AIMS: The association between dietary diversity and increased mortality risk is well-documented. However, it remains unclear whether and to what extent dietary diversity affects mortality through appendicular skeletal muscle mass (ASM). Therefore, we assessed whether ASM mediated the association between dietary diversity and mortality. METHODS: We used data from the Chinese longitudinal healthy longevity survey (CLHLS) (2011-2018). The baseline Dietary Diversity Score (DDS) was derived from 9 food items, and the Anti-inflammatory Dietary Diversity Score (AIDDS) was used to assess the diversity of anti-inflammatory foods in the diet. Cox regression models were employed to estimate the association of DDS and AIDDS with mortality. Interaction analysis was performed to analyze the association between DDS, AIDDS, and ASM in different groups. Subsequently, mediation analysis was performed to examine whether ASM partly accounted for the association. RESULTS: A total of 5422 participants (average age 85.99 years) were included in the analysis. Among them, 3241 participants died during the follow-up period. We observed that participants with higher DDS (HR = 0.907, 95 % CI: 0.842-0.977) and AIDDS scores (HR = 0.947, 95 % CI: 0.917-0.977) had lower mortality rates. Subgroup analyses showed no interaction between DDS, AIDDS, and ASM (p for interaction>
0.05). ASM mediated the 14.0 % association between DDS and mortality, and the 10.7 % association between AIDDS and mortality. CONCLUSIONS: Dietary diversity and anti-inflammatory dietary diversity could reduce mortality risk and promote longevity in older adults. The association between these factors was partially mediated by an increase in muscle mass among older adults.