Dietary sialic acid intake and incident dementia: evidence from a large prospective cohort study.

PURPOSE: Beneficial effects of sialic acid on cognition have been most often seen in cognitive development in infant models, whereas the relevant evidence from ageing population studies remains limited. We aimed to investigate the associations of dietary sialic acids and their subtypes (Neu5Ac and Neu5Gc) with the incident dementia in a large prospective study.

METHODS

A total of 210,796 middle-aged and older participants from UK Biobank were included in this study. Dietary sialic acids intake was estimated using repeated 24-h dietary recall questionnaires. Cox proportional hazards models were used to evaluate the association of sialic acid and its subtypes with dementia risk.

RESULTS

During a mean follow-up of 10.9 years, 2469 incident all-cause dementia were recorded, of which 1077 were Alzheimer's disease (AD), and 454 were vascular dementia (VaD). Compared with participants in the lowest quartile (median intake: 25.12 mg/d), participants in the third quartile of total sialic acids (median intake: 56.46 mg/d) were associated with a 18% lower risk of all-cause dementia (HR 0.82; 95% CI 0.73-0.92) and a 31% lower risk of VaD (HR 0.69; 95%CI 0.53-0.91), respectively. Similar associations were observed for Neu5Ac and Neu5Gc, respectively. After mutual adjustment, the association of Neu5Gc with all-cause dementia or VaD risk remained unchanged, whereas the association of Neu5Ac with dementia risk became non-significant after adjusting for Neu5Gc.

CONCLUSION

Our findings suggest a potential non-linear protective association between total sialic acid and risk of all-cause dementia and VaD.