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ASSOCIATIONS BETWEEN DIETARY VARIETY AND FRAILTY IN COMMUNITY-DWELLING OLDER PEOPLE WHO LIVE ALONE: GENDER DIFFERENCES

 

M. Yokoro1,2, N. Otaki2,3, M. Yano2, M. Tani3, N. Tanino2, K. Fukuo2,3

 

1. Department of Dietary Life and Food Sciences, Junior College Division, Mukogawa Women’s University, Hyogo, Japan; 2. Research Institute for Nutrition Sciences, Mukogawa Women’s University, Hyogo, Japan, 3. Department of Food Sciences and Nutrition, School of Food Sciences and Nutrition, Mukogawa Women’s University, Hyogo, Japan

Corresponding Author: Naoto Otaki, Department of Food Sciences and Nutrition, School of Food Sciences and Nutrition, Mukogawa Women’s University, 6-46 Ikebiraki-cho, Nishinomiya, Hyogo 663-8558, Japan. Email: otk_nao@mukogawa-u.ac.jp, Tel and Fax: +81-798-45-3728

J Frailty Aging 2021;in press
Published online December 12, 2021, http://dx.doi.org/10.14283/jfa.2021.49

 


Abstract

Objectives: This study aimed to investigate the influences of living arrangements on the association between dietary variety and frailty by gender in community-dwelling older people.
Design: A cross-sectional study.
Setting: Nishinomiya city, Hyogo prefecture, Japan.
Participants: A total of 4,996 randomly selected community-dwelling older people aged 65 years and older and living in Nishinomiya City.
Measurements: Survey questionnaires were distributed via mail. The frailty score was evaluated by the 5-item frailty screening index. Dietary variety was assessed using the dietary variety score developed for the general older Japanese population.
Results: A total of 2,764 community-dwelling participants aged ≥ 65 years responded to the questionnaires. After excluding missing data, 1,780 participants were included in the study analysis. The frailty scores in older men living alone were significantly higher than those in older men living with someone (P < 0.001). The dietary variety scores in older men living alone were significantly lower than those in older men living with someone (P < 0.001). However, differences in the frailty and dietary variety scores between living alone and living with someone were not were observed in older women (P = 0.360 and P = 0.265, respectively). In the multivariable regression analysis, the associations between dietary variety score and frailty score in living alone (β= −0. 271, P = 0.011) were stronger than those in living with someone in the case of older men (β= −0.131, P = 0.045). Similar associations between dietary variety and frailty were presented in older women living alone than in those living with someone (β −0.114, P = 0.002; β −0.088, P = 0.012, respectively).
Conclusions: Older men who live alone had higher frailty score and lower dietary variety. The associations between dietary variety and frailty were different according to living arrangements in both older men and older women.

Key words: Frailty, dietary variety, living alone, gender difference.


 

Introduction

The Frailty is a serious clinical and public health problem in countries with an aging society. Frailty is considered to be an age-related clinical condition characterized by a decrease in multiple physiological functioning, accompanied by an increased susceptibility to stressors and resulting in a higher risk of mortality (1, 2). Furthermore, frailty is also associated with other negative health outcomes including disability, falls, depression, dementia, hospitalization, and nursing home admission ((3–8). Prevention and management of frailty in the older population are important for the promotion of healthy aging.
Dietary variety is defined as the number of different foods or food groups consumed during a given period (9). A greater dietary variety improves adequacy of nutrient intake (10). Dietary variety is related to health problems in older people, such as malnutrition, lower physical performance, and depression (11–13). Older frail adults have a lower dietary variety as compared with older robust adults, and the severity of frailty is negatively associated with dietary variety (14). Therefore, dietary variety is important for frailty prevention in older people. However, dietary variety in this population is affected by various factors, such as gender, economic status, chewing ability, intellectual activity, and food accessibility (15–18).
The proportion of older adults who live alone is increasing worldwide. In Japan, among older people aged ≥65 years, the percentage of one-person households was 26.3% in 2015 (19). Although the percentage of older women aged ≥65 years living alone (21.1%) was higher than that of older men aged ≥65 years (13.3%) in 2015, the percentages of individuals living alone are rising annually in both men and women (19). In older people, living alone is a risk factor for frailty and is highly associated with frailty as compared with other living arrangements, especially in men (20). However, the reason why living alone results in a higher risk of frailty, especially in older men, is not fully understood.
Living alone is related to unhealthy food intake, such as lower fruit and/or vegetable and lower fish intake (21). Eating alone was associated with oral frail status in the general population of older people (22). Moreover, the relationships between living alone and unfavorable food intake in men are stronger than those in women (21). We hypothesized that dietary variety contributes to the difference in frailty risk by living arrangements in gender. This study aimed to examine the living-arrangement differences of dietary variety, frailty, and the association between dietary variety and frailty in community-dwelling older men and women.

 

Methods

Study participants

This study was conducted in Nishinomiya City, Hyogo Prefecture in Japan, in August 2020. Study participants were 4,996 randomly selected community-dwelling older people from the overall older population aged 65 years and older and living in Nishinomiya City using addresses recorded in the Health and Welfare Department in Nishinomiya City office. Inclusion criteria were community-dwelling older people aged ≥65 years residing in Nishinomiya City. Exclusion criteria were older people who were hospitalized or resided in nursing homes. The survey questionnaires were distributed through mail. The aims and details of this study were explained in writing, and the return of a completed survey questionnaires was considered a consent for study participation. A total of 2,764 participants (response rate, 55.3%) responded to the survey questionnaires. However, 984 respondents were excluded: 10 owing to their age being ≤64 years and 974 owing to incomplete questionnaires. Finally, 1,780 participants were included in the study analysis. A flow chart describing the inclusion of study participants is presented in Figure 1. The ethics committee of Mukogawa Women’s University approved this study (approval number 20-53).

Figure 1. Study participants

Survey questionnaires

Age, gender, living arrangements, height, weight, smoking habits, drinking habits, diseases on therapy, number of medications, economic status, social participation, dietary variety score, and frailty score were assessed using the questionnaire. Body mass index (BMI) was calculated as weight (in kilograms) divided by height (in meters) squared. Participants answered the duration in a day and weekly frequency of walking, moderate physical activity, and intense physical activity to assess physical activity. The International Physical Activity Questionnaire was used to evaluate the amount of physical activity (Mets-minutes/week) (23, 24).

Dietary variety assessments

Dietary variety was assessed by the dietary variety score developed for the general older Japanese people (25). Participants selected the intake frequencies of 10 food groups in the last week, namely, fish and seafood, meats, eggs, daily products, soybean and soybean products, green and yellow vegetables, seaweed, potatoes, fruits, and fat or oils, from the following choices: “eat almost every day,” “eat once every 2 days,” “eat 1 or 2 days a week,” and “hardly eat at all.” The choice of “eat almost every day” was scored 1, and other choices were scored 0. The sum of the 10 food group scores expressed the dietary variety score. The dietary variety score ranges from 0 to 10 points, and a higher score means higher dietary variety.

Frailty assessments

The 5-item frailty screening index developed by Yamada et al. was used to assess frailty (26). This frailty index comprised the following five questions: “Have you lost 2 to 3 kg or more in the last 6 months?” “Do you feel like you walk more slowly than before?” “Do you exercise at least once per week?” “Can you remember what happened 5 minutes ago?” “Do you feel tired for no reason during past two weeks?” Participants answered “yes” or “no” to these five questions. “Yes” was scored 1 and “no” was scored 0 in the following questions: “Have you lost 2 to 3 kg or more in the last 6 months?” “Do you feel like you walk more slowly than before?” “Do you feel tired for no reason during last 2 weeks?” “Yes” was scored 0 and “no” was scored 1 in following questions: “Do you exercise at least once per week?” and “Can you remember what happened 5 minutes ago?” The sum of these scores was used as the frailty score. The frailty score ranges from 0 to 5 points. Scores of 0, 1–2, and ≥3 indicated robust, prefrail, and frail, respectively.

Statistical analysis

The study participants were stratified according to gender and living arrangements. In each gender group, the participants were divided into two groups: living with someone and living alone. Living with someone included living with married partner, living with children, living with married partner and children, and living with other people. The characteristics of study participants as quantitative variables are expressed as the mean ± standard deviation (SD) (median). Categorical variables are expressed as numbers (percentage). The Mann–Whitney U and chi-squared tests for the quantitative variables and for the categorical variables were used to compare the participants who lived alone with those who lived with someone. We used the chi-squared test to compare eating frequencies of 10 food groups between living with someone and living alone. Multivariable linear regression analysis was used to analyze age-adjusted and multivariable-adjusted correlations between dietary variety and the frailty score. Continuous frailty score was used as a dependent variable in the linear regression analysis. Age (increased by 5 years), BMI (< 18.5, 18.5–24.9, ≥ 25 kg/m2), current smoking status (yes or no), habitual alcohol drinking (none, < 270 mL of alcohol, ≥ 270 mL of alcohol), number of illnesses (≥ 2), number of medications (none, 1–5, ≥ 6), economic status (secure, insecure), physical activity (< 300, 300–599, ≥ 600), and social participation (yes or no) were the covariates of multivariable-adjusted correlations (24, 27–29). IBM SPSS Statistics 26.0 (IBM Corp., Armonk, NY, USA) was used to analyze all statistical data. Two-tailed P < 0.05 was considered statistically significant.

 

Results

Characteristics of study participants

The characteristics of the overall participants and of participants who lived with someone or who lived alone in each gender group are presented in Table 1. In the overall participants, the medians of age and BMI were 73.0 years and 22.2 kg/m2, respectively. In both of men and women group, BMI, habitual alcohol drinking, number of illness, number of medications, physical activity, and social participation were not different between living with someone and living alone. In both of men and women group, proportions of economic insecure in the living alone group were significantly higher than that in living with someone (15.2% vs. 6.9%, P < 0.001 in men; 12.0% vs. 5.7%, P < 0.001 in women). The median age in the living alone group was higher than that of the living with someone group for women (75.0 vs. 72.0, respectively; P < 0.001), but not in men (73.0 vs. 73.0, respectively; P = 0.882). The proportion of current smoker in the living alone group is significantly higher than that in the living with someone group in men (22.8% vs. 11.4%, P = 0.004), but not in women. In the overall participants, the medians of dietary variety score and frailty score were 4.0 and 1.0, respectively (Table 2). Interestingly, the differences of dietary variety score and frailty score between living with someone and living alone varied by gender. The median dietary variety score in the living alone group was significantly lower than that in the living with someone group in men (3.0 vs. 4.0, respectively; P < 0.001) but not in women (4.0 vs. 4.0, respectively; P = 0.265). The median frailty score in the living alone group was significantly higher than that in the living with someone group in men (2.0 vs. 1.0, respectively; P < 0.001) but not in women (1.0 vs. 1.0, respectively; P = 0.360). Furthermore, the prevalence of frailty in the living alone group was significantly higher than that in the living with someone group in men (27.2% vs. 13.3%, respectively; P < 0.001) but not in women.

Table 1. Characteristics of study participants (n = 1780)

†Mann–Whitney U test; ‡Chi-squared test.

Table 2. Dietary variety and frailty scores of the study participants (n = 1780)

†Mann–Whitney U test; ‡Chi-squared test.

 

Differences of eating frequencies of 10 food groups between living with someone and living alone in men and women

The differences of eating frequencies of 10 food groups consisting dietary variety between living with someone and living alone in each gender group are presented in Table 3. In both of men and women, the proportion of respondents who answered “almost every day” of meat and green and yellow vegetables in the living alone group was significantly lower than those in the living with someone group (meat, 25.0% vs. 38.7%, P = 0.011 in men; 39.6% vs. 49.0%, P = 0.015 in women; yellow and green vegetables, 38.0% vs. 54.2%, P = 0.004 in men; 65.8% vs. 75.1%, P = 0.008 in women). Gender differences were found in eating frequencies of fruits, potatoes, and oils. The proportion of respondents who answered “almost every day” of potatoes in living alone was significantly lower than that in living with someone in women (5.3% vs. 9.7%, P = 0.043), but not in men (2.2% vs. 6.8%, P = 0.107). Moreover, the proportion of respondents who answered “almost every day” of fruits and oils in living alone was significantly lower than those in living with someone in men (fruits, 39.1% vs. 51.6%, P = 0.004; oils, 27.2% vs. 42.2%, P = 0.007), but not in women (fruits, 64.4% vs. 62.9%, P = 0.694; oils, 43.1% vs. 48.6%, P = 0.149).

Table 3. Food group intake by gender and living arrangements

†Chi-squared test.

 

Association between dietary variety and frailty score by gender and living arrangements

The associations between dietary variety and frailty score were analyzed using multivariate linear regression analysis. In both men and women, dietary variety negatively correlated with frailty score in crudes (standardized coefficient, −0.201, P < 0.01 in men; standardized coefficient, −0.144, P < 0.01 in women), age-adjusted models (standardized coefficient, −0.219, P < 0.01 in men; standardized coefficient, −0.150, P < 0.01 in women), and multivariate-adjusted models (standardized coefficient, −0.132, P < 0.01 in men; standardized coefficient, −0.097, P < 0.01 in women). The stratified analysis for dietary variety and frailty score based on participant gender and living arrangements is presented in Table 4. Significant associations between dietary variety and frailty score were found in both the living with someone group (standardized coefficient, −0.131, P = 0.045) and the living alone group (standardized coefficient, −0.271, P = 0.011) in men in multivariate-adjusted models, whereas the correlation in living alone was greater than that in living with someone. Likewise, similar associations between dietary variety and frailty presented in women (standardized coefficient, −0.088, P = 0.012 in living with someone; standardized coefficient, −0.114, P = 0.002 in living alone).

Table 4. Association between dietary variety and frailty score by gender and living arrangements*

*Continuous frailty score was used as a dependent variable in linear regression analysis; †Adjusted for age (increased by 5 years); ‡Adjusted for age (increased by 5 years), BMI (<18.5, 18.5–24.9, ≥25 kg/m2), current smoking status (yes or no), habitual alcohol drinking (none, <270 ml of alcohol, ≥270 ml of alcohol), number of illnesses (≥2), number of medications (none, 1–5, ≥6), economic status (secure, insecure), physical activity (<300, 300–599, ≥600), and social participation (yes or no).

 

Discussion

In this study, we found that both dietary variety and frailty scores were significantly lower in older men living alone than those in older men living with someone. In contrast, these differences were not observed in older women, although the association between dietary variety and frailty scores was stronger in those living alone than that in those living with someone in both men and women. Taken together, influences of living arrangements on the dietary variety and the frailty score might differ by gender in community-dwelling older people.
In this study, older men who live alone particularly had disadvantages for dietary variety and frailty compared with others. Fukuda et al. reported men who lived alone had lower dietary variety score than women who lived alone and discussed that the gender differences in dietary variety might be shaped by social factors related to eating habits, especially by gender role, which means Japanese older men had not been involved in preparing meals (17). In our results, living arrangements had no impact on both dietary variety and frailty in older women, who generally have been assuming roles of preparing meals in the Japanese society. However, we could not evaluate the forepassed participation level of preparing meals and current food skills. Further survey is needed to clarify the relevance of these factors on dietary variety in older people.
The dietary variety score used in this study was designed to evaluate the habitual dietary variety of older Japanese people. Dietary variety has been reported to be associated between BMI, physical performance, and frailty (9, 11, 13, 14). The dietary variety score was validated as being associated with nutrient intake using dietary records in older Japanese adults as follows: higher dietary variety was related to higher intakes of energy and protein, and the proportion of participants who had insufficient energy was decreased in the group with higher dietary variety as compared with the group with lower dietary variety (30). Adequate energy intake or protein intake is essential to prevent frailty (31, 32). Hence, a higher dietary variety score was associated with a lower frailty score. In this study, the associations between dietary variety and frailty score in older individuals living alone were stronger than those in older individuals living with someone for both men and women, whereas dietary variety was associated with frailty score in all stratified groups. Regardless of gender, this result suggests that improvement in dietary variety is more important for older people who live alone to prevent frailty than in older people who live someone.
In terms of food group intake, the eating frequencies of vegetables and fruits were lower in men who lived alone than in men who lived with someone. In women who lived alone, the frequency of eating vegetables was lower than that in women who lived with someone. Other reports indicated that living alone constituted a limiting factor for vegetable and fruit consumptions (33). In contrast, a diet high in vegetables and fruits contributes to a reduced risk of frailty (34). Therefore, several approaches to increase the intake frequencies of vegetables and fruits are required in older people who live alone. Men who lived alone had a lower frequency of consuming oils than men who lived with someone. Adequate energy intake is essential to prevent frailty (31). The appropriate use of oils in meals might be effective for preventing frailty.
There are several limitations in this study. First, the low response rate might have led to a nonresponse bias. Second, this was a cross-sectional study, and results should be interpreted with caution. We could not discuss causal relationships. Third, because this was a mail survey, all variables were self-reported data. Any biases due to self-reporting could not be controlled. Fourth, only 1,780 of the 2,764 respondents were included in the analysis. Because of the incomplete questionnaires, 984 of the 2,764 respondents were excluded from the analysis. The large amount of missing data reduced the statistical power of this study. Fifth, the numbers of older individuals living alone (n = 92, 11.5% in men; n = 225, 23.0% in women) were limited in our study. However, in the national census in 2015, the percentages of older men and women aged ≥65 years who lived alone were 13.3% and 21.1%, respectively (19). Therefore, in this study, although the numbers of men and women who lived alone were limited, the proportions of men and women living alone were reasonable. Sixth, self-reported data were used to assess BMI, existing illness, number of medications, and physical activity. Seventh, we did not quantitatively assess food intake or nutrient intake, although the dietary variety score has been validated as relating to nutrient intakes (30). In addition, although difficulties in eating, including chewing ability, affect dietary variety, we did not assess difficulties in eating in this study (15). Finally, although depression is a key factor of frailty, we could not assess psychological conditions in this study (5).
In conclusion, this study found that living-arrangement differences of dietary variety and frailty differed by gender in community-dwelling older people, and in both men and women, the associations between dietary variety and frailty were stronger in living alone than in living with someone. In particular, older men who live alone had lower dietary variety and higher frailty score. Moreover, living alone in men related to higher mortality, but not in women (5). Therefore, the results in this study suggest that social supports to promote healthy eating for older people who live alone, especially for older men who live alone, are needed.

 

Acknowledgements: This work was supported by JSPS KAKENHI grant number 20K19730. We thank the city employees at Nishinomiya City Office for their help in distributing survey questionnaires.

Conflict of interests: The authors declare no conflict of interest.

Ethical standards:The ethics committee of Mukogawa Women’s University approved this study (approval number 20-53).

 

References

1. Fried LP, Tangen CM, Walston J, et al. Frailty in Older Adults: Evidence for a Phenotype. Vol 56.; 2001. https://academic.oup.com/biomedgerontology/article/56/3/M146/545770
2. Rockwood K, Mitnitski A. Frailty Defined by Deficit Accumulation and Geriatric Medicine Defined by Frailty. Clin Geriatr Med. 2011;27(1):17-26. doi:10.1016/j.cger.2010.08.008
3. Vermeulen J, Neyens JCL, van Rossum E, Spreeuwenberg MD, de Witte LP. Predicting ADL disability in community-dwelling elderly people using physical frailty indicators: a systematic review. BMC Geriatr. 2011;11(1):33. doi:10.1186/1471-2318-11-33
4. Kojima G. Frailty as a Predictor of Future Falls Among Community-Dwelling Older People: A Systematic Review and Meta-Analysis. J Am Med Dir Assoc. 2015;16(12):1027-1033. doi:10.1016/j.jamda.2015.06.018
5. Soysal P, Veronese N, Thompson T, et al. Relationship between depression and frailty in older adults: A systematic review and meta-analysis. Ageing Res Rev. 2017;36:78-87. doi:10.1016/j.arr.2017.03.005
6. Kojima G, Taniguchi Y, Iliffe S, Walters K. Frailty as a Predictor of Alzheimer Disease, Vascular Dementia, and All Dementia Among Community-Dwelling Older People: A Systematic Review and Meta-Analysis. J Am Med Dir Assoc. 2016;17(10):881-888. doi:10.1016/j.jamda.2016.05.013
7. Vermeiren S, Vella-Azzopardi R, Beckwée D, et al. Frailty and the Prediction of Negative Health Outcomes: A Meta-Analysis. J Am Med Dir Assoc. 2016;17(12):1163.e1-1163.e17. doi:10.1016/j.jamda.2016.09.010
8. Cegri F, Orfila F, Abellana RM, Pastor-Valero M. The impact of frailty on admission to home care services and nursing homes: eight-year follow-up of a community-dwelling, older adult, Spanish cohort. BMC Geriatr. 2020;20(1):281. doi:10.1186/s12877-020-01683-9
9. Bernstein MA, Tucker KL, Ryan ND, et al. Higher dietary variety is associated with better nutritional status in frail elderly people. J Am Diet Assoc. 2002;102(8):1096-1104. Accessed September 13, 2019. http://www.ncbi.nlm.nih.gov/pubmed/12171454
10. Foote JA, Murphy SP, Wilkens LR, Basiotis PP, Carlson A. Dietary variety increases the probability of nutrient adequacy among adults. J Nutr. 2004;134(7):1779-1785. doi:10.1093/jn/134.7.1779
11. Yokoyama Y, Nishi M, Murayama H, et al. Dietary variety and decline in lean mass and physical performance in community-dwelling older Japanese: A 4-year follow-up study. J Nutr Health Aging. 2017;21(1):11-16. doi:10.1007/s12603-016-0726-x
12. Yokoyama Y, Kitamura A, Yoshizaki T, et al. Score-Based and Nutrient-Derived Dietary Patterns Are Associated with Depressive Symptoms in Community-Dwelling Older Japanese: A Cross-Sectional Study. J Nutr Heal Aging. 2019;23(9):896-903. doi:10.1007/s12603-019-1238-2
13. Tsuji T, Yamamoto K, Yamasaki K, et al. Lower dietary variety is a relevant factor for malnutrition in older Japanese home-care recipients: A cross-sectional study. BMC Geriatr. 2019;19(1):197. doi:10.1186/s12877-019-1206-z
14. Motokawa K, Watanabe Y, Edahiro A, et al. Frailty Severity and Dietary Variety in Japanese Older Persons: A Cross-Sectional Study. J Nutr Health Aging. 2018;22(3):451-456. doi:10.1007/s12603-018-1000-1
15. Kwon J, Suzuki T, Kumagai S, Shinkai S, Yukawa H. Risk factors for dietary variety decline among Japanese elderly in a rural community: a 8-year follow-up study from TMIG-LISA. Eur J Clin Nutr. 2006;60(3):305-311. doi:10.1038/sj.ejcn.1602314
16. Shibasaki K, Kin SK, Yamada S, Akishita M, Ogawa S. Sex-related differences in the association between frailty and dietary consumption in Japanese older people: A cross-sectional study. BMC Geriatr. 2019;19(1):211. doi:10.1186/s12877-019-1229-5
17. Fukuda Y, Ishikawa M, Yokoyama T, et al. Physical and social determinants of dietary variety among older adults living alone in Japan. Geriatr Gerontol Int. 2017;17(11):2232-2238. doi:10.1111/ggi.13004
18. Harada K, Masumoto K, Okada S. Distance to supermarkets and dietary variety among Japanese older adults: Examining the moderating role of grocery delivery services. Public Health Nutr. Published online 2020:1-8. doi:10.1017/S1368980020002219
19. Japan Cabinet Office. Annual Report on the Ageing Society: 2018 (in Japanese). Published 2018. Accessed February 4, 2021. https://www8.cao.go.jp/kourei/whitepaper/w-2018/html/zenbun/index.html
20. Yamanashi H, Shimizu Y, Nelson M, et al. The association between living alone and frailty in a rural Japanese population: The Nagasaki Islands study. J Prim Health Care. 2015;7(4):269-273. doi:10.1071/HC15269
21. Hanna KL, Collins PF. Relationship between living alone and food and nutrient intake. Nutr Rev. 2015;73(9):594-611. doi:10.1093/nutrit/nuv024
22. Ohara Y, Motokawa K, Watanabe Y, et al. Association of eating alone with oral frailty among community-dwelling older adults in Japan. Arch Gerontol Geriatr. 2020;87:104014. doi:10.1016/j.archger.2020.104014
23. Craig CL, Marshall AL, Sjöström M, et al. International physical activity questionnaire: 12-Country reliability and validity. Med Sci Sports Exerc. 2003;35(8):1381-1395. doi:10.1249/01.MSS.0000078924.61453.FB
24. Murase N, Katsumura T, Ueda C, Inoue S, Shimomitsu T. Validity and reliability of Japanese version of International Physical Activity Questionnaire. J Heal Welf Stat. 2002;49:1-9.
25. Kumagai S, Watanabe S, Shibata H, et al. [Effects of dietary variety on declines in high-level functional capacity in elderly people living in a community]. Nihon Koshu Eisei Zasshi. 2003;50(12):1117-1124. Accessed September 12, 2019. http://www.ncbi.nlm.nih.gov/pubmed/14750363
26. Yamada M, Arai H. Predictive Value of Frailty Scores for Healthy Life Expectancy in Community-Dwelling Older Japanese Adults. J Am Med Dir Assoc. 2015;16(11):1002.e7-1002.e11. doi:10.1016/j.jamda.2015.08.001
27. Takezaki T, Shinoda M, Hatooka S, et al. Subsite-Specific Risk Factors for Hypopharyngeal and Esophageal Cancer (Japan). Cancer Causes Control. 2000;11(7):597-608. http://www.jstor.org/stable/3554163
28. Johnston MC, Crilly M, Black C, Prescott GJ, Mercer SW. Defining and measuring multimorbidity: a systematic review of systematic reviews. Eur J Public Health. 2019;29(1):182-189. doi:10.1093/eurpub/cky098
29. Kuzuya M, Masuda Y, Hirakawa Y, et al. Underuse of Medications for Chronic Diseases in the Oldest of Community-Dwelling Older Frail Japanese. J Am Geriatr Soc. 2006;54(4):598-605. doi:https://doi.org/10.1111/j.1532-5415.2006.00659.x
30. Narita M, Kitamura A, Takemi Y, Yokoyama Y, Morita A, Shinkai S. [Food diversity and its relationship with nutrient intakes and meal days involving staple foods, main dishes, and side dishes in community-dwelling elderly adults]. Nihon Koshu Eisei Zasshi. 2020;67(3):171-182. doi:10.11236/jph.67.3_171
31. Salminen KS, Suominen MH, Kautiainen H, Pitkälä KH. Associations Between Nutritional Status, Frailty and Health-Related Quality of Life Among Older Long-Term Care Residents in Helsinki. J Nutr Heal Aging. 2020;24(3):319-324. doi:10.1007/s12603-019-1320-9
32. Coelho-Júnior H, Rodrigues B, Uchida M, Marzetti E. Low Protein Intake Is Associated with Frailty in Older Adults: A Systematic Review and Meta-Analysis of Observational Studies. Nutrients. 2018;10(9):1334. doi:10.3390/nu10091334
33. Choi YJ, Ailshire JA, Crimmins EM. Living alone, social networks in neighbourhoods, and daily fruit and vegetable consumption among middle-aged and older adults in the USA. Public Health Nutr. 2020;23(18):3315-3323. doi:10.1017/S1368980020002475
34. Kojima G, Iliffe S, Jivraj S, Walters K. Fruit and vegetable consumption and incident prefrailty and frailty in community-dwelling older people: The english longitudinal study of ageing. Nutrients. 2020;12(12):1-14. doi:10.3390/nu12123882
35. Kandler U, Meisinger C, Baumert J, Löwel H. Living alone is a risk factor for mortality in men but not women from the general population: A prospective cohort study. BMC Public Health. 2007;7:335. doi:10.1186/1471-2458-7-335