Despite popular belief, the use of nitrate and nitrite food additives is not a recent practice, but has been used for centuries to improve the preservation of meat products. However, it was not until the 19th century that they began to be used regularly.
However, during the 1950s and 1960s it was discovered that these compounds are involved in the formation of nitrosamines, some of which are carcinogenic. This sparked an intense debate around the use and safety of these additives that continues to this day and is fueled from time to time.
That is, in some ways, nitrates and nitrites can be dangerous , but they can also have health benefits. So what is the truth about nitrates and nitrites in the diet? Can they really be dangerous?
What are nitrates and nitrites?
Nitrates and nitrites are natural chemical compounds that contain nitrogen and oxygen . In nitrates, nitrogen is attached to three oxygen atoms, while in nitrites, nitrogen is attached to two oxygen atoms.
Both occur naturally in the human body and in some foods, such as vegetables. However, they are also used as preservatives in the production of cooked and cured meat products, especially to guarantee hygiene , since this type of food requires very special care throughout the production and conservation process. They are also added in many cases to give these types of products that characteristic flavor and color.
Given how high the consumption of processed meat is, you may be thinking that this is the main source of nitrates in our diet. However, in the average European diet, only about 5% of nitrates come from this source, while more than 80% enter through vegetables.
Vegetables acquire nitrates and nitrites from the soil in which they grow: nitrates are part of the natural mineral deposits; while nitrites arise from soil microorganisms that decompose animal matter. In other words, green leafy vegetables like spinach and arugula tend to be the crops with the highest nitrate content , followed by celery and beet juices, and carrots.
In turn, organically grown vegetables may have lower levels than non-organic ones, since synthetic nitrate fertilizers are not used in the former.
That said, there is a major difference in the way nitrates and nitrites enter meat compared to vegetables, and that also influences its carcinogenic effect.
Where are nitrates and nitrites found?
Nitrates are found in vegetables, in water and in processed meats; although we in our body also manufacture nitrites from nitrates, and it has been shown that they can be useful to keep the body healthy, since they seem to work as antimicrobials in the digestive system, as they are capable of destroying bacteria such as salmonella and shigella (Archer, 2002).
On the other hand, nitrates are also naturally found in water . The use of fertilizers in some areas can lead to high levels of nitrates that can be harmful to children. For this reason, health authorities regulate nitrate levels in drinking water (Ward et al., 2018).
However, the daily intake of nitrates depends on the usual diet, the region, the season of the year, the cultivation system, and the quality of the irrigation and drinking water.
It is also important to keep in mind that most of the nitrites that we come across are not consumed directly, but are converted from nitrates by the action of bacteria found in our mouth. In other words, the body also produces nitrates and secretes them in saliva (Lundberg, 2012).
Are nitrates and nitrites dangerous?
Nitrates and nitrites are essential compounds, but they can become dangerous if they form nitrosamines, substances with carcinogenic effects .
The problem is that a part of the nitrates we eat can be transformed into nitrites and these react with the amino acids present in the stomach, giving rise to the formation of these nitrosamines. In addition, when cooking meat products with added nitrites at high temperatures, nitrosamines can also be formed, although in this case it is produced in a lower proportion than during the digestion process (Honikel, 2018).
“What is carcinogenic is not so much the nitrates and nitrites, but the way they are cooked and their local environment. For example, nitrites in processed meats are very close to proteins. When cooked at high temperatures, this allows them to more easily form nitrosamines, the cancer-causing compound. "
Kate Allen, Executive Director for Science and Public Affairs at the World Fund for Cancer Research.
Allen also adds that nitrites are just one reason why processed meats contribute to intestinal cancer, and their relative importance is uncertain.
On the other hand, while a high intake of processed meats can increase the risk of cancer in the digestive tract, nitrates and nitrites also occur naturally in vegetables, and at the same time can reduce the risk of some cancers and others diseases (Gandini, Merzenich, Robertson & Boyle, 2000).
That is, when cooking vegetables you are less likely to produce nitrosamines . Also, people rarely cook vegetables over very high heat and they do not contain large amounts of protein.
All of this does not mean that we should be scared. The European Food Safety Authority (EFSA) reassessed the safety of both additives in 2017 and concluded that the levels to which we are exposed in a regular diet are safe for all groups. of population. In addition, it stated that at these levels, total exposure to nitrosamines is not a cause for concern .
How to reduce the risks of nitrites?
It is important to know that there are nutrients in our daily diet that are capable of stopping the nitrosamine formation mechanism , such as vitamin C and iron, which are precisely found in vegetables.
In addition, by consuming fruits and vegetables as fresh as possible, we avoid the formation of nitrites before consuming them, as well as washing them, since nitrates are soluble in water and we can eliminate a part of them.
Finally, to reduce the risk of nitrates and nitrites , avoid overcooking and at high temperatures (fried, grilled and barbecue) of fatty and marinated meats, since they generate nitrosamines.
conclusion
Some experts argue that having higher levels of nitrates and nitrites is not only safe, but beneficial, as long as they come from vegetables and not from processed meats. That is, if you want to eat the right types of nitrates and nitrites and avoid potentially carcinogenic ones, eat a very varied diet with at least 5 servings of fruits and vegetables a day, and avoid eating processed meats too often.
References
- Archer, DL (2002). Evidence that ingested nitrate and nitrite are beneficial to health. Journal of Food Protection . doi: 10.4315 / 0362-028x-65.5.872
- Honikel, K. (2018). The use and control of nitrate and nitrite for the processing of meat products. Meat Science . doi: 10.1016 / j.meatsci.2007.05.030
- Gandini, S., Merzenich, H., Robertson, C. and Boyle, P. (2000). Meta-analysis of studies on breast cancer risk and diet: the role of fruit and vegetable consumption and the intake of associated micronutrients. European Journal of Cancer. doi: 10.1016 / s0959-8049 (00) 00022-8
- Lundberg, J. (2012). Nitrate transport in salivary glands with implications for NO homeostasis. PNAS. doi: 10.1073 / pnas.1210412109
- Ward, M. H… and Breda, SG (2018). Drinking Water Nitrate and Human Health: An Updated Review. International Journal of Enviroment Research and Public Health. doi: 10.3390 / ijerph15071557
