Nitrates (and their precursors nitrites) are both naturally occurring substances and are produced by living cells. They’re involved in many important chemical reactions in the body. In themselves, they are not dangerous, but they can react with other compounds found in food or in the body to form carcinogenic compounds called nitrosamines. These reactions are more likely to occur in the presence of protein and iron, which is why processed meats can be problematical.
The formation of nitrosamines is much reduced in the presence of antioxidants which are found in vegetables. This is thought to be one reason why a diet high in vegetables is good for the heart and is helpful in lowering the risk of certain cancers.
Sodium nitrate is a naturally occurring chemical compound created during photosynthesis while sodium nitrite is synthetically made. Potassium and sodium nitrites and nitrates are commonly added to processed and cured meats to help preserve them and give them their characteristic pink colour and flavours.
These additives are used to inhibit the growth of harmful bacteria, including Clostridium botulinum, which can cause food poisoning. While nitrates and nitrites are also found naturally in plant foods, the levels added to meats are far higher.
Nitrosation is the process that creates carcinogens from nitrates and nitrites. Antioxidants, like vitamins C and E, stop nitrosation. Plant foods, that contain nitrates and nitrites, also contain these antioxidants whereas meat, that has nitrates and nitrites artificially added to it, does not also contain these antioxidants which is what causes the carcinogens to be produced.
N-nitroso compounds (NOCs) are found in processed meat and are formed internally from the intake of nitrite and nitrate. NOC formation is stopped by nitrosation inhibitors in fruit and vegetables but promoted by the heme (iron containing molecules) in red meat.
These carcinogens have been reported to cause various cancers including oesophagus, nasopharynx, stomach, colon and rectum.
Which processed meats are preserved with nitrites?
- Bacon
- Balogna
- Canned meats
- Corned beef
- Deli meats
- Ham
- Hot dogs
- Pepperoni
- Salami
- Sausages
NOTE: There are some ‘nitrate-free’ and ‘nitrite-free’ options of the above meats. Check the packaging.
When plant foods containing nitrates and nitrites are consumed, the body converts them into nitric oxide. Nitric oxide has various beneficial roles in the body such as increasing the blood flow and decreasing the blood pressure. Nitric oxide also, promotes heart health and helps with the release a variety of hormones and the sending of signals throughout the body. Nitric oxide can also improve exercise performance, benefit the respiratory system and help the body heal.
WARNING: In early life nitrate-rich foods can cause blue baby disease (methemoglobinemia). Therefore, foods such as spinach and beetroot should be fed in moderation until the infant reaches the age of one year. Symptoms of blue baby syndrome are shortness of breath, (the skin will turn blue due to lack of oxygen in the blood) and the baby may lose consciousness.
What plant foods contain nitrates and nitrites?
Nitrates can be used by plants and animals that consume the plants. Some bacteria in the soil can turn ammonia into nitrites. Although nitrite is not usable by plants and animals directly, other bacteria can change nitrites into nitrates a form that is usable by plants and animals.
Nitric oxide is important to help increase blood flow and energy and saturated fats reduce nitric oxide levels in the body in the following foods:
- Meat & dairy products
- Processed foods
- Fried foods
- Cooking oils
- Palm oil in processed foods
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