What Exactly Are Nitrates and Nitrites?
Nitrates ($NO_3^-$) and nitrites ($NO_2^-$) are chemical compounds of nitrogen and oxygen that exist naturally in soil, water, and plants. While they differ by only one oxygen atom, this slight chemical variation is significant because the body processes them differently depending on their source and surrounding nutrients.
When we consume nitrates, about 25% are absorbed into the bloodstream before being secreted into saliva. In the mouth, bacteria convert some nitrates to nitrites. These nitrites can then follow one of two paths, which largely determines their health effect: they can either become beneficial nitric oxide (NO) or potentially harmful N-nitroso compounds (nitrosamines).
The Health Benefits of Natural Nitrates from Vegetables
Most people consume far more nitrates from vegetables than from processed meats. Leafy greens like spinach, rocket, and lettuce, along with root vegetables such as beets, are among the richest natural sources. When nitrates from these plant sources are consumed, they are primarily converted into nitric oxide. This process is supported by the high levels of antioxidants, like Vitamin C, found naturally in vegetables, which inhibit the formation of harmful nitrosamines.
This conversion to nitric oxide offers several proven health benefits:
- Cardiovascular health: Nitric oxide is a potent vasodilator, meaning it helps to relax and widen blood vessels. This can lead to lower blood pressure and improved overall blood flow. Several studies link a diet rich in vegetables, and therefore nitrates, to a reduced risk of cardiovascular disease.
- Enhanced athletic performance: For athletes and fitness enthusiasts, nitrate supplements (often in the form of beetroot juice) are popular for improving oxygen delivery to muscles and boosting exercise performance.
- Cognitive function: Improved blood flow from nitric oxide production may also benefit brain function and cognitive performance.
The Risks Associated with Added Nitrates in Processed Meats
Nitrates and nitrites are added to processed meats like bacon, ham, salami, and hot dogs for two main reasons: to preserve them by inhibiting the growth of dangerous bacteria like Clostridium botulinum and to maintain their pink color and flavor.
The health risks from these added nitrates come from a different metabolic pathway. In the high-protein environment of meat, particularly when cooked at high temperatures (frying, grilling), nitrites can react with amines to form carcinogenic nitrosamines. The World Health Organization (WHO) and other health agencies classify processed meat as carcinogenic to humans, with nitrates and nitrites being one contributing factor alongside other compounds.
It is crucial to note that many products labeled "uncured" or "no nitrates added" still contain natural nitrates, typically from celery powder. The curing agent is derived from a vegetable source but behaves in the same way as synthetic nitrates once added to the meat, creating nitrosamines during cooking.
Natural vs. Added Nitrates: The Key Differences
| Feature | Natural Nitrates (Vegetables) | Added Nitrates (Processed Meats) |
|---|---|---|
| Primary Source | Leafy greens (spinach, rocket), root vegetables (beets, carrots) | Cured meats (bacon, ham, deli meat), sausages, hot dogs |
| Co-existing Nutrients | Rich in antioxidants (Vitamin C), vitamins, minerals, and fiber | High in sodium, saturated fats, and heme iron |
| Key Chemical Reaction | Converted to beneficial nitric oxide in the body | React with proteins during cooking to form carcinogenic nitrosamines |
| Health Impact | Associated with cardiovascular benefits, lower blood pressure | Linked to increased risk of certain cancers, particularly colorectal cancer |
| Protective Factors | Antioxidants inhibit harmful nitrosamine formation | Lack protective antioxidants, increasing risk during high-heat cooking |
Addressing Other Nitrate Concerns
While the focus on food sources is paramount, nitrates can also enter the body via other routes, most notably drinking water. High levels of nitrate in drinking water are a concern, especially for infants under six months of age. In infants, excess nitrates can cause methemoglobinemia, or "blue baby syndrome," a serious and potentially fatal condition where the blood loses its ability to carry oxygen. This is why water authorities regulate nitrate levels and why formula should never be prepared with water suspected of high nitrate contamination. Testing private well water is recommended if there is any doubt.
Making Informed Dietary Choices
To benefit from the cardiovascular advantages of natural nitrates while minimizing potential risks, a balanced approach is recommended. The consensus from health experts is clear: prioritize natural, plant-based sources and limit your intake of processed meats.
Actionable steps to consider:
- Embrace high-nitrate vegetables: Incorporate more leafy greens, beets, and celery into your diet. This supports nitric oxide production and provides a wealth of other essential nutrients.
- Limit processed meats: Reduce consumption of bacon, sausages, and deli meats, regardless of whether they are conventionally cured or use natural sources like celery powder.
- Cook processed meats with caution: When you do eat processed meats, avoid charring or overcooking them at high temperatures, as this increases nitrosamine formation.
- Increase antioxidants: Pair nitrate-containing foods with vitamin C-rich foods. The antioxidants in fruits and vegetables can help inhibit the formation of harmful nitrosamines, strengthening the protective effect of a plant-rich diet.
- Test well water: If your household uses a private well, have the water tested for nitrate levels, particularly if you have young infants.
Conclusion
The question of whether nitrates are bad for you is not a simple yes or no. The source of the nitrate is the most important factor in determining its effect on your health. Naturally occurring nitrates in vegetables, supported by antioxidants, are linked to significant cardiovascular benefits and appear to be largely safe. Conversely, nitrates added to processed meats are associated with health risks, including an increased risk of certain cancers, primarily due to the formation of nitrosamines during cooking. By focusing on a diet rich in whole, plant-based foods while minimizing processed meats, you can enjoy the benefits of nitrates and reduce exposure to potential harm. For more information on dietary nitrates and their health effects, visit Examine.com's Nitrate page.
