Association of serum vitamin C concentrations with Alzheimer's disease mortality among U.S. adults.

Background: The association between vitamin C status and Alzheimer's disease (AD) mortality remains unclear.

Methods: A total of 4864 adults aged 60 years or above from the National Health and Nutrition Examination Survey III 1988-1994 were included in this study. Serum vitamin C levels were measured by the fully automated electrochemiluminescence immunoassay. Death and underlying causes of death were ascertained by linkage to death records through December 31, 2019. Cox proportional hazards regression models were used to evaluate the association between serum vitamin C and AD mortality.

Results: During 65,251 person-years of follow-up (a median follow-up of 12.0 years), 158 deaths occurred from AD. After adjustment for age, sex, race/ethnicity, socioeconomic status, lifestyle and dietary factors, body mass index, baseline diseases and vitamin C supplement use, compared with participants with deficiency serum vitamin C concentrations (< 53 µmol/L), the multivariate-adjusted HR (95% CI) for AD mortality was 0.62 (0.39-0.99) for participants with adequate serum vitamin C concentrations (53-70 µmol/L) and 0.64 (0.34-1.18) for participants with saturate serum vitamin C concentrations (> 70 µmol/L).

Conclusion: In this nationally representative sample of US adults, higher serum vitamin C was significantly associated with lower risk of AD mortality. These findings suggest that maintaining adequate vitamin C status may aid in lowering AD mortality risk.