Correlation between skeletal muscle mass and Chinese healthy eating index in older adults

Abstract

BACKGROUND: With the deepening of China's aging population, low skeletal muscle mass has become a serious public health problem. Diet is closely linked to muscle mass; however, existing research has mostly focused on the effects of a single nutrient, and there is still a lack of systematic exploration of the relationship between China's overall dietary pattern and skeletal muscle quality. OBJECTIVE: To analyze the correlation between Chinese Healthy Eating Index and skeletal muscle mass in older adults, providing scientific basis for dietary optimization and prevention of low skeletal muscle mass. METHODS: Based on the 2018 China Longitudinal Healthy Longevity Survey (CLHLS), 8,114 participants were included. Dietary quality was assessed using the Chinese Healthy Eating Index, and skeletal muscle mass was evaluated using the skeletal muscle mass index. Low skeletal muscle mass was diagnosed according to the 2019 Asian Working Group for Sarcopenia criteria. Multivariate logistic regression was used to explore the association between Chinese Healthy Eating Index and low skeletal muscle mass. RESULTS AND CONCLUSION: (1) Univariate analysis showed that the highest quartile (Q4) of overall Chinese Healthy Eating Index (OR=0.52, 95%CI: 0.46-0.59), animal-based Chinese Healthy Eating Index (OR=0.85, 95%CI: 0.75-0.97), and plant-based Chinese Healthy Eating Index (OR=0.43, 95%CI: 0.38-0.49) were significantly associated with low skeletal muscle mass (P < 0.001). (2) Multivariate logistic regression showed that compared with the lowest quartile (Q1), the highest quartile (Q4) of overall, animal-based, and plant-based Chinese Healthy Eating Index were associated with 30% (OR=0.70, 95%CI: 0.60-0.83, P < 0.05), 20% (OR=0.80, 95%CI: 0.68-0.94, P < 0.05), and 20% (OR=0.80, 95%CI: 0.69-0.94, P < 0.05) lower risk of low skeletal muscle mass, respectively. Trend tests further indicated a significant association between higher dietary quality and lower risk of low skeletal muscle mass (P_trend < 0.001). (3) Subgroup analysis showed that in female participants, compared with Q1, the highest quartile (Q4) of overall, animal-based, and plant-based Chinese Healthy Eating Index were associated with 43% (OR=0.57, 95%CI: 0.45-0.72, P < 0.05), 29% (OR=0.71, 95%CI: 0.56-0.88, P < 0.001), and 33% (OR=0.67, 95%CI: 0.54-0.83, P < 0.001) lower risk of low skeletal muscle mass, respectively. No significant association was found in males. The results indicate that higher dietary quality is significantly associated with lower risk of low skeletal muscle mass, and adopting a healthy diet is an effective intervention to prevent skeletal muscle loss.

1. Introduction

China is facing a severe challenge of population aging [1]. The seventh national census shows that people aged 60 and above account for 18.7% of the population, and those aged 65 and above reach 13.5% [2]. With the intensification of population aging, health problems among the elderly are increasingly prominent [3-6]. Studies have shown that human skeletal muscle mass gradually decreases from the age of 40 [7], and accelerates after the age of 70, significantly affecting the health of the elderly. Low skeletal muscle mass not only increases the risk of falls [8] and fractures [9], but is also closely related to mortality and disability [10-11]. Therefore, early identification and intervention of low skeletal muscle mass is particularly important.

The occurrence of low skeletal muscle mass is the result of multiple factors [12]. In addition to being closely related to unchangeable physiological factors such as age and gender, lifestyle and environmental factors also play an important role [13-14]. Studies have found that insufficient physical activity, inadequate protein and energy intake, vitamin D deficiency, and poor lifestyle habits can accelerate the reduction of skeletal muscle mass [15-17]. In addition, chronic diseases such as diabetes [18], obesity [19], cardiovascular disease [20], and inflammatory states have also been confirmed to be closely related to an increased risk of low skeletal muscle mass [21]. Social determinants of health such as low socioeconomic status, insufficient education, and poor nutritional accessibility can also indirectly affect skeletal muscle health through diet and health behaviors [22-24]. Therefore, the prevention and control of low skeletal muscle mass requires multidimensional intervention, among which dietary quality is one of the most critical and feasible factors.

Dietary quality is closely related to skeletal muscle mass, especially in the elderly population [25]. In recent years, foreign studies have often used dietary quality assessment tools such as the Healthy Eating Index and Mediterranean Diet Score to explore the potential impact of dietary patterns on skeletal muscle health [26]. Studies have shown that high-quality dietary patterns can delay muscle loss and reduce the risk of skeletal muscle mass reduction by reducing chronic inflammation and alleviating oxidative stress [27-29]. However, these studies mostly focus on European and American populations, whose dietary structures are significantly different from those of Chinese people, making it difficult to directly apply them to the domestic population. In contrast, systematic research on the Chinese population is still relatively limited. Current domestic research on nutrition related to skeletal muscle mass mostly focuses on individual nutrients (such as protein, vitamin D, etc.), lacking systematic exploration of the overall dietary pattern. Therefore, this study aims to analyze the correlation between the Chinese Healthy Eating Index and skeletal muscle mass in the elderly, providing scientific evidence for dietary optimization and prevention of low skeletal muscle mass.