Nitrates are inorganic compounds that can be found in nature and in several foods we eat. In this lesson, we’ll learn more about what nitrates are, what foods contain them and what side effects might occur if we consume too many of them.

What Are Nitrates?

Can you guess how much bacon you’ve consumed in your lifetime? While you were enjoying this cured meat for breakfast, or maybe even added to your ice cream, did you know it contains something called nitrates?

Nitrates are inorganic compounds made up of nitrogen and oxygen, NO3 (one nitrogen and three oxygen molecules). These compounds combine with other elements like sodium and potassium to make sodium nitrate or potassium nitrate. They are used as preservatives and color fixatives in cured meats and have other industrial uses, such as in gunpowder, explosives, fertilizers, and glass enamels.

When we eat nitrates, they are converted into nitrites in our digestive system, which are then converted to ammonia and disposed of by the body. Nitrites are also inorganic compounds made up of nitrogen and oxygen, but instead of three oxygen molecules they have two, NO2.

Nitrates are not generally harmful unless they are consumed in massive quantities. Nitrites, on their own and in moderation, are also generally not harmful. However, nitrites can be degraded into carcinogenic compounds by high heat and also by digestive enzymes. Nitrites are particularly good at preventing botulism – an anaerobic form of bacteria that causes paralysis and death – which is why small amounts of these compounds are added to cured meats. Neither nitrates nor nitrites are good at preventing contamination by other kinds of bacteria, like E. coli.

Nitrate occurs naturally in the soil, either by itself or as a compound such as sodium nitrate. The largest natural deposits of sodium nitrate are located in Chile and Peru. The War of the Pacific (1879-1884) was over control of these deposits and pitted Chile against Peru and Bolivia. Early in the 20th century, synthetic sodium nitrate began to be produced, and by the 1940’s, the demand for naturally-produced sodium nitrate dropped dramatically.


Nitrates are present naturally in root vegetables like carrots and potatoes, and also in green, leafy vegetables like spinach and kale. Nitrites, however, are highly reactive and generally are not found in nature. Sodium nitrate and sodium nitrites are added to cured meats like bacon and deli meats and also to poultry and fish.

Less than 10 percent of nitrate in our diet comes from meat products, but these same products account for 60 to 90 percent of the nitrite eaten. The bacteria in our digestive systems supply a small amount of nitrate. Dairy products, grains, and fruits contribute practically no nitrates or nitrites to the food supply.

Side Effects

The conversion of nitrates to nitrites can interfere with the oxygen carrying capacity of blood, particularly in infants under six months old. Hemoglobin, which carries oxygen, is converted to methemoglobin, which does not carry oxygen. In adults, methemoglobin can be changed back into hemoglobin, but this change does not occur in infants. This is an acute condition that causes shortness of breath and blueness of the skin, known as methemoglobinemia or blue baby syndrome. Brain damage and death can result.

A shortage of stomach acid, and/or a reduction in the production of the enzyme that controls methemoglobin, may allow high levels of nitrates to accumulate and may also increase sensitivity to nitrates.

Research has shown links between high levels of nitrates and increased risk of death from Alzheimer’s, diabetes, and Parkinson’s disease. There are also links between nitrates and gastric, esophageal, and colon cancers.

Lesson Summary

In summary, it is important to remember:

  • Nitrates occur naturally in the soil
  • Nitrates are used to preserve cured meats
  • Nitrates convert to nitrites in the body

High levels of nitrates have been linked with increased risks of Alzheimer’s, diabetes, and Parkinson’s, along with gastric, esophageal, and colon cancers.

About Nitrates

Nitrate chemical composition

*Inorganic compounds made of one nitrogen and three oxygen atoms
*Found organically in the soil and in root and leafy green vegetables
*Can be produced synthetically
*Have food and industrial applications
*Generally not harmful to the body if consumed in moderation
*Dangerous condition called methemoglobinemia can affect infants who consume nitrates
*High levels of nitrates linked with increased risks of Alzheimer’s, diabetes, Parkinson’s and certain cancers

Learning Outcomes

When you are finished with this lesson, you should be able to:

  • Explain what nitrates are and where they are found
  • Discuss the possible side effects of high levels of nitrates in the body