These days, it seems like there are plenty of things to worry about when it comes to our food. Sugar, trans fat, pesticides…the list of what can do us harm goes on too long. For many people, that list of cautionary ingredients includes nitrates.
Nitrates in processed meats, such as bacon and cold cuts, have long had a bad rap, yet there’s also been a lot of talk about the potential health and performance benefits of nitrates you get from chomping on salads and sucking back beet shots.
The relationship between dietary nitrates and health is a lot more nuanced than merely saying “they’re bad for us” or “they’re great for us.” It turns out these compounds can be more beneficial when sourced from some foods, and likely detrimental when they come from others. Confusing? Yes, which is why we dove into the science to explain what nitrates are and how they can influence your health and your cycling.
What are nitrates and how are they different from nitrites?
Nitrates occur naturally in some plants, which source them from the soil they grow in, and are also legally added by food manufacturers to processed meats—in the form of sodium nitrate—as a preservative, or to enhance flavor, color, and texture. About 80% of the nitrates in the typical American diet hail from vegetable consumption. Interestingly, nitrate levels might be lower in organic produce than conventionally grown produce, as synthetic nitrate fertilizers aren’t used. Some nitrates are also found in drinking water, mainly from wide-scale agricultural fertilizer use.
Though nitrates and nitrites often get used interchangeably, they are not exactly the same substances. Nitrates are compounds that are composed of nitrogen and oxygen molecules. Your body makes some nitrates each day, but the majority of nitrates come from your diet.
The difference between nitrates and nitrites is the oxygen they possess. Nitrates are composed of three oxygen atoms (NO3-), while nitrites have two oxygen atoms (NO2-). So they are relatively related to one another.
The nitrates you eat from vegetables and meats turn into nitrites in your body with the help of bacteria present in mouth saliva (yes, your mouth also has its own microbiome). Nitrites are then converted into nitric oxide (good) or nitrosamines (not so good). Research shows that the use of an anti-bacterial mouthwash can noticeably cut down this oral manufacture of nitrites from nitrates.
Top plant-based sources of nitrates:
- Arugula
- Beets
- Bok Choy
- Cabbage
- Carrot
- Celery
- Lettuce
- Kale
- Mustard Greens
- Parsley
- Rhubarb
- Spinach
- Swiss chard
Top meat sources of nitrates:
- Bacon
- Deli meat, including roast beef and turkey
- Ham
- Hot Dogs
- Jerky
- Pepperoni
- Sausages
So are nitrates good or bad for you?
We can think of nitrates as the Dr. Jekyll and Mr. Hyde of food compounds. Their bright or dark side depends on the source.
First, the good about nitrates in food
When we eat nitrates that occur naturally in plants, our body transforms them to nitric oxide, which has been shown to help relax blood vessels which can then have several health benefits, such as reducing blood pressure and improving circulation. This, in turn, can improve overall heart health. In 1998, three U.S. scientists received the Nobel prize for their discoveries about the role of nitric oxide in the cardiovascular system.
To illustrate some of those benefits, a meta-analysis of previous research found evidence that higher intakes of vegetable-derived nitrates can have a positive benefit on several cardiovascular disease risk factors, including lowering blood pressure, reducing arterial stiffness, and improving endothelial functioning which is important for blood clot regulation.
An investigation published in the European Journal of Epidemiology in 2021, involving more than 53,000 people, determined that consuming as little as 60 milligrams of nitrates from vegetables daily (that’s about what you get from 1 cup of green leafy vegetables) may significantly reduce the risk for heart disease and heart failure. Heart disease remains a leading cause of death for both men and women in the United States.
Some preliminary research suggests that higher intakes of nitrates can also improve cognitive functioning, especially as we age, likely by boosting blood flow to the brain.
It’s worth noting that nitrate-rich plants provide many other health-promoting vitamins, minerals, and antioxidants that are good news for your health. That’s one reason why it’s very hard to reliably estimate dietary nitrate intake, because content in food is hugely variable. This means that studies investigating the effects of nitrate on health need to be interpreted with caution, as higher nitrate intake might simply be a marker of greater vegetable intake so some of the health benefits attributed to nitrates may instead be caused by the overall nutrition boost that the nitrate-containing vegetables provide to the diet.
It appears that cyclists and other athletes can do a lot worse than getting ample amounts of plant-derived nitrates in their diet. The nitric oxide produced from nitrates allows blood vessels to relax and widen (dilate), which increases blood flow throughout the body including to working muscles. It’s believed that this improves oxygen and nutrient delivery to muscles allowing them to perform more optimally when on the move. Improvement in physical performance may also be due to nitrates increasing the efficiency of mitochondria. Mitochondria are the parts of cells that produce energy.
A review study published in 2021 in the Journal of the International Society of Sports Nutrition found that a high dose of nitrates can increase muscle power output by about 5 percent. This is good news if your rides involve bursts of intense efforts like hill intervals that require a boost of muscular power.
Separate research in The Journal of Nutrition determined that people who had the highest habitual intake of nitrates from vegetables (91 mg a day, or about what is found in 1 1/2 cups of leafy greens) performed better on tests of muscular strength and functioning than those who consumed the least. This review study found evidence that nitrate supplementation could help someone improve their endurance exercise capacity. And consuming beetroot juice, an especially rich source of nitrates, has been shown to help improve performance on certain resistance training exercises, as well as increase the speed of exercise recovery.
But we don’t yet have enough data to show that the amount of nitrates someone would eat from whole plant foods is enough to bring on PR results. Most studies use a concentrated source of nitrates, such as beetroot juice. It’s also possible that novice athletes will reap more rewards from nitrates than seasoned athletes where performance gains from nutrition and supplementation are likely less pronounced. Also, levels of nitrates in beet products targeted to athletes can vary greatly so it’s hard to know what you are getting.
Still, if the thought that taking in more nitrates is going to help you achieve better results from your workouts and races ends up spurring you to consume more veggies that is a big win.
Now, the bad about nitrates in food
So, what about those nitrates in bacon and hot dogs? You won’t see a lot of headlines declaring pepperoni as a heart champion or performance booster. How can nitrates be harmful when added to meat but healthy in vegetables? Because the nitrates added to processed meats (again, that’s often to hinder the growth of potentially harmful bacteria and to help improve color) are fairly inert by themselves, the answer lies in how the compounds in these foods get converted into other molecules in the human body.
From the start, you consume the nitrates added to processed meats which are then converted to nitrites by bacteria in your mouth that you then swallow. A compound abundant in meat (and absent in veggies) called heme, which lends red meat its color, seems to react with the nitrites resulting in the formation of a molecule called nitrosylated-haem. It’s this molecule that likely interacts with degraded bits of amino acids—protein fragments our body produces during the digestion of the protein in meat—to form nitrosamines, which are compounds that have been associated with health issues, including an increased risk of certain cancers. This increased risk of disease mainly comes from damaging DNA, which is essentially the first step in cancer development.
Nitrosamines appear to also form during the production of nitrate-containing processed meats and also during the cooking of them. High cooking heat can increase the production of nitrosamines by creating a reaction between the sodium nitrite and protein in the meat. Cooking vegetables, however, is less likely to produce nitrosamines as they don’t contain the amounts of protein needed to cause their formation during heating. Sausages, smoked meats, bacon, and luncheon meats appear to be among the richest sources of nitrosamines.
A recent and well-publicized World Health Organization report found that with each 50-gram portion of processed meats a person eats per day (that’s about three slices of deli meat) the odds of colorectal cancer rises by about 18%. WHO classifies these foods as a Group 1 carcinogen—the same designation as tobacco.
It might be the uptick in nitrosamines that explains why studies suggest that higher intakes of red meat, and processed versions, in particular, can be detrimental to long-term health. A study published in 2021 in the American Journal of Clinical Nutrition using data from 21 countries found that consumption of processed meat—but not unprocessed or red meat like beef, pork, lamb, and veal—may raise the risk of major heart disease and death.
It’s important to keep the dangers of processed meat in context. As always, the poison is in the dose. The dangers are going to be more real for people who eat processed meats every day compared to having the occasional grilled hot dog or roast beef sandwich. You have to look at things in the context of the overall diet. Eating a small amount of processed meat as part of a diet that is rich in nutritious whole foods is likely not of serious concern.
Still, there are a few ways to help mitigate the risk.
Because high heat can contribute to nitrosamine formation, it’s recommended to cook processed meats at lower temperatures. An example would be to microwave bacon instead of sizzling it in a frying pan, which can reduce nitrosamine production.
Consuming plenty of vitamin C and other antioxidants could help block the production of nitrosamines in the body—and offset some of the potentially negative effects of processed meats. (The positives of this additional vitamin C has mostly been shown in animal and in vitro studies.) Manufacturers are starting to add vitamin C to cured meats for just this reason.
So if you are going to eat foods like sausages and deli meats, be sure to serve them with a healthy amount of colorful veggies, which are rich in vitamin C and other antioxidants. But these will not necessarily offer protection against the effects of nitrosamines that might already be present in processed meats before digestion.
Your best bet: Reduce the amount of processed meat you eat. And that goes for processed meats labeled “natural” or “nitrate-free” too. Manufactures can label their product “nitrate-free” if they have not directly added nitrates to the product during production. However, some natural and organic ways of preserving meat, such as using celery salt, will add nitrates to the product since celery salt naturally contains nitrates and will likely still lead to nitrosamine production after consumption via the same process discussed above.
In fact, some “nitrate-free” labelled meats like bacon may contain more total nitrates than conventional options depending on the amount of the nitrate-containing natural preserving agent that is added during production.
The takeaway on nitrates in food
Nitrates from plants and those added to meat behave differently in the body. So it’s important to know your source. Increasing your consumption of nitrate-rich veggies may boost your health and improve athletic performance and there is no recommendation to limit the intake of nitrates from these foods. But it’s best to limit your intake of nitrates from processed meats, which are linked to health concerns. That way, the benefits of nitrates will almost certainly outweigh the downsides, even if you enjoy the occasional bratwurst.
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Matthew Kadey, M.S. R.D. is a Canada-based registered dietitian and nutrition journalist with two decades of experience in reporting about food and nutrition for dozens of print and online publications. Kadey is the author of Rocket Fuel: Power-Packed Food for Sports + Adventure. He is also an adventure cyclist and creator of several bikepacking routes in North America and beyond. Find him at matthewkadey.com, @rocketfuelfood