Mmmm bacon. Was there ever anything so delicious? But did you know that you’re probably consuming more than just meat and salt? People have used salt to preserve meat (through fermentation) for thousands of years. But today, meat processors use chemical compounds called nitrates and nitrites to keep meat free of foodborne bacteria and help it stay fresher for longer. In particular, these chemicals are potassium nitrate and sodium nitrite, the most commonly used preservatives in meat products today.
Like salt, these chemicals remove moisture for bacteria to feed on and kill or prevent bacteria by dehydrating them. Nitrates and nitrites also change the color, flavor, and texture of meat. But unlike salt, nitrates and nitrites can impair brain and body function (according to the New Jersey Department of Health and Human Services). However, not all nitrates are harmful. A 2018 study in Aging and Disease suggests that naturally occurring nitrates in plant foods may positively impact physiological function. Here’s what you should know about the benefits and risks of nitrates in food.
What are nitrates?
According to Healthline, nitrates (NO3) are made up of three nitrogen atoms and one oxygen atom. Dietary nitrates, such as those found in plant foods, are relatively harmless. However, when swallowed, saliva breaks down nitrates into nitrites (NO2) with one nitrogen atom and two oxygen atoms. This chemical switch can occur in two ways. Nitrates either turn into nitric oxide, which is good, or turn into nitrosamines, which is bad. A 2020 review published in Antioxidants showed that nitrosamines can cause cancer.
The nitrates turn seems to depend on the type of nitrate-rich foods consumed. Nitrates found in plant foods are high in antioxidants, and researchers believe these antioxidants counteract the harmful effects of nitrosamines and help protect against cancer. However, the researchers concluded that consuming high levels of nitrates from animal products inhibits DNA repair and damages important cancer control genes. This can increase your risk of cancer, especially stomach and thyroid cancer.
Where are nitrates found in food?
Nitrates occur naturally in some vegetables, processed meats, and drinking water (according to Livestrong). Each of these nitrate sources affects the body and brain differently. A 2018 study in Aging and Disease found that vegetables, especially green, leafy ones, account for 80% to 90% of dietary nitrates. Beneficial foods high in nitrates include leafy greens like spinach, Swiss chard, lettuce, mustard, arugula, and kale. Root vegetables like onions, garlic, beets, and radishes are good sources of dietary nitrates, along with watercress, turnip greens, celery, bok choy, and Chinese cabbage.
Some fruits contain lower levels of nitrates, including apples, oranges, peaches, pears, watermelons, kiwis, grapes, and strawberries. Beets are particularly high in good nitrates, which are converted to nitric oxide by the digestive system. According to Harvard Health Publishing, nitric oxide dilates blood vessels to lower blood pressure, and drinking beet juice may help control blood pressure. According to Healthline, dietary nitrates act as antimicrobials that can kill salmonella (and other bacteria) in the gut.
However, a 2009 article in the American Journal of Clinical Nutrition advises against feeding infants homemade baby food made from vegetables high in nitrates, including carrots and green beans. Excess nitrates can provoke hypoxia and cyanosis in babies under 3 months.
Nitrates can contaminate water and poison babies
Water contributes 15% to 20% of nitrate sources. Nitrates in water typically leach into private wells from drains containing fertilizer, septic system failures, or compost heaps placed too close to water sources (according to the Vermont Health Department). Water with a nitrate content of more than 10 milligrams per liter is considered unsafe. When nitrate levels reach 5 milligrams per liter, the water should be treated to reduce nitrate levels. Because nitrates cannot be seen, tasted, or smelled in water, it is recommended that those with private water systems have their water tested for nitrates every five years.
The Environmental Protection Agency (EPA) warns that nitrates cannot be boiled out of water or filtered using standard carbon-based filters like Brita. Drinking or eating food cooked or mixed with contaminated water can make it harder for red blood cells to carry oxygen through the blood. A 2009 article in the American Journal of Clinical Nutrition advises against feeding babies homemade baby food made from vegetables high in nitrates, including carrots and green beans.
And babies shouldn’t drink bottles of nitrate-contaminated water due to the risk of methemoglobinemia or “blue baby syndrome.” High nitrite levels can poison babies and turn skin grey-blue. Any sign of this condition requires emergency medical attention (per the Vermont Health Department).
Processed meat contains dangerous levels of nitrates and nitrites
The 2018 study in Aging and Disease states that 10% to 15% of nitrate intake comes from animal products, including processed foods. The 2009 article in the American Journal of Clinical Nutrition recommends limiting consumption to 18 ounces per week of fresh beef, pork, and lamb that do not contain nitrates or nitrites. However, the same article warns that eating processed meats, which contain nitrates and nitrites, increases the risk of cancer. And the risk of colon cancer increases in proportion to the amounts of processed meat eaten.
The addition of the antioxidants sodium erythorbate or sodium ascorbate (vitamin C) may reduce the risk of eating processed meats that have been preserved with nitrates and nitrites. WebMD recommends avoiding bacon, ham, hot dogs, and processed meats that contain nitrates and nitrites because these meats contain the highest levels of toxic compounds. And even choosing processed meats that are labeled as nitrate and nitrite free doesn’t guarantee you can avoid the nitrate and nitrite levels.
The United States Department of Agriculture (USDA) allows manufacturers to cann processed meats with sources that contain natural nitrates, such as celery powder (via GoodRx Health). In fact, a review conducted by Consumer Reports found that of 31 different samples of packaged cured meats, the samples labeled nitrate and nitrite-free contained roughly the same levels of these compounds as the traditional meat.
How to minimize the risks associated with the consumption of nitrates
You can minimize the negative health effects of nitrates and nitrites in many ways. Start eating plenty of fruits and vegetables, including leafy greens, which contain antioxidant compounds that may protect against free radicals, inflammation, and cancer (according to Harvard TH Chan School of Public Health). If you just can’t resist the supreme deliciousness of bacon, limit your intake and try to find fresh bacon and other animal products at a farmer’s market or local grass-fed meat vendor.
When you buy processed meats from the grocery store, Healthline recommends checking ingredient labels for potassium nitrate, potassium nitrite, sodium nitrate, and sodium nitrite, as well as celery salt or other high-nitrate natural preservatives. And cooking bacon longer at a lower temperature or in the microwave can reduce nitrosamine build-up. Keep in mind that meat that has little or no nitrates or nitrites as a preservative won’t last as long, so either eat it earlier or freeze it to preserve freshness.