing
and swallowing runny foods with low viscosity, or
foods consisting of both liquid and solid pieces such as
miso soup, the location of the bolus at the initiationof swallowing under stage II transport will be thehypopharynx. Therefore, those with more severe
dysphagia will be at greater risk of aspiration.
Taking into consideration the importance of using
standardized foods to ensure safe chewing andswallowing exercises, we developed a chew-swallow
managing food (CSM). We designed the CSM to havean initial hardness that requires chewing, and thus
induces stage II transport, and to transform in texture
to a puree with chewing, thus enabling swallowing
with a minimal risk of aspiration.
The aim of this study was to examine the validity
and safety of the CSM as a training food for chewing
and swallowing by comparing the swallowing motionsof patients with dysphagia when ingesting CSM versus
pureed food.
Subjects and Methods
The study protocol was approved by the institutional
review board of Fujita Health University (ApprovalNo. 13-289).
1. Participants
The participants consisted of 14 patients who requireda videofluorographic examination of swallowing (VF)after suspecting dysphagia, and who were judged tobe capable of swallowing pureed foods. Exclusion
criteria were unstable physical status and insufficient

comprehension of verbal instructions. Prior to starting
the study, we provided each participant, and in somecases, a family member, with an explanation of thestudy, and the participants provided their written
informed consent.
The participants comprised eight men and six
women, with a mean age of 74 ± 8.7 years. Regarding
the primary diseases of the participants, five hadsuffered a stroke, two had a brain tumor, three had aneuromuscular disease, two had pharyngeal cancer,
and two had a respiratory disease. Regarding theseverity of their dysphagia as measured using theDysphagia Severity Scale (DSS) [10, 11], one
participant was classified under “food aspiration,”nine were classified under “water aspiration,” twounder “occasional aspiration,” one under “oralproblem,” and one under “minimum problem.”
Regarding the participants’ dental condition, five had
no molar occlusion and did not require dentures, four
were using dentures, and five required dentures but
were not using them.
2. Methods
We positioned the participants in the posturerecommended for VF and conducted the videoendoscopic
evaluation of swallowing (VE). We inserted a fiberscopeof 3.6 mm in diameter (ENF Type P4, Olympus,
Tokyo) into the nasal cavity, and positioned the tip ofthe endoscope at the level of the soft palate so that we
could observe the entire pharyngeal cavity. We
recorded the endoscopic images during the feeding
process onto a mini digital video tape (mini-DV)
player. To enable confirmation of the number ofchewing and swallowing movements afterward, werecorded the participants eating the food and the VE
images with another video camera and saved theimages on a DVD.
For the test foods, we used 4 g of the CSM and 4 gof a commercial pureed product (Nameraka yasai
kabocha [soft vegetable pumpkin], Kewpie, Tokyo),which falls under Category 4 of the Universal Design
Food [12]. The participants were instructed to eat threesamples of each food while the endoscope wasinserted. The order in which the participants ingested
these samples was randomized.
The properties of the test foods are shown in Table 1.
We measured these properties using the method
indicated in the Consumer Affairs Agency’s licensing
standards for “Foods for special dietary uses” and“Foods for persons with dysphagia” [13].
After the food was placed in the mouth by theexaminer using a spoon, the participant was instructedto eat the food freely. Participants were told to swallow
3 mL of water if any food residue was observed in theoral cavity or pharynx after swallowing.

Jpn J Compr Rehabil Sci Vol 8, 2017

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Shibata S et al.: Efficacy of a novel training food for mastication and swallowing among dysphagia patients

Table 1. Characteristics of CSM and pureed food.
Texture*Hardness （N/m2）
Cohesiveness
Adhesiveness（J/m2）

CSM
Brown sugar lump

Stock

Soy sauce

4.2×104
0.4
1.8×103

3.9×104
0.4
1.8×103

3.7×104
0.4
1.5×103

Puree**
3.4×103
0.8
1.1×103* Shoushokuhyou Notification No. 277.
** Universal Design Food Concept.
3. Data acquisition
3.1 Number of swallows and chewing cycles
We defined the swallow as coinciding with theappearance of a white-out in the VE images. The VE
administrator counted the number of times theparticipant swallowed until the participant indicatedfinishing eating the sample. The number of chewing
cycles was measured by counting the number ofvertical movements of the jawbone between the timeof intake and the time of the first swallow. Thismeasurement was performed by an examiner otherthan the VE administrator. We used the video images
recorded on the external camera to corroborate thenumber of swallows and chewing cycles, if necessary.
3.2 Location of the leading edge of the bolus atswallowing initiation
Based on the VE images recorded by the VE
administrator, we identified the locations of the leadingedge of the bolus immediately before the first swallow.
We classified these locations into the following: (1)oral cavity: VE images show that there was nopremature spillage of the bolus into the pharynx; (2)tongue base to valleculae: VE images show that theleading edge reached the valleculae prior toswallowing; and (3) valleculae to pyriform sinus: VE
images show that the leading edge passed thevalleculae and reached the pyriform sinus.
3.3 Food residue and aspiration
An examiner, other than the VE administrator,
evaluated the food residue in the oral cavity by direct
observation and in the pharynx by VE images. Basedon a previous study, we classified the degree of residue
into four levels: (1) none, (2) trace, (3) less than half,and (4) half or more. The VE images were used to
identify residue in the valleculae and pyriform sinus.
The residues on the dorsum of the tongue and floor of
the mouth were identified by direct observation after
the final swallow in each trial.
Laryngeal penetration and aspiration were evaluatedusing the VE images and quantified with the PenetrationAspiration Scale (PAS) [14].
4. Data analysis
We used a paired t-test to evaluate the differences in
Jpn J Compr Rehabil Sci Vol 8, 2017

the mean numbers of chewing cycles and swallows
between the CSM and pureed food. We used the
Wilcoxon signed-rank test to compare the differencesin the amount of residue, location of the leading edgeof the bolus at swallow initiation, and PAS scores.
Statistical analyses were performed using IBM SPSS
software version 23.0 (SPSS Inc., IBM, Armonk, NY,
USA), with a statistical significance threshold of p <0.05.
Results
With regard to the mean number of swallows (mean ±standard deviation [SD]), there was no significant
difference between the CSM and pureed food (2.4 ±1.5 vs. 2.0 ± 1.0, p = 0.083; see Figure 1A). The mean
number of chewing cycles until the first swallow wassignificantly higher for the CSM than for pureed food(34.6 ± 18.2 vs. 6.5 ± 6.7, p < 0.001; see Figure 1B).
There was no significant difference between the
CSM and pureed food in terms of the location of theleading edge of the bolus at swallow initiation. The
location in both cases was primarily in the valleculae
to pyriform sinus (78.6% and 81.0%; see Table 2).
The amount of residue in the dorsum of the tongue
and valleculae differed significantly between the CSM
and pureed food (p = 0.001, p = 0.047; see Table 3).
The residue in the dorsum of the tongue was highestwith the CSM, but this represented only trace residue
in most cases.
The residue in the valleculae with the pureed foodwas Level 3 (less than half) in 23 of 42 cases (54.8%).
With the CSM, two of the 42 cases (4.8%) had Level 4(half or more) residue, but Levels 1 (none), 2 (trace),and 3 residues were similar with 11/42 cases (26.2%),
14/42 cases (33.3%) and 15/42 cases (35.7%),
respectively.
There was no significant difference in the distributionof residue in the pyriform sinus. Twenty-four (57.1%)
of 42 cases with CSM had Level 2 (trace) to Level 3(less than half) residue in the pyriform sinus, compared
to 25 (59.5%) of 42 cases with the pureed food. In
addition, the rates for Level 1 (none) were 18/42(42.9%) cases and 17/42 (40.5%) cases, respectively.
Regarding the PAS scores, none of the participants
aspirated with either the CSM or the pureed food.

Shibata S et al.: Efficacy of a novel training food for mastication and swallowing among dysphagia patients
85

Figure 1. Number of chewing cycles and swallows.
A. Number of swallows until finishing the 4-g sample of CSM/puree.
B. Number of chewing cycles until the first swallow of the 4-g sample of CSM/puree.
Figures indicate the mean + standard deviation (SD). According to the Wilcoxon signed-rank test,
the number of swallows did not vary significantly between the CSM and pureed food, but the numberof chewing cycles was significantly higher with CSM (p < 0.001).
CSM, chew-swallow managing food.
Table 2. Location of the leading edge of the bolus for CSM and puree.

Oral cavity
Oropharynx-valleculae
Hypopharynx-pyriformsinus
Total

CSM

Puree

Total

1
33
8

3
34
5

4
67
13

42

42

84

p=0.096.
Wilcoxon signed-rank sum test.

Table 3. Post-swallow residue.
A. Dorsum of the tongue

B. Floor of the mouth

CSM

Puree

Total

Hal for more
Less than half
Trace
None

0
2
16
24

0
0
4
38

0
2
20
62

Total

42

42

84

CSM

Puree

Total

Hal for more
Less than half
Trace
None

2
1
2
37

0
0
1
41

2
1
3
78

Total

42

42

84

CSM

Puree

Total

p=0.001.

p=0.066.

C. Valleculae

D. Pyriform sinus
CSM

Puree

Total

Hal for more
Less than half
Trace
None

2
15
14
11

0
23
16
3

2
38
30
14

Hal for more
Less than half
Trace
None

0
15
9
18

0
11
14
17

0
26
23
35

Total

42

42

84

Total

42

42

84

p=0.047.


p=0.536.
Wilcoxon signed-rank sum test.
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Shibata S et al.: Efficacy of a novel training food for mastication and swallowing among dysphagia patients

Table 4. Penetration-aspiration scale.
CSM

Puree

Total

1
2
3
4
5
6
7
8

40
0
0
1
1
0
0
0

38
0
2
1
1
0
0
0

78
0
2
2
2
0
0
0

Total

42

42

84

p=0.751.
Wilcoxon signed-rank sum test.
With the CSM, there were two cases of laryngeal
penetration that reached the vocal folds, and with thepureed food, there were four cases of laryngeal
penetration, two of which did not reach the vocal folds
and two of which did (p = 0.751; see Table 4).
Discussion
1. Efficacy of CSM as a training food for chewing
and swallowing
We developed the CSM as a training food for use indirect training, particularly for inducing chewing andswallowing. In the case of conventional foods, theproperties of the food may mean that it scatters in thepharynx during chewing, which can lead to aspiration. In
addition, in the case of two-phase food, which consists ofliquid and solid pieces, it is reported that the components
with low viscosity are transported to the hypopharynx
earlier [7-9]. Such conditions markedly increase therisk of aspiration in patients with dysphagia. Therefore,
we designed the CSM to have two features: (1) an
initial hardness that requires chewing and thus induceschewing, bolus formation, and transport of the bolus(stage II transport); and (2) the texture transforms withchewing to a pureed food such that it can be swallowedwith a minimal risk of aspiration.
After testing the CSM on patients with chewing andswallowing difficulties, we found that the number ofchewing cycles was significantly larger for the CSM
than with the pureed food. The location of the bolus
during the first swallow was in the valleculae in manycases for both the CSM and pureed food. The numberof swallows was approximately two for both the CSM
and pureed food, and there was no occurrence of
aspiration with either test food. These findings suggestthat when ingested by persons with dysphagia, CSM
can recreate the series of motions involved in chewing
and swallowing by appropriately inducing chewing,
which in turn leads to bolus formation, bolus transport,
and finally swallowing.
For both the CSM and pureed food, the amount of
Jpn J Compr Rehabil Sci Vol 8, 2017bolus residue in the oral cavity and pharynx was within
the range of Level 2 (trace) to Level 3 (less than half)
residue, and there was no significant difference in therate of residue in the pyriform sinus. This finding
implies that the CSM has similar properties to pureed
food immediately before swallowing, meaning thateven patients with dysphagia, with their reduced
pharyngeal constriction ability, can swallow it easily.
We did not observe any significant difference
between the two test foods in terms of the rate ofpharyngeal penetration. This finding suggests that theCSM does not excessively liquefy or congeal whenchewed and mixed with saliva but rather has similar
properties to pureed food.
2. Comparison between elderly participants wholive at a residential facility and have no dysphagia
and those with dysphagia
In the past, we conducted a similar study involving
23 elderly people (mean age: 83 ± 9 years) who were
living in a residential facility, had no dysphagia, andingested their food normally [15]. A comparison
between the participants in the previous study andthose in the present study revealed that both sets ofparticipants exhibited significantly higher amounts ofchewing with the CSM than with the pureed food. The
results of the amount of residue were also the same forboth sets of participants. Specifically, while there weredifferences in the amounts of residue in the dorsum of
the tongue, valleculae, and pyriform sinus, these were
all within the range of Level 2 to 3 (i.e., trace to lessthan half) for both the CSM and pureed food. However,among the participants in the previous study, the mostcommon location (40.6%) of the leading edge of thebolus at swallowing initiation in the case of pureed
food was the oral cavity, but among the participants inthe present study, the equivalent location was thevalleculae. Another difference was that compared tothe participants in the previous study, the participantsin the present study exhibited a higher number ofchewing cycles for both the CSM and pureed food.
One possible reason why the location of the leadingedge of the puree bolus at swallowing initiation tended
to be the valleculae for patients with dysphagia might
be that there was a greater rate of stage II transport andpremature spillage of the bolus. Because they have
reduced tongue function, patients with dysphagia
experience difficulty with bolus formation andtransportation of the bolus from the oral cavity to thepharynx [16-18]. Thus, unlike elderly people who
retain their oral cavity functions, patients withdysphagia are unable to swallow the bolus whole
while it is held in the oral cavity, and therefore, must
transport the bolus several times. The latter would
explain why the bolus reached as far as the valleculae
at the time of swallowing initiation. On the other hand,an inability to keep the tongue in contact with the soft
palate during chewing might explain the high rate ofShibata S et al.: Efficacy of a novel training food for mastication and swallowing among dysphagia patients87

premature spillage of the bolus in this group ofpatients.
3. Application of CSM
CSM can serve as a training food for chewing andswallowing, if the person who ingests it meets thefollowing criteria: (1) must notice that there is a solid
piece of food in their oral cavity and must have asufficient level of consciousness to initiate chewing;(2) must have the ability to start chewing as instructed;
and (3) must be able to do so without being in a
reclined position, which would encourage premature
spillage into the pharynx during chewing.
4. Limitations of this study
The results of this study demonstrated that the CSM
successfully induces chewing, and its texture afterchewing is transformed so that it can be swallowed assafely as pureed food. However, the results do notclarify the severity levels of dysphagia for which CSMbased chewing exercises can be applied effectively.
Chewing involves the synchronized motions of thejaw and tongue, including trituration. Since we could
not visually confirm the synchronized motions of thejaw and tongue, we relied on the visual assessment of
the vertical movement of the jawbone to measure thenumber of chewing cycles.
Acknowledgments
I would like to thank the members of the Department of
Rehabilitation, Fujita Health University who cooperated
with the research needed to complete this study.

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