Diet and lifestyle behaviours simultaneously act on frailty: it is time to move the threshold of frailty prevention and control forward

Frailty research is a challenging topic in the life sciences. In recent years, many scholars have conducted a large number of prospective cohort studies for the treatment of frailty, and our scientific hypothesis is that by regulating the diet and lifestyle characteristics of the population before the onset of frailty, the threshold of frailty treatment can be moved forward, and the focus of medical work can be shifted to prevention and health care. After the field investigation in China, our hypothesis was confirmed: older Chinese women who do not exercise or spend less than 0.5 h a day at the same time, occasionally exercise and exercise at a low intensity, feel more tired at work, and eat too many staple foods (> 450 g per day) are not conducive to staying robust.

Prevalence of frailty in Chinese older female population.

Our study found that frailty prevalence in older Chinese women was 15.9%, which is higher than that in 2019 in China’s community of the older population [12.8%, (10.5%, 15.2%)] [5]. The increase in the value and COVID-19 has a certain relationship; most COVID − 19 poor prognosis and death occurs in older people. Clinical samples test results showed that C-reactive protein, interleukin 6, lactate dehydrogenase, calcitonin, transferrin of older samples, elevated cortisol levels were different degree of meaningful, and vitamin D levels were significantly lower (generally accepted biomarkers of frail) [14]. During the pandemic, social isolation has become a part of the daily lives of the older population in China. Family conflict, depression, anxiety, and other emotions caused by isolation reduce collective disease tolerance and further exacerbate frailty [15].

After age stratification with a span of 5 years, the overall prevalence of frailty and pre-frailty increased first and then decreased with age, showing an inverted “U” shape change. The peak of the inverted “U” appeared in the 70–74 age group, indicating that the physical injury and disease manifestation of the study participants increased in the young-older age group (60–74-year-old). Awareness and behaviour of self-care in women over 75 years of age began to increase, while the prevalence of frailty decreased.

Fitting and performance evaluation of a three-classification decision tree model.

To draw intuitive and in-depth conclusions, we focused on the detailed quantification of dietary intake and lifestyle behavioural factors that influence frailty. The constructed three-classification decision tree model focused on the systematic screening of influencing variables; that is, on the basis of single factors, filters, and embedded variable screening methods were adopted, and the variable assignment was analysed in combination with professional knowledge. The decision tree model was adopted as the auxiliary model for this analysis because its result is an intuitive and easy-to-understand tree. It can not only screen the main factors affecting frailty again, but also clearly show the interaction between factors and the contribution degree of each type of effect, avoiding the classification problem that complex parameter estimation cannot be expressed by functions [16].

In the training and test sets, Model 3 exhibited excellent performance, and the values of each index were relatively average. The accuracy, sensitivity, and specificity ranges of Model 3 were between 75% and 84%, and the AUC was greater than 0.800. The intake of fruit, milk, eggs, sedentary behaviour, and sleep time were not reflected in the final results, but this does not mean that the older adults did not need to pay attention; in fact, the final results were refined in layers of screening, the importance of variables was relatively high, and more attention needed to be paid.

Effects of dietary intake and lifestyle behaviour on population.

The dietary and lifestyle questionnaire used in this study, combined with authoritative research and surveys, retrospectively summarises the work experience of our group, which is in line with the actual situation of women. Before the survey, each investigator received uniform training and learned a clear definition of each indicator to ensure the authenticity and reliability of the results as much as possible.

Eating too many staple foods (> 450 g per day) is detrimental to robustness. Women in southern China mainly consume rice as their staple food, while women in northern China mainly consume pasta; however, both rice and pasta are the main sources of carbohydrate intake, and excessive intake of carbohydrates can lead to obesity and overweight [17]. Sarcopenic obesity is a clinically functional disorder in which obesity and sarcopenia coexist. It is characterised by a decrease in lean body mass accompanied by excessive accumulation of adipose tissue, particularly visceral fat, and is highly prevalent in older women [18]. Previous studies on frailty have focused on supplementing protein diets in diagnosed populations to regulate metabolism and improve muscle mass [19]; however, our study suggests, for the first time, that carbohydrate restriction appears to be more important than protein supplementation in healthy people (who have not progressed to frailty). Restricting carbohydrate intake has performed well in women for weight loss, insulin resistance, and blood glucose and lipids [20]; however, proper carbohydrate intake (not low-carbohydrate and high-carbohydrate diets) can increase muscle glycogen stores, muscle mass, and bone mass [21] and prevent osteoporosis. Notably, a combination of exercise and reduced carbohydrates in the diet appears to reduce the loss of muscle mass caused by ketosis [22].

Therefore, we conducted a comprehensive analysis of life behaviours, in which exercise time, intensity, and frequency were identified in the model. Further quantitative results showed that not exercising or exercising for less than 0.5 h a day, while occasionally exercising and exercising at a low intensity, does not contribute to maintaining physical robustness. Randomised clinical trials have demonstrated that exercise can significantly improve the quality of life in older adults, reduce age-related oxidative damage and chronic inflammation, and improve mitochondrial function, actin profile, the IGF-1 signalling pathway, and insulin sensitivity [23, 24]. A combination of exercise and dietary nutrition is recommended for the prevention and treatment of frailty [25].

We propose that, after maintaining good diet and exercise habits, work fatigue in older women should be reduced. Self-perception of work is a comprehensive measure of women’s psychological and social health; we define “work” as social work and family work in this study. In society, Chinese women work until the age of 55 before they can retire, and the working hours of the freelance self-employed depend on their economic pressure. In the family, women are expected to take care of their older parents, children, and grandchildren, as well as provide emotional support and household chores. Owing to the intensification of aging and the extension of women’s life expectancy, women have been in this stage for a longer period of time, increasing their energy, emotional, and economic investment. If they feel tired, it means that an increase in age and changes in social roles have increased their psychological pressure, which is also the root cause of mental illness. Frailty is a biopsychosocial syndrome [26], and epidemiological evidence suggests that more than one-third of older patients with depression [27] are frail; therefore, we do not recommend that older women remain stressed at work, as this can easily lead to psychologically related disorders and thus frailty.

Although our study is based on a cross-sectional survey, it has the following three advantages: First, our research perspective is based on the representative provinces and cities of China, and the geographical and age distribution of the research objects is uniform, which can reflect the objective reality of frailty in older Chinese women; second, based on the two dimensions of dietary intake and life behaviour, we comprehensively evaluated the comprehensive effect of the factors in two dimensions on the population simultaneously. Finally, we explain and predict the comprehensive effect of frailty in two dimensions, and the results prove the simplicity and feasibility of the medical focus from frailty treatment to frailty prevention.

This study has some limitations. The intensity of cross-sectional investigations in epidemiological studies is still low in causal judgments, and we cannot tell whether a negative combination of factors causes frailty or frailty results in a negative combination of these factors. Follow-up studies should obtain information on a larger sample. Despite these limitations, our work innovatively suggests the feasibility of shifting the focus of frailty efforts and providing positive information for day-to-day prevention of frailty.