If chemistry and food science have never been your jam, there are probably a lot of food-related words that you know of but don’t actually know anything about. But when it comes to what you eat and how it impacts your health, nitrates and nitrites both rank high on the list of “What even are they?!” terms you should know.
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Registered dietitian Devon Peart, RD, MHSc, explains what nitrates and nitrites are, including which foods they’re found in and how they affect your health, for good and for bad.
Nitrates and nitrites are naturally occurring chemicals that are similar in structure. They’re both made of nitrogen and oxygen, but nitrates contain three oxygen atoms and nitrites only two oxygen atoms. But for your purposes, what does that mean?
“Nitrates and nitrites are natural chemicals that are found in soil and water as part of the earth’s nitrogen cycle,” Peart explains. “They’re naturally present in the human body and in some foods, and nitrates are also added to some foods.”
The nitrates and nitrites that occur naturally in our bodies and in whole foods (like plants, which we’ll talk about momentarily) aren’t concerning. They’re normal and healthy.
But if you’ve heard that you should avoid foods that contain nitrates and nitrites, there’s some truth to that advice: When they’re added to certain foods, that’s when they start causing trouble — namely, by raising your risk of cancer.
Nitrates and nitrites occur naturally in leafy green vegetables like spinach, romaine and kale, as well as in root vegetables like beets, celery and carrots.
“Most of the nitrates and nitrites we consume come from plant foods we eat,” Peart says. But plants aren’t the only purveyors of nitrates and nitrites, which is where the problems start to occur.
“We also add nitrates and nitrites to meat products (and to some cheeses) as a preservative, to prevent the growth of harmful bacteria, and sometimes to boost the color and palatability of food,” she continues. “They can even add extra umami flavor.”
Yum! Sounds great, right? Not so fast.
The issue, Peart says, isn’t with the nitrates themselves but with their potential to form nitrosamines, carcinogenic compounds that can increase your risk of various cancers
“Research shows that the source of the nitrates matters,” Peart says. “Eating too many processed meats containing added nitrates and nitrites is associated with an increased risk of cancer, but eating plants that have nitrites or nitrates in them has not been associated with increased cancer risk.”
Let’s break down the differences between nitrates and nitrates found in plants and the kind added to meats and cheeses.
On ingredient labels, you might also see added nitrates and nitrites listed as “sodium nitrite” or “potassium nitrate.” Some common foods that include them are:
But what makes the nitrates and nitrites in some foods problematic and not in others? Several factors may be involved, including food prep methods.
“When meat is cooked at high heat, like during frying or grilling, nitrates and nitrites can react with the amino acids in the meat protein to form nitrosamines,” Peart explains. “Most nitrosamines are known carcinogens, which means they’re associated with an increased risk of cancer.”
Vitamin C can stop nitrates from turning into nitrosamines, she says: “One reason we don’t see increased cancer risk with leafy greens, for example, could be due the vitamin C in plant foods.” Vitamin C is sometimes added to processed meats to try to prevent cancer-causing compounds from forming.
What about meats that are labeled “organic,” “natural” or “preservative-free”? This usually means they contain nitrates or nitrates that occur naturally in plants, which have been processed into powders or juices and added to the food as a preservative.
“This is somewhat misleading, though, because the nitrates can still be converted to nitrosamines,” Peart warns, “so they’re not necessarily healthier.”
Remember: Not all nitrates and nitrites are bad news — in fact, quite the opposite. “Naturally occurring nitrates and nitrites help our digestive system by protecting against certain bacteria,” Peart states.
They can also transform into nitric oxide, which has known health benefits. In-depth research from the last 15 years shows that nitrate from vegetables might have heart health benefits like:
Research is ongoing, but nitric oxide may have a positive impact on or improve outcomes for conditions like:
If you’re an athlete, the energy/performance/recovery benefit might sound familiar. “Many athletes drink beetroot juice to harness the potential performance-enhancing effect of the naturally occurring nitrates in beets,” Peart says.
“Include plenty of vitamin C-rich foods in your diet, too, like citrus fruits,” Peart advises, “because vitamin C helps your body absorb and use nitric oxide.”
It depends on which foods you’re getting them in.
“The nitrates and nitrites in processed meat are chemically identical to naturally occurring nitrates in plant foods, but eating those plant foods is not associated with increased cancer risk,” Peart clarifies. “There is, however, an increased risk associated with eating processed meats, if you have them often.”
And then, there’s the simple fact that vegetables are just really healthy, generally, providing other health benefits like antioxidants, fiber and micronutrients. Processed meats, on the other hand, are ultra-processed foods that are also high in saturated fat and sodium, which are known to negatively impact your health (and especially your heart).
As with so much of the guidance around nutrition, Peart emphasizes that moderation is key.
“Having an occasional slice of bacon (or two!) doesn’t pose an increased health risk,” she says. “But we should limit the amount of processed meat in our diets and aim to enjoy a wide variety of health-enhancing plant foods.”