Better diet quality is associated with healthier aging among urban elderly

1 Introduction

Increases in the quality of life and improvements in public health over the past decades have led people worldwide to live longer today. The World Health Organization (WHO) estimated that the share of the world population aged 60 years and older would double from 1 billion in 2020 to 2.1 billion in 2050, thus outnumbering the share of children below 5 years old [1]. In Indonesia, there are currently more than 29.3 million elderly aged 60 years and over, or 10.8% of the total population [2]. This number is expected to increase by 20% in 2024 and reach 74 million or around 25% of the total population in 2050 [3].

Population aging poses considerable concerns and challenges for countries’ economies. Older populations with poor health conditions could impose an economic burden on society and therefore, their health should be of concern [4]. In Indonesia, about 43% of the elderly people come from the lower-income class [5]. They are vulnerable to poverty and are not enjoying a decent level of welfare. In 2019, 51.1% of Indonesian elderly experienced health complaints and illness conditions [3] while about 25% of them were frail [6]. It appears therefore primordial to seek for strategies to ensure healthy aging among the elderly population.

According to the WHO, healthy aging is defined as the process of developing and maintaining functional ability that enables well-being in older age [7]. Healthy aging is indeed a complex multidimensional concept that involves numerous life aspects, including social and psychological well-being, self-perceived health, health behaviors, absence of illness and disability, cognitive function, and security [8, 9]. The impact of diet on health has been well established. Healthy diet has been demonstrated to be an important element in aging and support a healthy aging process [10, 11]. Promoting a healthy diet in elderly would be vital to help them prevent age-related diseases and preserve their overall good health status during aging.

This study aimed to investigate the association between diet quality and parameters related to healthy aging in Indonesian elderly living in urban areas. Diet quality was assessed using the healthy eating index (HEI-2015), a scoring metric designed to measure individual diet quality by assessing its compliance with the U.S. Dietary Guidelines for Americans (DGAs) [12]. The healthy aging index (HAI) is an index of physiological aging built upon indicators for different physiological parameters indicating organ structure and function [13]. In this study, we also analyzed the cross-correlation between the components of the HEI-2015 and HAI to determine which food groups played major roles in a healthy aging process and which particular physiological parameters are influenced by such food groups. The findings of this study would provide novel insights into the importance of good diet quality in supporting the healthy aging experience of older urban population in Indonesia.

2 Methods

3 Results

As shown in Table 2, the older adult population involved in this study consisted mainly of female (53%), married (67%), and non-smoking (62%) individuals who have completed their primary education (39%). Young elderly aged 60–69 years composed the majority of the population studied (62%). Since the subjects in this study were at least 60 years of age and the retirement age in Indonesia was set to 57 years old, almost all subjects did not work anymore during the time this study was held. Therefore, we asked them about their monthly expense, instead of their income, to obtain information regarding their economic status. In terms of weight status derived from the body mass index (BMI), the majority of the subjects were considered as normal (62%) with a relatively high proportion of overweight and obese individuals (19% and 13% respectively). Only 29% of the subjects reported regular physical activities. Significant difference within groups regarding the HEI-2015 and HAI scores was found on the following variables: sex, age, education level, and weight status.

Table 3 demonsrates a strong and significant association between the HEI-2015 and HAI scores (ρ=–0.85, p<0.05). Such a correlation was further confirmed using a linear regression analysis with the HEI-2015 score as predictor and the HAI score as response variable (β=–0.08, 95% CI: –0.13–(–0.02), p < 0.05). Age and education level were also significantly correlated with the HEI-2015 and HAI scores. A further correlation analysis has led us to identify some components of the HEI-2015 with strong correlations with the HAI score, including whole fruits, total vegetables, sodium, and added sugars. The physiological parameters of the HAI that correlated strongly with the HEI-2015 score were systolic blood pressure and random blood glucose.

One of the main objectives of this study was to assess the association of diet quality and health aging in urban elderly population. A similar study conducted by Fauziyana in 2020 [17] failed to establish such an association. In the study, the HEI-2015 was used to assess diet quality while healthy aging was defined by parameters that differed from our study, including active daily living (ADL) to measure physical function, mini mental state examination (MMSE) to measure cognitive function, geriartic depressive screening scale (GDSS) to measure psychological health, and social engagement index. The diet quality found in the study was considered to be poor with the HEI-2015 score of (46.1±8.5) that did not differ much from the HEI-2015 score concluded in our study (48.8±3.5) (Table 2). However, in the same study [18], significant correlations were found between the elderly’s nutritional status measured by Mini Nutritional Assessment short form (MNA-SF) and all the healthy aging-related parameters mentioned previously [17], except for physical functionality measured by ADL. In our study, we could establish a positive association between diet quality and parameters related to healthy aging.

In this study, we observed that female elderly exhibited a better diet quality and health status compared to male elderly, as demonstrated by a higher HEI-2015 score and a lower HAI score (Table 2). This phenomenon was due to male subjects tending to adopt a less healthy lifestyle compared to female subjects. The proportion of smokers and people reporting no regular physical activities was higher in male (76% and 64% respectively) than in female subjects (5% and 49% respectively). Moreover, among the total of 435 overweight and obese participants involved in this study, 72% appeared to be male. Older subjects aged 80 years or older, along with subjects with lower education level also demonstrated overall lower diet quality and health status within their respective groups. Previous studies have confirmed that highly-educated individuals had better diet quality and health while smoking was associated with lower diet quality and health [13, 20].

The HAI score generated from this study was (5.2±0.3), relatively higher from the score generated in previous studies ranging from 1.5 to 4.3 [16, 21]. A higher HAI score represents a lower health status. Therefore, the health status of our subjects were considered to be lower compared to other subjects in the previous studies. Smoking and physically inactive subjects exhibit significantly higher HAI scores, but not HEI-2015 scores, compared to non-smoking and physically active subjects. A recent meta-analysis study revealed that physical activity was positively associated with healthy aging (ES: 1.39, 95% CI = 1.23–1.57) [22]. Another meta-analysis study reported that non-smokers had more than double the odds of experiencing healthy aging (OR: 2.36, 95% CI: 2.03–2.75) compared with current smokers [23].

Using the Spearman’s correlation test, we identified different independent variables associated with the HEI-2015 and HAI scores, among which age and education level appeared to be associated in a negative and positive manner respectively with diet quality and health status (Table 3). These findings confirmed the previous results presented in Table 2. A strong and significant correlation between the HEI-2015 and HAI scores (ρ=–0.85, p < 0.05) encouraged us to determine how different components of both parameters might correlate to each other. Among all the 13 components of the HEI-2015, 4 appeared to be strongly associated with the HAI score: whole fruits, total vegetables, sodium, and added sugars. With regard to the HAI, the systolic blood pressure (SBP) and random blood glucose (RBG) correlated strongly with diet quality (HEI-2015). Indeed, higher consumption of fruits and vegetables has been shown to reduce the risk of hypertension and type 2 diabetes [24, 25]. Conversely, excessive sodium and sugar consumption was associated with a higher risk of hypertension and type 2 diabetes [26–29].

The findings regarding the HEI-2015 score in this study would also allow to evaluate different components lacking in the elderly diet. The HEI-2015 score obtained in this study was considered as poor diet quality (Krebs-Smith). Other studies led by Indonesian researchers also showed poor diet quality (HEI-2015 score < 50) in healthy Indonesian women and preschool-age children living in the urban area [14, 15]. According to the 2020–2025 Dietary Guidelines for Americans [30], the HEI-2015 score of American citizens ranged from 51 (teenagers of 14–18 years) to 63 (elderly aged 60 or older). The cut-off for good diet quality is the HEI-2015 score of at least 80 [12]. By analyzing the consumption level of each HEI-2015 component in Table 3, we could propose some nutritional recommendations for urban elderly population in order to improve their diet quality. The 3 components that appeared to contribute the least partial scores for the integral HEI-2015 score were sodium (1.6/10), refined grains (1.9/10), and whole grains (2.5/10). Therefore, to improve the diet quality of the urban elderly population, we would recommend increasing the consumption of whole grains and reducing the consumption of salt and refined grains. Implementing this could be challenging. On one hand, consuming whole grains since is not part of Indonesian food culture. On the other hand, the elderly should consume less white rice (the major source of refined grains in Indonesian diet) and use less salt (the main source of sodium) in their daily diet. Some strategies could be proposed, such as replacing white rice with brown rice or choosing whole-wheat bread over white bread to reduce the consumption of refined grains and increase the consumption of whole grains at the same time. Regarding the sodium intake, the concerned elderly people could opt for low sodium products in the market or get used to consuming less salty foods.

This study had some limitations. Firstly, the 24-hour dietary recall was only done one time with the participants. It is recommended to use at least two recalls, on a weekday and on a weekend, to obtain a more representative individual diet habit. Secondly, the variables of smoking status and physical activity in this study were designed to be nominal (yes/no questions) while the association of these variables with the HEI-2015 or HAI scores could have been analyzed if such variables had been set to be ordinal or continuous (e.g. how many cigarettes do you usually smoke in a day? or how often do you practice sports ?). Finally, the HEI-2015 has not been validated in Indonesia. Adjusting the HEI-2015 with the Indonesian dietary guidelines and food habit would provide a better picture about the diet quality of Indonesian subjects. As recommendations, further studies could include a wider elderly population, including those living in rural area since their eating habit and lifestyle would be different from their urban counterparts. Follow-up studies after introducing certain diet recommendations to an elderly population could also be performed to look for improvements in some health status or overall well-being.

5 Conclusions

To conclude, our study highlights the importance of diet quality in maintaining the health status of the elderly as they grow older, a phenomenon known as healthy aging. The focus of studies on late adulthood should indeed be shifted from extending lifespan to extending healthspan: preserving overall good health status during aging to optimize individual’s intrinsic capacity as they age. It is therefore important that the older adults in the population be willing to adopt a healthier lifestyle for a healthier aging experience. Our study suggested that the HEI-2015 could be used as a dietary standard to support healthy aging experience in the elderly. In addition, keeping a healthy body weight, quitting smoking, and being physically active would help maintain the health status of the elderly during aging.