Abstract
BACKGROUND: Low muscle mass exhibits a high prevalence in population, with its incidence increasing with age. Body mass index (BMI) has been identified as an independent predictor of poor muscle quality, and people with higher BMI have higher risk of low muscle mass. Nutrition interventions have been demonstrated efficacy in mitigating its effects. The Healthy Eating Index-2020 (HEI-2020) assesses overall diet quality but lacks studies on its association with low muscle mass. This study aims to investigate the association between the HEI-2020 and low muscle mass and to explore the mediating role of BMI among middle-aged individuals. METHODS: Participants aged 40-59 were recruited from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. Muscle mass was quantified using the ratio of appendicular lean mass (ALM) to BMI, with low muscle mass criteria defined at 0.789 kg/kg/m(2) for men and 0.512 kg/kg/m(2) for women. The HEI-2020 score was constructed based on two days of 24-hour dietary recalls and consists of 13 components. Logistic regression models analyzed the associations between HEI-2020, its components, and low muscle mass. Mediation analysis assessed the role of BMI in the association between HEI-2020 and low muscle mass. RESULTS: The sample comprised 4,355 individuals with a median age of 50 (45, 55) years, of whom 9.7% had low muscle mass. The HEI-2020 scores ranged from 22.85 to 91.33, with an average score of 52.10 ± 11.78. Participants in the highest HEI-2020 score quartile had a 65% lower risk of low muscle mass compared to those in the lowest quartile. Adequate intake of vegetables, fruits, beans, proteins and fatty acids, along with restricted intake of added sugars, was associated with lower risk of low muscle mass. BMI was identified as a mediator, accounting for 33.1% of the association between HEI-2020 and low muscle mass. CONCLUSIONS: HEI-2020 was inversely associated with low muscle mass among middle-aged individuals. The impact of a healthy diet on muscle mass is partially mediated by BMI. Adhering to the healthy eating patterns and keeping a healthy weight is conducive to the maintenance of muscle mass and the prevention of low muscle mass.