Plant-based nitrates have positive effects on human health

A new study from Edith Cowan University (ECU) has found that nitrates from plant sources are associated with a lower risk of death, while nitrates from other sources, such as animal foods, processed meat and tap water, are associated with a higher risk of death.

Nitrate, a compound found in vegetables, meat, and drinking water, has become a topic of debate due to its potential health effects. Emerging evidence suggests that dietary nitrate may play a role in preventing cardiovascular disease (CVD), dementia, and diabetes. However, concerns about a possible link between nitrate intake and cancer have created uncertainty around the consumption of high-nitrate vegetables.

The project was led by Dr Nicola Bondonno, who found that among 52,247 participants in the Danish Study of Diet, Cancer and Health, moderate to high intakes of nitrates from plants and vegetables were associated with a 14% to 24% lower risk of overall mortality, cardiovascular mortality and cancer. The work is published in the European Journal of Epidemiology.

While the study could not attribute nitrates from plants as the sole factor contributing to human health, given that plants and vegetables contain many other protective compounds that are themselves associated with reduced risk of CVD, cancer and mortality, the study highlights the value of higher intake of nitrate-rich vegetables in reducing mortality risks.

The study also added to evidence that there is no reason to worry about cancer risks from eating nitrate-rich vegetables such as leafy green vegetables and beets.

In contrast, high intake of animal-derived nitrates was associated with a 9% and 12% increased risk of total and CVD mortality, respectively. High intake of animal-derived nitrites, a compound formed from nitrates, was associated with a 25%, 29%, and 18% increased risk of total, CVD, and cancer mortality, respectively.

Meanwhile, high intakes of nitrates and nitrites from processed meat were associated with a 12% to 22% increased risk of total and cancer mortality, while only nitrites, which are allowed to be added to meat, were positively associated with CVD mortality.

Participants with high nitrate intake from tap water had a higher risk of total mortality and CVD mortality, but not cancer mortality.

Dr Bondonno, who now works at the Danish Cancer Institute, noted that the source of nitrates determines the body's response to nitrates.

"In simple terms, nitrates can take two different pathways when they enter the body. One pathway leads to the formation of a compound called nitric oxide, which improves blood flow, lowers blood pressure, and supports overall cardiovascular health.

"But nitrates can also pass through the second pathway, forming a group of compounds called nitrosamines, which are considered carcinogenic and have been linked to cancer. Antioxidant compounds in vegetables are thought to direct nitrates through the first pathway."

The recommendations emerging from the latest study are consistent with accepted knowledge about the optimal human diet: eat more plant foods and fewer animal products, and limit processed meats.

"Most of the concerns about nitrate consumption are usually related to cancer, but one of the most interesting findings of this study is that nitrates in drinking water are more strongly associated with heart disease mortality.

"Nitrates from plants and vegetables protect against a variety of deaths. But when nitrates come from animal sources or tap water, they increase your risks, mainly of heart disease, but also of some cancers."