Nitrates in drinking water and meat linked to dementia, but vegetables offset risk

Danish researchers have found that dietary nitrate from vegetables may lower dementia risk. However, they linked the same nutrient found in drinking water and in animal foods to a higher risk. 

The study in Alzheimer’s & Dementia followed over 54,000 participants for up to 27 years. They found that nitrate from plants boosted nitric oxide production, supporting beneficial vitamins and antioxidants.

Furthermore, the team calls for re-evaluation of water nitrate limits, as low levels of 5 mg/L have been associated with higher dementia risk. In the EU and Denmark, the regulatory limit for drinking water is currently set at 50 mg/L. 

However, the team cautions that, since their study is the first and only one, further research is needed to examine this link. Additionally, because the research is observational, it cannot establish that nitrate is the direct cause of dementia.

Nitrate sources and health implications

Nitrates from processed meats and water lack the beneficial compounds found in plants, which may ultimately cause brain damage, the study cautions.

Nitrates from processed meats and water lack the beneficial compounds found in plants, which may ultimately cause brain damage, the study cautions.“When we eat nitrate-rich vegetables, we are also eating vitamins and antioxidants, which are thought to help nitrate form the beneficial compound nitric oxide while blocking it from forming N-nitrosamines, which are carcinogenic and potentially damaging to the brain,” says Dr. Nicola Bondonno, a postdoctoral research fellow at Edith Cowan University, Australia, and the Danish Cancer Research Institute.

“Meat contains compounds such as heme iron, which may actually increase the formation of N-nitrosamines. We think this is why nitrate from different sources has opposite effects on brain health, but we need laboratory studies to confirm exactly what’s happening,” says Bondonno.

Participants consuming nitrates from vegetables, about a cup a day of baby spinach, have lower dementia risk, she adds.

Drinking water remains healthy

The team found that participants drinking water with nitrates at levels below the current regulatory limits have a higher dementia rate. This limit in Denmark and the EU is set at 50 mg/L, but the researchers point out that the risks start at significantly lower levels.

“Water doesn’t contain antioxidants that can block the formation of N-nitrosamines. Without these protective compounds, nitrate in drinking water may form N-nitrosamines in the body,” comments Bondonno.

“Importantly, our results do not mean that people should stop drinking water. The increase in risk at an individual level is very small, and drinking water is much better for your health than sugary drinks like juices and soft drinks. However, our findings do suggest that regulatory agencies should re-examine current limits and better understand how long-term, low-level exposure affects brain health.” 

Further studies are required to confirm the nitrate-dementia link, and the team says other factors, such as diet and lifestyle, cannot be ruled out from the association.

“Eating more vegetables and less red meat and processed meat is a sensible approach based on our findings and decades of other research on diet and health,” concludes Bondonno. 

Nutrition and dementia connection

Previous research has shown that diet and nutrients can affect dementia risk. For example, higher omega-3 blood levels were linked to reduced early-onset dementia risk despite genetics. 

Meanwhile, poor carbohydrate quality is correlated with increased dementia and Alzheimer’s disease risk. A separate study established a similar link between obesity and high blood pressure and higher dementia risk.

Other scientists did not find any evidence that calcium increases the long-term risk of dementia in older women, debunking theories that the mineral supplements could improve cognition.

However, any amount of alcohol consumption was found to raise dementia risk, challenging the previously held beliefs on the benefits of light drinking.