Relationship between nutritional status and functional capacity in the elderly of Amirkola City

Abstract

BACKGROUND:

Nutrition is significantly related to the quality of life in the elderly. Functional capacity, which deals with the ability of the elderly to perform activities of daily living (ADLs) and instrumental activities of daily living (IADLs), is considered an important health indicator. The purpose of the present study was to investigate the nutritional status and functional capacity in the elderly population of Amirkola City.

MATERIALS AND METHODS:

This cross-sectional study was part of the second phase of the Amirkola Elderly Health Cohort (AHAP), which was conducted on 800 randomly selected over 60 years of age. Nutritional status was assessed using the Semi-Quantitative Food Frequency Questionnaire (SQFFQ), and functional capacity was evaluated using the Katz Index and Lawton Scale, including ADLs and IADLs. Data analysis was performed using SPSS software, and a P value of less than 0.05 was considered statistically significant.

RESULTS:

There were 437 (54.6%) males and 363 (45.4%) females among 800 elderly respondents. The mean nutritional and energy intake was greater in the able group than in the disabled group. According to multiple logistic regression analysis, the most significant factors affecting ADLs were age (OR = 4.93, 95% CI: 1.15–21.10, P = 0.028) and the number of chronic diseases (OR = 3.21, 95% CI: 1.10–9.36, P = 0.03). There was a significant relationship between IADLs and the number of chronic diseases (OR = 1.17, 95% CI: 1.07–1.29, P = 0.01), age (OR = 4.73, 95% CI: 1.20–18.61, P < 0.001), and gender (OR = 2.27, 95% CI: 1.52–3.38, P < 0.001).

CONCLUSIONS:

This study found a positive correlation between nutritional status and functional capacity in the elderly population of Amirkola City. Therefore, planning for nutritional status improvement can be effective in improving the functional capacity and quality of life of the elderly.

Introduction

Aging is characterized by gradual, progressive, and spontaneous degenerative changes in most body systems and physiological functions. Fundamentally, it is a process, not a disease, and many of its associated problems can be prevented.[1,2] According to a 2012 World Health Organization report, the global elderly population is projected to increase from 605 million to 2 billion by 2050, with the most significant growth occurring in developing countries.[3] Iran is also experiencing an aging population, with the number of elderly Iranians expected to double between 2015 and 2030.[4] Proper nutrition is a fundamental and essential need for the elderly, as it significantly impacts their health and quality of life. Numerous studies worldwide have demonstrated the crucial role of nutritional status in the health and disease of older adults.[5] Malnutrition is on the rise globally, even in developed countries. Studies conducted in Asia revealed that between 2005 and 2012, 16%–78% of hospitalized elderly individuals suffered from malnutrition.[6] A meta-analysis of 25 studies involving over 3,000 elderly individuals from primarily developed countries revealed that approximately 9% of the elderly were malnourished, and 45% were at risk of malnutrition. Malnutrition rates were even higher in developing countries.[7,8] Functional capacity refers to the ability to perform daily tasks, including activities of daily living (ADLs) and instrumental activities of daily living (IADLs).[9] Maintaining functional capacity is a crucial health indicator among the elderly, and its loss is associated with increased mortality.[10] As individuals age, disability rates gradually increase.[7,8,11,12] Mobility limitations are prevalent in up to 50% of individuals aged 76 and older, leading to dependency. Research indicates that elderly individuals are three times more likely to be dependent compared to younger adults. A significant correlation exists between motor ability and nutritional status in the elderly. Elderly individuals who have lost mobility due to social isolation and lack of social interaction often experience poorer mental health and are at a higher risk of malnutrition due to factors such as pressure ulcers.[7,8,12] Elderly individuals who require assistance from family or caregivers in their daily lives generally have a lower quality of life and overall health. An examination of the relationship between daily living activities and demographic variables revealed that the level of daily living activities and the independence of elderly individuals in performing these activities increases when the individual is married and has a higher education level, better economic status, greater physical activity, and younger age. Additionally, IADLs also improve in the elderly with these characteristics.[13,14,15] Functional dependence can negatively impact the nutrition of elderly individuals by limiting their access to a healthy diet.[16,17] Studies have shown that physical inactivity and poor nutrition are factors that can impair the functional independence of the elderly and increase their risk of developing chronic diseases such as metabolic syndrome, cardiovascular disease, and psychological disorders such as depression. These factors can significantly contribute to declines in cognitive and psychomotor function.[18] Malnutrition is a common problem among the elderly and can be identified, prevented, and treated. Improving nutritional indicators in the elderly is a key factor in maintaining and promoting their health, and can contribute to achieving the goal of “healthy aging” by preventing diseases and reducing recovery time. Therefore, this study aims to investigate the relationship between nutritional status and functional ability among the elderly in Amirkola City.

Materials and Methods

Study design and settings

This cross-sectional study included all individuals ≥60 years in the city of Amirkola in northern Iran as part of the second phase of the Amirkola Health and Aging Project (AHAP) cohort study, which has been conducted since 2011.

Study participants and sampling

Out of the 2,135 individuals enrolled in the second phase of the cohort, 800 elderly individuals who met the inclusion criteria and had available data on nutritional status and functional capacity were randomly selected for the study. Elderly individuals with severe cognitive impairment and those unable to respond to questions were excluded from the study.

Data collection tools and techniques

Demographic data, including age, gender, education level, marital status, living situation (alone or with others), and history of chronic diseases, was collected through a questionnaire administered via interviews with elderly individuals or their close relatives.

To assess nutritional status, the Semi-Quantitative Food Frequency Questionnaire (SQFFQ) was used.[19] This retrospective method involved asking participants to estimate their consumption of various foods over a specific period by using a predefined food list. In addition to the frequency of consumption, serving sizes were also recorded. The obtained nutrient intake data was then compared to reference values such as the recommended dietary allowance (RDA) or recommended dietary intake (RDI) to determine the percentage of recommended intake achieved by each individual. Individuals who consumed less than two-thirds of the RDA for fat, protein, carbohydrates, and energy were considered to have nutrient deficiencies. The validity and reliability of this questionnaire were assessed using a study conducted by Dr. Bijani et al.[20]

ADLs and IADLs were assessed through interviews with the participants themselves or their caregivers. The Katz Index[21,22] was used to assess ADLs, including seven questions related to eating, dressing, bathing, grooming, toileting, transferring, and continence. Each question was scored on a scale of 0, 1, or 2, with 0 indicating complete dependence, 1 indicating partial independence, and 2 indicating complete independence. A total score of 14 or higher was considered independent.

IADL was assessed using the 10-item Lawton scale, which covers activities such as using the telephone, shopping, preparing meals, doing housework, taking medications, managing finances, doing heavy housework, climbing stairs, and walking approximately one kilometer. Questions 1–7 were scored on a scale of 1, 2, or 3, with 1 indicating complete dependence, 2 indicating partial independence, and 3 indicating complete independence. Questions 8, 9, and 10 were scored as 0 or 1, with 0 indicating dependence and 1 indicating independence. The total IADL score ranged from 0 to 24, with a score greater than 20 considered independent and a score of 20 or less considered dependent.[21] The content validity of the IADL questionnaire in the study by Nanjani and Azadbakht was reported as 0.82, with sensitivity and specificity of 71% and 77%, respectively.

A theoretical framework was drawn in a conceptual graph [Figure 1].

Figure 1.

Model for the factors affecting activities of daily living (ADLs) and instrumental activities of daily living (IADLs)

Ethical considerations

Patient confidentiality was maintained, and data were reported in an aggregated form without identifying individuals. The study was approved by the Ethics Committee of Babol University of Medical Sciences (identifier: IR.MUBABOL.HRI.REC.1400.211; study ID: 724133413).

Statistical analysis method

Data were analyzed using SPSS software, and the Chi-square test, Pearson correlation coefficient, and multiple logistic regression model (Enter method) were employed. A P value less than 0.05 was considered statistically significant.

Results

As shown in Table 1, there was a significant association between age (P < 0.001), education level (P < 0.001), and the number of comorbidities (P < 0.001) with both ADLs and IADLs. The percentage of disability in IADL was higher among those aged 70 and over compared to those under 70 (73.4% vs. 26.6%). Similarly, the percentage of disability in IADL was higher among illiterate individuals (87.5%) compared to those with higher education levels. These findings were also observed for ADLs, with higher rates of disability among those aged 70 and over (87.1%) and those who were illiterate (96.8%). However, gender (P < 0.001) and BMI (P = 0.012) were only significantly associated with IADLs. The majority of individuals with disabilities in IADL had a BMI of 25 or higher (79.4%) and were female (59%). There was no significant association between gender (P = 0.280), BMI (P = 0.346), and ADLs.

Table 1.

Association between activities of daily living (ADLs) and instrumental activities of daily living (IADLs) with demographic variables among elderly individuals in Amirkola Cohort

ADL										IADL
Variables		Total (n=800)		Independent (n=769)		Not-Independent (n=31)		P*		Independent (n=432)		Not-independent (n=368)		P*
Age, n (%)
Lower than 70 years		387 (48.4)		383 (49.8)		4 (12.9)		<0.001		289 (66.9)		98 (26.6)		<0.001
70 and more		413 (51.6)		386 (50.2)		27 (87.1)				143 (33.1)		270 (73.4)
SEX, n (%)
Male		437 (54.6)		423 (55)		14 (45.2)		0.280		286 (66.2)		151 (41)		<0.001
female		363 (45.4)		346 (45)		17 (54.8)				146 (33.8)		217 (59)
Education level, n (%)
Illiterate		486 (60.8)		456 (59.3)		30 (96.8)				164 (38)		322 (87.5)
Elementary		164 (20.5)		164 (21.3)		0 (0)		0.001		125 (28.9)		39 (10.6)		<0.001
Lower than diploma		102 (12.8)		101 (13.1)		1 (3.2)				98 (22.7)		4 (1.1)
University		48 (6)		48 (6.2)		0 (0)				45 (10.4)		3 (0.8)
BMI, n (%)
Lower than 25		190 (23.8)		188 (25.3)		2 (14.3)		0.346		123 (28.5)		67 (20.6)		0.012
25 and more		567 (70.9)		555 (74.7)		12 (85.7)				308 (71.5)		259 (79.4)
Number of chronic diseases, mean±SD		3.73±2.19		3.68±2.16		5.41±2.57		<0.001		3.19±2.05		4.43±2.18		<0.001

*Findings of chi-square test

As shown in Table 2, there was a significant correlation between dietary variables such as daily protein, fat, carbohydrate, and energy intake and both ADLs and IADLs (P < 0.05). The average intake of all macronutrients and energy was significantly higher in individuals capable of performing IADLs and ADLs compared to those who were disabled (dependent).

Table 2.

Relationship between macronutrients and energy intake with instrumental activities of daily living and activities of daily living in the elderly of Amirkola Cohort

ADL								IADL
Nutrient variable		Independent (n=769)		Not-independent (n=31)		P*		Independent (n=432)		Not-independent (n=368)		P*
Protein (gr)		60.53±22.93		50.32±19.24		0.039		65.75±23.38		53.10±20.13		<0.001
Fat (gr)		52.35±29.50		34.12±31.77		0.001		59.96±29.60		41.88±26.92		<0.001
Carbohydrate (gr)		290.99±104.97		213.48±91.15		0.009		316.13±106.39		254.55±92.42		<0.001
Energy (kcal)		1802.52±724.85		1091.43±879.25		<0.001		2033.36±662.41		1471.60±719.42		<0.001

*findings of Independent sample t-test

To determine the impact of various factors on ADLs and IADLs, a multivariate logistic regression analysis was conducted. As shown in Table 3, the most significant predictors of ADLs were age (P = 0.028, OR = 3.49, 95% CI: 1.15–10.70) and number of chronic diseases (P = 0.003, OR = 1.32, 95% CI: 1.10–1.61). Specifically, individuals aged 70 years or older were 3.49 times more likely to have difficulties with ADLs compared to those younger than 70. Additionally, for each additional chronic disease, the odds of being unable to perform ADLs increased by 32%. However, no significant relationship was found between ADLs and ever nutritional and energy-related variables such as daily protein (0.717), fat (P = 0.313), carbohydrates (P = 0.102), and energy intake (P = 0.426). The chance of disability in performing IADLs significantly increased with an increase in the number of chronic diseases (P = 0.01, 95% CI = 1.07–1.29, OR = 1.71), ages above 70 years (P < 0.0001, 95% CI = 1.20–1.31, OR = 4.733), and female gender (P < 0.0001, 95% CI = 1.52–1.42, OR = 2.277). Regarding education level, illiterate elderly individuals (P > 0.0001, OR = 14.365, 95% CI: 4.06–50.87) and those with only primary education (P = 0.044, OR = 3.810, 95% CI: 1.04–14.04) were significantly more dependent on IADLs compared to those with university education.

Table 3.

Association of influencing variables on disability in activities of daily living and instrumental activities of daily living based on a multivariate logistic regression model in the elderly population of Amirkola Cohort

ADL						IADL
Nutrient variables		OR (95% CI)		P		OR (95% CI)		P
Protein malnutrition (Yes vs. No)		1.28 (0.34–4.99)		0.717		0.52 (0.26–1.04)		0.066
Fat malnutrition (Yes vs. No)		1.72 (0.58–5.16)		0.330		1.51 (0.99–2.32)		0.060
Carbohydrate malnutrition (Yes vs. No)		3.16 (0.80–12.60)		0.102		1.28 (0.66–2.50)		0.466
Energy malnutrition (Yes vs. No)		0.50 (0.1–2.69)		0.426		1.79 (0.87–3.73)		0.118
Number of chronic diseases		1.32 (1.10–1.61)		0.003		1.17 (1.07–1.29)		0.001
Age (years) (≥70 vs. <70)		3.49 (1.15–10.70)		0.028		4.73 (3.20–7.01)		<0.001
Sex (Female vs. male)		1.02 (0.41–2.58)		0.961		2.27 (1.52–3.45)		<0.001
BMI (25 and above vs. below 25)		–		–		0.64 (0.42–1.10)		0.055
Education level		–		–
Illiterate     Elementary     Lower than diploma University						14.36 (4.06–50.87) 3.81 (1.04–14.04) 0.61 (0.13–3.03) Ref.		<0.001 0.044 0.541 –

Discussion

The findings of this study, based on data from the second phase of the Amirkola Elderly Cohort, revealed that the mean intake of all macronutrients (carbohydrates, protein, and fat) and total energy intake was higher in individuals capable of performing IADLs and ADLs compared to those who were dependent. These results align with findings from studies by Alam et al.,[23] Lin et al.,[24] Song et al.,[25] Kiesswetter et al.,[26,27] and Torres et al.,[28] which indicated that elderly individuals with better nutritional status were more independent.

In this study, a significant correlation was found between age and the number of chronic diseases and functional capacity (IADLs and ADLs). Additionally, gender and education level were significantly associated with IADLs in both unadjusted and adjusted models. These findings are consistent with studies by Moser et al.[29] and Hettiarachchi et al.,[30] which identified age as a risk factor for functional disability. As individuals age, decreased appetite, and changes in taste and smell can lead to more restricted food choices. On the contrary, Torres et al.[28] suggested that the aging process, by reducing physiological reserves, increases the risk of various diseases, leading to disability in the elderly. Contrary to these studies, Cacador et al.[31] argued that age was not a significant factor influencing nutritional status and ADLs, as their study examined age in conjunction with other diseases, potentially leading to interference in the assessment of the impact of these two factors on nutritional status and functional disability.

One of the significant factors affecting functional ability in this study was the number of comorbid chronic diseases. The functional ability of elderly individuals with no or one comorbid disease was found to be better compared to those with two or more comorbidities. These findings align with previous studies,[32,33] which demonstrated that functional disability is primarily attributed to chronic diseases. Similarly, Lin et al.[24] showed that a higher number of chronic diseases is a strong predictor of functional disability. This is likely due to the increased age and number of comorbidities, which lead to a loss of physical capacity.

In addition, the results of our study were contrary to the findings of Moser et al.[29] that the number of chronic diseases was not significantly associated with functional disability, perhaps due to the small sample size. Kiesswetter et al.[26,27] also did not observe a relationship between functional ability and the number of chronic diseases, and this finding could be due to living conditions (care for the elderly at home).

In this study, individuals with higher levels of education had significantly better IADL scores compared to illiterate individuals. This finding aligns with the studies by Danielewicz et al.,[34] Kanwal et al.,[35] and Park et al.,[36] which demonstrated a significant association between education level and functional limitations. This is likely because higher education levels can facilitate access to healthcare services. On the contrary, our findings also align with those of Moser et al.[29] and Beltz et al.,[37] who found no significant association between education level and functional ability.

In the present study, a significantly higher percentage of men (66%) were independent in terms of IADLs compared to women (33%), indicating that women were 2.27 times more likely to be dependent. Similar to our findings, the studies by Alam et al.[23] and Kiesswetter et al.[26,27] also found a significant association between IADLs and gender. However, our findings contradict those of Song et al.,[25] which could be attributed to the older age of our participants and the predominance of women in our study population.

In the present study, no significant relationship was observed between BMI and functional ability, which is similar to the finding of Cacador et al.[31] that BMI was not a suitable factor for functional ability because the height of individuals decreases with age, which in turn causes a higher estimate of BMI than its actual value. This finding is contrary to some previous studies[38,39] that showed that higher BMI was a protective factor against functional disability. Perhaps the discrepancy between these two studies is due to environmental, nutritional, cultural, economic, and other factors.

Limitations

Due to the cross-sectional nature of this study, we were unable to establish a causal relationship between nutritional variables and functional disability. Furthermore, as this study was conducted at the county level, generalizing its findings to the entire country is challenging given the diversity of ethnicities and cultures. Therefore, future studies at the national and multicenter levels are recommended, considering factors such as race, ethnicity, urban and rural populations, and other influential variables such as income and socioeconomic status.

Conclusion

The findings of this study demonstrate a positive correlation between nutritional status and functional capacity among the elderly population in Amirkola City. Therefore, by early identification of individuals at risk of malnutrition and functional disability and by addressing underlying factors through education on proper nutrition and functional capacity, we can promote continued independent living and improve the quality of life for the elderly. Furthermore, by aligning elderly healthcare strategies with international benchmarks, these recommendations can improve functional capacity, reduce the burden of age-related disabilities, and enhance the overall quality of life for aging populations. Implementing evidence-based nutrition and functional health policies will play a pivotal role in promoting “healthy aging” as a national and global priority.

Conflict of interest

The authors declare no competing interests.

Funding Statement

This research did not receive any specific grant.