Nitrate Levels in Tap Water May Raise Dementia Risk

Nitrate levels in drinking water may increase the risk of dementia, even when levels fall far below current safety limits, research suggests—raising questions about regulatory standards in the United States and Europe.

The study published in December 2025 in the journal Alzheimer’s & Dementia observed a higher dementia risk at drinking water nitrate levels as low as 5 milligrams per liter (mg/L)—well below current regulatory limits of 50 mg/L in the European Union (EU) and Denmark, and 10 mg/L set by the Environmental Protection Agency (EPA) in the United States.