Nitrates & Nitrites

I’m excited about 2017 because this year is all about content. I want to answer all of your nitty-gritty nutrition questions. Today is all about nitrates and nitrites. Should you avoid them? What are they? Do you need to toss out your beloved turkey sandwich lunch? We’ll dissect it all here.

What and where are they?

Nitrate occurs naturally in soil, water, and some foods (1). It can be detected in fruits, vegetables, cereals, fish, and dairy products. Foods high in naturally-occurring nitrate include beets, spinach, celery, turnip greens, and radishes, among others. Nitrate can also be found in water that has been contaminated by animal waste or by fertilizers containing nitrogen, which can subsequently increase the level of nitrate in a given plant (2). Alternatively, nitrite is not normally present in plant tissue unless nitrate has been converted to nitrite from food spoilage. It may also be present in plants from from fertilizer use. Soil levels significantly contribute to varied ranges of nitrates and nitrites in foods.

Nitrate and nitrite may also be used as food additives. On an ingredient label, they are listed as: sodium nitrate, potassium nitrate, sodium nitrite, or potassium nitrite. Nitrates and nitrites are used as preservatives (2,3). They are most commonly found in highly processed meats, like deli meats, bacon, sausage, smoked meats, cured meats, canned meats, or hot dogs. They serve an important role in the prevention of botulism, and also add flavor and provide the “pink” coloring (2,3). Botulism is caused by the bacteria Clostridium botulinum, and although it occurs rarely, is often fatal (3).

The Downside

Excessive intake of nitrites can cause a condition called methemoglobinemia which affects the body’s ability to carry oxygen throughout the body (1,4). Infants less than four months are particularly susceptible to methemoglobinemia (1). Young kids might also be more susceptible to nitrite poisoning (e.g. from overfertilized plants) (4). Infant foods meant for infants less than 6 months of age are not permitted to have nitrites (2). Home tap water with nitrate or nitrite levels exceeding Environmental Protection Agency (EPA) standards can cause “blue baby syndrome” in infants less than 6 months, which can be life-threatening if not treated immediately (3).

Nitrates and nitrites may react with amines or amides in the digestive tract which can form N-nitroso compounds (NOC), which are cancer-forming in animals and might be cancer-forming in humans (1,2). Notably, dietary antioxidants, which are abundant in fruits, vegetables, and nuts, prevent the formation of NOCs (5). The International Agency for Research on Cancer has determined nitrites and nitrates as “probably carcinogenic,” which by its own definition states there is limited evidence of carcinogenicity in humans (4,5).

So, shouldn’t this be an easy answer? We just avoid foods with nitrates and nitrites?

It’s not that simple. First, remember that nitrates occur naturally in a number of plant foods. In fact, the amount of naturally occurring nitrates and nitrites in plant foods is significantly higher than the amounts in processed meats containing added nitrates and nitrates (for example: 0.3 mg/100 g in lunch meat or 1.3 mg/100 g in bacon compared to 186 mg/100 g in raw spinach). Shockingly, about 80% of dietary nitrates comes from eating vegetables (6).

Second, there may be beneficial effects of nitrates on the body. We won’t dig into why here, but nitrates and nitrites from fruits and vegetables might contribute to lowering blood pressure (6). Further, some research to suggests nitrates in foods may enhance endurance and sports performance, which is why you see beet supplements on the counter of every popular running store right now. Also, recall a diet rich in a variety of plant foods provides antioxidants which prevent the formation of NOCs.

Third, nitrates and nitrites prevent botulism, which may be fatal. It’s probably not worth getting botulism if you are already planning to consume highly processed meats made with added nitrates and nitrites.

The Take-Home Message

The science behind nutrition is rarely black and white, and it’s ever-evolving. It’s important to remember that most people are not exposed to high enough levels of nitrates or nitrites to cause adverse health effects (4). In my professional opinion, I don’t think you need to avoid foods naturally high in nitrates or nitrites, and I don’t necessarily think you need to seek out “nitrate or nitrite-free” processed meats, although you can if you prefer. I would definitely limit your high-fat, highly processed meats, like bacon, sausage, and hot dogs (they are high in saturated fat in sodium which increases the risk for cardiovascular disease and events – I always suggest limiting to once or twice per week at most), and we should eat diets rich in antioxidants which are replete in plant foods. For lunch meats, choose low sodium, and be aware that turkey is leaner than ham. You can always decrease deli meat at lunch by switching it up with repurposed dinner leftovers. If you are concerned about an infant or child with nitrate or nitrite sensitivity, discuss with your local water supplier about levels in your tap water, and avoid high nitrate foods before 6 months of age.

Have a question you want me to answer? Let me know here!

References:

1. Nitrate. National Institutes of Health. https://www.progressreport.cancer.gov/prevention/nitrate. Updated November 2015. Accessed January 10, 2017.
2. Joneja JV. The Health Professional’s Guide to Food Allergies and Intolerances. Chicago, IL: Academy of Nutrition and Dietetics; 2013.
3. Complete food and nutrition guide. Duyff RL. Complete Food and Nutrition Guide, 3rd ed. Hoboken, NJ; John Wiley & Sons, Inc.; 2006.
4. Toxic substances portal – Nitrate and nitrite. Agency for Toxic Substances & Disease Registry. https://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=1186&tid=258. Updated November 23, 2015. Accessed January 10, 2017.
5. Agudo A, Cantor KP, Chan PC, et al. IARC monographs on the evaluation of carcinogenic risks to humans. World Health Organization International Agency for Research on Cancer. https://monographs.iarc.fr/ENG/Monographs/vol94/mono94.pdf. Updated 2010. Accessed January 11, 2017.
6. Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: The physiologic context for potential health benefits. Am J Clin Nutr. 2009; 90(1):1-10.

Updated January 16, 2017.

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