Original Article

診療と新薬 2023; 60: 637‑643

Eﬀects of Consuming Foods Containing Lutein,
Zeaxanthin, Dha, EPA, and Piperine fromLong Pepper (Hihatsu) on Deep Vision:

診療と新薬 WebA Placebo-Controlled, Randomized, Double-Blind, Parallel-Group Study

Koji FURUNISHI 1)／Nobuki OKADA2)／Yumiko IDE 3)／
Saeko YAGI 4)／Shigeru IMAI 5)
1) Kenso Factory Corporation
2) Marga Japan Corporation
3) Shibuya Kamiyama-cho Clinic4) Jikoukai Yagi Hospital5) Leverage Brain Inc.

● Abstract
Purpose: Lutein and zeaxanthin are pigments present in the eye macula that protect the retina from harmful
light. This randomized, placebo-controlled, double-blind, parallel-group, study was conducted to investigate
the eﬀects of test foods containing DHA(Docosahexaenoic Acid), EPA(eicosapentaenoic acid), and piperinefrom long pepper (Hihatsu), in conjunction with lutein and zeaxanthin, on deep vision in healthy adults.
Methods: The study included healthy adult men and women. Sixty-four participants (32 in each group) were
given test or placebo foods containing lutein, zeaxanthin, DHA, EPA, and piperine from long peppers (Hihatsu)
for 8 weeks and VDT(Visual Display Terminals) work was performed before, 4 weeks after, and 8 weeks after
intake. VAS(Visual analog scale) analog scale questionnaire was administered, and a weekly questionnaire wasalso conducted during the dietary intake period.
Results: Following 8 weeks of consumption, deep vision was signiﬁcantly improved in the test food groupcompared to the placebo group immediately after VDT work. No adverse events or side eﬀects attributable toconsumption of the test food were observed during the study period.
Conclusion: Consumption of foods containing lutein, zeaxanthin, DHA, EPA, and piperine from long peppers(Hihatsu) helped maintain deep vision in healthy participants.
(UMIN-ID: UMIN000048088)
Key words: lutein, zeaxanthin, DHA, EPA, piperine from honeysuckle, deep vision, VAS

INTRODUCTION
In our modern lifestyles, the prevalence of working withelectronic displays, commonly referred to as video
display terminal (VDT) work, has been linked to anincreased incidence of visual function impairment due tothe undue strain placed on the eyes1) 〜 3). Workers engaged
in VDT work for long periods of time are aware of various
nonspecific symptoms (eye fatigue, redness, and pain)
called eyestrain, which has attracted attention as a major
occupational health problem4) 〜 7). Furthermore, in this ageof widespread smartphone usage, every person possessesa smartphone, and prolonged screen viewing has become
a commonplace occurrence. Smartphone screens are also
electronic displays, and the eye focus adjustment disordercaused by continuous screen viewing is called smartphonepresbyopia8). Suzuki et al9). investigated the duration ofsmartphone use among university students and reported
that users who spent more time using smartphones
tended to have reduced eye regulation and a longer near
point of adjustment. Thus, the daily implementation of
the VDT workload is thought to decrease eye function
and lead to a decrease in the quality of daily life. In
addition, the VDT work is thought to aﬀect deep vision,
which measures stereoscopic perception by keeping theeyes ﬁxed at the same focal position for long periods oftime.
VDT work causes deterioration of eye function andworsening of subjective symptoms such as eyestrain.
Studies on the reduction of eye strain caused by VDTwork through the intake of food have been conducted,
and their efficacy has been reported for various22 （638）

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food components, including anthocyanins 11)12) andastaxanthin13)14).
Xanthophyll pigments accumulate in the central retinaof the eye, 1.5 to 2.0 mm in diameter. This area, called
the macula, is the site where lutein and zeaxanthin areformed via cell-tissue association 15)16) . Lutein istransported to and developed in the macula via oral
intake. The developed macula is believed to buffer the
stimulation of short-wavelength visible light, such as blue
light, and limit the risk of ocular tissue damage17)18). It has
also been reported that macular pigment-filled retinas
improve visibility by enhancing contrast sensitivity foreyes, particularly for individuals frequently engaged in
VDT work19). In addition, deep vision is not only relevant
to VDT work but may also be relevant to sports vision.
Sports vision refers to the visual function important for
sports activities. Previous studies found a correlation
between athletes and high athletic performance in various
sports and vision. The required vision abilities vary fromsport to sport. For example, deep vision to estimate thedistance between moving objects and dynamic visualacuity to track the movement of a moving object areconsidered necessary for various visual functions during
competitions. We have previously investigated theinhibitory effects of foods containing lutein, zeaxanthin,
DHA, EPA, and piperine derived from Japanese cyprinid
diets on the reduction of deep vision after an extensive
VDT workload. We used foods that contain lutein,zeaxanthin, Japanese cyprinid extract, and fish oil, andfound signiﬁcant improvement in deep vision. Therefore,
this study aimed to conﬁrm the eﬀects of foods containing
lutein, zeaxanthin, and piperine from lLong pepper(Hihatsu) on the reduction in deep vision that occurs after
a deep vision VDT workload. Furthermore, a stratified
analysis of the results was performed.

I SUBJECTS AND METHODS
1. Test design
This was a randomized, placebo-controlled, and parallelgroup trial (1:1 allocation ratio of the test food intake
group to the target food intake group). In accordancewith the principles outlined in the Declaration of Helsinki(amended in October 2013), this study was conductedfollowing the Ethical Guidelines for Life Sciences andMedical Research Involving Human Subjects (Ministry of
Education, Culture, Sports, Science and Technology,
Ministry of Health, Labour and Welfare, notice enacted
March 23, 2021) and the Guidance on Ethical Guidelines
for Life Sciences and Medical Research Involving Human
Subjects (Ministry of Education, Culture, Sports, Scienceand Technology, Ministry of Health, Labour and Welfare,notice enacted April 16, 2021). The study plan was
reviewed and approved by the Ethics Review Committeeof the Japan Council for Clinical Research (JCCR) on July21, 2022. The study was then pre-registered with UMIN-

第 10 号（2023 年 10 月）

CTR (UMIN000048088) on July 21, 2022, under the study
title Veriﬁcation study of the eﬀects of test food intake
on deep vision before the implementation of the study.
The study protocol has not yet been published. This
study was conducted at the Shibuya Kamiyama-cho Clinic
from July 2022 to November 2022. No major changes
were made to the study protocol during the study period.
2. Test participants
The participants met the selection criteria listed below
and did not meet the exclusion criteria. The selection
criteria were:1) healthy adult male and female
participants aged 20 years or older but less than 65 years;2) participants with corrected distance vision of 0.6 or
better; 3) participants who were able to use theelectronic daily logging application (e-DCA); and 4)
participants who were fully informed of the purpose andc o n t e n t o f t h i s s t u d y, u n d e r s t o od t h e c o n t e n t ,volunteered freely, and agreed in writing to participate.
Exclusion criteria were as follows: (1) Patients withserious diseases of the brain, liver, kidney, heart, lungs,
digestive organs, blood, endocrine system, or metabolic
system; (2) Patients with diseases requiring constant
medication or with a history of serious diseases requiring
medication; (3) Patients currently undergoing treatment
at a medical institution for diseases of the digestivesystem or with a history of digestive system surgery(excluding appendicectomy); (4) Patients with
ophthalmological diseases, a history of ophthalmologicalsurgery, or who regularly use eye drops for treatment or
prevention; (5) Patients with a history of hypersensitivity
to test food ingredients; (6) Patients who regularly use
pharmaceuticals, health foods, or supplements; (7)Pregnant, lactating, or women intending to become
pregnant during the study period; (8) Patients who have ahistory of lifestyle-related diseases, and (9) those who
were judged to be unsuitable as participants based on
their answers to the lifestyle questionnaire. In addition,
this study was conducted at Shibuya Kamiyama-cho
Clinic.
3. Intervention
The test foods were soft capsule foods containing lutein,zeaxanthin, DHA, EPA, and piperine from long peppers(Hihatsu) or a placebo food in which lutein, zeaxanthin,
DHA, EPA, and piperine from long peppers (Hihatsu)
were replaced by crystalline cellulose. There were nodifferences in the appearance or taste of the two foods.
Table 1 shows the compositions of the test foods. The
participants consumed four capsules of the assigned testor placebo food once daily with water or lukewarm waterfor 8 weeks.
4. Outcomes
The primary outcome measure was deep vision. The
secondary outcome was the VAS questionnaire on the

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Table 1 Composition of test food
Test product name
Additive
LuteinZeaxanthin
Involved
DHA
component EPA
Piperine from Long pepper（Hihatsu）
Form
Daily

Test foodPlacebo foodMarigold pigment oil（lutein ＋ zeaxanthin）,

Dextrin, saﬄower oil, olive oil,

DHA puriﬁed ﬁsh oil（DHA ＋ EPA）
, Longpepper（Hihatsu）extract powder

glycerin fatty acid ester, glycerinfatty acid ester-2, beeswax

10 mg/4 tablets
2 mg/4 tablets
398.7 mg/4 tablets
36.3 mg/4 tablets

−
−
−
−

120μg/4 tablets−

softgel capsule
4 tablets（2160 mg）/daysoftgel capsule
4 tablets（2160 mg）/daystate of the physical condition before and after VDTwork. In addition, changes in physical condition during
the intake period were set as safety endpoints. The
outcome measures did not change at the start of thestudy.
1) Deep vision
Deep visual acuity was measured six times before,
immediately after, and 20 min after the end of the VDTwork using a visual testing device (Kowa AS-27a Kowa
Co., Ltd., Tokyo, Japan) in a three-rod method, and theaverage value of the errors was adopted. Deep vision wasmeasured before, 4 weeks after, and 8 weeks afteringestion, before VDT work, immediately after work, and20 min after the end of work.
2) VAS questionnaire on the state of experience before
and after VDT work
The VAS method was used to interview the participants
about their experiential state with respect to eyefatigue, eye focus adjustment, and headache before
VDT work, immediately after work, and 20 minutes after
the end of work. Additionally,100 mm line segments wereinterviewed at both ends, with the best state being 0 mm
and the worst state 100 mm, and the length of the line
segments was measured and evaluated by the amount ofchange from the VDT work before VDT. The VAS
questionnaire was administered before, 4 weeks after,and 8 weeks after intake, before VDT work, immediately
after work, and 20 minutes after the end of work.
3) Safety endpoints
As a safety test, the participants were asked to recordchanges in their physical condition and medication use
during the intake period using a daily logbook.
5. Test Method
Participants underwent a VDT workload test at the timeof their visit to the clinic, in which they played an Othellogame for 45 min without moving the screen, followed by
15 min of free viewing of a news site on a smartphone.
This task was repeated twice (for 2 hours). VAS
questionnaires were administered before, immediately
after, and 20 minutes after the VDT task was completed
to measure the participants deep vision and their current
state of experience.
During the intake period, the participants were asked torespond to a daily diary on their health and intake status,and once a week, a VAS questionnaire on quality of life
was also administered. The study period was August 1,
2022, with a follow-up end date of November 4, 2022
6. Sample size
The sample size was calculated from the results of theprevious study by calculating the diﬀerence and standard
deviation between the test food intake group and theplacebo food intake group for the primary endpoint of
deep visual acuity, and the required sample size wascalculated with a power of 80% and a signiﬁcance level of
5%. In addition, the required sample size per group was
set to 30 or more to account for dropouts.
7. Randomization
Randomization was performed by generating random
numbers using computer software. Initially, a pre-test
involving 111 patients who visited the clinic wasconducted. After the pre-test, 64 participants werepreferentially selected from among those who met the
selection criteria, did not meet the exclusion criteria, andhad good results in the depth vision test. After selecting
the participants, the allocation manager created an
allocation table using the stratiﬁed blocked randomization
method, with sex, age, BMI, deep vision, and correctedvision as stratification factors. The allocation manager
confirmed the unidentifiability of each test product andaffixed a sticker with the subject s ID to the packaging
surface of the test and placebo foods. Throughout the
study s duration, the allocation list was securely24 （640）

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第 10 号（2023 年 10 月）

Eligibility assessment（n ＝ 111）

Excluded（n ＝ 47）
Did not meet theinclusion criteria（n ＝ 47）

Randomized（n ＝ 64）

Allocation to placebo food group（n ＝ 32）
Allocated and given test（n ＝ 32）
Allocated and given placebo（n ＝ 0）

Allocation to group with foods containing lutein,zeaxanthin, DHA, EPA, Hihatsu extract（n ＝ 32）
Allocated and given test（n ＝ 32）
Allocated and given placebo（n ＝ 0）

Study completed（n ＝ 32）

Study completed（n ＝ 32）

Analyzed（n ＝ 32）

Analyzed（n ＝ 32）

Fig. 1 Subject Selection Flowmaintained within a locked cabinet, sealed to prevent any
unauthorized access. The allocation manager refrained
from opening the list until the conclusion of the study,
thus upholding the principle of double-blindness, which
was maintained for both the participants and the study
implementers.
8. Statistical analysis
Statistical analyses were performed using SAS 9.4 (SASInstitute Inc.) The values used in the analysis were theactual measured values or the change from before intake,and the results are presented as mean ± standard
deviation. The two-sided significance level for all tests
was set at 5%. The primary endpoint of the deep visualacuity was measured. The VAS score of the questionnaire(VAS change from before VDT work is shown as thevalue immediately after VDT work and 20 minutes after
VDT work). Statistical analysis was performed using theStudent s t-test between the test food intake group andthe placebo food intake group without considering

multiplicity. No additional analyses, such as subgroup or
adjusted analyses, were performed in this study.

II RESULTS
The subject selection process is illustrated in Fig. 1. Of
the 118 participants who consented to participate in the
study, 111 participants who came for a pre-test were pretested, and 64 participants were preferentially selectedfrom those who met the selection criteria and did notmeet the exclusion criteria and had good results in thedepth vision test. Thirty-two participants in the test foodintake group and 32 participants in the placebo foodintake group were assigned at the start of the study. The
study was completed with no dropouts, discontinuations,or loss to follow-up. All 64 participants were included in
the efficacy analysis population, and the participants
consumed the assigned foods.. The safety analysis
population consisted of 64 participants who had consumed
the study foods at least once. The participants

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Table 2 Subject background

Age
Near vision（logMAR）
Distant vision（logMAR）
Deep visual acuity
Male/Female

Test food（n ＝ 32）

Placebo food（n ＝ 32）

Average ± Std. Dev.

Average ± Std. Dev.

p value

45.53 ± 12.05

43.81 ± 11.15

0.4805− 0.0386 ± 0.1570
0.00255 ± 0.07803
5.64 ± 4.46
14/12

− 0.0803 ± 0.1034
0.01107 ± 0.09018
6.60 ± 6.08
12/20

0.21480.68770.46990.7994

Table 3 Results of deep vision
Timepoint

SCR

4W

8W

Intergroup comparison

Load periodGroup# of cases

Average ± Std. Dev.

Before VDT task

Test foodPlacebo food32
32

5.64 ± 4.46
6.60 ± 6.08

0.4699Immediately after VDT task

Test foodPlacebo food32
32

17.10 ± 11.82
20.38 ± 13.24

0.301320 minutes after VDT task

Test foodPlacebo food32
32

5.98 ± 6.41
6.45 ± 6.57

0.7737

Before VDT task

Test foodPlacebo food32
32

9.79 ± 11.48
8.58 ± 11.43

0.6746

Immediately after VDT task

Test foodPlacebo food32
32

20.50 ± 16.65
17.41 ± 13.08

0.411720 minutes after VDT task

Test foodPlacebo food32
32

10.84 ± 11.93
7.66 ± 10.76

0.2660

Before VDT task

Test foodPlacebo food32
32

8.05 ± 11.04
9.59 ± 13.88

0.6245

Immediately after VDT task

Test foodPlacebo food32
32

10.79 ± 5.45
14.10 ± 7.59

0.049220 minutes after VDT task

Test foodPlacebo food32
32

7.32 ± 9.14
7.83 ± 9.57

0.828

t-test

SCR, screening; W, weeks; VDT, visual display terminal

backgrounds in the eﬃcacy analyses are listed in Table 2.
1. Eﬃcacy Evaluation
1) Deep vision
Table 3 lists the results of deep vision. Deep vision is a
visual function that captures the perspective, solidity,
depth, and dynamics of an object. In the Screening test,
there were no significant differences between the twogroups before VDT work, immediately after VDT work,and 20 minutes after VDT work. At week 8, the test foodintake group showed a significant difference after VDTwork. Speciﬁcally, at week 8, the test food group showeda significant improvement compared to the placebogroup, with a shorter error margin immediately after
VDT work.

2) VAS questionnaire on post-VDT experience
Table 4 presents the results of the VAS questionnaire
assessing participants post-VDT work experiences.
Regarding the change from before to immediately after
VDT work after 8 weeks of intake, the test food intake
group showed significantly fewer symptoms andsuppression of headache symptoms than the placebo foodintake group.
2. Safety Evaluation
Subjective symptoms, adverse events, and adverse
reactions were reported by both groups which wererecorded in the daily logbook and during hospital visits,
as part of the safety evaluation. Speciﬁcally, 19 incidents
were documented among seven participants in the test
food intake group, while 13 events were recorded in nine

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Table 4 VAS questionnaire on patient response after VDT task（Diﬀerence in VAS scores before and after VDT task）
Immediately after VDT work
Item

Group

4W

8W

Intergroup p value
4W

8W

Eye fatigue

Test foodPlacebo food19.94 ± 16.84
16.84 ± 16.39

17.78 ± 14.64
20.16 ± 18.65

0.40110.8298Eye focusing

Test foodPlacebo food

12.69 ± 22.42
11.72 ± 17.51

11.16 ± 20.33
14.34 ± 18.02

0.79330.9038Headache

Test foodPlacebo food

3.34 ± 12.66
6.19 ± 14.97

2.28 ± 11.22
4.66 ± 9.90

0.80790.00444W

8W

20 minutes after VDT work
Item

Group

Intergroup p value
4W

8W

Eye fatigue

Test foodPlacebo food

9.16 ± 17.96
4.00 ± 15.63

8.78 ± 21.67
10.72 ± 14.94

0.34020.1771

Eye focusing

Test foodPlacebo food6.38 ± 17.11
2.78 ± 15.07

2.91 ± 20.25
5.81 ± 17.97

0.49330.1811Headache

Test foodPlacebo food2.25 ± 11.93
2.84 ± 12.02

0.91 ± 9.26
3.47 ± 11.06

0.58570.1834

VDT, visual display terminal; W, weeks

participants from the placebo food intake group. Several
participants developed colds or other symptoms, mainly
during the intake period, but all were mild, and a causal
relationship with study participation was ruled out by thestudy investigators. Based on the above, the safety of theconsumption of the test foods over an 8-week period wasconsidered acceptable.

III CONSIDERATIONS
The purpose of this randomized, placebo-controlled, andparallel-group study was to investigate the eﬀects of test
foods containing DHA, EPA, and piperine from long
peppers (Hihatsu), in addition to lutein and zeaxanthin,on eye function in healthy adults. The results showedthat deep vision improved immediately after VDT in the
8th week of intake. The results showed that the test foodwas eﬀective in improving deep vision.
In addition to lutein and zeaxanthin, DHA, EPA, andHijatsu extract were added to the test food. According toa study conducted by Kizawa et al on healthy adults,
foods containing lutein, zeaxanthin, and astaxanthin wereassociated with reduced occurrences of difficulty infocusing the eyes and difficulty in seeing objects up
close, nearby, and letters after VDT work, compared toplacebo foods. This study also showed that headaches
immediately after VDT work were signiﬁcantly reducedin the test food intake group compared to the placebo

food intake group in the subjective evaluation.
Improvements in deep vision may also be related tospatial perception such as depth perception. The inclusionof DHA and EPA, in addition to lutein and zeaxanthin, in
the test food may have resulted in an improvement in
depth perception and the perception index. Spatial
perception is an essential aspect of daily life. For
example, when driving a car, spatial awareness isessential for assessing the distance to the vehicle in front,
the gap to the adjacent vehicle, and the proximity to thestop line. Moreover, deep vision is of considerable
importance in various sports contexts. For example, inbasketball free throws and baseball hitting, it is importantto accurately perceive the distance to move toward apredetermined time or target. The results of this study
show the possibility of improving the spatial perception
abilities needed in daily life. The limitations of this study
include the fact that the participants were VDT workers
and the mechanism of action was not fully investigated. It
is expected that the results for participants other than
VDT workers and the mechanism of action will be
elucidated in the future. In this study, 19 adverse eventsoccurred in seven participants in the test food intake
group, but none of them were causally related to theintake of the test food; therefore, the intake of the test
food was considered to be more beneﬁcial than harmful.

診療と新薬・第 60 巻

CONCLUSION
This randomized, placebo-controlled, and parallel-groupstudy was conducted to investigate the effects of an
8-week intake of foods containing lutein, zeaxanthin,
DHA, EPA, and piperine from long peppers (Hihatsu) on
visual function after VDT work and safety during thei n t a k e p e r i od i n h e a l t h y a d u l t m a l e a n d f e m a l eparticipants. The outcomes of this study showed that foodintake containing lutein, zeaxanthin, DHA, EPA, andpiperine from Japanese spruce improved deep visualacuity after VDT work. In addition, as for the change inthe state of feeling immediately after VDT work frombefore VDT work, the test foods signiﬁcantly suppressed
headache symptoms compared to the placebo foods after
8 weeks of intake, indicating that the test foods also help
suppress unpleasant symptoms caused by VDT work.
Conflict of Interest: This study was funded by MargaJapan, Inc. The commission was paid to the testingorganization. The funding agency provided the test foods.
The authors included employees of the test provider,
Marga Japan Inc. The authors declare no conflicts ofinterest.
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