Solving the Nitrate Puzzle: Contradictory Hazards and Benefits of Nitrate

Recent research has shown that dietary nitrate, found in sources such as meat, water, and vegetables, has both potential hazards and benefits. Early studies suggested a link between nitrate and cancer, but no human studies have confirmed this (1^✔ ✔Trusted Source
Nitrate: The Dr. Jekyll and Mr. Hyde of human health?

Go to source). In fact, clinical and observational studies support the idea that nitrate sourced from vegetables can actually prevent cardiovascular diseases like heart disease, dementia, and diabetes (2^✔ ✔Trusted Source
Vegetable nitrate intake, blood pressure and incident cardiovascular disease: Danish Diet, Cancer, and Health Study

Go to source).

The key to understanding this contradiction may lie in where the nitrate comes from. Nitrate-rich vegetables contain substances like vitamin C and polyphenols, which may inhibit the formation of harmful N-nitrosamines associated with cancer (3^✔ ✔Trusted Source
Nitrate and Nitrite in Health and Disease

Go to source).

However, current dietary guidelines do not differentiate between nitrate from different sources. It is crucial to conduct further research to update these guidelines and clarify the potential risks and benefits of nitrate consumption (4^✔ ✔Trusted Source
Dietary exposure to nitrites and nitrates in association with type 2 diabetes risk: Results from the NutriNet-Santé population-based cohort study

Go to source).

In the meantime, it is recommended to obtain nitrate from vegetables, particularly dark green, leafy vegetables, and beetroot, in moderate amounts to reap the cardiovascular health benefits (5^✔ ✔Trusted Source
Beetroot, a Remarkable Vegetable: Its Nitrate and Phytochemical Contents Can be Adjusted in Novel Formulations to Benefit Health and Support Cardiovascular Disease Therapies

Go to source).

Unveiling the Hazards and Benefits of Nitrate on Health

Dr. Catherine Bondonno led a review of nitrate research and says the key may lie in where it comes from.

“We get nitrate from three major dietary sources: meat, water, and vegetables,” she said.

“Nitrate’s reputation as a health threat stems from 1970 when two studies showed it can form N-nitrosamines, which are highly carcinogenic in laboratory animals.

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“However, no human studies have confirmed its potential dangers, and our clinical and observational studies support nitrate preventing cardiovascular disease, if it’s sourced from vegetables.

“So the review looked to unpack all of that, identify new ways forward and ways that we can solve this puzzle because it's really time to address it: it's been 50 years.”

Urgency Required to Change the Dietary Guidelines Regarding Nitrate

Despite recent research indicating the source of nitrate may affect its health benefits and risks, current dietary guidelines relating to nitrate have been in place since the 1970s and don’t differentiate between nitrate from meat, vegetables, and water.

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Dr. Bondonno said while the 1970s animal studies reported a small incidence of malignant tumors, there was evidence not all nitrates deserve to be “tarred with the same brush”.

“For instance, unlike meat and water-derived nitrate, nitrate-rich vegetables contain high levels of vitamin C and/or polyphenols that may inhibit the formation of those harmful N-nitrosamines associated with cancer,” she said.

Dr. Bondonno said it was vital more research was conducted so guidelines could be updated.

“The public are unlikely to listen to messages to increase intake of nitrate-rich vegetables if they are concerned about a link between nitrate intake and cancer.”

However, she stressed while official guidelines hadn’t changed, the apparent benefits of nitrate had seen many people potentially put themselves at risk.

“We need to be sure nitrate-rich vegetables don’t actually have an increased risk of cancer if we consume a higher amount,” she said.

“High dosage nitrate supplements are already used to improve physical performance in sport, while vegetable nitrate extracts are being added to cured meat products with a “clean label” claim, purporting to be better for you.

“So we really need to get this right.”

But, what do we eat, then?

Given its divided experts in the field, Dr. Bondonno said it’s understandable people may be confused as to whether nitrate is good or bad for them.

“They’re probably thinking, ‘If I can’t have a salad, what can I have?’,” she said.

Despite the debate, she said current evidence suggests people should aim to get their nitrate from vegetables — but there was no need to go overboard.

“Dark green, leafy vegetables and beetroot are good sources, our research shows one cup of raw, or half a cup cooked per day is enough to have the benefits on cardiovascular health,” she said.

“We know processed meat isn’t good for us and we should limit our intake, but whether it’s the nitrate in them that is causing the problem or something else, we don’t know.

“It just further emphasizes the need to investigate dietary nitrate to clarify the message for people.

“The potential cancer link was raised 50 years ago; now it’s time to conduct an in-depth analysis to distinguish fact from fiction.”

References:

1. Nitrate: The Dr. Jekyll and Mr. Hyde of human health? - (https://www.sciencedirect.com/science/article/pii/S0924224423000894)
2. Vegetable nitrate intake, blood pressure and incident cardiovascular disease: Danish Diet, Cancer, and Health Study - (https://pubmed.ncbi.nlm.nih.gov/33884541/)
3. Nitrate and Nitrite in Health and Disease - (https://pubmed.ncbi.nlm.nih.gov/30271668/)
4. Dietary exposure to nitrites and nitrates in association with type 2 diabetes risk: Results from the NutriNet-Santé population-based cohort study - (https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1004149)
5. Beetroot, a Remarkable Vegetable: Its Nitrate and Phytochemical Contents Can be Adjusted in Novel Formulations to Benefit Health and Support Cardiovascular Disease Therapies - (https://pubmed.ncbi.nlm.nih.gov/33049969/)

Source-Eurekalert