Nitrates and Nitrites: Are They Dangerous or Beneficial to the Human Body?

2023-06-18 17:46:46

Whether nitrates and nitrites are dangerous to the human body depends on what kind of food it comes from. (Shutterstock/Epoch Times Synthesis)

When they hear nitrates and nitrous acid, people tend to turn pale when they talk about it, because it is generally known that they can generate carcinogenic nitrosamines. But this kind of understanding may be biased-scientists point out that nitrate and nitrite are actually very important to the human body. As for whether such substances will cause danger to the human body, it depends on the type of food it comes from.

People often think that nitrates are only found in processed meats.They are used as food additives in processed meats and some cheeses, mainly toPrevents the growth of botulism,Improves microbiological safety and extends shelf life.

In fact, they occur naturally in food and are part of the nitrogen cycle between the air, land and water environments.

Nitrate and nitrite, which are nitrate (-NO3) and nitrite (-NO2) A water-soluble compound bound to a metal cation such as sodium or potassium ions.

Nitrates in the human body aretwo sourcesone is produced spontaneously in the body, and the other is ingested.

A certain amount of nitrate is a normal part of the nitrogen cycle in the body.In the United States, per capita nitrate intake is about40 to 100 mg per day，In Europe the figure is 50 to 140 mg.

And most of the nitrates and nitrites we get from our dietfrom fruits and vegetablesthey can account for up to 1% of the total nitrate in the diet80% to 90%。

People often think that nitrates are only found in processed meats, but in fact, fruits and vegetables also contain nitrates necessary for the human body. Green leafy vegetables such as spinach, cabbage, and lettuce are nitrate-rich vegetables. (Shutterstock, Fotolia/Epoch Times Composite)

what happens when nitrates enter the body

Nitrate ingested into the human body will be fully absorbed in the stomach and small intestine, and circulate in the blood, saliva and tissues, and about 75% of the nitrate will eventually be excreted from the urine through the kidneys.

Interestingly, the concentration of nitrate in saliva is 10 times higher than in plasma.

As for the nitrite in our body, about 80% to 85% is formed by the conversion of nitrate in the body, and the proportion of nitrite ingested through food is actually very small. Most nitrite is further converted to nitric oxide (NO) in the acidic environment of the stomach.

Is it true that nitrates cause cancer?

Nitrates are considered harmful because under certain conditions (such as stomach acid and heat) they may react with amines to produce carcinogenic nitrosamines.The upper limit of daily intake of nitrate and nitrite given by the World Health Organizationrespectively3.7mg/kg and 0.06-0.07mg/kg。

Although this mechanism exists objectively, the researchers proposed that the epidemiological investigation of nitrate and tumors showed that,no clear evidenceIt has been confirmed that dietary nitrates increase tumorigenesis.

Recently, a review published in the journal “Trends in Food Science and Technology”, after a comprehensive analysis of different sources of nitrate, clearly pointed out that dietary nitrate, especially nitrate in vegetables, can prevent cardiovascular Diseases and other chronic diseases, and people’s awareness that nitrates may form carcinogenic nitrosamines obscures the protective effect of nitrates on the human body.

“Nitrates’ reputation as a health threat began in 1970, when two studies showed that it could form nitrosamines, which are highly carcinogenic to laboratory animals.” Study Nitrates: Humans, published May 2023 Healthy Dr. Jekyll and Mr. Hyde? “The corresponding author, Catherine Bondono, a senior research fellow at the School of Medicine and Health Sciences, Edith Cowan University, Australianews Letter“However, without any human studies confirming its potential danger, our clinical and observational studies support the protection of nitrates against cardiovascular disease—if it comes from vegetables,” Zhong said.

Nitrates are considered harmful because under certain conditions (such as stomach acid and heat) they may react with amines to produce carcinogenic nitrosamines. (Shutterstock)

Nitrates reduce risk of heart disease, dementia, diabetes

worth emphasizing is,Dietary nitrates have several cardiovascular health benefits and can help reduce the risk of diseases such as heart disease, dementia and diabetes.

Nitrates go through a series of reactions in the body to produce nitric oxide, a gas signaling molecule. In 1998, three American scientists were honored for discovering the role of nitric oxide in the cardiovascular systemwon the nobel prize.Nitric oxide has gradually been found to play a role in numerous physiological processesimportant role– including regulation of vascular tone, neurotransmission, mitochondrial respiration, and skeletal muscle contraction.

Dietary nitrates are an exogenous source of nitric oxide, an important substance in the body—a realization that has changed the way people think about nitrates. This has also led to a large number of studies conducted by scientists in the past decade, proving the cardiovascular health benefits of plant sources of nitrate.

Consuming nitrate-rich foods (mainly green leafy vegetables) increases the body’s nitrate stores. Promoting the conversion of nitrate in the body to nitrite and then to nitric oxide can improve cardiovascular fitness and exercise tolerance indicators.

Human experiments have confirmed that supplementing nitrate with beetroot juice can reduce blood pressure in hypertensive patients, and supplementing sodium nitrite can improve vascular endothelial function and reduce the hardening of elastic arteries in the elderly.

Nitrate supplements have also been shown to enhance skeletal muscle function and, in some cases, improve exercise performance. During intense exercise, higher nitric oxide levels in the blood increase the transport of oxygen and the uptake of oxygen into the muscles.

There is growing evidence that low nitrate intake is associated with diabetes, inflammation, eye disease and poor muscle function, and that low nitrate intake is also a major risk factor for falls and fractures.

Human experiments have confirmed that nitrate supplementation with beetroot juice can reduce blood pressure in hypertensive patients. (Shutterstock)

Recommended intake of nitrates through fruits and vegetables

The study led by Bondono pointed out that when countries and relevant agencies set dietary guidelines on nitrates, they did not distinguish between specific sources-such as nitrates from meat, vegetables and water.

“For example, unlike meat and water source nitrates, nitrate-rich vegetables contain high levels of vitamin C or polyphenols that may inhibit the formation of harmful N-nitrosamines associated with cancer”,

Current evidence suggests people should look to get nitrates from vegetables – but there’s no need to overdo it, she said. Dark green, leafy vegetables and beets are rich in nitrates. And she said that a cup of raw or half a cup of cooked vegetables a day is enough to benefit cardiovascular health.

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Editor in charge: Li Fan

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