What do nitrites do to your body?

January 14, 2026 •

4 min read

According to the World Health Organization (WHO), excessive intake of nitrites under conditions that lead to endogenous nitrosation is considered a probable carcinogen. Understanding the dual role of nitrites in the body—as both a beneficial precursor to nitric oxide and a potential source of harmful nitrosamines—is crucial for making informed dietary decisions.

Quick Summary

Nitrites have complex effects on the body, including producing beneficial nitric oxide that regulates blood pressure and potentially forming harmful nitrosamines linked to cancer. Health outcomes depend heavily on the source of the nitrites, whether from nutrient-rich vegetables or processed meats cooked at high temperatures. Excessive exposure can also cause methemoglobinemia.

Key Points

Dual Function: Nitrites in the body can be converted into beneficial nitric oxide or harmful nitrosamines, depending on factors like their source and presence of antioxidants.
Cardiovascular Benefits: Nitrites from vegetables support heart health by converting into nitric oxide, which dilates blood vessels, lowers blood pressure, and improves endothelial function.
Increased Exercise Performance: Nitric oxide production from nitrites enhances physical performance by increasing mitochondrial efficiency and reducing the oxygen cost of exercise.
Cancer Risk: When nitrites in processed meats are cooked at high heat, they can form carcinogenic nitrosamines, a risk mitigated by the antioxidants found in vegetables.
Methemoglobinemia: Excessive nitrite exposure can cause methemoglobinemia, a condition where the blood loses its ability to carry oxygen, which is especially dangerous for infants.
Source Matters: Nitrites from vegetables are generally considered safe and beneficial, while those from processed meats, especially in excess, carry health risks.
Moderation is Key: Limiting processed meat consumption while enjoying a vegetable-rich diet is the recommended approach to managing nitrite intake and balancing health outcomes.

The Dual Nature of Nitrites in Your Body

Nitrites are compounds containing one nitrogen atom and two oxygen atoms (NO2-), and they exist naturally in the environment, foods, and within the human body. While they are often associated with the curing process of processed meats like bacon and hot dogs, the majority of dietary nitrites are actually derived from leafy green and root vegetables, where they originate as nitrates that are later converted. The overall health effects of nitrites are determined by a delicate balance in the body's chemistry. In one pathway, they can be reduced to beneficial nitric oxide (NO), a vital signaling molecule. In another, under specific conditions, they can form carcinogenic nitrosamines.

The Beneficial Pathway: Nitric Oxide Production

When nitrites are metabolized in the body, particularly from vegetable sources rich in antioxidants, they can be converted into nitric oxide. This pathway is a cornerstone of cardiovascular health.

Cardiovascular Benefits

Blood Vessel Dilation: Nitric oxide signals the smooth muscle cells surrounding blood vessels to relax, causing them to widen. This vasodilation improves blood flow and reduces blood pressure.
Improved Endothelial Function: Nitrite intake, especially from vegetables, has been shown to improve the function of the endothelium, the inner lining of blood vessels, contributing to overall heart health.
Reduced Blood Pressure: Studies have demonstrated that dietary intake of nitrites from sources like beetroot juice can significantly lower blood pressure in both healthy individuals and those with hypertension.
Inhibition of Platelet Aggregation: Nitric oxide can inhibit the aggregation of platelets, which helps prevent the formation of dangerous blood clots.

Enhanced Exercise Performance

In addition to their cardiovascular effects, nitrites can improve physical performance. The conversion to nitric oxide increases the efficiency of mitochondria, the energy-producing organelles in cells. This can lead to a lower oxygen cost during high-intensity exercise and an increase in time to exhaustion.

The Detrimental Pathway: Nitrosamine Formation and Methemoglobinemia

While nitrites can be beneficial, they can also pose risks under certain circumstances. These risks are primarily associated with the consumption of processed meats and exposure to high heat.

Carcinogenic Nitrosamines

Formation Conditions: When nitrites in processed meats are exposed to high heat during cooking (e.g., frying bacon), they can react with amino acids to form N-nitroso compounds, or nitrosamines.
Cancer Risk: The International Agency for Research on Cancer (IARC) classifies ingested nitrites, under conditions that lead to endogenous nitrosation, as a probable human carcinogen (Group 2A). This link is most strongly associated with processed meats and an increased risk of gastrointestinal cancers, especially colorectal cancer.
Role of Antioxidants: Vegetables, unlike processed meats, naturally contain antioxidants such as Vitamin C. These compounds can inhibit the formation of nitrosamines, explaining why the nitrites in vegetables are not linked to the same cancer risks.

Methemoglobinemia

Excessive exposure to nitrites, such as from contaminated well water or over-ingestion, can lead to methemoglobinemia, a life-threatening condition.

Oxidation of Hemoglobin: Nitrites can oxidize the iron in hemoglobin, the protein that carries oxygen in the blood. This creates methemoglobin, a form of hemoglobin that cannot bind oxygen.
Oxygen Deprivation: A high level of methemoglobin in the blood reduces its oxygen-carrying capacity, leading to tissue hypoxia. Symptoms can include bluish skin (cyanosis), dizziness, headaches, and, in severe cases, seizures, coma, or death.
Infant Vulnerability: Infants under six months are particularly susceptible due to a higher gastric pH, which allows for greater conversion of nitrates to nitrites, and their lower levels of the enzyme needed to convert methemoglobin back to hemoglobin.

Nitrites from Different Sources: A Comparison


Feature	Nitrites from Vegetables	Nitrites from Processed Meats
Associated Health Effects	Protective against cardiovascular diseases; improves blood flow and blood pressure.	Linked to increased risk of certain cancers (especially colorectal) and potential methemoglobinemia.
Formation of Nitrosamines	Inhibited by naturally occurring antioxidants like Vitamin C.	Promoted by exposure to high heat during cooking, especially in the presence of protein.
Primary Dietary Source	Leafy greens (spinach, arugula), beetroot, and celery.	Cured and preserved meats (bacon, salami, hot dogs).
Associated Nutrients	Accompanied by beneficial vitamins, antioxidants, and fiber.	Associated with high levels of sodium, saturated fats, and potentially other carcinogens formed during processing.
Chemical Identity	Chemically identical to those in processed meat, but the surrounding food matrix is different.	Chemically identical, but interact differently due to the food environment.

Understanding the Nitrite Conversion Process

The journey of nitrates to nitrites and finally to their active products is complex. About 5–7% of dietary nitrates are reduced to nitrites by bacteria in the mouth. These nitrites then enter the systemic circulation. In healthy individuals with sufficient stomach acid and antioxidant levels, the conversion largely favors beneficial nitric oxide. However, factors like high consumption of processed meats, low antioxidant intake, and high-heat cooking push the chemistry towards the formation of harmful nitrosamines, increasing health risks. The body’s own production of nitrites also contributes to this delicate balance.

Conclusion: A Balanced Perspective on Nitrites

The impact of nitrites on your body is not a simple matter of 'good' or 'bad.' The effect depends heavily on their source and the context in which they are consumed. While the nitrites found in vegetables, supported by a wealth of antioxidants, can promote heart health and exercise performance, the nitrites added to processed meats—especially when cooked at high temperatures—have been linked to increased cancer risk. The key lies in understanding this dual nature and moderating intake from processed sources. Focusing on a diet rich in vegetables ensures you reap the benefits of nitric oxide production while mitigating the risks associated with harmful nitrosamine formation.

Visit the CDC for more information on the health effects of nitrites.

Frequently Asked Questions

No, not all nitrites are bad. The health effects of nitrites largely depend on their source. Nitrites from antioxidant-rich vegetables can form beneficial nitric oxide, while nitrites in processed meats cooked at high heat can form harmful nitrosamines.

Nitrates (NO3) have three oxygen atoms, while nitrites (NO2) have two. In the body, nitrates are converted to nitrites by bacteria, primarily in the mouth. These nitrites can then either be converted into beneficial nitric oxide or harmful nitrosamines.

Nitrites are converted into nitric oxide (NO) in the body. Nitric oxide is a signaling molecule that causes blood vessels to relax and dilate, which in turn lowers blood pressure and improves blood flow.

In processed meats, nitrites are in close proximity to proteins. When cooked at high temperatures, they can react to form nitrosamines, which are carcinogenic compounds. The risk is associated with the cooking method and the food matrix, not the nitrite itself.

Methemoglobinemia is a condition caused by excessive nitrite exposure, where nitrites oxidize the iron in hemoglobin, rendering it unable to carry oxygen. This can cause oxygen deprivation in tissues and lead to symptoms like cyanosis and, in severe cases, death.

Infants under six months are more vulnerable due to their underdeveloped digestive systems and lower levels of the enzyme that converts methemoglobin back to hemoglobin. Exposure to high nitrite levels, often from contaminated well water used in formula, is a significant risk factor.

Yes, you can. Limiting consumption of processed and cured meats is the primary strategy. Additionally, pairing processed meats with Vitamin C-rich foods can help inhibit nitrosamine formation, and cooking at lower temperatures can reduce the risk.