Association of serum 25-hydroxyvitamin D and physical frailty with cardiovascular health in US adults

Evidence on the association between cardiovascular health (CVH) and frailty remains limited, and the role of serum 25-hydroxyvitamin D (25(OH)D) in this relationship is not fully understood. This study aimed to examine the association between frailty and CVH and to investigate the independent association of serum 25(OH)D and its potential interaction with frailty. This cross-sectional study used data from the National Health and Nutrition Examination Survey 2007 to 2018, including 8015 adults aged ≥20 years. Frailty was assessed using a frailty index, and CVH was evaluated based on the American Heart Association’s Life’s Essential 8 metrics. Multinomial logistic regression models accounting for the complex survey design were applied to assess associations. Frailty was highly prevalent in the study population. After multivariable adjustment, higher frailty levels were significantly associated with an increased risk of poor CVH in a graded manner. Serum 25(OH)D levels were independently and inversely associated with poor CVH. Stratified analyses showed that the association between frailty and CVH varied by sex and 25(OH)D status. However, no statistically significant multiplicative interaction between frailty and serum 25(OH)D levels was observed. Frailty was significantly associated with poorer CVH in US adults, demonstrating a clear dose–response relationship. Serum 25(OH)D levels were independently associated with CVH, whereas no statistically significant multiplicative interaction between frailty and serum 25(OH)D was observed. These findings highlight the importance of addressing multiple modifiable risk factors to improve CVH.