nutrients
ArticleAssociation between Food Store Availability and theIncidence of Functional Disability among
Community-Dwelling Older Adults: Results from theJapanese Gerontological Evaluation Cohort Study
Ryo Momosaki 1, * , Hidetaka Wakabayashi 2 , Keisuke Maeda 3 , Hiroshi Shamoto 4 ,Shinta Nishioka 5 , Kaori Kojima 6 , Yukako Tani 7 , Norimichi Suzuki 8 ,Masamichi Hanazato 8 and Katsunori Kondo 8,9
1
2
3
4
5
6
7
8
9

*

Department of Rehabilitation Medicine, Teikyo University School of Medicine University Hospital,
Mizonokuchi, Kanagawa 213-8507, Japan
Department of Rehabilitation Medicine, Yokohama City University Medical Center, Kanagawa 240-8555,
Japan; noventurenoglory@gmail.com
Department of Palliative and Supportive Medicine, Graduate School of Medicine, Aichi Medical University,
Aichi 441-8108, Japan; kskmaeda@aichi-med-u.ac.jp
Department of Neurosurgery, Minamisoma Municipal General Hospital, Fukushima 975-0033, Japan;
shahonvs17@gmail.com
Department of Clinical Nutrition and Food Service, Nagasaki Rehabilitation Hospital, Nagasaki 850-0854,
Japan; shintacks@yahoo.co.jp
Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine,
Shizuoka 431-3125, Japan; kaworikojima@gmail.com
Department of Global Health Promotion, Tokyo Medical and Dental University, Tokyo 113-8510, Japan;
tani.hlth@tmd.ac.jp
Center for Preventive Medical Sciences, Chiba University, Chiba 260-0856, Japan;
suzu-nori@chiba-u.jp (N.S.); hanazato@chiba-u.jp (M.H.); kkondo@chiba-u.jp (K.K.)
Department of Gerontological Evaluation, Center for Gerontology and Social Science, National Center for
Geriatrics and Gerontology, Aichi 474-8511, Japan
Correspondence: momosakiryo@gmail.com; Tel.: +81-44-844-3333; Fax: +81-44-844-3201

Received: 9 July 2019; Accepted: 26 September 2019; Published: 4 October 2019


Abstract: This study sought to clarify the association between food store availability and theincidence of disability in older adults. This study utilized a population-based cohort study of
independent Japanese adults aged ≥65 years, which was a 6 year follow-up of participants in
the Japan Gerontological Evaluation Study. A total of 31,273 respondents were extracted. Food
store availability was evaluated based on the existence of food stores within 500/1000 m of thehome. We utilized participant-reported subjective measurement as well as geographic information
system-based objective measurement for the evaluation. The incidence of disability was determinedusing municipal data on eligibility for long-term care insurance benefits. There were 7643 (24.4%)
community-dwelling participants with low subjective food store availability and 5673 (18.1%) withlow objective food store availability. During the follow-up period of 6 years, the cumulative incidenceof disability was 20.9%, with a significant association between low subjective food store availability
and increased disability. Participants who reported low subjective food store availability had asignificantly higher likelihood of developing disability (hazard ratio = 1.18, 95% confidence interval:
1.11–1.25) than those who reported high subjective food store availability after adjusting for age, sex,sociodemographic status, environmental status, walking and going out, dietary food intake, bodymass index, and comorbidities. Low subjective food store availability was associated with early onsetof disability. Accessibility of food stores might contribute to maintaining a disability-free life.
Keywords: food environment; food stores; functional disability

Nutrients 2019, 11, 2369; doi:10.3390/nu11102369

www.mdpi.com/journal/nutrients

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1. Introduction
Life expectancy is increasing worldwide, with a resultant increase in the elderly population who
are at high risk of physical frailty, sarcopenia, progressive functional disability, dependency, andinstitutionalization, and will have serious social, medical, and economic impacts [1]. Malnutrition isconsidered a major risk factor of frailty, sarcopenia, impairment, and disability [2]. The Asia-Pacific
Clinical Practice Guidelines for the Management of Frailty provisionally recommend that screening
should be performed for frail older adults who have unintended weight loss to identify possible
reversible causes and that protein and caloric supplementation/food fortification should be consideredin such individuals [3]. The clinical guidelines for sarcopenia state that appropriate nutritional intake
could prevent the onset of sarcopenia and is therefore recommended [4].
Personal dietary habits, as well as accessibility to food in terms of whether a variety of foods canbe obtained, are considered to affect nutritional status. Many older adults face obstacles to accessing
food due to a decline in walking and movement ability. As humans, we eat every day, so the foodenvironment can affect us all and has a great influence. People who reside far from a grocery store arereported to have a 25%–46% lower likelihood of healthy dietary habits than those with the most storesnearby among community-dwelling residents in the United States [5]; low subjective accessibility offood increases the risk of low dietary variability among community-dwelling older adults in Japan [6].
According to Sharkey et al., objective and subjective indices of accessibility to a food store, suchas further distance to the nearest grocery store, food stores that stock a diverse array of fresh andprocessed fruit, or those with a wide assortment of fresh and processed vegetables, were associatedwith reduced regular intake of fruit and vegetables based on data from community residents in the
United States [7]. Also, cohort data targeting community-dwelling older adults in Japan showed thatliving in a food environment located in a poor neighborhood can possibly lead to malnutrition [8],while improved access to food stores was associated with higher body mass index (BMI) [9].
Previous studies have shown that the food environment might impact incidence of mortality anddementia in older people [10,11]. If one’s main reason for going out is to shop at a neighborhood
grocery store, food store availability might influence the incidence of functional disability in manyolder adults. However, the relationship between food store availability and functional disability has
not been sufficiently verified so far. This study sought to verify the association between food store
availability and the incidence of functional disability among older community-dwellers.
2. Materials and Methods
2.1. Study Population
We used prospective cohort data of a large-scale population-based study that involved older
Japanese people aged ≥65 years from the Japan Gerontological Evaluation Study (JAGES) [12].
Data from JAGES were collected from eight municipalities in four prefectures (Hokkaido,
Yamanashi, Aichi, and Nagasaki). Baseline data were collected from August 2010 to January 2012.
Self-administered questionnaires were sent by mail to independently living individuals in the relevant
community. From 52,180 participants who had no certified need for long-term care insurance, we useddata on 31,273 participants, after excluding participants with missing information on subjective and/or
objective food store availability (20,907 participants). All the participants were duly notified thatparticipation in the JAGES project was voluntary and that returning the completed questionnaire
would be considered as consent to participate. Ethics approval (No. 13–14) was obtained from the
Ethics Committee at our university.
2.2. Measurements and Variable Definitions
Subjective food store availability was evaluated based on a self-reported questionnaire.
The questionnaire consisted of a single question on subjective food store availability: “How many foodstores or facilities that sell fresh fruits and vegetables are within 1 kilometer of your house?”, rated on

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a 4-point scale (“none”, “few”, “some”, “many”) [6]. We defined “many” and “some” as high, and“few” and “none” as low subjective food store availability.
Objective food store availability was evaluated using geographic information system (GIS)-based
methods [13]. Our study utilized 500 m mesh data from the Commercial Establishment Survey ofthe Ministry of Economy, Trade and Industry [14]. Food stores comprised department stores, generalmerchandise retailers, convenience stores, and specialty grocery stores. On the premise that all kindsof stores were uniformly distributed in the 500 m mesh, the number of stores along a straight line
in a 500 m radius of the residence of each participant was then calculated according to the area of
proportional distribution of the map area. All spatial calculations were performed with ArcGIS 10.1
software. Participants who had stores along a straight line within a radius of 500 m from the center of
their residential community blocks were categorized as having high objective food store availability
and those without stores within a radius of 500 m were categorized as having low objective food store
availability. We defined 500 m or less as a reasonable “walkable” distance to a food store, which has
been used in similar studies [15,16].
The primary outcome was functional disability, which we defined as certified need for care or
support under the long-term care insurance system of Japan [17]. Follow-up of participants was
carried out for 6 years based on their incident functional disability. Incident functional disability data
was obtained from databases of public municipal long-term care insurance. Participants who had
been recently certified as needing care or support through Japan’s long-term care insurance systemwere deemed as having functional disability [18]. Eligibility for insurance certification is determinedbased on a national standardized procedure that includes a medical examination by a physician andassessment of physical status and cognitive function.
Demographic variables included age and sex in the baseline survey. Sociodemographic status,
walking and going out, driving status, neighborly relationships, nutritional status, and comorbidities
were evaluated with a self-reported questionnaire. Variables of social and demographic status wereeducational attainment, yearly income, living arrangements, employment status, and marital status.
Yearly income was adjusted for household size, where income was divided by the square root of thenumber of individuals per household. Variables of walking as well as going out comprised daily
walking time and frequency of going out. For nutritional status, variables were BMI and fruit/vegetableintake and meat/fish intake rate over the previous month. Standard BMI categories were then used
to classify participants as obese, overweight, normal, or underweight [19]. Neighborly relationships
were evaluated as described by Nakamura et al. [6] by asking about the kind of relationship they havewith others in their neighborhood. The responses included the frequency of exchanging greetingsor conversing with neighbors and borrowing/lending items, and based on the results, participants
were classified as having either a high- or low-level relationship with their neighbors. Variables
about comorbidities included therapy for medical conditions/symptoms and symptoms of depression.
Multiple answers were permitted, and so participants were required to state whether or not they wereat the time receiving medical treatment for malignancy, cardiac disease, stroke, high blood pressure,diabetes mellitus, arthropathy/neuralgia, traumatic fracture, pulmonary disease, and gastrointestinal
disorder and dysphagia. Using the Geriatric Depression Scale-15 (Japanese version) [20], symptoms ofdepression in older adults were assessed and participants were classified into either a non-depressedor depressed group. Cognitive function was categorized as “decline” versus “no decline” and wasevaluated with a self-reported questionnaire [21]. Also, we calculated the population density ofhabitable land in the residential school districts of each participant using the 2010 census results
and data for land utilization tertiary mesh (2010) from the National Land Numerical Information of
the Ministry of Land, Infrastructure, Transport and Tourism, based on a topographic map of Japan(1:25,000). All non-developed areas, such as rivers, lakes, forests, and wasteland, were excluded fromthe calculations. All covariates with missing data were classified as “missing.” Categories for eachvariable are shown in Table 2.

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Baseline characteristics of the study participants were defined, and then multivariate cox regression
analysis was applied to evaluate the association between food store availability and incident functional
disability during the 6 years of follow-up. Four models were generated: Model 1: adjusted for age andsex; Model 2: further adjusted for sociodemographic status (educational attainment, marital status, andemployment status, yearly income, and living conditions) as confounding factors to examine whether
the relationship between food store availability and disability was independent of other aspectsof environmental status; Model 3: additionally adjusted for environmental status (driving status,
neighborly relationships, and population density) to investigate whether the relationship between foodstore availability and functional disability was independent of other environmental factors; and Model
4: further adjusted for walking and going out (daily walking time and rate of going out), dietary foodintake (frequency of fruit/vegetable and meat/fish intake), BMI, and comorbidities (malignancy, heartdisease, stroke, hypertension, diabetes mellitus, joint disease/neuralgia, traumatic fracture, respiratory
disease, digestive disease, dysphagia, depression, and cognitive decline) as potential mediating factors
linking food store availability to functional disability. Analyses were performed using SPSS Statistics
19 (IBM Corp., Armonk, NY, USA).
3. Results
Table 2 shows the baseline characteristics of the participants and the incidence of functional
disability after the 6 year follow-up period. Among all participants (n = 31,273, mean age: 74.1 years),
20.5% worked, 84.2% lived with others, 70.1% were married, 7.6% were underweight, 32.5% had
cognitive decline, 24.4% had low subjective food store availability, 18.1% had low objective food store
availability, and cumulative incidence of functional disability after 6 years was 20.9%. Male, super-old(>80 years) and non-car users tended to have low subjective and objective food store availability.
Participants with both low subjective and objective food store availability tended to have low rates
of going out. The prevalence of comorbidities was similar between participants with low food store
availability and those with high food store availability. Participants with low subjective and objective
food store availability tended to have high functional disability.
Results of Cox regression analysis are shown in Table 3. Participants who reported low subjective
food store availability had significantly higher likelihood of developing disability (hazard ratio = 1.20,
95% confidence interval: 1.13–1.27; p < 0.001) than those who reported high food store availability
after age and sex adjustment (Model 1). These hazard ratios were unchanged and remained
statistically significant following additional adjustments for sociodemographic and environmental
status (Model 2,3). The hazard ratio was slightly reduced but remained statistically significant(hazard ratio = 1.18, 95% confidence interval: 1.11–1.25; p < 0.001) after further adjustment forpotential mediating factors (walking and going out, nutritional status, and comorbidities) (Model 4).
However, objective food store availability showed no significant association with disability after age
and sex adjustment in Model 1 (hazard ratio = 0.98, 95% confidence interval: 0.92–1.05; p = 0.61).
In addition, no significant difference in objective food store availability was evident between Model 2(hazard ratio = 0.98, 95% confidence interval: 0.92–1.04; p = 0.60), Model 3 (hazard ratio = 1.00, 95%
confidence interval: 0.93–1.06; p = 0.82) and Model 4 (hazard ratio = 1.00, 95% confidence interval:
0.94–1.08; p = 0.84).

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Table 1. Baseline characteristics of participants and incidence of functional disability after 6 years.
All Participants

Subjective Food Store Availability

Objective Food Store Availability(n = 31,273)

Low (n = 7643)

High (n = 23,630)

Low (n = 5673)

High (n = 25,600)

Sex

Male
Female14,411 (46.1)
16,862 (53.9)

3227 (42.2)
4416 (57.8)

11,184 (47.3)
12,446 (52.7)

2589 (45.6)
3084 (54.4)

11,822 (46.2)
13,778 (53.8)

Age (years)

65–69
70–74
75–79
≥80

8255 (6.4)
9644 (0.8)
7390 (23.6)
5984 (19.1)

2035 (26.6)
2230 (29.2)
1794 (23.5)
1584 (20.7)

6220 (26.3)
7414 (31.4)
5596 (23.7)4400 (18.6)

1377 (24.3)
1677 (29.6)
1406 (24.8)
1213 (21.4)

6878 (26.9)7967 (31.1)
5984 (23.4)
4771 (18.6)

Educational attainment (years)

<6
6–9
10–12
≥13
Others/missing

684 (2.2)
13,719 (43.9)
10,606 (33.9)5503 (17.6)
761 (2.4)

213 (2.8)3592 (47.0)
2447 (32.0)1160 (15.2)
231 (3.0)471 (2.0)
10,127 (42.9)8159 (34.5)4343 (18.4)
530 (2.3)

205 (3.6)
2912 (51.3)
1622 (28.6)
804 (14.2)
130 (2.3)

479 (1.9)
10,807 (42.2)
8984 (35.1)
4699 (18.4)
655 (2.5)

Employment status

Working
RetiredNever worked
missing

6420 (20.5)
17,333 (55.4)
3532 (11.3)
3988 (12.8)

1456 (19.1)
4057 (53.1)
1000 (13.1)
1130 (14.8)

4964 (21.0)
13,276 (56.2)
2532 (10.7)
2858 (12.1)

1295 (22.8)
2710 (47.8)708 (12.5)
960 (16.9)5125 (20.0)
14,623 (57.1)
2824 (11.0)
3028 (11.8)

Yearly income (yen, millions)<2.00
2.00–3.99≥4.00
missing

13,279 (42.5)
9645 (30.8)
2732 (8.7)
5617 (18.0)

3378 (44.2)
2188 (28.6)
584 (7.6)
1493 (19.5)

9901 (41.9)
7457 (31.6)
2148 (9.1)
4124 (17.5)2643 (46.6)
1520 (26.8)
441 (7.8)
1069 (18.8)

10,636 (41.5)
8125 (31.7)
2291 (8.9)
4548 (17.8)

Living conditions

Live alone
Live with others
missing4193 (13.4)
26,330 (84.2)
487 (1.6)

1143 (15.1)
6318 (83.2)
130 (1.7)3050 (13.0)
20,012 (85.5)357 (1.5)

712 (12.6)
4833 (85.8)
90 (1.6)3481 (13.6)
21,497 (84.7)
397 (1.6)

Marital status

MarriedWidowedDivorced
Never married
Other/missing

21,908 (70.1)
6783 (21.7)
1197 (3.8)
713 (2.3)
672 (2.1)

5031 (65.8)
1926 (25.2)
314 (4.1)
195 (2.6)
177 (2.3)

16,877 (71.4)
4857 (20.6)
883 (3.7)
518 (2.2)495 (2.1)

4006 (70.6)
1209 (21.3)
184 (3.2)
123 (2.2)
151 (2.6)

17,902 (69.9)5574 (21.8)
1013 (4.0)
590 (2.3)
521 (2.0)

Driving status

Non-car users
Car users
missing

7865 (25.1)
10,328 (33.0)
13,080 (41.8)

2392 (31.3)
2647 (34.6)
2604 (34.1)

5473 (23.2)
7681 (32.5)
10,476 (44.3)

1772 (31.2)
2120 (37.4)
1781 (31.4)

6093 (23.8)
8208 (32.1)
11,299 (44.1)

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Table 2. Baseline characteristics of participants and incidence of functional disability after 6 years.
All Participants

Subjective Food Store Availability

Objective Food Store Availability(n = 31,273)

Low (n = 7643)

High (n = 23,630)

Low (n = 5673)

High (n = 25,600)

Neighborly relationships

High level
Low level
missing

21,653 (69.2)
7532 (24.1)
2088 (6.7)

5197 (68.0)
1960 (25.6)
486 (6.4)

16,456 (69.6)
5572 (23.6)
1602 (6.8)

4224 (74.5)
1052 (18.5)
397 (7.0)

17,429 (68.1)
6480 (25.3)
1691 (6.6)

Frequency of going out

Everyday≥2 times/week≤1 time/week
missing

16,031 (51.3)
8750 (28.0)4759 (15.2)
1733 (5.5)

3320 (43.4)
2311 (30.2)
1553 (20.3)
459 (6.0)

12,711 (53.8)6439 (27.2)
3206 (13.6)
1274 (5.4)

2352 (41.5)
1746 (30.8)1265 (22.3)
310 (5.5)

13,679 (53.4)7004 (27.4)
3494 (13.6)
1423 (5.6)

Daily walking time

≥1 h/day<1 h/day
Missing9139 (29.2)
20,249 (64.7)
1885 (6.0)

2127 (27.8)5007 (65.5)509 (6.7)7012 (29.7)
15,242 (64.5)
1376 (5.8)

1731 (30.5)3577 (63.1)
365 (6.4)

7408 (28.9)
16,672 (65.1)
1520 (5.9)

Frequency of meat/fish intake≥1 time/day<1 time/day
missing

12,126 (38.8)
17,273 (55.2)
1874 (6.0)

2658 (34.8)
4469 (58.5)
516 (6.8)

9467 (40.1)
12,804 (54.2)
1358 (5.7)

2198 (38.7)
3148 (55.5)
327 (5.8)9928 (38.8)
14,125 (55.2)
1547 (6.0)

Frequency of vegetable/fruit intake≥1 time/day<1 time/day
missing

23,508 (75.2)
6075 (19.4)
1690 (5.4)

5495 (71.9)
1697 (22.2)
451 (5.9)

18,013 (76.2)
4378 (18.5)
1239 (5.2)

42.7 (74.2)
1175 (20.7)
291 (5.1)

1931 (75.4)
4900 (19.1)
1399 (5.5)

Body mass index

Underweight < 18.5
Normal 18.5–24.9
Overweight 25–29.9
Obese ≥ 30
missing2367 (7.6)
21,433 (68.5)
5767 (18.4)
732 (2.3)
974 (3.1)

589 (7.7)5228 (68.4)
1367 (17.9)
203 (2.7)
256 (3.3)

1778 (7.5)
16,205 (68.6)4400 (18.6)
529 (2.2)
718 (3.0)410 (7.2)
3750 (66.1)
1157 (20.4)
141 (2.5)215 (3.8)

1957 (7.6)
17,683 (69.1)
4610 (18.0)
591 (2.3)
759 (3.0)

Comorbidities

Malignancy
Heart disease
StrokeHypertension
Diabetes mellitus
Joint disease/ Neuralgia
Traumatic fracture
Respiratory disease
Digestive disease
Dysphagia

1383 (4.4)
3785 (12.1)
4.7 (1.3)
12,330 (39.4)
2819 (12.2)
1242 (4.0)
2024 (6.5)
652 (2.1)
307 (1.0)
191 (0.6)351 (4.6)
972 (12.7)
88 (1.2)
3107 (40.7)
896 (11.7)
369 (4.8)567 (7.4)
163 (2.1)
87 (1.1)
74 (1.0)1032 (4.4)
2813 (11.9)
319 (1.3)
9223 (39.0)
2923 (12.4)
873 (3.7)
1457 (6.2)
489 (2.1)
220 (0.9)117 (0.5)229 (4.0)
677 (11.9)
76 (1.3)2302 (40.6)
644 (11.4)
242 (4.3)
4.3 (7.1)
123 (2.2)
50 (0.9)34 (0.6)1154 (4.5)
3108 (12.1)
331 (1.3)
10,028 (39.2)
3175 (12.4)
1000 (3.9)
1621 (6.3)
529 (2.1)
257 (1.0)
157 (0.6)

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Table 2. Cont.
All Participants

Subjective Food Store Availability

Objective Food Store Availability(n = 31,273)

Low (n = 7643)

High (n = 23,630)

Low (n = 5673)

High (n = 25,600)

Depression

Non-depressed
Depressed
missing

18,831 (60.2)
7285 (23.3)
5157 (16.5)4056 (53.1)
2247 (29.4)
1340(17.5)

14,775 (62.5)
5038 (21.3)
3817 (16.2)

3381 (59.6)
1364 (24.0)
928 (16.4)

15,450 (60.4)
5921 (23.1)
4229 (16.5)

Cognitive function

DeclineNot decline

10,158 (32.5)
21,115 (67.5)

2673 (35.0)
4970 (65.0)7485 (31.7)
16,145 (68.3)

1902 (33.5)
3771 (66.5)8256 (32.3)
17,344 (67.8)

Incidence of functional disability

Non-certification
Certification

24,741 (79.1)
6532 (20.9)

5800 (75.9)
1843 (24.1)

18,941 (80.2)
4689 (19.8)

4451 (78.5)
1222 (21.5)

20,290 (79.3)
5310 (20.7)

Categorical data are expressed as a number (%).

Table 3. Hazard ratios with 95% confidence intervals for incident functional disability with objective and subjective food store availability.
Model 1 HR (95% CI)

Model 2 HR (95% CI)

Model 3 HR (95% CI)

Model 4 HR (95% CI)

Subjective food store availability

High
Low

Reference
1.20 (1.13 to 1.27)

Reference
1.20 (1.13 to 1.26)

Reference
1.20 (1.13 to 1.26)

Reference
1.18 (1.11 to 1.25)

Objective food store availability

High
Low

Reference
0.98 (0.92 to 1.05)

Reference
0.98 (0.92 to 1.04)

Reference
1.00 (0.93 to 1.06)

Reference
1.00 (0.94 to 1.08)

HR hazard ratio, CI confidence interval, ref reference group. Model 1: Adjusted for age and sex. Model 2: Model 1 + adjustments for sociodemographic status (education attainment,
marital status, employment status, yearly income, living situation). Model 3: Model 2 + adjustments for environmental status (driving status, neighborly relationships, and population
density). Model 4: Model 3 + adjustments for walking and going out (daily walking time and rate of going out), dietary food intake (frequency of fruit/vegetable and meat/fish intake),
body mass index, and comorbidities (malignancy, heart disease, stroke, hypertension, diabetes mellitus, joint disease/neuralgia, traumatic fracture, respiratory disease, gastrointestinal
disease, dysphagia, depression, and cognitive decline).

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4. Discussion
Low subjective food store availability was associated with early onset of disability amongcommunity-dwelling older adults, but this was not the case for objective food store availability.
The association remained after adjustments for age, sex, sociodemographic and environmental status,
walking and going out, nutritional status, and comorbidities.
As reported by Tani et al., subjectively lower accessibility of healthy food stores measured was
associated with mortality [10] and dementia [11], however, they did not examine the association offood store availability and disability. To our knowledge, this is the first report that utilized large-scaledata to assess the relationship between food store availability and the incidence of functional disability
among older community dwellers.
Earlier studies on food store availability were mainly cross-sectional studies that were carried out
in areas of low population density, and by inference in environments with a low food store density(e.g., United States, but the United Kingdom is an exception) [22]. Our study was conducted in Japan
within a setting with a substantially high population density and high density of food stores, comparedwith settings of similar studies in the West.
Objective and subjective food store availability appear to have different meanings. Foodaccess has five dimensions, comprising availability, accessibility, affordability, accommodation, andacceptability [23,24]. In our study, objective food store availability evaluated only availability of foodstores. We found an association between subjective (but not objective) food store availability andonset of disability. This pattern was consistent with findings from previous study, which showed that
healthy outcomes were more strongly associated with subjective evaluations of availability but notwith objective evaluations [25,26]. Another previous study revealed a high level of mismatch between
perceived and objective indices (14%) [25]. Even in areas with low objective food store availability,
it is possible for evaluations of subjective food store availability to be high among individuals who
have high walking ability, access to public transportation and/or mobile catering options, a person or
persons who shops for food on their behalf, or who can grow their own food.
We hypothesized that a food environment that is subjectively evaluated is a better representationof individual differences in self-cultivated food, shopping behaviors, or accepting food from people
living close by; not all of these could be addressed by objective evaluation. Several conditions could
influence subjective food store availability, for example, traffic around the store, the form of the
sidewalk (inclination, stairs), store opening hours/days, security around the store, attributes of othershoppers and store staff, price and assortment of goods, and the store environment (spaciousness ofthe shop, easy entry, existing amenities such as washrooms and material resources) [27].
The association between subjective food store availability and incidence of functional disability
persisted after adjusting for potential mediating factors in Model 4 and could be attributed to otherunobserved factors. We speculate that improved food store availability promotes activities of dailyliving, such as selection of food items, shopping, carrying items, and cooking, which could contribute tomaintenance of activities of daily living. Moreover, there is a possibility that we could not subjectively
recognize the food stores that sell only low-variety, distasteful, and low-quality foods. Lack of dietaryvariety has been significantly associated with the progression of frailty in community-dwelling older
persons [28]. If food store availability is poor, there is a tendency to stock up on canned foods andready-to-eat foods and this causes dietary imbalance. Increased opportunities to eat a variety of foods
and maintain a well-balanced diet might be responsible for the maintenance of physical status andcognitive function in our study.
Our results suffered from the risk of reverse causation. Participants with many comorbidities anddeclined physical function might answer low availability of subjective food store and move to a placenear the food store. Model 4 included the comorbidities taking the problem into account.
A strength of our study was that we evaluated the impact of subjective, as well as objective,
food store availability on disability, investigating these relationships in a high-density setting; using
a relatively large sample size added to the statistical power in detecting associations. Nevertheless,there were several limitations in our study. Firstly, the type and size of food stores or the variety,Nutrients 2019, 11, 2369

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quality, and price of food items were not considered, all of which are possibly significant factors formaking healthy food choices. Secondly, the study area may not necessarily be a reflection of Japanas a whole. It is thus necessary for our findings to be reproduced in other regions, particularly in alarger metropolis. Thirdly, home-delivery meals or food services were not taken into account. Fourthly,
there is a possibility that food store availability is a product of unmeasured proxy variables related
to regional characteristics, such as regional economic affluence and the number of facilities where
people gather, which were not adjusted for in the analysis. Fifthly, our database does not contain any
time-dependent variables such as the change of food access over 6 years. Sixthly, the self-reported
questionnaire that evaluated subjective food store availability did not ask about any other fresh foods
than fresh fruits and vegetables. However, we speculated that food stores that sell fresh fruits andvegetables are highly likely to sell other fresh foods.
Low subjective food store availability was associated with early onset of disability, but low
objective food store availability was not. Accessibility of food stores might contribute to maintaining adisability-free life. Studies that evaluate the mechanisms involved in the variations in these indices offood store accessibility are required in the future.
Author Contributions: Conceptualization, R.M., H.W., K.M., H.S., S.N., and K.K. (Katsunori Kondo); methodology,
R.M., Y.T., and K.K. (Katsunori Kondo); formal analysis, R.M.; data curation, N.S., M.H., and K.K. (Katsunori Kondo);
writing—original draft preparation, R.M.; writing—review and editing, R.M. and Y.T.; supervision H.W., K.M.,
H.S., S.N., K.K. (Katsunori Kondo), Y.T., N.S., M.H., and K.K. (Kaori Kojima); project administration, R.M.
Funding: This work was supported by Health and Labour Sciences Research Grants of the Ministry of Health,Labour and Welfare of Japan (H30−Junkankitou−Ippan−004) and JST-OPERA program grant (JPMJOP1831).
Acknowledgments: We would like to thank the members of the Japan Gerontological Evaluation Study(JAGES) project.
Conflicts of Interest: The authors declare no conflicts of interest.

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