Nitrates and nitrites are not only found in drinking water and vegetables but also in processed foods. Nitrates can increase the risk of poisoning, high blood pressure, destroy vitamins, and even pose a cancer risk. So, how can we prevent nitrates from entering our bodies?
Substances Found in Various Foods
Professor Nguyen Ba Duc, Vice President of the Vietnam Cancer Society, stated that many compounds known as N-nitroso have recently been recognized as carcinogenic in both humans and animals. There are concerns that nitrites from processed meats, nitrates in vegetables, and nitrosamines (which form when nitrites combine with amino acids in foods) may have cancer-causing effects.
Some processed meats contain nitrites – (Photo: BBC).
High levels of nitrosamines can accumulate in the liver over time, potentially leading to toxic effects or even liver, stomach, and esophageal cancers.
Nitrates and nitrites occur naturally and can also be found in meat preservatives and other products like butter, cheese, and beer, which may contain soluble nitrosamines.
Dr. Tran Anh Tuan from Hung Viet Oncology Hospital indicated that naturally occurring nitrates are found in various plants, with concentrations varying based on soil conditions and the amount of fertilizer used.
Between 5% and 20% of dietary nitrates are converted into nitrites, which are found in some vegetables (like potatoes). Nitrites are sometimes used to preserve processed meats and fish (as they are toxic to bacteria) and to give typical coloration to processed meats and fish.
Nitrates from these food additives account for about 6% of the total nitrate intake in an individual’s diet. Products with relatively high nitrate concentrations include:
- Ham: Often the highest source of nitrates in the diet. A 100g serving of processed ham can contain up to 890 mcg of nitrates.
- Bacon: Bacon can contain up to 380 mcg of nitrates per 100g. Nitrates and nitrites are common in bacon production, but some brands label their packaging as nitrite-free. However, testing may reveal otherwise.
- Frozen meat: Processed frozen foods are a harmful source of nitrates. On average, processed frozen meat can contain up to 500 mcg of nitrates per 100g, while uncooked deli meats contain about 300 mcg in the same amount.
- Sausages are among the many processed meat products available on the market. On average, sausages contain about 50 mcg of nitrates per 100g of meat, along with approximately 9 mg of nitrites.
Additionally, the body absorbs nitrates from drinking water and certain vegetables that are high in nitrates. Nitrates from drinking water account for about 21% of the total nitrate intake that an average person consumes daily.
The contamination of water sources with nitrates is primarily due to the excessive use of inorganic fertilizers in agriculture and industrial waste.
70% of the nitrates absorbed by the body come from vegetables. To date, the reasons why some vegetables have high nitrate levels are not fully understood, but three factors are involved: genetics, light exposure, and nutritional conditions.
Among these, genetics is a significant factor, and the ability to accumulate high nitrates occurs only in a few types of vegetables such as cauliflower, cabbage, broccoli, lettuce, peas, carrots, and beets.
How to Avoid High Nitrate Intake and Its Health Issues?
Processed foods contain high levels of nitrates and nitrites, so their consumption should be limited – (Illustrative Image).
Experts indicate that nitrites and nitrates are toxic to living organisms and humans because their metabolic product, nitrosamines, can be harmful to fish and shrimp and cause illness in humans. In reality, nitrates in food are generally non-toxic, but once inside the body, they are converted to nitrites, which are toxic.
Under certain conditions, nitrates can be converted to nitrites by intestinal bacteria. Nitrites oxidize hemoglobin in red blood cells, converting hemoglobin (Hb) into methemoglobin (MetHb), which cannot transport oxygen, leading to a lack of oxygen in the body.
When experiencing nitrite poisoning, the body cannot perform respiratory functions, showing symptoms such as shortness of breath, cyanosis, and respiratory failure. Notably, nitrites also destroy certain vitamins in the A and B groups, such as B1 and B2. When nitrate levels range from 19 to 125 ppm, they can raise blood pressure. Nitrites are also a cause of certain food allergies.
To prevent nitrates and nitrites from causing illness, it is essential to limit foods high in nitrates and nitrites in meals and avoid introducing large amounts of these substances into the body. Especially, young children are more susceptible to nitrate poisoning because their intestines are less acidic, allowing nitrates to convert to nitrites more quickly.
Furthermore, young children lack sufficient enzymes in their blood to convert methemoglobin back to hemoglobin. Children with this condition often appear pale and may experience health issues.
Thus, children should not consume excessive amounts of foods containing nitrates, should avoid using the water from boiling nitrate-rich vegetables or groundwater (which has a high risk of nitrate contamination) for mixing formula.
Pregnant women should also avoid consuming foods high in nitrates. When selecting processed foods, it is important to avoid products with additives that contain nitrates and nitrites, such as potassium nitrate and potassium nitrite.
Foods to Limit
- Processed meats such as deli meats, bacon, and sausages… These can increase the risk of colorectal cancer if consumed too frequently.
- Foods high in saturated fats can contribute to weight gain. Being overweight increases the risk of various types of cancer.
- Alcohol can increase the risk of cancers of the mouth, throat, esophagus, liver, breast, and colorectal cancer. Men should not exceed 2 drinks per day, and women should not exceed 1 drink per day.
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