Nitrates are found mainly in vegetables through the use of fertilizers, and nitrites in processed meats, where they are used as a preservative against botulism. Nitrogen compounds can also be supplied with drinking water. Excessive amount of nitrogen compounds in food is dangerous to he alth and can cause, among others, cyanosis, anemia, intestinal dysfunction, and cancer. We advise you on how to avoid excess nitrates and nitrites in the diet.

NitratesandNitritesare derivatives of nitric acid. Nitrates come from nitric acid (V) HNO3 , and nitrites from nitric acid (III) HNO2 . The number of oxygen atoms to which nitrogen is bound in a chemical affects its properties.

Nitrates and nitrites - toxicity

Nitrates are generally safe for humans, and nitrites become toxic in too high doses. Nitrates are present in food mainly of plant origin due to the use of fertilizing mineral fertilizers. As a result of fertilization, they also end up in surface waters and are found in tap water.

They can also be found in feed and water fed to farm animals. Nitrates and nitrites are used in the production of various types of meat products and cheeses. Their role is primarily to conserve.

Nitrogen compounds inhibit the development of pathogenic microorganisms (mainly Clostridium botulinum, producing a strong toxin called botulism), act as antioxidants and improve the sensory value of the finished product, e.g. maintain its desired color.

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In the dairy industry, they are used in the production of maturing cheeses, in which they prevent lactic acid re-fermentation and the so-called flatulence of cheeses.

Nitrogen compounds can be toxic to humans, therefore the Regulation of the European Community Commission of 2006 strictly defined the maximum content of nitrates and nitrites in food products. According to the World He alth Organization, the Acceptable Daily Intake (ADI) for nitrates is 5 mg / kg body weight, and for nitrites - 0.1 mg / kg body weight

This is due to the fact that nitrates themselves are not toxic to humans, but in the acidic environment of the stomach at pH<4, a także pod wpływem bakterii bytujących w przewodzie pokarmowym są przekształcane do azotynów, które w nadmiarze są niebezpieczne dla zdrowia.

Nitrates and nitrites - sources in food

Based on the estimated food intake of nitrates and nitrites in 1996-2005 in Polish households, it was found that vegetables are the main source of nitrates in the diet and they provide 89% of these compounds on average, and nitrites are mainly supplied (in 69%) from meat and processed meat.

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It is important that the average Polish diet does not exceed the acceptable daily intake of nitrogen compounds. Average nitrate intake is 132-190 mg NaNO3/ person / day, i.e. 56.8% ADI, and nitrite - 3-3.5 mg NaNO2 / person / day, which is 58% of the ADI.

Research conducted in Poland in 2013 shows that vegetarians consume nitrates at the level of 95.8% ADI, and vegans - 128.4% ADI.

Nitrates in vegetables

Nitrates are present in fresh vegetables, and nitrites are present only in a small amount. However, their concentration increases with storage. A large amount of nitrates in vegetables results from the use of artificial fertilizers.

Nitrate content also depends on the plant species and environmental conditions. Vegetables are divided into categories according to their nitrate storage tendencies:

  • accumulating small amounts, e.g. tomato, cucumber, pepper, peas, green beans
  • medium amounts, e.g. carrots, parsley, celery
  • accumulating significant amounts, e.g. lettuce, spinach, early cabbage, radish, beetroot, potato

The greatest amount of nitrates is found in root vegetables, tubers and vegetables intended for early harvest. These compounds can accumulate in different parts of the plant.

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Generally, it can be assumed that the more thickened and hard part of the plant, the more nitrates it contains. For example, cucumbers contain the most of them in the peel, in broccoli and cauliflower - in the stem, in cabbage - in the dome and the outermost leaves, and in carrots - at the end of the root. In the Polish diet, the main sources of nitrates are:

  • potatoes - 30.6%
  • beetroot - 19.7%
  • cabbage - 17.2%
  • other root - 11.1%
  • carrots - 4.3%
  • onion - 3.1%

During cooking, the nitrate content of vegetables is reduced by about 50%, and the rest goes into the stock. The concentration of nitrates in juices is similar to their amount in fresh vegetables.

The content of nitrogen compounds in fresh vegetables [mg / kg]

ProductAverage contentLimit values ​​
Tomatoes6,5200
Cucumbers313,1400
Radish2 122,11500
Cauliflower131.8400
Potatoes245,2250
Buraki1571.02000
Cabbage829,41000
Carrot242,5500
Onion121.8250
Parsley (root)499.2500
Parsley133.9500
Celery489,3500
Pepper136,2250
Szczypior981.5750
Por229.7250
Lettuce1155,24500
Rhubarb2419,1200

Products that are hazardous to he alth

Nitrates and nitrites - the source can be water

Water is the second most common delivery medium for nitrates and nitrites. These ions occur naturally in water, but in large amounts they get into it as a result of washing away from fertilized farmlands and percolating through the ground.

On the basis of water quality research in Poland, it was found that much more nitrogen compounds are contained in water from rural than municipal water supply. The content of nitrates in water in rural areas may exceed the acceptable safety standards.

Well water from private intakes may also be characterized by an increased concentration of nitrates. It is estimated that as many as 1 million families from rural areas consume water contaminated with nitrates.

The permissible amount of nitrates in drinking water is 50 mg / l for an adult and 10 mg / l for a child, and nitrite is 0.5 mg / l and 0.02 mg / l, respectively.

Especially people who use private water intakes should use water filters to reduce the concentration of nitrogen compounds in it.

Nitrite in meats and cheeses

Nitrite is commonly used as a preservative in processed meat, hence as much as 69% of these compounds in the diet come from cold cuts and sausages.

Milk and dairy products provide only 3.2% of the nitrite in the diet. Due to the growing awareness of consumers and aversion to nitrites, manufacturers often include the information "E250 - preservative" on product labels instead ofchemical name sodium nitrite.

However, it must be remembered that certain amounts of nitrogen compounds must be present in processed meat to ensure their microbiological safety. The more meat and less additives a sausage contains, the better.

Nitrite is practically absent in raw meat and provides only about 1% of these compounds in the diet. According to the standards, sausages and other meat products may contain a maximum of 150 mg / kg of sodium nitrite, and 100 mg / kg in canned food.

The content of nitrogen compounds in meat products [mg / kg]

ProductAverage content
Cooked pork ham84.0
Pressed turkey fillet142,6
Luxury stew100,6
Sausage (8 kinds)121,5
Lencz110.3
Spam (2 types)68.8
Mortadela74,3
Turkey sausages37.0
Turkey roast51,6
Roulade (2 types)68,0
White headcheese87.7
Ham (12 kinds)82,1
Smoked meat (2 types)81,1
Canned goulash english26.0
Luncheon25,6
Canned pork luncheon35,3
Tourist canister22.3
Canned Tyrolean31.0
Conserve25.0

The share of individual food groups in the supply of nitrates and nitrites in the diet is as follows:

NITRATES

  • vegetables and preserves 89.3%,
  • fruit and preserves 3.2%,
  • meat and preserves 2.5%,
  • cereal products 2.4%,
  • milk and milk products 1.1%,
  • other products 1.5%

NITRITE

  • meat and preserves 69%,
  • cereal products 16.4%,
  • vegetables and preserves 7.3%,
  • milk and milk products 3.2%,
  • other products 4.1%

Nitrates and nitrites - are they dangerous to your he alth?

Nitrates are compounds that are generally safe for humans, but if consumed in high concentrations, they can irritate the mucosa of the small intestine and cause malabsorption syndrome.

Ok. 25% of nitrates are converted into toxic nitrites, which can form carcinogenic nitrosamines. Nitrite and nitrosamines showwide negative impact on he alth:

  • can cause cyanosis and tissue hypoxia
  • can cause anemia
  • reduce the absorption of vitamin A and B vitamins
  • disrupt the absorption of protein, fat and carbohydrates
  • contribute to the damage of some brain structures
  • disrupt the thyroid gland
  • disrupt the functioning of the mucosa of the small intestine
  • reduce the immune capacity of the small intestine
  • can cause cancer of the stomach, colon and others
  • are suspected of increasing the risk of high blood pressure, insulin resistance, Alzheimer's disease, and fatty liver

Nitrogen compounds in food and methemoglobinemia

Nitrite oxidizes the iron ions contained in hemoglobin, resulting in the formation of methaemoglobin. The red blood pigment loses its ability to transport oxygen, leading to hypoxia in the central nervous system and the heart muscle.

Cyanosis develops as a result of nitrite poisoning, which manifests itself

  • a bluish, bluish tinge to the skin and mucous membranes
  • stomach pains
  • vomiting
  • with diarrhea
  • headaches and dizziness
  • shortness of breath

In methaemoglobinaemia, blood pressure drops, and even collapses.

The symptoms become more severe the more methaemoglobin circulating in the blood and the more hypoxic the tissues are. Cyanosis, the so-called blue baby syndrome is especially dangerous in infants and young children, who may be poisoned by nitrogen compounds present in water and food.

Their bodies convert nitrates into toxic nitrites much faster. In a he althy organism, the concentration of methaemoglobin (MtHb) is not higher than 1-2% of hemoglobin (Hb).

The concentration of MtHb at the level of 5% of Hb was found in employees of nitrogen plants near Tarnów, which was manifested by hyperactivity and headaches. MtHb in a concentration of 70% Hb causes death from hypoxia.

Nitrogen compounds and cancer

Nitrates and nitrites are precursors of nitro compounds that have been proven to be carcinogenic and cause fetal malformations by damaging the genetic material.

In experimental animals, even small doses of nitrosamines (5 µg / g) cause neoplastic changes, and in food products there may be even 500 µg / g of them.

Foods with nitrite added as a preservative are the most dangerous, i.e. cold cuts and other meat products, as nitrites are formed from nitrites under the influence of high temperature.

These compounds influence the development of esophageal cancer,stomach, large intestine, pancreas, prostate, ovaries and breasts, and in children they increase the risk of developing leukemia.

You must do it

How to avoid excess nitrates and nitrites in food?

  • Eat as little processed meat as possible - smoked, s alted and cured. Every sausage, sausage, sausage, as well as smoked fish contain nitrites, as they effectively prevent the growth of botulinum bacteria. It's good to be aware of this and, if possible, prepare cold cuts yourself from fresh meat
  • Avoid suspiciously "pink" processed meats. The white sausage should be slightly gray, as are pork sausages. The intense pink color shows that the manufacturer has certainly added a lot of nitrite
  • Pay attention to the vegetables that contain the most nitrates (beetroot, celery, spinach, radish, lettuce, carrots, cabbage) and try not to make them the basis of your diet, but only diversify it
  • Do not store vegetables in foil as lack of oxygen favors the conversion of nitrates to nitrites
  • Avoid parts of vegetables in which these compounds accumulate, e.g. cucumber peel, carrot and beetroot root tips, noodle and outer cabbage leaves. Choose only he althy and undamaged vegetables
  • If possible, do not buy industrially produced vegetables. Those from organic farming contain 2-4 times less nitrates
  • Choose vegetables that contain little nitrates as often as possible - tomatoes, cucumbers, asparagus, artichokes, eggplant, green peas, green beans, mushrooms, peppers
  • Buy daily juices or make them yourself and drink them as soon as possible to avoid the formation of toxic nitrites
  • Vegetables are best cut just before consumption. This will minimize the amount of nitrite formed
  • When buying herbs in a pot, wait 1-2 weeks before adding them to your dishes. Meanwhile, rinse with clean water to reduce the nitrates from the leaves
  • Filter the water, especially if you use your own well
About the authorAleksandra Żyłowska-Mharrab, dietician Food technologist, dietitian, educator. A graduate of Biotechnology at the Gdańsk University of Technology and Nutritional Services at the Maritime University. A supporter of simple, he althy cuisine and conscious choices in everyday nutrition. My main interests include building permanent changes in eating habits and individually composing a diet according to the body's needs. Because the same thing is not he althy for everyone! I believe that nutritional education is very important to bothchildren and adults. I focus my activities on spreading knowledge about nutrition, analyze new research results, and make my own conclusions. I adhere to the principle that a diet is a lifestyle, not strict adherence to meals on a sheet of paper. There is always room for delicious pleasures in he althy and conscious eating.

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