Background and aims: To determine the associations between osteosarcopenic adiposity (OSA) and both all-cause mortality and life expectancy, and to investigate whether adherence to a healthy diet can modify these associations. Methods: Utilizing data obtained from 201 223 UK Biobank participants, we assessed body composition for OSA and a healthy diet score was used to assess dietary quality. Results: Compared to participants with no body composition abnormality, the adjusted HRs (95% CIs) of all-cause mortality for those with 1, 2, and 3 (OSA) abnormalities were 1.13 (1.08, 1.18), 1.28 (1.21, 1.35), and 2.01 (1.58, 2.56) after adjustments, respectively. Compared with participants with no body composition abnormality, OSA patients with poor dietary patterns had a higher risk of all-cause mortality (HR = 2.92, 95% CI: 1.96, 4.36) than those with medium (HR = 1.73, 95% CI: 1.27, 2.37) and healthy dietary patterns (HR = 1.39, 95% CI: 0.34, 5.60). Specifically, a lower intake of fish and a higher intake of processed meat contributed to such different associations. Compared with participants without body composition abnormality, those with 1, 2, and 3 (OSA) body composition abnormalities had 0.31 (95% CI: -0.07, 0.69), 0.62 (95% CI: 0.16, 1.09) and 3.03 (95% CI: 1.05, 5.00) years of reduced life expectancy at age 45 years. Conclusions: Body composition abnormality, particularly OSA, is associated with both increased risk of all-cause mortality and reduced life expectancy. Nevertheless, it is noteworthy that adopting a healthy dietary pattern appears to mitigate these associations.
