New research from Edith Cowan University (ECU) and the Danish Cancer Research Institute (DCRI) suggests that sources of nitrate in a person’s diet may play an important role in dementia risk.
In a large study that followed more than 54,000 Danish adults for up to 27 years, researchers examined how nitrate and nitrite intake from various sources is related to the development of dementia, including early-onset dementia. Their findings revealed a striking contrast. Higher nitrate intake from vegetables was associated with a lower risk of dementia, and higher exposure to nitrates and nitrites from animal products, processed meat, and drinking water was associated with a higher risk of dementia.
Dementia is influenced by a combination of genetic and lifestyle factors, but researchers say diet may also be another important piece of the puzzle.
Plant-based nitrates are associated with lower dementia risk
According to ECU Associate Professor Catherine Bondonno, the protective effects associated with nitrate-rich vegetables may be related to how the body processes nitrates.
“When you eat nitrate-rich vegetables, you’re also getting vitamins and antioxidants. These are thought to help nitrates produce the beneficial compound nitric oxide, while also blocking the production of N-nitrosamines, which are carcinogenic and can damage the brain.”
“Unlike vegetables, animal foods do not contain these antioxidants. Additionally, meat also contains compounds such as heme iron that can actually increase the production of N-nitrosamines. We believe this is why nitrates from various sources have the opposite effect on brain health, but laboratory studies are needed to confirm exactly what is happening,” she said.
Researchers believe that the combination of nitrates, vitamins, and antioxidants naturally found in vegetables may help support brain health. Foods of animal origin do not contain similar protective compounds and can promote the production of potentially harmful substances.
Dr. Bondonno said the practical takeaways from the study’s findings are relatively simple. Participants who ate more nitrates from vegetables (roughly equivalent to one cup of baby spinach per day) had a lower risk of dementia.
In contrast, high nitrate intake from animal foods, especially red and processed meat, was associated with increased risk.
“Eating more vegetables and less red and processed meat is a prudent approach based on our findings and decades of other research on diet and health,” she added.
Nitrates in drinking water raise new questions
The study also identified a link between nitrates in drinking water and dementia risk, the first time researchers have reported such a link.
Participants exposed to nitrates in drinking water had higher rates of dementia, even at concentrations below current regulatory limits. However, Dr. Bondonno stressed that additional research is needed before any firm conclusions can be made.
“Water does not contain antioxidants that can block the formation of N-nitrosamines. Without these protective compounds, nitrates in drinking water can form N-nitrosamines in the body,” she says.
In Denmark and throughout the European Union, the current limit for nitrates in groundwater and drinking water is 50 mg/L. Researchers observed an increased risk of dementia in people exposed to water with concentrations as low as 5 mg per liter of nitrate.
Despite these findings, researchers stress that people should not stop drinking water.
“Importantly, our results do not mean people should stop drinking water. The increased risk at an individual level is very small, and drinking water is much better for your health than sugary drinks like juice or soft drinks. However, our findings suggest that regulators should reconsider current restrictions and better understand how long-term, low-level exposures affect brain health.”
Research Shows Associations, Not Cause and Effect
The researchers cautioned that the study was observational, and while they could identify a link, they could not prove that nitrates directly cause dementia.
Therefore, the results need to be confirmed in additional studies. The research team also notes that other aspects of the participants’ diet, lifestyle, and health may have contributed to the observed relationships.
Still, the results suggest that where nitrates come from may be just as important, if not more important, than how much is consumed. Nitrates from vegetables are associated with a lower risk of dementia, while nitrates and nitrites from processed meats, animal products, and drinking water are associated with higher risks, highlighting the importance of considering dietary sources when assessing long-term brain health.
