Nitrates and nitrites are compounds that occur naturally in the human body and some foods, such as vegetables. Manufacturers also add them to processed foods, such as bacon, to preserve them and make them last longer.

In some forms, nitrates and nitrites can be hazardous. However, they may also have health benefits.

This article reviews nitrates and nitrites in the diet.

Nitrates and nitrites are two different types of compound.

Nitrates (NO3) consist of one nitrogen atom and three oxygen atoms. Nitrites (NO2) consist of one nitrogen atom and two oxygen atoms.

Nitrates are relatively inert, which means they’re stable and unlikely to change and cause harm.

However, bacteria in the mouth or enzymes in the body can convert them into nitrites, and these may be harmful.

In turn, nitrites can either turn into:

  • nitric oxide, which is beneficial for the body
  • nitrosamines, which can be harmful

There’s more information about these below.

Manufacturers add nitrites to meat to preserve them. They’re the reason why cured meat is pink or red. In meat, nitrites turn into nitric oxide. This reacts with proteins in the meat, changing its color and helping preserve it. (1).

Without nitrites and other additives, the meat would turn brown quickly.

Summary Nitrates and nitrites are compounds consisting of nitrogen and oxygen atoms. Nitrates can turn into nitrites, which can then form either nitric oxide (good) or nitrosamines (bad).

Food producers often add nitrates and nitrites to processed meats, such as bacon, ham, sausages, and hot dogs.

These added compounds help to:

  • prevent the growth of harmful bacteria
  • add a salty flavor
  • improve the meat’s appearance by giving it a red or pink color

A high intake of processed meats may increase the risk for cancer in the digestive tract. Some people believe that nitrates and nitrites are the reason for the increased risk (2, 3).

However, nitrates and nitrites also occur naturally in vegetables, which may reduce the risk for some types of cancer and other diseases (4, 5).

In fact, according to one study, people obtain around 80% of their dietary nitrates from vegetables (6).

The body also produces nitrates and secretes them into saliva (7, 8).

Nitrates and nitrites circulate from the digestive system into the blood, then into saliva, and back into the digestive system (9).

They may be useful in keeping your body healthy, as they seem to function as antimicrobials in the digestive system. They can help to kill bacteria, such as Salmonella (10, 11).

They can also turn into nitric oxide (NO), an important signaling molecule (12).

Nitrates also occur naturally in water. In some areas, fertilizer use may lead to high levels of nitrates that can be harmful to children. For this reason, health authorities regulate nitrate levels in drinking water (13).

Summary Nitrates are present in small amounts in processed meats and in larger amounts in healthy foods like vegetables. They also occur in drinking water, and the human body produces nitrates, too.

Under some circumstances, nitrite loses an oxygen atom. Then, it turns into nitric oxide, an important molecule.

Nitric oxide (NO) has various functions in the body. It can be toxic in high amounts, but it can also help protect the body (14).

Most importantly, it’s a signaling molecule. It travels through the artery walls and sends signals to the tiny muscle cells around the arteries, telling them to relax (15).

When these cells relax, the blood vessels dilate, and blood pressure goes down.

Nitroglycerin is a drug that contains nitrates. Healthcare providers use it to treat heart failure and other conditions (16).

Nitroglycerin can prevent or reverse angina, a type of chest pain that occurs when the heart muscle doesn’t get enough oxygen due to low blood flow.

Dietary nitrates and nitrites can also change into nitric oxide, dilate the blood vessels, and lower blood pressure (17).

Studies have shown that foods that are high in nitrates and nitrites, such as beetroot or beetroot juice, can reduce blood pressure. In one study, blood pressure fell by up to 4–10 mm/Hg over a period of a few hours (18, 19, 20).

High blood pressure is a key risk factor for heart disease and stroke, common conditions that can both be life threatening.

Summary In the body, nitrites can turn into nitric oxide (NO), a signaling molecule that causes blood vessels to dilate and reduces blood pressure.

Studies suggest that nitrates can enhance physical performance, especially during high intensity endurance exercise.

Some people often use beetroot or beetroot juice for this purpose, because they contain high levels of nitrates.

The reason for this improvement in physical performance may be due to nitrates increasing the efficiency of mitochondria. Mitochondria are the parts of cells that produce energy (21).

A few studies have shown that beetroot can reduce the oxygen cost of exercise by 5.4%, increase time to exhaustion when running by 15%, and improve sprinting performance by 4% (22, 23, 24).

Summary Studies suggest that dietary nitrates and nitrites can enhance physical performance, especially during high intensity endurance exercise.

Nitrates and nitrites are essential compounds, but they can become hazardous if they form nitrosamines. Nitrosamines can form if you cook nitrates or nitrites at high heat. (25).

There are different types of nitrosamines, and many can increase the risk for cancer. (26).

Nitrosamines are some of the main carcinogens in tobacco smoke, for example.

Bacon, hot dogs, and processed meat can contain high levels of both sodium nitrite. They’re also high in protein, which is made up of amino acids. On exposure to high heat, this combination creates the perfect conditions for nitrosamines to form (27).

Cooking vegetables, however, is less likely to produce nitrosamines. People rarely cook vegetables at very high heat, and they don’t contain large amounts of protein.

Summary When nitrites and amino acids are present, carcinogenic compounds called nitrosamines can form during cooking with high heat.

Manufacturers have to limit the amount of nitrites they use in processed meats by law, because of the dangers that nitrosamines pose.

They also have to add vitamin C, which inhibits nitrosamine formation (28).

The processed meat that you eat today contains less nitrite than it did a few decades ago.

You can reduce your risk of nitrosamine exposure by making wise choices when shopping for processed meats, such as bacon.

Some outlets sell quality bacon that’s nitrate-free. The ingredients should show that the bacon doesn’t have high levels of additives that contain nitrates.

You should check the labels for:

  • sodium nitrate (E251)
  • sodium nitrite (E250)
  • potassium nitrate (E252)
  • potassium nitrite (E249)

It’s worth checking the ingredients. Some natural and organic ways of preserving meat, such as celery salt, may contain nitrates. As a result, some "nitrate free" bacon may contain more nitrates than conventional bacon (29).

To be sure of getting bacon that’s low in nitrates, you can try the following:

  • Buy local where possible or from a farmers market.
  • Find a supplier of bacon from pasture-raised pigs.
  • Fry or cook bacon at a lower heat for longer and avoid burning it.

One older study suggests that cooking bacon in a microwave is the best way to minimize nitrosamine formation (30).

Here’s a video with instructions on how to do this.

Nitrates are a form of preservative, and bacon that’s low in nitrates may not last as long. You can preserve it for longer by freezing it.

Summary You can reduce your risk of nitrosamine exposure by carefully selecting processed meat products that are low in additives that contain nitrates.

Nitrates and nitrites are compounds that occur naturally in the human body and some foods. They’re also added to certain processed foods to extend shelf life.

They can change into nitric oxide, dilate your blood vessels, and lower blood pressure. Moreover, they may enhance physical performance.

Still, the carcinogenic compound nitrosamines can form if you cook nitrates or nitrites at high heat, which poses a health risk.

Due to strict regulations, there are less nitrites in processed foods today, as manufacturers have to limit the amount they use.

You can reduce your risk of nitrosamine exposure by carefully studying the label when shopping for processed meats to find a product with limited or no additives that contain nitrates.