Medically reviewed by Simone Harounian, MS
Nitrate is a nitrogen-oxygen compound naturally found in soil, water, and some foods. Most of the nitrate you're exposed to comes from eating food and drinking water that contains the chemical.
When obtained through fruits and vegetables, nitrate might provide health-protective benefits. But when obtained through other sources, nitrate might have negative health effects. A majority of people are not exposed to enough nitrate for there to be any concern. However, taking in too much nitrate can potentially put you at risk for certain health complications.
What Is Nitrate?
Nitrate is a natural component of certain plants. In particular, they are found in many vegetables, such as spinach and lettuce. When you take in nitrate through your diet, it is converted to another nitrogen compound called nitrite. Like nitrate, nitrite is found naturally in plants. Around 50-75% of humans' nitrate intake and nitrite comes from vegetables and fruits.
Nitrates can also enter drinking water, primarily through agricultural runoff from fertilizer since nitrate is used in fertilizer for crops and lawns.
Once in your body, dietary nitrates and nitrites can react with compounds known as amines and amides. When this happens, N-nitroso compounds (NOCs) are formed. NOCs have been shown to be cancer-causing substances (carcinogens) in animals, so it's believed NOCs might cause cancer in humans, as well.
However, not all sources of nitrate may have the same harmful effect. While vegetables are a main source of dietary nitrate, they also have compounds that prevent NOCs from forming. Human research that has linked dietary nitrate to cancer has more so focused on nitrates you ingest through water or food from areas where use of nitrogen-based fertilizers is common. In fact, nitrate likely has a positive effect on health if the source is a fruit or vegetable.
Besides being used as an ingredient in fertilizer, nitrate is also used to preserve food, make medications, and produce munitions and explosives.
Sources of Nitrate
Nitrate is found naturally in soil, water, and air. Your body also makes it. But there are also dietary sources of nitrates that you may take in each day.
The vast majority of nitrate humans consume comes from leafy, green vegetables and root vegetables. Examples of nitrate-rich vegetables include:
Nitrate that is naturally in vegetables is not considered harmful since the plants have compounds to counteract the potential cancer-causing effect of NOCs, which come from nitrate.
Nitrate is a common additive in a variety of red and processed meats. Nitrates are added because they act as preservatives, helping to prolong the shelf life of meat products and prevent oxygenation. Nitrates also work to improve flavor, give meat its characteristic pinkish-red color, and prevent bacteria growth.
Nitrates are added to many meats and meat products that have been dried, cured, canned, or fermented, such as lunch meats and jerky. Some raw meat also contains nitrate. Examples of meat that may contain nitrate include:
Nitrate is sometimes found in the drinking water supply due to runoff from agricultural sites, fertilizer, landfills, and septic systems, as well as through waste from industrial and food processing sites. Nitrate is most commonly found in private wells and public water supplies near areas where farming is prevalent. For instance, high concentrations of nitrates have been found in drinking water in Iowa and Nebraska—two states known for farming.
Nitrate in water can be removed through water treatments like distillation, exchange osmosis, or ion exchange. If you suspect that your source of drinking water may contain nitrates, you can reach out to the local health department for water testing.
Nitrate has even been found in some bottled water. To protect consumers, the U.S. Food and Drug Administration requires that bottled water with a nitrate-nitrogen concentration of more than 45 milligrams per liter be labeled with the phrase “Contains Excessive Nitrate.”
Editor's Note: You can have the amount of nitrate in your body tested through a blood or urine sample. However, since your body naturally makes the substance anyway, the tests might not be too helpful in seeing if you've been exposed to nitrate. If you're concerned about potential nitrate exposure, it's be better to test the water instead.
Being exposed to too many nitrates from water and foods other than natural plant sources can have several negative health impacts.
Because nitrates from non-vegetable sources can interact with amines and amides and form NOCs, some nitrates may increase your risk of certain cancers. Animal studies have suggested this, and some human studies seem to confirm the relationship. Although findings have been slightly mixed, taking in a high amount of nitrates from meat or drinking water have been linked to a number of different cancers, including:
Still, the U.S. Environmental Protection Agency has not classified nitrate as a carcinogen. Meanwhile, the International Agency for Research on Cancer has said that nitrate is probably cancer-causing for humans.
Nitrates that have been added to meat or that are found in drinking water may also increase the risk of methemoglobinemia, a blood disorder that makes it so oxygen cannot be effectively released to the body's tissue. Methemoglobinemia is particularly dangerous to young infants.
When consumed by people who are pregnant, nitrates from drinking water could increase the chance of birth defects, such as neural tube defects like spina bifida.
In vegetables, nitrate supplies the body with nitric oxide, a molecule that has many potential benefits for cardiovascular health. Nitric oxide acts as a vasodilator, meaning it relaxes the blood vessels. This allows for more efficient blood and oxygen flow. A diet rich in nitrates from vegetables and fruits has been linked to:
Improved athletic performance
Increased oxygen saturation (the amount of oxygen in your blood)
Fewer symptoms in people with heart failure
Improved blood flow in the brain after a stroke
Because of these benefits, nitrates are sometimes used in medications to treat angina (chest pain) and other heart conditions.
A Quick Review
Nitrate is a chemical compound that is found naturally in some of the foods humans eat. It’s particularly common in root and leafy green vegetables. When consumed through plant-based food sources, nitrates may help lower blood pressure and improve the flow of oxygen throughout the body. However, nitrates in drinking water and processed meats may pose health risks because of the other chemicals with which they react. Nitrates from these sources have been linked to some cancers and other conditions. If you're concerned about the amount of nitrates you're ingesting—particularly if you live near a farm or use well water—consider having your water tested for nitrates.
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