Source-specific nitrate intake and incident dementia in the Danish Diet, Cancer and Health Study.

INTRODUCTION

Dietary nitrate, through conversion to nitric oxide, which supports vascular and nervous system function, may lower dementia risk but may also form neurodegenerative N-nitrosamines, depending on the nitrate source.

METHODS

We investigated associations between source-specific nitrate and nitrite intake and incident and early-onset dementia (<65 years) in 54,804 dementia-free participants from the Danish Diet, Cancer and Health Cohort Study over ∼27 years. Nitrate and nitrite intakes were derived from food frequency questionnaires and nitrate and nitrite databases.

RESULTS

Higher plant-sourced nitrate intake was non-linearly associated with lower rates of incident dementia (fifth vs first quintile hazard ratio 95% confidence interval: 0.90 [0.83, 0.98]), while increased risk was seen for higher intakes of animal-sourced, additive-permitted meat-sourced, and tap water-sourced nitrate. Similar associations were seen for source-specific nitrite intake and were more pronounced for early-onset dementia. No clear effect modification was observed.

DISCUSSION: These findings highlight the importance of nitrate source in dementia risk and warrant further investigation.

HIGHLIGHTS: Plant nitrate is associated with a lower risk of incident and early-onset dementia. Animal and tap water nitrate are associated with an increased risk of dementia. Encouraging consumption of plant-based nitrate sources may lower risk of dementia.