TABLE OF CONTENTS

Nitrate is an organic or inorganic compound that is a derivative of the elements of nitrogen and oxygen. Inorganic nitrates are formed by bacteria and are typically used as the main ingredient in fertilizers in agriculture (Collins Dictionary; Businessdictionary.com).  On the other hand, organic nitrates are manufactured compounds that are generally used in explosives (Businessdictionary.com). When consumed, nitrates, along with water are converted into nitric oxide in the human body.

Nitrates and Nitrites, which are often used synonymously, are the main substance that gives processed or cured meats such as sausages, bologna, bacon, etc, their pink or reddish hue. It also protects cured meats against lipid oxidation (Govari et. al, 2018).

While used industrially and in some processed foods, nitrates are also naturally found in some vegetables such as spinach, arugula, celery, rocket, lettuce, carrots and beetroot (EFSA, 2008).  In this case, the nitrates are taken up by the plants as a nutrient and then assimilated into cell protein (Panos, 2008).   However, this type of nitrate is considered ‘dietary nitrate’ and healthy for humans in recommended amounts, unlike its chemically-laden counterparts which are used in industrialized products and processed foods among other things (Ward et al, 2005).

Nonetheless, research contents that foods which naturally contain nitrates should not be fed to children under three (3) months old as these foods can be contaminated with higher levels of nitrates due to the use of fertilizers or manure(Preboth, 2005).

In general, nitrates or rather, their converted counterparts are considered toxic and can cause severe burns if they come into contact with the skin as well as the development of certain cancers and other diseases when consumed in high amounts (Ward et. al, 2005; Encyclopedia Britannica).  Let’s discuss!

The Discussion 

Nitrates and Nitrites which function as preservatives in processed or cured foods have been a controversial subject over the years. This is especially due to the potential formation of nitrosamines, which is the substance that is formed when nitrates are used in high concentrations in foods that are then cooked at high temperatures.

This usually occurs in the case of processed or red meat which usually requires high heat for cooking penetration (Kuhnle and Bingham, 2007). Nitrosamines are generally considered carcinogenic (Agency for Toxic Substances and Disease Registry, 1989).  As such, their consumption can cause the body to become toxic which can lead to the development of certain cancers.

One of the principal uses of nitrates dates back more than Fifty (50) years ago and was generally used as fertilizers in agriculture.  However, its use in agriculture accelerated in the 1950s to what it is today (Ward, 2009).  This was particularly due to its ability to be soluble in water. Nitrate fertilizers include ammonium, sodium, potassium and calcium salts.  However, over the years, its usage has spanned that of being used on crops to be chemically produced and used in food products as well as in drinking water.

While nitrates consumed in high amounts can cause severe health effects in humans, recent research has indicated their beneficial effects on health when it is consumed in reasonably low amounts.  Some of the benefits include the lowering of blood pressure as well as cardiovascular health (Lundberg et al, 2006; 2011).

While the controversy continues, here are four (4) reasons to seriously re-consider consuming foods, particularly processed, with these ingredients.  These include the development of Methemoglobinemia or ‘blue-baby syndrome, cancer, particularly gastric cancer, thyroid function issues and birth defects. The article will also discuss the differences between nitrates and nitrites, substances that are most often used interchangeably as well as misunderstood.

Four (4) Reasons to avoid the consumption of foods with Nitrates and Nitrites.

• It May cause Blue-baby syndrome.
• May cause the development of certain types of cancers.
• It May cause thyroid issues.
• May cause birth defects.

Nitrates and Methemoglobinemia or ‘blue-baby syndrome

While nitrates are usually found in processed foods, it is also found in drinking water that has been contaminated with high levels of the substance.  This in effect can cause a condition known as methemoglobinemia or blue baby syndrome.

Methemoglobinemia is a condition that occurs in infants under six (6) months of age as a result of the body’s inability to deliver the required levels of oxygen to the body (Ward et. al, 2005).  This usually happens when infants are exposed to high levels of nitrates usually via elevated levels in drinking water (Ward et. al, 2005).  This condition has been documented for more than Fifty (50) years worldwide ever since the first diagnosis in 1945 (Environmental Working Group -EWG).

The first mention of methemoglobinemia’s association with high levels of nitrates in drinking water was reported in 1945 by Hunter Comly who was a pediatric resident in Iowa City.  The report concurred that infants who ingest water that was contaminated with high levels of nitrates were likely to develop this condition, particularly those who were experiencing gastrointestinal disturbance (Comly 1945; Fan et al. 1987).

Research has shown that any concentration of nitrates above Fifty (50%) percent in drinking water can result in death.  As such, the Environmental Protection Agency in the United States has set the maximum contaminant level at 10 mg/L or 10 ppm (parts per million), especially when it comes to the contaminant levels in drinking water.  Above this level, nitrates can cause severe toxicity to humans (Toxicology Committee, 1995).

Nonetheless, research has found that even levels below 10 ppm can be harmful to humans which can result in the development of methemoglobinemia (Sattelmacher, 1964; Simon, 1962). However, one must also take care to ensure that they do not consume untreated water in wells, which can be contaminated with nitrates due to the effects of manure, fertilizers or even septic tanks (Preboth, 2005).

While some studies have shown that nitrates above certain levels can affect infants, emerging research has raised significant scientific doubt as to whether there exists a causal link to blue baby syndrome (Avery, 1999; Addiscott and Benjamin, 2006).  These researchers suggest that the condition ‘blue baby syndrome’ could be caused by several other factors such as gastric upset, protein intolerance as well as heavy metal toxicity.  However, they did denote that, while these factors could be among the prominent factors, they did agree that nitrate may have played a minor role in the development of this condition.

Notwithstanding, the European Food Safety Authority states that consumer exposure to nitrates and nitrites was well within the safety limits for all population groups.  However, the Authority did admit that children may be exposed to higher concentrations if their diet mostly comprises foods with nitrates.

Nitrates and Cancers, particularly Gastric and Colorectal Cancer

Cancer is a disease that can arise due to many factors, including environmental and lifestyle.  However, an increasing number of researchers are finding a causal link between nitrates and the increased risk of cancers particularly gastric and colon (Aarhus University, 2018).  According to a study by Aarhus University in 2018, colorectal cancer is the third leading cause of cancer worldwide and the 1^st in Denmark, which was particularly found to have high amounts of nitrates in their drinking water.  According to the research, the risk of cancer arises when nitrate is converted to N-nitroso, a carcinogenic compound.

In the United States, the established maximum contaminant levels of nitrate in water are 10 ppm (EPA, 1991).  However, while nitrates in vegetables may sometimes be in greater concentration than that of water, research indicates that it is still considered good for human health and beneficial and not harmful as in the case of water contamination (US EPA, 1991).

This was concurred by Ward et. al, 2005 who stated that the intake of dietary nitrate is less likely to cause an increase in nitrosation compounds due to the presence of nitrosation inhibitors in vegetables such as vitamin C and other antioxidants.  The ascorbic acid (Vitamin C) reacts with oxygen, by forming dehydroascorbate, thus reducing the amount of nitrites which could be oxidized to nitrates (Honikel, 2008).

Nonetheless, L’hirondel et. al, (2006) argue that if the nitrate in drinking water is stated to be toxic if greater than 10 ppm, then the nitrates found in certain foods, particularly leafy vegetables which are comparatively higher, would likely be toxic regardless of the presence of ‘so-called’  nitrosation inhibitors.

This argument seems to have been concurred (while not clear) by Dang, Vu et al, (1994) who expounded that the research of Ward et al, (2005), has forgotten that the metabolizing of nitrates in humans starts in the mouth via the salivary gland.  As such, nitrate would be reduced to nitrites in the mouth and then to nitric oxide and nitrosating compounds, which can react with N-nitroso agents and thus lead to the development of specific cancers, and reproductive issues as well as diabetes.

Therefore, while Ward et. al, (2005) touted that nitrate in foods is healthier and beneficial to humans, L’hirondel et al, (2006) believe that the substance is toxic even if ingested via food or drinking water.  According to Lundberg et. al, (1994), about 25% of nitrates are secreted in the saliva. However, according to Bartholomew and Hill, (1984), the majority of the nitrates that the body absorbs are excreted in the urine while a considerable amount is reabsorbed from the kidney as well as the salivary gland.

Notwithstanding proponent’s studies, Ward et, al. (2005) still theorized that Vitamin C and other dietary antioxidants inhibit nitrate ill-effects in humans, a point of view that was also shared by several studies such as (Bartsch et al 1998; Mirvish et. al 1998; Vermeer et. al. 1999). Further, all of these studies contend that one’s risk of cancer increases with the consumption of drinking water contaminated with nitrates of 10 ppm or higher, especially for those whose diet consists mostly of red meat and low levels of vitamin C (De Roos et. al, 2005).  Nonetheless, research still denotes that the long-term effects of nitrates and nitrites in the diet can lead to the formation of carcinogens in the human body (Andree et al, 2010; Honikel, 2008).

Nitrates and Thyroid Function Issues

Studies have denoted that the ingestion of nitrate can inhibit the uptake of iodine and thus affect the normal functioning of the thyroid gland (De Groef et al, 2006).  Iodine is an essential nutrient that helps to maintain brain and thyroid health.  The findings of De Groef et. al, (2006) were concurred by several studies including one conducted in the Netherlands on a group of women.  In this study, there was an increased prevalence of thyroid hypertrophy among women who consume water with high levels of nitrates (Van Maanen et al. 1996).

Conversely, those who consumed water with nitrate levels of less than 50 mg/L were not affected by this condition.  Surprisingly though, the research shows that women whose diets were prevalent with dietary nitrates had an increased prevalence of hypothyroidism but not hyperthyroidism.

Nitrates and Birth Defects

While high levels of nitrates are said to lead to certain types of cancers, research has shown that pregnant women who consume water that is contaminated with nitrates can experience varying birth defects ranging from fetal deaths to spontaneous abortion and even growth retardation (Ward et al, 2018).  However, while several studies have found a positive relationship between drinking water with high levels of nitrate and birth defects (Center for Disease Control and Prevention, 1996), other researchers have found no positive association (Aschengrau, 1989).

Even though these studies were conducted Twenty (20) years ago and may be discounted by many, most recent research (Fan and Steinberg 1996; Manassaram et al. 200) still suggests that high doses of nitrates do have a toxic effect on reproduction.  In addition, nitrates have also been found to be mutagenic and as such, possess an even more increased possibility of ill effects on the human body (Luca et al. 1987).

What is Processed Meat or Foods?

Processed meats or foods in general, are those which have been modified to extend their shelf life and enhance their taste.   As such, this alteration of the food changes how it looks and tastes.  Some of the main methods of processing foods include smoking, curing (using nitrates and nitrites) as well as adding salt or some other form of preservatives.  Processed meats include sausages, salami, ham, corn beef and bacon among others.  Some meat sauces also fall into this category, as such, you will have to ensure that you read the ingredients list of your food purchases.

Like so many other food ingredients, nitrates and nitrites have had their share of controversies over the years. One minute it is safe and in another it is deadly.  However, more and more research has been surfacing that has proven the latter.  As such, this article will attempt to decipher some of these findings in an attempt to assist you in your quest for health and wellness.

Nitrates vs. Nitrites

Nitrates and Nitrites are often used interchangeably; However, there is a difference.  Both nitrates and nitrites naturally occur in the environment as part of the nitrogen cycle and are critical to all living systems, especially plants.  Nonetheless, for nitrogen to be utilized it must be converted to an active form and this is where nitrates come in.

Therefore, when nitrates are created in the atmosphere through rainstorms etc, it is transported to the soil and hence to crops.  The microorganisms in the soil then form nitrates via the breaking down of animal matter.

When humans eat these foods, the nitrates are converted to nitrites via the salivary gland; it is further converted to nitric oxide as it interacts with gastric gas in the stomach.  As per meat products, nitrates are naturally converted to nitrites either via that which is naturally occurring in the meat or by adding bacteria that contain nitrates reductase activity (Sebranek and Bacus, 2007; Hammes, 2012).  Nitrates in the diet become an issue when it is converted to nitrites or N-nitroso Compounds.

Further, nitrates are usually converted into nitrous acid, nitric acid and nitrates in meat products (Honikel, 2004).  These can then act as oxidizing, nitrosating agents or toxic substances. (Honikel, 2004).  However, research denotes that the carcinogenic effects can be inhibited if vitamin C and vitamin E (alpha-tocopherol) are used in the curing process (Parthasarathy & Bryan, 2012).

Nonetheless, nitrates and nitrites are chemicals that are used mainly as food additives and contribute flavour to cured meat, inhibit the growth of microorganisms, particularly Clostridium botulinum, and effectively control rancidity by inhibiting lipid oxidation (Pearson and Gillett, 1996).

Illustrative Summary

Here is a summary of the Four (4) reasons to avoid the consumption of foods with Nitrates and Nitrites.

Let’s Sum It Up!

 Nitrates and Nitrites are compounds that are commonly used as additives in processed foods particularly sausages, bologna, bacon and red meat in general.  When used, nitrates and nitrites affect the quality of the food, help to kill bacteria as well as extend its shelf life.  The controversy of nitrates and nitrites arises when they are converted to N-nitroso compounds which are known to be carcinogenic.

Some of the potential health effects of consuming nitrates, particularly over 10ppm, which is the allowable amount, include methemoglobinemia or what is called ‘Blue baby syndrome’, cancers, particularly gastric and colorectal, thyroid dysfunction as well as birth defects.

While recent research has contended that nitrates in high amounts are toxic to human health, some researchers have indicated that in small amounts, nitrates can be beneficial to one’s health such as lowering one’s blood pressure and improving cardiovascular health.

Nonetheless, for meat products, many countries have set limits for nitrates and nitrites.  The prevalent established limits are set to 10 ppm or less.  The higher concentration is usually stated to cause toxicity and potential health effects.

The debates will certainly continue as the years go by, especially as people become more health-conscious about what they put in their bodies or even on their skin.  However, it is always best to continue to do your research and not take any chances with your health.  Without it, you are either living in pain or spending all you have to feel well or worse yet, dead.

You can read more on other foods that can help the body fight against diseases in these posts:

• Is Ginger truly great for our health? Here are five (5) researched reasons that say it is.

• Apple cider Vinegar – The must-have product of any wellness pantry – Here are Five (5) reasons why!

(First Published – September 15, 2019 – Updated – June 11, 2024).

References

• Aarhus University. “Nitrate in drinking water increases the risk of colorectal cancer, study finds.” ScienceDaily. ScienceDaily, 20 February 2018. <www.sciencedaily.com/releases/2018/02/180220095019.htm>.
• Addiscott, T.M, Benjamin, N. (2006). “Nitrate and human health”. Soil Use and Management. 20 (2), pp. 98–104. doi:10.1111/j.1475-2743.2004.tb00344.x.
• Andrée S, Jira W, Schwind KH, Wagner H, Schwägele F (2010). Review:  Chemical safety of meat and meat products. Meat Sci 86, pp. 38–48.
• Aschengrau A, Zierler S, Cohen, A. (1989). Quality of community drinking water and the occurrence of spontaneous abortion. Arch Environ Health, 44(5):283-90.
• ATSDR (Agency for Toxic Substances and Disease Registry). 1989. Toxicological profile for N‐nitrosodimethylamine. Prepared by the Syracuse Research Corporation for ATSDR in collaboration with the U.S. Environmental Protection Agency. U.S. Public Health Service, Washington, D.C. 119 pp.
• Avery, A. (1999) Infant Methemoglobinemia – Reexamining the Role of Drinking Water Nitrates. Environmental  Health Perspectives, Volume 107, Number 7.
• Bartholomew B, Hill MJ (1984) The pharmacology of dietary nitrate and the origin of urinary nitrate. Food Chem Toxicol 22, pp.789-795.
• Bartsch H, Ohshima H, Pignatelli B. (1988).  Inhibitors of endogenous nitrosation. Mechanisms and implications in human cancer prevention. Mutat Res, 202(2), pp.307–324.
• Comly, H.H. (1945). Cyanosis in infants is caused by nitrates in well water. JAMA 129,112–116.
• Dang Vu, Paul JL, Gaudric M, Guerre J, Yonger J, Ekindjian OG. (1994). N-Nitroso compounds, nitrite and pH in human fasting gastric juice. Carcinogenesis., 15,  pp.2657–2659. 
• De Groef B, Decallonne BR, Van der Geyten S, Darras VM, Bouillon R. (2006). Review: Perchlorate versus other environmental sodium/iodide symporter inhibitors: potential thyroid-related health effects. Eur J Endocrinol, 155(1), 17-25.
• DeRoos AJ, Ward MH, Lynch CF, Cantor KP (2003).  Nitrate in public water supplies and the risk of colon and rectum cancers. Epidemiology.
• Environmental Protection Agency (2003). National Primary Drinking Water Standards (EPA-816/F-03–016), Washington DC, Office of Water. Available at: www.epa.gov/safewater.
• Fan AM, Willhite CC, Book SA. (1987).  Evaluation of the nitrate drinking water standard concerning infant methemoglobinemia and potential reproductive toxicology. Regul Toxicol Pharmacol, 7(2):135–148.
• Fan AM, Steinberg VE (1996).  Health implications of nitrate and nitrite in drinking water: an update on methemoglobinemia occurrence and reproductive and developmental toxicity. Regul Toxicol Pharmacol 23(1 Pt 1):35–43.
• Govari (Μ. ΓΚΟΒΑΡΗ, M & Pexara, Andreana. (2018). Nitrates and Nitrites in meat products. Journal of the Hellenic Veterinary Medical Society. 66. 127. 10.12681/jhvms.15856.
• Hammes, P.W (2012).  Metabolism of nitrate in fermented meats: The characteristic feature of a specific group of fermented foods.  Food Microbiol, 29:151-156.
• Honikel KO (2008) The use and control of nitrate and nitrite for the processing of meat products. Meat Sci 78:68-76.
• Kuhnle, G.G, Bingham, S.A. (2007). “Dietary meat, endogenous nitrosation and colorectal cancer” Biochemical Society Transactions, 35(5), pp. 1355-7.
• L’hirondel, J. L., Avery, A. A., & Addiscott, T. (2006). Dietary nitrate: where is the risk? Environmental health perspectives, 114(8), A458–A461. doi:10.1289/ehp.114-1552029.
• Luca D, Luca V, Cotor F, Raileanu L (1987).  In vivo and in vitro cytogenetic damage induced by sodium nitrite. Mut Res, 189:333–339.
• Lundberg JO, Weitzberg E, Lundberg JM, Alving K (1994).  Intragastric nitric oxide production in humans: measurements in expelled air. Gut, 35:1543−1546.
• Lundberg JO, Carlstrom M, Larsen FJ, Weitzberg E (2011).  Roles of dietary inorganic nitrate in cardiovascular health and disease. Cardiovasc Res , 89:525–532.
• Lundberg JO, Feelisch M, Bjorne H, Jansson EA, Weitzberg E (2006). Cardioprotective effects of vegetables: is nitrate the answer? Nitric Oxide 15:359–362.
• Manassaram, D.M, Backer, LC, Messing, R, Fleming LE, Luke B & Monteilh, C.P(2010). “Nitrates in drinking water and methemoglobin levels in pregnancy: a longitudinal study”. Environmental Health. 9: 60. doi:10.1186/1476-069X-9-60. 
• Mirvish, S.S, Grandjean, A.C, Reimers KJ, et al (1998).  Effect of ascorbic acid dose taken with a meal on nitrosoproline excretion in subjects ingesting nitrate and proline. Nutr Cance, 31(2):106– 10.
• “Nitrates.” A Dictionary of Food and Nutrition. Retrieved June 28, 2019 from Encyclopedia.com: https://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/nitrates.
• ‘Nitrates’ (n.d). Retrieved July 13, 2019 from Collinsdictionary.com. https://www.collinsdictionary.com/dictionary/english/nitrate.
• Panos, S. (2008). In Handbook of Water and Energy Management in Food Processing.   Woodhead Publishing Series in Food Science, Technology and Nutrition.
• Parthasarathy, D.K, Bryan, N.S. (2012). “Sodium nitrite – the cure for nitric oxide insufficiency.” Meat Science, 92(3), pp. 274-9.
• Pearson AM, Gillett TA (1996) Processed Meats, 3rd ed. Chapman & Hall, New York, NY.
• Preboth, Monica (2005-12-15). “AAP Clinical Report on Infant Methemoglobinemia”. American Family Physician. 72 (12): 2558. 
• Sattelmacher, P.G (1962). Methemoglobinemia from nitrates in drinking water. Schriflenr. Ver. Wasser Boden. Lufthyg., No. 21(in German).
• Sebranek JG, Bacus JN (2007) Cured meat products without direct addition of nitrate or nitrite: what are the issues? Meat Sci.77:136–147.
• Simon, C., Manzke, H., Kay, H., & Mrowetz, G (1964). On the occurrence, pathogenesis, and possibilities for prophylaxis of the methemoglobinemia caused by nitrite.  Z. Kinderheilkunde, 91: 124-138.
• Spontaneous abortions possibly related to ingestion of nitrate-contaminated well water–LaGrange County, Indiana, 1991-1994. Centers for Disease Control and Prevention (CDC).  MMWR Morb Mortal Wkly Rep. 1996 Jul 5; 45(26):569-72.
• U.S. EPA (U.S. Environmental Protection Agency) 1991. National primary drinking water regulations, final rule. Fed Reg 56:3526–3597.
• Van Maanen JM, Welle IJ, Hageman G, Dallinga JW, Mertens PL, Kleinjans JC(1996). Nitrate contamination of drinking water: relationship with HPRT variant frequency in lymphocyte DNA and urinary excretion of N-nitrosamines. Environ Health Perspect. 1996 May; 104(5):522-8.
• Vermeer IT, Moonen EJ, Dallinga JW, Kleinjans JC, Van Maanen JM(1999).  Effect of ascorbic acid and green tea on endogenous formation of N-nitrosodimethylamine and N-nitrosopiperidine in humans 3. Mutat Res, 428(1-2):353–361.
• Ward MH, deKok TM, Levallois P, Brender J, Gulis G, Nolan BT,VanDerslice (2005).  Drinking-water nitrate and health–recent findings and research needs. J, International Society for Environmental Epidemiology. Environ Health Perspect,113(11):1607-14.
• Ward, M. H., Jones, R. R., Brender, J. D., de Kok, T. M., Weyer, P. J., Nolan, B. T. & Van Breda, S. G. (2018). Drinking Water Nitrate and Human Health: An Updated Review. International journal of environmental research and public health, 15(7), 1557. doi:10.3390/ijerph15071557.